400% Efficient Micro Bore Heat Pump. How does it work?

[@fredgray2376]

The most informative video on heat pumps I have seen. Thanks.

[@hughrattray9354]

Thanks, I really appreciate the comment. Having spent a lot of time learning about heat pumps I am keen to inform others as much as possible. Please let me know if you have any specific questions that I could cover in a follow up video.

[@davidscott3292]

I agree with that, not least because of the informed, measured and articulate presentation.

[@fredgray2376]

I am getting my house ready for a heat pump - 'draughtproofing' and insulation. The area I find most difficult to understand is ventilation/air changes. This is a significant proportion of calculated heat loss. I would be interested to hear your views on this. My understanding is that standards for required air changes per hour were established many years ago when occupancy rates were usually higher, most people smoked indoors, cooking and washing produced vast amounts of water vapour,, and heating was by open coal fires followed or paraffin heaters. So what is appropriate today? Is there an MCS minimum requirement? I read somewhere that the standard in the US is 0.3 changes per hour for homes with up to four occupants. Octopus have used 1 or 2 changes per hour when calculating the heat loss in my house.

[@JamesRattray]

@@fredgray2376 Microgeneration Certification Scheme (MCS) the UK nationally recognised quality assurance scheme for renewable heating products, such as heat pumps says:- Buildings Constructed Pre 2000 - Air change rates for older existing buildings (From 1.5 to 3 times). Those with several chimneys and/or subject to preservation orders may require greater infiltration allowance than shown in the tables see link below. Buildings Constructed 2000 or later - Air change rates for modern buildings with double glazing and regulatory minimum insulation (From 1.5 to 2 times). New buildings constructed after 2006 and complying with all current building regulations (From 0.5 to 1.5 times). Here is the link to the MCS spread sheet where these values are tables based on room types and chimneys etc. Be warned the spread sheet automatically down loads when you put this this link into Google mcscertified.com/wp-content/uploads/2019/09/MCS-Heat-Pump-Calculator.xlsm

[@fredgray2376]

@@JamesRattray Thanks James, a lot of information there - there's so much to learn!

[@andrewdeacon4384]

Very helpful throughout but especially so regarding microbore experiences, radiators and excluding TRVs on some radiator to increase efficiency by avoiding a buffer tank. Thank you for producing this, definitely essential viewing for anyone interested in the topic!

[@neilmcbrideart]

Very reassuring to hear 10mm microbore is OK for Heat Pump. Thank you for the info.

[@hughrattray9354]

Thanks for your comment. I can confirm the good performance has been continued over the whole year - I cover that in my video showing 12 months performance

[@soundslight7754]

Fantastic details from someone who knows well what they're talking about

[@givemethejob3293]

Well done for not letting the thick fitters overule logic. Real engineers are hard to find. Great video thank you!

[@hughrattray9354]

Thanks

[@Evergreensands]

Fantastic video and supreme interviewing and explanatory commentary.

[@maxwellsmart3156]

Excellent and scientific video with actual data and references! Seems like a model installation everyone can learn from!

[@JamesRattray]

I think the distinct advantage is this is from someone who has absolutely no interests in any products, other than sharing what he has learnt. It has generated discussion here in the comments and behind the scenes. It is a journey we are all on, in our small ways to try and reduce climate change and reduce our impact on the world we live in. Thank you Maxwell for commenting.

[@hughrattray9354]

Thank you for your comment it is much appreciated. I hope that it encourages a few more people to make the step to a heat pump and also gives them some guidance on what to ask for. If you have any suggestions on what I should cover in a follow up please let me know. It was -5C here last night and it is still below freezing and the heat pump is easily coping..

[@kevinschoales844]

We are gas safe installers, this is good advice for us as new to heat pumps. Big learning curve, especially regards buffer tanks. Thanks very much.

[@JamesRattray]

@@kevinschoales844 I totally agree, we are all, whether we are users or installers on a massive learning curve as you say. As with all change all through human history, there are a pile of sceptics trying to pour as much cold water on as they can. It is really refreshing to hear your words, I always think the first stage in any change is recognising it is different, the second is how best to go about effecting it. Good luck, I would love to have your attitude as my heat pump installer. It is a journey both the installer and customer need to make together.

[@hughrattray9354]

@@kevinschoales844 Thanks for your comment. I will do a follow up video after the winter but I couldn't be happier with the performance of my heat pump so far. We had a full house over Christmas and it worked really well. Good luck to your transition to heat pump installation I am sure there will be a huge upsurge in demand.

[@timpayne7676]

Fantastic video. There are literally only a handful of videos explaining the process in a useful way.

[@matthewbellamy486]

Thanks for the video. Very useful indeed. I too have microbore so it's good to know it's all possible. I've currently a 36kw Valiant gas boiler, and have built my own energy monitoring system to track flow/return, room temp (actual and desired) and boiler output in Kw as it tries to modulate to the load. The measurement systems links to the Vaillant eBus system directly and gets the data from the boiler itself rather than via thermocouples etc.., (tech used is: ebusd interface, MQQT messaging, Node-red data manipulation, influxDB data storage and Grafana data presentation - all running on a Raspberry Pi. Took me over a year to work out how to do it! Interesting to hear your views on over-sizing too... I've found that my 36Kw is WAY too big for my 3,500sq foot house (albeit with 22 rads). Most days it takes only about 6.3kW to keep things at a constant 20 degrees inside, which is right at the very bottom end of what the boiler can modulate down to, though this requires some on/off periods so the more likely demand is perhaps nearer 4kW continuous (which my boiler can't ramp down to). Before I built the monitoring system, the rads barely got warm and I found the boiler was ramping up to 36kW at start up then cutting out almost immediately due to over-temp on the flow, so was operating in a continuous on/off cycle every 5 mins or so. Had been like that for years too! I trimmed the max output to 23kW which is sufficient to prevent this overshoot, and it quickly ramps back to 6.3kW to maintain a sub-55 degrees flow rate (for maximum condensing). It all goes to show that without the measurement and data, we have zero idea what's happening with our systems and no way of tuning it. I'll be taking a closer look at the sites you mentioned. I'd be interested to hear how your system coped with the recent cold spell we're in the middle of, too. Thanks again,

[@hughrattray9354]

Impressive that you have built your own monitoring system. Well done. I wish, with hindsight, I had fitted the open energy monitoring system whilst I had gas installed. It would be very interesting to see how the gas system operates including its flow rates and efficiencies and would have provided a very good benchmark.

[@MarkGaudie]

Your right with heat pump sizing. I had quotes from installers wanting to put a 16kW heat pump in. Absolute joke. My heat loss calc was only 6kW. I ended up using an elite heat geek installer and my system is very good!

[@hughrattray9354]

I am a great admirer of what Heat Geek do. I tried to get one of their certified installers. All were too busy but I found a good installer in the end

[@waqasahmed939]

@@hughrattray9354 That's really quite good I'm planning on: Super insulating my flat roof Super insulating the walls of said flat roof Upgrade all my piping Getting Jaga Strada radiators Getting an MVHR Switching from a gas cooker to an induction one so then I'd truly know how much gas I require for heating / hot water Then I can get a heat pump It's a slow, and expensive process

[@hughrattray9354]

It is satisfying though. Good luck

[@kevinschoales844]

​@@waqasahmed939 What insulation are you using ?

[@85parrot]

Also very happy i've paid for heat geek. My first quote was for a 14kw system. Ive got a 1930s 3 bed detached with half underfloor heating. The heat geek heat loss calc came to 6kw worst case scenario so I'll be going for a 5kw vaillant which can do up to 7kw if required, a a few upsized radiators. A 14kw would have cost a fortune to run

[@SuperPatrick71]

At 7:08 you can see the maintenance switch quite near the heatpump. This is not compliant (R290) with installing instructions and regulations. Besides that, this is a nice system.

[@hughrattray9354]

Thank you - I have tyaken that up with the installer and they are going to rectify it.

[@karma3101]

The more I see actual fact based videos like this one, the more convinced I am to replace my old oil fired boiler with a heat pump.

[@JamesRattray]

There is a very good grant for replacing your oil boiler right now £7,500. I don't know how long that grant will last, is one factor to consider. I do think the points Hugh makes in this video need to be weighed up. Insulation, especially in the communal living areas, then radiators. Also your electricity tariff. In my opinion there is nothing to beat a well set up heat pump. We installed our first heat pump in 2009 in the Cairngorm National Park in Scotland, one of the coldest areas of the UK. It has not put me off them.

[@hughrattray9354]

Thanks, I am pleased to hear that.

[@JamesRattray]

We have just produced a video on the Open Source Energy Monitor system, where you can find live information on the performance of heat pumps. I thought you might be interested. Here is the link kzbin.info/www/bejne/pp3Veqylqaisfqs

[@nwatson4022]

First class video James! Many thanks and please continue as you planned. Looking forward to the follow up videos.

[@hughrattray9354]

Thanks for the comment.

[@JamesRattray]

We have just produced a video on the Open Source Energy Monitor system, where you can find live information on the performance of heat pumps. Here is the link kzbin.info/www/bejne/pp3Veqylqaisfqs

[@jackb8194]

Great video. Did you work out the volume of water in your radiators and pipes, both when limited to the open flow area and also the total house when all the bedrooms were heated? Thank you

[@hughrattray9354]

Yes I did. As I result I added a 25ltr volumiser to ensure the cycle time was not too frequent when the house was not full. It works fine - I am very pleased

[@jackb8194]

@ 🙏what was the minimum volume with/without volumiser

[@hughrattray9354]

The 8 radiators in the core of the house hold 56ltrs of water with the addition of the pipes I estimated 77lts total. To that I added a 25ltr volumiser taking me to around 100ltrs for the core. The minimum power output from the heat pimp when it is 10C outside is ~ 3.5Kw (worst case cycling condition). The heat pump temperature difference from off to on is 8C for the Vaillant. The result, for the worst case situation, about a 40 minute on time followed by a 40 min off time. Which is fine and it is what I am experiencing.

[@gonzo_the_great1675]

Excellent video. Pitched right at my level. Not that I'm on microbore, but still a lot of useful info and confirmation of my thoughts on heat pumps.

[@trashmail8]

I'm the owner of an older (1950's) but well-insulated home and currently asking various parties for their ideas regarding the switch to a (hybrid) ASHP configuration. I was told that I would need a buffer since I don't have any floor heating (and the floor put in by the previous owners is way to expensive and gorgeous to break it open). Because I don't have any floor heating and regular (type 22) radiators, I wouldn't have enough water volume in the system without a buffer for e.g. defrosting the heat pump. That was the explanation that was given to me by one installer why a buffer would be needed in my house. Not sure about that yet. Currently investigating modern solutions that combine both a buffer and a heat water tank in one unit. Like the Vaillant allSTOR for example, but something smaller since I don't have the physical space for such a beast of a unit. Currently warming the house using a gas burning Vaillant EcoTec Plus. Running at 40C I've seen it being able to keep the house warm at -7C at night, so that is promising! But I don't know what it is. I've grown a serious aversion against burning stuff for both heating and transportation. Maybe the switch to an electric car has toggled something. Burning stuff feels like barely progressing beyond the steam age! 😛

[@hughrattray9354]

I don’t think a hybrid system qualifies for the grant. Why not just go for a heat pump? An alternative to a buffer tank is a volumiser. That is plumbed in parallel in your system so there is no mixing etc. (I have one fitted). It does what it says and just adds more water to the system. Big radiators also add water volume. I must admit I don’t get the need for a buffer tank for the defrost cycle. If you follow the link, in the notes, to the heat pump monitoring site and look at my (Newport) heat pump on the night of the 2nd December, when it was very cold. You can see the heat pump doing multiple defrost cycles. At no point does the water temperature in the heating system drop below the room temperature. So the system copes very well without a buffer. Radiators can warm the house very well so you don’t have to have UFH. Running your radiators at lower temperature with your current system is a very good way of seeing if you are heat pump ready (I did the same thing). If 40C flow keeps your house warm at -7C I would say yours is already heat pump ready and you should get very good performance from one. I agree with your point on burning stuff. As soon as you start on the renewables route you want more! Good luck with your investigations.

[@hughmarcus1]

Viessmann aren’t well known in the UK yet but are market leaders in Germany & Austria. Their air source units are excellent. I was an air source skeptic but they’ve convinced me.

[@hughrattray9354]

@@hughmarcus1 That is good to hear. I think it is key that they provide information and support to prospective buyers

[@trashmail8]

@@hughrattray9354 Thank you so much for your elaborate reply! 🙏 I had not heard about a volumiser yet and I'll dive into your Newport heat pump stats. Very good to hear that the water temperature did not drop below room temperature, which is basically what matters. I think I might have been on the hybrid path because a) I fairly recently bought the house and the EcoTech plus is barely a year old. b) The fear of not getting enough ASHP performance when it's very cold to heat up the fairly large house (~ 220m2 / 980-ish m3 ) c) Not sure if I've got enough physical space for a hot water tank. 🤔 Still trying to find my way.

[@hughrattray9354]

Good luck

[@kaf2303]

Nice, regardless of whether you are changing heating systems Insulation & air tightening are the most important things. Cheers

[@JamesRattray]

That is a very good point you make. I am Hugh's brother, my name is at the top of this channel. I am currently upgrading our house to 2020 standards. It all starts with insulation, but what you point out, is air tightness is a huge factor. Older houses have more drafts, newer houses have less, if built well. The number of air changes an hour, is one of the factors in working out the size of heat pump you require. One change to two changes an hour significantly increased the amount of heat you need, irrespective of the type of type of heating system you install.

[@hughmarcus1]

@@JamesRattrayit’s an old saying but it’s true. You can’t heat a draught.

[@waqasahmed939]

Absolutely. The very reason why what I want is a slow, expensive process is purely because I'm looking to reduce my heat demand in the first place In addition, I think if you then require a smaller heat pump you're not using as many resources both for the heat pump itself AND in terms of the overall energy infrastructure

[@waqasahmed939]

@@JamesRattray As long as you have ventilation too. I'm looking to retrofit an MVHR after air tightness

[@B0jangle5]

An excellent explanation which was very easy to follow and cut through all the sensationalist crap that's kicking about. I'm really looking forward to the other videos about the upgrade work.

[@hughrattray9354]

Thanks for the comment

[@JamesRattray]

You might be interested in the video we have just produced on the Open Source Energy Monitor system. This allows you to see live heat pump data across the UK kzbin.info/www/bejne/pp3Veqylqaisfqs

[@mikeroberts8412]

Thank you, useful insights and informative to my continued heat pump research. Especially useful information regarding the expansion tank.

[@JamesRattray]

We have just produced a video on the Open Source Energy Monitor system, as there was a lot of interest in where you can find live information on the performance of heat pumps. Hope it is of interest kzbin.info/www/bejne/pp3Veqylqaisfqs

[@simonkamel5782]

Thank you for a very informative video covering all the points thoroughly. Just had one question: Whereabouts in the system did you install the deaerator?

[@hughrattray9354]

Thank you - The deareator is located by the hot water tank and it is on the flow (incoming) pipe. It is located before the three way valve which diverts water to the tank or heating as required.

[@stevecharles8202]

Great video series - thanks. I am wondering if i can get away with 7kw instead of the 10kw unit (10kw being a better match for my heat loss at -2 DOT) - it seems designin for worst case (-2 outside temp) means that the unit is oversized for most of the year! I was wondering what your calculated heat loss was? And how well matched the 7kw is in your case?

[@hughrattray9354]

Thanks for your comment. In the end my calculations were quite close to the actual heat loss. The air changes per hour are a huge factor and hard to measure or calculate. A couple of things for you to consider; Do you want all the rooms at the design temperature? We tend to have bedrooms a bit cooler. You could look at the gas consumption, from your smart meter data, to work out how much energy you are actually using in the cold spells. Is there a bit of insulation you could do to bring down the heat loss slightly? The 7kw Vaillant arotherm Plus can provide >9Kw at -2C and can drop to 3Kw at 10C. The 10Kw version is 11.2Kw at -2C and 6.3Kw at 10C. It also has a lot higher minimum flow rate than the 7Kw I think you are right to look very hard a weather you need to go to the 10Kw.

[@stevecharles8202]

Thanks for the reply - after seeing your video I checked my gas usage, correlating with coldest days on weather underground!... Two 3 day periods in Nov/Dec '23 (-2 min to 3 C) and Jan 24 (-5 min to 4) - both showed ~10.5kW - pretty much bang on my calculated value for the whole house (DOT -2) - then I remembered to check combi boiler efficiency which is only quoted as 90.1% efficiency - so in theory 9.5 kW (100% efficiency) - this usage is including instant combi hot water... also, although I had already fitted new 'oversize' rads in existing house, the new extension had no heating downstairs during these periods (2.2 kW of heat loss) so I'm thinking the 9.5kW above would be an extreme worst case?!....

[@hughrattray9354]

@@stevecharles8202 I used 90% efficiency when I did the same exercise but I think this is quite generous to the gas boiler. This will only be achieved in ideal conditions where the flow temperature is low so it is condensing and the boiler is running continuously. Search “In-situ monitoring of efficiencies of condensing boilers and” and you will find a study by the department of energy and climate change of real world efficiencies of gas boilers. The figure for gas combi boilers on average was 82.5%. The study was done in 2009 but I don’t think gas boilers have changed much since then.

[@roi1719]

thx so much for sharing your expirience in such a detai! i learnd alot

[@hughrattray9354]

you are welcome - hoping to spread the word

[@chester6343]

Not bad, do an update if we get an extended cold snap please

[@hughrattray9354]

Yes we will do that - the coldest period this winter was around the 2nd December - the temperature dropped to -5C but not for long

[@davidfellowes1628]

Your end point of how to optimise your system with the solar & battery is so important. I have 25kWp array with 3 x Powerwall and are setting off on a house refurb so this is pertinent. Where I have really struggled is finding anyone in the industry that can think about systems and designs when the client has an almost endless supply of 7p energy (that in a few years will decline further towards zero, or should more batteries are installed). A heat pump and battery is another configuration for terraced houses etc.

[@hughrattray9354]

I think Octopus energy is thinking about the system as a whole but it is not in place yet. Intelligent Octopus is integrating car charging and recently they sent out a survey asking which heat pumps and house batteries they should try to integrate. I answered Powerwall and Vaillant heat pumps. If they can integrate these extra devices they will be able to help the grid make use of the power it has without burning fossil fuels. I believe the UK still spends hundreds of millions of pounds on wind curtailment. Once more systems are integrated they can give it away or sell it at low prices to consumers. I think cheap rates / free power will be a feature going forward but it will not be at fixed times so we will need much more intelligence on the system.

[@davidfellowes1628]

@@hughrattray9354 What a great reply Hugh. I am on the same page which why I found the vlog so enlightening. As an oil & gas project manager for 30 years in my past life, I have spent the past decade trying to understand change and the last five years of it the building industry and how backward it is. This with an exponential age of innovation coming, so design and should stay ahead of change. So back to business, I have done things backwards because the refurbishment planning was delayed. I have (or my kids have to be correct) loads of energy and in fact are a VPP. My challenge is getting an old house, parts of which are +100 years old, properly insulated. But, even here there is a question to answer - how well insulated should it be because energy is, as you say, going to zero cost in a decade. So windows, thermal bridges and an ancient basement below part of the ground floor certainly needs insulating better. Your point on living areas was well made. But, again here there are questions of converting radiators from a pellet burner to heat pump solely, or a hybrid system including UFH in the living area. Once one moves upstairs the low cost electricity is the only game in town supported by the solar and battery storage. But, and here you may be able to help, I plan to have a nodes. Each node would have a DB and cold water supply for a bathroom and would service adjacent rooms, with probably four nodes in number. This way we stop hot water and power running all over the place, and again with solar & batteries makes sense. I'm also acutely aware that AC (each with its own transformer) is not the future. But again the industry is backward in coming forward with low voltage DC systems and devices. Many thanks Hugh for all the feedback.

[@cryptickcryptick2241]

Greetings from across the pond. You tube suggested this and it is fascinating to see a very different system. From Tennessee, which is somewhat similar in temperature, many people heat with heat pumps. Heat pump technology has greatly improved in the last few years. In America, most people use forced air furnaces and heat pumps. These have gotten to be incredible efficient and cheap, particularly, the minisplit heat pumps. Last year, on my 1,300 square foot house small two bedroom house, I installed a 24,000 BTU mini-split heat pump. At the time, my HVAC company had suggested a $7,000 USD natural gas split system, instead I bought and self-installed a $2,000 mini-split heat pump. I estimated self installation saved about $2,500. Our government, in it wisdom upped energy standards, and all HVAC equipment rose about 30% in prices and recently a neighbor with a larger house had a $17,000 system installed. I am a big fan of the mini-split air source heat pumps. Here they systems are cheap starting at $600 for the equipment. In larger homes, one can easily install multiple systems. This has a redundant effect, if one system goes out, the other can still heat and cool. Many large homes already do this with central HVAC systems having one for each floor. Your system is obviously working very well for you, but if I was considering how to solve your problem, I would have put several mini-split systems in the home. At some point, if you are looking to add a little capacity, want a redundant system, want air conditioning to control humidity in the summer, you might find it interesting to explore those solutions. In America some people use a boiler type heating systems, but I find it interesting how different countries developed heating and cooling systems very differently. America developed the forced air furnace, UK uses boilers, Asia uses mini-splits. There is more than one way to cook an egg.

[@hughrattray9354]

Interesting to hear about the different approach where you are. Very few split systems are installed here now. The heat pump I have has the R290 refrigerant which I am told gives very high efficiency but cannot be used in a split system because it is flammable. I can see the redundancy benefits of more than one unit.

[@jamaiscontente]

A great video. Thanks for sharing. Makes it a lot more clear re the flowrate and specific room by room analysis needed and removal of extra items that can fail that add no value. Realised that cast iron rads I have would help get the most from the 6 hours as still warm at 9am if used till 6am. On floors that are above ground the level, with the Go tarrif you are on it could be worth considering adding some extra thermal mass to any pipes that are helpful to get the most from the cheap 6 hours. Of course this means doing work when floors are next changed or in renovation work. Balancing slow response to demand and balancing IR solar in the (Passivhaus approach) is something I am looking at yet with mixed with the use of a planned 32kwh battery. Re the energy monitor did you measure with other devices the temp as it might have slight calibration difference or accuracy percentage that is exacerbated in day to day use. If you know water boils at 100C on most UK levels and a calibrated device measuring the temp of the metal on a kettle shows 97C then the 3C is approx loss on metal to air conductivity transfer. It could be something like that in the sensor differences. I hope Vallient take your question seriously and are helpful in understanding the desire for accuracy.

[@hughrattray9354]

Thanks for your reply. The idea of adding thermal mass to the system is an interesting one. It would help to take advantage of the cheap rate but would also make the system slower to respond. I wonder if heat pump systems will be designed with thermal storage in the future so a separate tank, for example, could be used to store hot water that would be called upon when grid prices are high. Regarding the energy monitor accuracy differences, the heat meter flow and return temperatures converge, to within 0.1C, when the heat pump is off which leads me to believe they are accurate. I have been monitoring the data from the Vaillant and the Open energy monitor. In December the energy used and the heat output for both systems were very close so the error seems to be with the calculation. Vaillant works out the COP with the formula heat output + elec energy/ elec energy. The heat meter formula is heat output/ elec energy. I will continue to monitor this and see if I can understand the discrepancy.

[@plumbertime]

I’d love to now take the heat pump out and fit a 9kw system boiler and see how they compare.

[@hughrattray9354]

Have a look at the open energy monitor forums someone has fitted a heat meter to a gas system boiler and is monitoring efficiency. Also, Search “In-situ monitoring of efficiencies of condensing boilers and” and you will find a study by the department of energy and climate change of real world efficiencies of gas boilers. The figure for gas combi boilers on average was 82.5%. The study was done in 2009 but I don’t think gas boilers have changed much since then.

[@imaginitivity7853]

You might find heatpunk useful. I realise it's after the fact, but it allows a good deal more detail in your calculations than a spreadsheet

[@hughrattray9354]

I have just had a look at heatpunk and it does look excellent. Thanks for pointing that out.

[@Umski]

I discovered heatpunk via another channel - just started inputting my data into it to see how it compares to my ‘cheat’ calculations with real figures 😊

[@jimmysrealcooking554]

I design thermal plant , heat exchangers , gas turbines. I’ve tested heat pumps. The difference in your performance between manufacturer and open energy could well be accuracy of thermocouples. They are typically good to 1C. You are taking a difference between in and out temperature. If each is 1c out in 5c difference , the error is considerable. It could just be innocent instrument accuracy.

[@jimmysrealcooking554]

On second thoughts : there is a way to wire thermocouples so they give you a temperature difference , rather thsn absolute values. Maybe they do that. When the machine is shut down / starting up and the temperature in and out are the same , does it read zero difference or is there already an offset? Hmm.

[@lumbarsupport]

Pump power is a key issue - what is the make/model/power/pressure rating of the pump used in this system? I have a 16 radiator system fed by 8mm microbore. My ASHP circuit operates using a primary pump/large bore primary circuit to a low loss header, then a secondary pump to large radiators via 8mm microbore which, on return, bypasses the LLH to join the primary return circuit. In the 6 months Oct'23-Mar'24 my SCOP was excellent at 4.2, but I'm still open to suggestions that there could be further improvement with a direct one pump system.

[@hughrattray9354]

The heat pump is a Vaillant 7Kw which is capable of 9Kw output at -2C. The maximum pump pressure is 80KPa, the maximum flow rate is 1200ltrs/hr and the minimum flow rate is 650ltrs/hr. I managed to find a copy of the pump curves. What are the figures for your secondary pump? How have you measured SCOP? The data from my Vaillant heat pump overstates COP by quite a high margin so I use the data from the open energy monitor instead.

[@lumbarsupport]

@@hughrattray9354 Thanks! Pump pressure is a little confusing. 80KPa is 0.8 bar but my primary pump has a max pressure rating of 10 bar which seems like way more than enough to feed the whole system while barely breaking sweat! I wonder if it's possible to calculate the theoretical pressure drop across a 16 rad/8mm microbore network?

[@hughrattray9354]

@@lumbarsupport I did work out the pressure drop through my system using John Cantor’s tools for pressure drop (details are in the video notes). He has a very handy tool that allows you to vary flow rate and pipe diameter. The pressure drop across the radiators is very low (0.2kpa). I calculated the overall pressure drop across the system to be 20kpa. I have 22 rads and 10mm microbore.

[@KavanOBrien]

How and where do you apply for the grant ?

[@hughrattray9354]

Your installer should apply for the grant as soon as you give them the go ahead. The grant is then paid to them when the installation is complete and, in my case, they then paid it to me fairly promptly.

[@JamesRattray]

You need to choose a MCS approved installer mcscertified.com/about-us/ who have agreed to follow the Renewable Energy Code of Conduct (RECC) www.recc.org.uk/ RECC provide a list of Top Tips for consumers which I strongly recommend you read - I have found many installers are asking for payment terms in breach of these guidelines. It is your money you are risking, I personally would be very cautious about advance payments where you are left exposed www.recc.org.uk/consumers/top-tips

[@KavanOBrien]

@@hughrattray9354 thank you very much.

[@antonymelling8831]

Hi James , really enjoying your content- keep up the great work. When you say “keep 6 radiators open without the control . Do I understand correctly that you remove the trv ( or open it fully ) and leave the lock shield valve -as adjusted. How does this affect the radiator balancing ?. Thanks

[@hughrattray9354]

I have left the Evhohome valves on there for now and set the temperature to maximum permanently. I haven’t done anything to balance the radiators but they seem fine. I bought some temperature probes from Amazon and Velcroed them to the flow and return of each radiator in turn. All the rads seem to have a very similar delta T of about 2.5C. (Vaillant heat pumps seem to run with low delta T) There is one particular radiator that has a very long run of 10mm pipe to and from the 22mm backbone, but even this one seems alright. It takes longer to heat up but in the steady state it seems fine.

[@derekpaisley620]

Great video, I am in the final stages of getting my heat pump. Like you i measured my heat loss, confirmed by a heat geek loss calc, and octopus one. 7kw valliant will be the hp. I also have mixergy hot water tank to link to. I haven't insulated the suspended timber floor yet next summer for that job. I also have a solax 6kw inverter ans 15.6 battery and 5.8kwp . Look forward to your next video.

[@hughrattray9354]

I also had an uninsulated timber floor. Insulating it and draft proofing it made a huge difference.

[@JamesRattray]

We have just produced a video on the Open Source Energy Monitor system, there was a lot of interest about where you can find live information on the performance of heat pumps. Hope it is of interest kzbin.info/www/bejne/pp3Veqylqaisfqs

[@MarkGaudie]

I’ve got the same heat pump and mine is also 7kW. It’s absolutely brilliant and with my solar and battery is super cheap to run.

[@hughrattray9354]

We will have to spread the word.😊

[@85parrot]

What size is your solar and battery set up? I have a smaller house and single occupant with low energy use. I have just installed 3kw solar amd a 5kw battery, about to get 5kw heat oump installed. Im hoping i'll predominantly be able to power the pump from solar/cheap energy via the battery.

[@MarkGaudie]

@@85parrotI have a 3.6kW solar array but it’s split over 2 roofs one array is east for morning sun and the other in the back is south facing. I could add some more on a west facing roof at a later date. My battery is 30kWh so pretty big. I very rarely use any grid energy on day rate. When it’s around -4 I use some day rate from around 20:00 to 23:30 then my night rate kicks in again at 23:30.

[@matthieu8292]

amazing content, so much hands on knowledge and constructive feedback shared , thank you! 👍

[@hughrattray9354]

Thank you.

[@sologog8129]

Bravo, thank you. Keep us posted please.

[@hughrattray9354]

Let me know if youn have any specific questions and I will try to answer them when I do a full review after the winter.

[@JamesRattray]

We have just produced a video on the Open Source Energy Monitor system, as there was a lot of interest in where you can find live information on the performance of heat pumps. Hope it is of interest kzbin.info/www/bejne/pp3Veqylqaisfqs

[@billyt9921]

Can you help me understand the economics of a heatpump. As i understand it, electricity costs 3.9 times as much as gas per KWh. How can these systems be more economical than a high efficiency combi boiler?

[@B0jangle5]

The SCOP quoted is over 4.0. This means for every unit of electricity he buys he receives 4 units of heat. So providing this keeps up (which looks very likely given the time of year, these values were taken) then it will work out slightly cheaper than gas to run. This is compounded further by the use of cheaper off peak electricity which is very close to the price of gas. It's worth noting that a high efficiency gas combi only produce their quoted ~94% efficiency when it is mild outside and they have been set to low flow temperatures.

[@hughrattray9354]

Everyone’s cost will be slightly different due to electricity tariffs and usage patterns but here is an attempt based on my rates. Gas costs 7p/kwh but gas boilers are at best 90% efficient. To do this they need to be modern, correctly sized and run at low flow temperatures. They are typically between 70% and 90% efficient so if I assume 85% efficiency a unit of heat from gas will cost 8.2p/kwh. Standard electricity price here is 30p/kwh so with a COP of 4 the cost of a unit of heat from a heat pump is 7.5p/kwh. So slightly cheaper than gas. However, in my case I get a 7p rate on my electricity for 6 hours at night so I can heat my hot water and pre-heat the house at night. and a unit of heat at this time is much lower than gas at 1.75p/kwh. There are now tariffs out aimed at heat pump users like Cosy Octopus which give cheaper rates at some time. If you have solar panels or a house battery costs will be lower still. I am helping my sister in-law with a heat pump install and I am confident it will be significantly cheaper than gas.

[@johnh9449]

Because a gas boiler is only 80% to 90% efficient whereas a heat pump is 400% efficient (4.4 to 5 times better), so that more than cancels out the cost per kWh advantage of gas to favour electricity with a heat pump using far less energy input. Plus when you also factor in cheap overnight electricity at about the same price per kWh as gas it suddenly becomes 3.9 times better and cheaper!

[@hughrattray9354]

@@johnh9449 I agree. That is despite extra taxes on electricity that the government had said they will remove.

[@paulkainer269]

@@johnh9449 just be aware, as outside air temperature drops then the COP also drops. So it changed depending the environment it is in

[@derekgoffin5807]

My wife is against a heat pump because we visited a house with a running air to water heat pump which was very noisy inside the house. It had the expected fan noise outside near the unit but my feeling was that they had done something wrong inside. How noisy is your system inside? Perhaps compared to the water pump noise and pipe expansion noise of a gas central heating system.

[@hughrattray9354]

My heat pump is completely silent inside the house and very quiet outside by the heat pump. Because the flow temperatures don’t change a lot I don’t even get the ticking noise due to thermal expansion. I think there must have been something wrong with the installation you visited. I suggest you search “visit a heat pump”, a lot of us have offered to show people our installations so you should find some close to you that you could visit.

[@davidreece1642]

Thanks for this James. I've a 5 bed house and I've had recommendations of 17kW,14kW both of these wanted 14 rads replaced and recently 12kW but without any rad replacement. All have said that without their recommended power it would fail the MCS requirements. My question is how did you persuade them that you were right and they were wrong?

[@hughrattray9354]

Oversizing is a major cause of heat pumps running inefficiently. After a year of operation I can confirm my 7kw unit is more than adequate for my house. Video to follow. To answer your question, you have to make sure the heat loss calculations are done properly and, ideally do your own. I would be happy to share my email address so we can discuss the issue in more detail. Let me know if you want to do that. I find it very frustrating that installers are routinely putting in heat pumps that are too big.

[@davidreece1642]

@@hughrattray9354 Yes I'd like to do that. For further info the two quotes from 2 years ago "space heating energy " requirement 29678 kWh/17kW HP and 27883kWh/14kW HP. The recent quote 33191kWh/12kW HP no alterations with approx 204 m2 over ground and first floors.

[@hughrattray9354]

@@davidreece1642 I will reply to your email when I get home in a couple of days

[@davidreece1642]

@@JamesRattray Got it.

[@terryrigden4860]

Very informative thank you very much

[@MichaelPickles]

That is very interesting great love it, I'm using roughly 200 kW hours of gas per day at -4. So roughly 8.33 kilowatts an hour

[@Marcovaldo]

Congratulations on the video. I'm writing to you from Italy, where we have different construction systems, but I'm interested in yours. If you have old pipes, you could consider cleaning the old terminals and piping with new products that could increase the efficiency of the system. Then, you could also increase the flow rate with upgraded circulators

[@hughrattray9354]

Thanks for your comments. I am satisfied that my system is working efficiently. I think your suggestions make sense if you do not get sufficient flow rate and your efficiency is not good.

[@davidfellowes1628]

Excellent video indeed. The Open Energy Monitoring data is a good start, but shortly with AI we should be able to fully interrogate and learn from all the information. What a change this would be from the past and an industry in denial. Thank you.

[@Sithehandyguy-London]

Hi James. Very informative video Have you thought about setting up a website for prospective owners and also installers.

[@bvqbvq]

An excellent discussion of your design, installation and evaluation. It looks like I have been following a similar path so far during my investigation phase. I have a couple of outstanding issues that I cannot reconcile: 1. I have a 1992 5-bedroom self-build house with moderate insulation. What I don't like is the location of many of my downstairs radiators. I have 2 options: move them or switch to UFH. My downstairs floor is 50mm polystyrene insulation over a concrete base. This makes moving radiators difficult and I cannot decide how effective UFH will be if I have to reduce the insulation to half the thickness. 2. Space for the indoor components. At the moment I have floor standing combi in the kitchen. I don't believe that the space liberated by its removal would be sufficient for the hot water tank, expansion vessel, pump, etc. From what I have seen of most installations, none of this looks tidy and so in my case it would have to be boxed in. I already have 4kW of solar but no batteries as yet, doing so would allow me to leverage my savings with a time-of-day tariff. I did contemplate a multi-split air-to-air system but I have too many rooms and would require a multitude of outdoor units or go for a VRV system at some considerable cost.

[@JamesRattray]

I am currently refurbishing a 1970s house. (The video was produced by my brother Hugh, I was the camera man and video editor). Taking your first point - It has concrete base, as your does. This gives me similar dilemmas as you are having. One advantage I have, over your situation, is that I have not moved in. This gives me more leeway than if I was living there. I have decided to install underfloor heating (UFH) using 25mm grooved XPS board with 100mm centres, with an additional 10mm of plain XPS underneath. The UFH will be in the living areas, open plan sitting, dinning and kitchen. Above the UF heating tubes I plan to install wood effect ceramic tiles. The reason I have chosen underfloor heating, instead of radiators is because UFH is meant to provide a more even heat through the room, as opposed to localised radiators. I also understand that I will be able to run the heating at lower temperatures and this improves the efficiency of the heat pump. I will produce a video of all this, once the work has been completed and I can share my conclusions as to whether I made the right choices. Your 2nd point. I wonder if it does take up more room. If I were in your shoes I would ask a number of heat pump installer to come and give quote and see what they say about the space. I think you might be surprised. Heat pumps are such a new technology for us in Britain that the installers are on a learning curve too, by asking more than one you are likely to get a more balanced response. Thank you commenting and brilliant you too are trying to make a difference. Good luck.

[@bvqbvq]

@@JamesRattraythanks for the detailed reply. I haven't done any heat loss calculations of the UFH solution using only a 25mm insulator below the grooved board. My reasons for preferring this solution are the same as yours. My only problem is doing the work whilst keeping the house habitable. I see that some hydroblock heat pumps have integral expansion vessels and pumps, this would save some space in the house just leaving the cylinder and the diverter pipework. Nobody wants to come and give me a quote unless I pay them a substantial amount of money for the survey. This is refundable if I go with them but it makes it expensive to get comparative quotes since I will only be using one of them. I did see a tidy indoor solution from Daikin, it looks like a fridge freezer with the cylinder and everything inside the one unit, that would work well for me.

[@JamesRattray]

@@bvqbvq I think there is a glut of work for heat pump installers, so they are the ones being choosy about their customers, instead of visa versa. I approached about a dozen heat pump installers and ended up with four who were serious or came near fitting what we needed. Many wanted to fit their system irrespective of what we wanted and disappear on to the next job. It's a long haul, but we are talking about significant investments here, even with the grant. None of us want to get it wrong. I am still on the journey, I keep have to remind myself to be patient and one step at a time .... I am lucky to have my brother Hugh who has done much of the homework to guide me.

[@stevehorner8302]

so how much does it all cost

[@JamesRattray]

Hugh talks about cost of the installations in this video (11mins 45 secs) kzbin.info/www/bejne/pYu6cnmdiqybaNE

[@markchristopher6889]

How much was your installation great video

[@hughrattray9354]

Thanks for your comment. My installation (September 2023) was in the region of £12k before the grant and for that I added 7 new type 22 radiators and moved two others. I received a £5k grant towards that but the grant has now been increased to £7.5K. After nearly a year I am delighted with the comfort, performance and the running cost of the heat pump. I will aim to do another video summarising the first year.

[@MarkGaudie]

I have no buffer tank and I’m using zero zoning. What heat curve are you running on your system? I’m running 0.60 heat curve.

[@hughrattray9354]

I use 0.55 at the moment Still experimenting though. I am not sure how well weather compensation works when it is cycling.. More to learn..

[@JamesRattray]

Mark you might be interested in the new video we have just produced on the Open Source Energy Monitor system. There was a lot of interest in where you can find live information on the performance of heat pumps. This hopefully helps those interested in seeing other peoples heat pump installations and heat curves kzbin.info/www/bejne/pp3Veqylqaisfqs

[@barrydonaldson]

Hi James. Apologies if I missed this info, but what size is your microbore? Ours is a mere 8mm so a high temp Heat Pump seems to be required...

[@hughrattray9354]

The microbore in my property is almost all 10mm with the loft having 8mm pipes. 8mm throughout does pose more of a problem. The reason that heat pumps need higher flow rate is they like to have low delta T (temperature difference from the inlet to outlet. For a heat pump typically 5C for gas it can be much higher. Have you checked whether high temperature heat pumps operate with higher delta T ? If not hey won’t solve your problem. John Cantor provides a flow rate simulator (link in the notes) which you could use to work out how many radiators you need open to ensure adequate flow rate.

[@joewentworth7856]

Great. I have an independant electricity meter which include the circulation pumps for ufh and rads. So it does give differing usage figures to vaillant . but perhaps vaillant is excluding other elec use. PCBs controllers? Interesting the heat produced is reasonably consistent.

[@symosys]

Excellent informative video.

[@hughrattray9354]

Thank you

[@CoolMusicToMyEars]

Only problem wiith 10mm microbore pipe is it gets clogged up, better flow I've been informed is 28mm (main piping to manifold unit) I wish I put 28 mm then reduce that to 15mm for radiators, but once a system is upto temperature I feel less water in piping might be better, but a must is good insulation, with air source heat pump & to be honest with combination Boiler, the open energy system looks good 👍

[@hughrattray9354]

I agree that 15mm pipes to the radiators would be better. Regarding clogging up, I have had the 10mm pipes with the gas system for about 30 years without any problem. The flow rates are higher with the heat pump so hopefully that will ensure they remain clear. Good insulation is critical regardless of the heating source. Open energy monitor is fantastic. I highly recommend the system.

[@MarkGaudie]

This is almost like watching a video of my own setup. I also use Octopus intelligent tariff.

[@hughrattray9354]

Very satisfying I find. Low cost and better for the environment.

[@JamesRattray]

Mark you might be interested in the video we have just produced a video on the Open Source Energy Monitor system, as there was a lot of interest in where you can find live information on the performance of heat pumps. Hope it is of interest kzbin.info/www/bejne/pp3Veqylqaisfqs

[@stuartdixon747]

Excellent presentation. I would be interested to know how frequently it goes into defrost and how long each defrost cycle takes. As I assume the defrost times will impact the COP?

[@hughrattray9354]

On the coldest night recently (2nd December) the temperature dropped to -5.5C and during that time it ran a defrost cycle every 35 to 50 minutes. The defrost cycle lasted about 5 minutes. The heat pump was still not running at 100% so was fully capable of meeting needs. I suggest you have a look yourself on heat pump monitoring, the link is in the notes with the video.. My set-up is the one in Newport. On the right of the listing there is a graph symbol click on that and you can see the monitoring system real time. I think there are about 100 heat pumps on there that you can look at.

[@JamesRattray]

Stuart, We have just produced a video which talks about the defrost cycle as shown on the Open Source Energy Monitor system. You might find it of interest in answering your question kzbin.info/www/bejne/pp3Veqylqaisfqs

[@Lfreeman98]

Very interesting/informative & great detail. Just a shame you could not have captured some gas usage data after the insulation improvements to truly compare energy usage before/after.

[@hughrattray9354]

Yes, if I had a time machine I would go back and fit the heat meter to the gas system and fully characterise that first. I did measure the difference in heat loss in other ways which I will go through separately.

[@MarkGaudie]

I’m looking at a home energy monitoring system I can access remotely to my phone.

[@JamesRattray]

We have just produced a video on the Open Source Energy Monitor system, as there was a lot of interest in where you can find live information on the performance of heat pumps. Hope it is of interest kzbin.info/www/bejne/pp3Veqylqaisfqs

[@law7872]

Thank you for making the comprehensive video. Do you have a second circulator pump on your system, in addition to the circulator in the outside unit?

[@hughrattray9354]

No, just the pump in the monobloc heat pump. I have a large system with 20 radiators and it doesn't have any problems. Also the circulation pump is the Vaillant is very efficient using no more than 65watts.

[@Lewis_Standing]

brilliant the only criticism i'd give is that people with microbore throughout might look at the title and think great! HP would be easy, no replumb required. But in reality its because you do not have primaries that are microbore that have made your retrofit possible and your efficiency so high.

[@hughrattray9354]

Thanks. I agree people still need to investigate their plumbing and do some basic flow rate calculations. I think one would be very unlucky to have to replace all the plumbing though

[@JamesRattray]

Lewis, you might be interested in the video we have just put out on the Open Source Energy Monitor system, where you can find live information on the performance of heat pumps. There is a section where you can investigate the type of installation for each heat pump installation. kzbin.info/www/bejne/pp3Veqylqaisfqs

[@Lewis_Standing]

​@@JamesRattraywonderful 👍 I'll be sure to share this with a heating engineer who's currently trying to convince me all properties would need a £25k retrofit with 42mm piping 🙄 Do you link to your data on the open energy website? I'll look on the other video too, thanks.

[@hughrattray9354]

@@Lewis_Standing @jamesRattray I will be very interested to hear the response from the heating engineer to the video and also the real monitoring information for my heat pumps, and others. The data for my heat pump is available live on Open energy monitor. My heat pump is the only one on the system in Newport I have never heard of anyone proposing 42mm piping that seems complete over kill. I came across a couple of installers who wanted to replumb the whole house but they could not explain to me in engineering terms why that was necessary. The reason we put this video out was to show that major replumbing work was not required as long as you took a few precautions. My install, before the grant, was less than half the price of the estimate you have been given. You might need to find another installer. It took me a long time to find an installer I was happy with.

[@Lewis_Standing]

@@hughrattray9354 no he stopped talking to me and seemed to be thinking that everyone would want to keep on off heating. Therefore I think his large pipe sizing and repiping comments were to enable oversizing of HP and quick heat up times at lower flow temperatures. Probably that's how he's customers use their current heating systems and there's pros and cons of on off heating Vs weather compensation but he didn't seem to give much room for change.

[@grahamwoodier5066]

Excellent video with plenty of useful information - thanks. I have a situation with 10mm piping to radiators and the prospect of ripping it out has been one of the factors putting me off the move to a heat pump. I am concerned that I won't be able to achieve adequate room temperatures in cold weather and noticed that you didn't really mention this. I saw at one point that you were achieving 19c but that would not be sufficient to keep my wife happy as she needs a minimum of 21c generally and 22c when sitting. How have you got on during the last few days of cold weather?

[@hughrattray9354]

Thanks. The heat pump easily provided plenty of heat during the recent cold period although, as you would expect the efficiency dropped in such cold conditions. The COP on the 2nd December (the coldest day) was 2.9 but the temperature was between -5C and 1C I suggest you have a look yourself on heat pump monitoring, the link is in the notes with the video.. My set-up is the one in Newport. On the right of the listing there is a graph symbol click on that and you can see the monitoring system real time. I think there are about 100 heat pumps on there that you can look at. If your 10mm pipes are connected in parallel to a 22mm backbone like mine each radiator should be able to put out about 2Kw of heat. This is limited by the maximum flow rate that you can put through 10mm pipes. Insulation helps reduce the required heat and more radiators in parallel helps too, Look up mass flow rate calculation on the Heat Geek site. Also look at John Cantor’s Heating simulator and pressure and flow rate calculator. Both are referenced in the notes. I might try to include how I did my calculations in the next video.

[@grahamwoodier5066]

Hi, Thanks for responding. I have taken a look at your live monitor but I can't see any information about what you achieve in terms of room temperature when it is really cold outside - perhaps I am not looking at the data correctly? I find with my existing gas boiler that achieving 22c room when it is -2c outside takes a long time. 19c is easy and at that temperature the boiler is only firing for about half the time. In my system half the radiators are fed by 10mm copper from a 22mm backbone but the other half are fed from a backbone that has been reduced to 15mm. I had a Heat Geek recommended heating engineer come to see my house (4-bed, detached, late 80's, cavity wall insulation, double glazing, extra loft insulation) last year but he felt the 10mm would have to go. This is why I was interested in your experience. If I have a heat pump fitted and the house adjusted to accommodate new pipes and bigger radiators I will be a dead man if my wife isn't warm enough. @@hughrattray9354

[@hughrattray9354]

The monitor software should show you a single temperature which comes from the open energy probe. I think it shows 19 to 20C. I have Evohome TRVs in each of the rooms and that tells me the rooms are over 20C. Our house has never been warmer as we don't have the swing in temperature that we had with gas. I think the Heat Geek engineer might be right if you have several radiators running off one 10mm supply. All my 10mm only supply one radiator. The reason I did so much research was for the same reason you are concerned. The house had to be warm enough!!!

[@JamesRattray]

We have just produced a video on the Open Source Energy Monitor system, explaining a bit how to access the data. Hope this helps kzbin.info/www/bejne/pp3Veqylqaisfqs

[@healeydave]

Did I miss it, or did you not mention which installer you used ?

[@JamesRattray]

A word of caution regarding the installers. I am Hugh's brother James (the person whose name appears on this channel), I am going through the process of installing a heat pump. I am approaching MCS accredited installers, they are authorised to access the BUS (Boiler Upgrade Scheme) grant. They have also agreed to follow the RECC (Renewable Energy Code of Conduct). One of the stipulations of this code to the consumer is "Never pay more than 25% of the contract price up front; check it will be protected." This is stipulation in the code is being broken by a good percentage of installers I contacted. Not all. Let me give you an example, which is not untypical. The installer asked for 25% of the total price with order confirmation. No mention of deposit protection. On enquiring about protection, I was told it was deposit protected. It made me suspicious as to whether deposits are only protected when challenged. Other installers did give deposit protection scheme name in their quote at the outset. The next bit of advice I would give is phone the installer's deposit protection scheme provider to check:- 1. The installer registered with them? 2. The level of deposit protection in £s they offer? One installer's deposit protection scheme provided 25% cover but to a maximum of £5,000. The installer was asking for £7,500+. Leaving me exposed to £2,500 not protected. In addition to the deposit installers are asking for advance payments. Their payment schedules say: Advance Payments (no more than 3 weeks before delivery date). £15,000+ Leaving a balance payable following final commissioning £440. No protection here. Remember the code advises us "Never pay more than 25% of the contract price up front ..." This is clearly in breach of the RECC code. Here is the link to the full code www.recc.org.uk/pdf/consumer-leaflet.pdf First and foremost this is bad practice, which I suspect is being fuelled by the BUS grants. When I challenged the Chief Executive of one of the installers about his payment schedule and the exposure to risk he was me to take. He said, "This is standard practice in the industry". Well I can tell you it is not. I did find one installer who asked for a deposit with the balance once the system was installed. Another installer was prepared to modified their payment schedule so the next payment was when all the materials arrived on site. Part of the issue here, is rightly, the installer only receives the BUS grant after the heat pump has been commissioned and entered in the MCS scheme. So the installers have to wait for the final £7,500. At least that is their argument. But ask yourself, how many suppliers stipulate upfront to their business customers? In my experience it is standard to get 30 days credit and often longer. Upfront payments are only demanded from customers with a credit risk in the business world. As a home owner, it all comes down to what level you are willing to gamble with your hard earned cash. Sadly we hear too often of businesses going bust and customers who made payments upfront loosing their savings. This practice will only change if enough of us consumers refuse to make deals such as these. Sorry a long response, but I do feel strongly about it. My Quantity Surveyor friend who works in the building industry tells me never pay for anything up front in this industry. A small deposit is OK if they need to do work before arriving on site. Sadly too many members of the public appear to take these risks which fuels this bad practice.

[@hughrattray9354]

I used Swift Mechanical in Clevdon - if you go with them mention my name and this video. Are you in the right area?

[@healeydave]

@@JamesRattray Were you not tempted to use the people Hugh used ?

[@healeydave]

@@hughrattray9354 Ah, no, according to Maps, I'm about 80 miles away 😩

[@hughrattray9354]

@@healeydave Probably too far

[@cryptickcryptick2241]

You should send this video to the various Heating and cooling companies you had out to quote such and install and did not understand what you were tying to do.

[@hughrattray9354]

Good idea, I will do that. I wonder if they will watch it. I suspect that the installers don't often follow up on an installation. I met my installers at a friend's property a couple of days ago and they complimented me on the video and were pleased to see the data.

[@R_star_-yl3fv]

Great video and very helpful. I’m new to this and was wondering if there are any companies who know how to install as you have suggested would be super helpful as I’m not at all experienced in this area but need to replace a log burner in a house we are buying which is off the gas grid.

[@GaryCalcott]

Interesting report, thanks. We’re interested in the EU08L from Lambda which has, on paper, way better efficiency than anything from Vaillant. Out of interest, do you have underfloor heating? Most houses in continental Europe do (plus radiators) and thus most configurations will have a buffer tank with independent thermal layers.

[@hughrattray9354]

I don't have UFH but I did put in bigger radiators. I haven't heard of buffer tanks with thermal layers.

[@jimmyc38]

Good video thank you - intrigued that you kept Evohome; I’m in a similar situation but mines a modern house with UFH, I too to micro bore though mine are from 15mm. What do you use the Evohome for now?

[@hughrattray9354]

Thanks. I use the Vaillant sensocomfort as the main controller for the heat pump in the living area. That controls the flow temperature through weather compensation. Evohome then sets the temperature and schedule for the bedrooms and bathrooms. Since the heat pump is on most of the time it works okay.

[@antoinec1066]

Very interesting video. Thank you. You are telling that your house was poorly insulated but your gas consumption during cold days was only 75kW which seems very low compared to my 300KW a day in my late 1930’s 5 bed house. You probably had already done a lot on your insulation….

[@hughrattray9354]

Thanks for the comment. I have improved the insulation significantly particularly for the living areas and I plan to do a video on what I have done in the near future. The other factor is that I have a Honeywell Evohome zoning system which means I can control the temperature and schedule for peripheral rooms. I did this when I was still on gas and it saved a lot of energy.

[@antoinec1066]

@@hughrattray9354 I have evohome since 2016 too. Great bit of kit. It has greatly improved comfort but only marginally improved consumption (about 10%). I managed to get another 10% by fine tuning my flow temperature. I have to work on insulation as I don’t have cavity wall insulation but being quite exposed to the elements I have been reluctant to move forward as I don’t want to end up with damp. I wish I knew more about open therm and weather compensation before having a Worcester Bosch boiler installed in 2016 as they are clearly not the best fit for evohome… I am a long way before I get an airspace eat pump but your video shows that this is doable with a bit of planning.

[@JamesRattray]

@@antoinec1066 We have just produced a video on the Open Source Energy Monitor system, as there was a lot of interest in where you can find live information on the performance of heat pumps. It might let you see what other people have done with their installations. Hope it is of interest kzbin.info/www/bejne/pp3Veqylqaisfqs

[@BillFlavell]

Excellent video, packed with facts--very many thanks! I too have a 5-bed house with microbore pipes, an 8kWp solar array and a 13kWh battery. My house is only 5 years old, so it benefits from good insulation and draught proofing. I've been deterred from installing a heat pump because I expected to have to run the system at a high temperature with resultant low efficiency. Now, you've convinced me to take another look. Thank you! BTW, what capacity battery do you have? I installed an air2air heat pump a year ago that heats and cools the lounge and one bedroom. Unfortunately, I'm told this disqualifies me from claiming the £7.5k government grant. If anyone can confirm or deny that, I would be very grateful.

[@JamesRattray]

Hi Bill, I am James the name at the top of this channel. Hugh the video producer's brother. I am just applying for the Boiler Upgrade Scheme (BUS) grant. Here are some links that might help answer your question. BUS supports the decarbonisation of heat in buildings. Before applying for the scheme, you should read the BUS guidance for property owners. www.ofgem.gov.uk/environmental-and-social-schemes/boiler-upgrade-scheme-bus/property-owners There is a very detailed document on the Boiler Upgrade Scheme for property owners covering eligibility I can't see anything about part installed heat pumps. It appears to be all about replacing gas and oil heating systems. It needs a more detailed read. www.ofgem.gov.uk/sites/default/files/2023-12/Boiler%20Upgrade%20Scheme%20Guidance%20for%20Property%20Owners%20v2.4.pdf Also you can contact Ofgem support team: [e-mail] Tel: [phone]

[@BillFlavell]

@@JamesRattray many thanks James. Very helpful!

[@JamesRattray]

Hi Bill, I thought you might be interested in this video on the Open Source Energy Monitor system, where you can find live information on the performance of heat pumps. It is an opportunity to look at other people's set ups and how they are performing before you decide if you will take the plunge. Hope it is of interest kzbin.info/www/bejne/pp3Veqylqaisfqs

[@joewentworth7856]

Im stuck with vaillant data. Discovered open energy too late. My claimed scop for the first year is 520% which i doubt. I have tuned it carefully but 4xx% far more likely. Good to see yours do not match.

[@hughrattray9354]

I am keen to get to the bottom of the difference so I am logging the details from both systems. Looking at November the big difference seems to be in the electrical power that each system thinks it has used. The Vaillant tells me it 277Kwh whilst Open Energy Monitor shows 374Kwh. The heat output figures from both systems are similar. I will report back further as I understand it more.

[@graemeross1998]

Mine is 460%

[@JamesRattray]

Joe, We have just produced a video on the Open Source Energy Monitor system, as there was a lot of interest in where you can find live information on the performance of heat pumps. You might like to see what other Vaillant pumps are giving in terms of SCOP kzbin.info/www/bejne/pp3Veqylqaisfqs

[@nazkhan182]

Great video, can i ask when you say that some radiators are open all the time, is this most of the time or when the outside temperature drops to a certain level? Thank you

[@hughrattray9354]

Thank you for your comment. I would advise leaving the chosen radiators open all the time and letting the main heat pump controller manage the radiators that are left open. The heat pump controller will only heat the radiators when it is cold enough to do so. Other radiators can then be set as you like.

[@cryptickcryptick2241]

With cheap night time power it might be worth exploring how to take advantage of the situation.One method would be to use your house as a thermal battery. Heat the house at night and then let it cool off during the day. Heat pumps have limited heating per hour, as they are meant to run all the time, but with programable thermostats you could tell the system to heat at night and then coast during the day. This may or may not work. Other factors to consider is that the outside air at night is colder, and with the system gets lower efficiency at lower temperatures and at higher usage. One could make an argument you should run the unit when it is warmest outside to pump that heat in. One could also make an argument one should run the heat pump when it the power is the cheapest. Most of the heat content of a house is in the materials, not the air. Due to thermal mass in a home, it takes about 5 hours to bring all the building materials, brick, stone, drywall, furnishings, flooring, up to a new temperature. It also take a while for that temperature to drop. In America, I pay the same for power no matter when it is consumed, in your case it would take some calculations and looking at both heat pump efficency charts and outside air temperature differences to figure out when the best time to run the system is. Ultimately, optimizing this too much right now could be counter productive to the message that heat pumps actually work in England, a message that this video clearly gets across.

[@hughrattray9354]

Thanks for your comment. I am attempting the strategy you suggest to some extent. I have decided to go for the lowest cost approach rather than the most efficient (highest COP). I heat the hot water at 11.30pm when the low cost tariff starts. After that I put the heating on with a higher target temperature to store some heat. When the high costs start I leave the heat pump on but reduce the thermostat setting. The night time rates are so much lower (less than 25% of the main rate) that I don’t need to do the maths. There is a loss in heat pump efficiency but nowhere near 75%. Maybe in the summer I should heat the hot water in the day from my solar when the air is warmer. On your final point, heat pumps definitely work in the UK (I am in Wales). There is so much bad press about heat pumps here. Lobby groups, paid by the fossil fuel companies, have been caught feeding this rubbish to journalists.

[@glockieme]

Great information. Many thanks

[@hughrattray9354]

Thank you

[@LeiChat]

Thanks for the video. May I ask whether you chose the Gledhill cylinder or if it was recommended by your installer?

[@hughrattray9354]

Thanks for your question. I let the installer specify the tank. I will do some trials on heat loss when I am away from the house for a few days by leaving the hot water cycle on and seeing how much energy is needed to hold the temperature. One frustration I have, and I think this is common to most tanks, is that I can't tell how much hot water is in the tank. The temperature monitor used by the heat pump is very low down so even when that is showing low temperatures there can be plenty of hot water left. I have put a cheap probe thermometer at the water outlet and that does help to give me some idea on the remaining water. I also considered a Mixergy tank and decided that it did not fit they way I wanted to use the tank as an energy store. Heat Geek also do a good video on the Mixergy tank and why it may not be a good fit for a heat pump.

[@LeiChat]

@@hughrattray9354 Thank you. I was considering paying to have one or two extra sensor pockets on a customised cylinder. The Gledhill cylinders compare favourably for standing heat loss based on the small amount of research I have done so far. With our current 180L Kingspan cylinder I've observed a drop of around 10 degrees over four hours at the lower sensor pocket. Like you I ruled out Mixergy. The thermal buffer sounds great, but I didn't like the dependency on connectivity to their cloud service.

[@hughrattray9354]

@@LeiChat The Gledhill tank does have another thermal pocket and I have a surplus sensor. How would you utilise the extra sensor? Would it connect to the Vaillant heat pump controller?

[@LeiChat]

@@hughrattray9354 I'm not sure, sorry. Perhaps there's a way to add it to your OpenEnergyMonitor setup? I have a myenergi eddi which has an optional relay/temp sensor board that supports two thermistors. Like you, I have one in the immersion pocket and one cable tied to the output at the top of the tank.

[@JamesRattray]

@@LeiChat We have just produced a video on the Open Source Energy Monitor system, as there was a lot of interest in where you can find live information on the performance of heat pumps. Hope it is of interest kzbin.info/www/bejne/pp3Veqylqaisfqs

[@AndyPook]

As said in other comments, this is excellent! So good to have an detailed walk through of a real property. One item would help me clarify how things work out... At time 4:40 you show the gas usage on a cold day of around 3kWh (averaged over 24h). Mine is similar (2.7kWh) but the heat loss calc here gives just over 6kW. I'm guessing your heat loss was similar or higher. Obviously one is kWh averaged over a day, the other is kW which the measure of an instant. How do these two numbers (2.7kWh gas usage and 6kW heat loss) corelate?

[@hughrattray9354]

Thanks for your comment. Before I installed a heat pump I did a lot to make sure that it would be big enough and do a good job. As well as looking at the gas usage in a cold spell I also measured the heat loss in individual rooms on cold nights (3C or below). I would heat the room to 20C and then put a metered fan heater in the room and measure how much heat the room then needed to stay at 20C. With this information I attempted to get a correlation with my heat loss calculations. In the end I was pretty close. Your insulation must be better than you have allowed in your calculations which is great. How you track down the difference is the problem.

[@AndyPook]

I'm interpreting the "heat loss" calculation as... if it is -3c outside, I need to add/emit 6kW heat in order to keep it at 20c inside. So, if it is consistently -3c outside for an hour, that's 6kWh. So the calc is suggesting the extreme upper limit for needed heat input. The survey can only provide approximations for the heat qualities of the various materials (windows, doors, walls, roof) The months where I'm getting 2.7kWh from (that's an average over the entire month) averaged about 2c with 1/4 of the days going down to -2c. So, some of the discrepancy is the ~5c higher temp. I'm sure some of this stuff is non-linear and I'm using lots of averages and approximations

[@AndyPook]

Also, I liked that your main open circuit rads _are_ your buffer tank :) You don't need an extra buffer when you have all that water moving around anyway

[@over-engineered]

agree, don’t turn your (gas) heating off at night! my 1960’s house is set to 18C at night. keep it warm.

[@davidscott3292]

In this video doing that is argued to be justified because of very low tariff to run the heat pump. Without that it would not make sense.

[@over-engineered]

@@davidscott3292 But if you run Gas CH system at lower flow temperature as needed, then the mass of the building doesn’t cool down. Then you don’t need to run Gas CH at high temperature to recover comfortable temperature. Advantage is boiler nearly always in condensing mode.

[@JamesRattray]

@@davidscott3292 David, you can have a look at what other heat pumps are doing, in terms of operation in this video, we have just produced a video on the Open Source Energy Monitor system. There was a lot of interest in where you can find live information on the performance of heat pumps. I think the big difference between a heat pump and say a gas or oil fired boiler is the running temperatures. This will let you see different sets across the UK. Hope it is of interest kzbin.info/www/bejne/pp3Veqylqaisfqs

[@joewentworth7856]

Excelent. A small point i think with a flamable refrigerent your isolator should be further away from the unit. I maybe wrong.

[@hughrattray9354]

Many thanks for the comment. I did discuss this with the installer and they said it was fine as it is a considerable distance from any rooms or doors of living areas in the house. The door behind it is into a garage. I also looked at the Vaillant installation document and they showed a covered location like mine was fine as long as it was away from any side walls. I was concerned about cold air circulating back into the heat pump as well as a possible refrigerant leak.

[@joewentworth7856]

​@@hughrattray9354 that's sound right. I think the fire risk is a bit over stated. Considering the r290 charge is less than 1/10th of a bottle of patio heater gas. Also most houses have an unlimited supply of flammable gas piped directly I to the center of the home!

[@danmfeist]

@@hughrattray9354 the unit positon is fine, where your installer hasn't followed the guidelines correctly is regarding the position of the electiral isolator. This should be outside the manufacturer specified "protection zone", but it isn't.

[@hughrattray9354]

Thank you. I will take that up with them.

[@streaky81]

There's an energy loss between the heat pump and the tank, that's why the COP figures are different because it is seeing different data. Assuming from that the numbers are correct, it's showing fairly large loss - which given the length of outdoor piping is fairly plausible tbh.

[@hughrattray9354]

That is something I have considered and I am sure it plays some part in the explanation. I am keen to get to the bottom of the difference so I am logging the details from both systems. Looking at November the big difference seems to be in the electrical power that each system thinks it has used. The Vaillant tells me it is 277Kwh whilst Open Energy Monitor shows 374Kwh. The heat output figures from both systems are similar. If the loss was from the external pipes I would expect to see a big difference in the heat figures not the power figures. I will investigate further.

[@v_0]

Maybe they’re not accounting for the circulation pumps?

[@hughrattray9354]

The circulation pump is definetly included in the open energy monitor calculations. The Vaillant circulation pump is very efficient, never using more than 65W. This is very important because the circulation pump runs most of the time with a heat pump. I am not sure if Vaillant's own statistics measure the power of the circulation pump.

[@watchandlearnfast]

Hi James, how many square feet does your home have?

[@JohnnyMotel99]

It would make sense if rad manufacturers started making rads to contain a larger volume of water.

[@hughrattray9354]

That would help heat pumps

[@ollielarsson-d8y]

The heat pump hasn't been installed correctly. You need an R290 clearance requirement for the isolator switch. In many cases, Vaillant won't stand by their warranty under these circumstances.

[@hughrattray9354]

I willlook into that - Thanks

[@jonscoey7912]

The things people really need to see are evaded here. 1, the overall installation cost of the heat pump and all the heating/insulation upgrades that are needed. 2, the overall running costs for the heatpump. I'm keen to see how long it will take to re-coup the installation cost. Its all very well clicking on technical diagrams blinding people with science but none of that means anything to Mrs Jones down the road. I say all this with the greatest of respect but heat pumps, at the moment, are not a cost effective alternative nor are they a practical solution in 70% of the houses around the UK.

[@hughrattray9354]

I plan to do another video on the insulation work I have done. This video was long enough without including any more detail. Insulation will reduce costs for any heating system so if you don’t have reasonable levels of insulation running costs will remain high and your comfort in the house will be impacted. Heat pumps are much more efficient where you can keep radiator temperatures low through good insulation and higher output radiators. However, gas and oil condensing boilers cannot be run too hot either if you want them to be efficient. To achieve the high efficiencies advertised you need to ensure the flue gasses condense. It is a complex subject but,as a rule of thumb, you need to ensure the return temperatures are below 50C (not too far from heat pump temperatures). Have a look at the article in Heat Geek

[@JamesRattray]

Costs are covered in this video from 5mins - kzbin.info/www/bejne/pYu6cnmdiqybaNE

[@jonscoey7912]

But how much money are you spending making the property suitable to run a heat pump? For instance, insulation, larger radiators not to mention the actual installation cost of the heat pump etc etc. With these added costs and the amount of electricity a heat pump actually draws, it would take years to re coup these costs. Its complete false economy. I ill gaurantee could set up a gas boiler to run on opentherm/weather compensation for a dam sight less without the need for extra insulation and all the other things needed to make a heat pump work.

[@davecavaghan7889]

How much did it cost you in pounds and pence?

[@hughrattray9354]

The total gross cost including the radiators and the heat meter was just over £12k. I received a £5k grant. The grant is now £7.5K

[@davecavaghan7889]

What did your solar and battery cost

[@kjeldschouten-lebbing6260]

The issues with the heatpump going "on and off" is mostly due to not using any buffertank. A buffertank should allow you to limit the amount of on/off cycles per day, increasing heatpump lifespan.

[@JamesRattray]

Do you mean buffer tank or volumizer? The volumizer increases the amount of fluid circulating in the system, a buffer tank is a secondary liquid chamber.

[@hughrattray9354]

Thanks for your comment. The reason the heat pump cycles (switches on and off) is that it is producing more power than the house needs. So the minimum power from the Vaillant 7Kw, when it is running at its lowest level of 25%, and it is 10C outside is about 3Kw. The living rooms in the house will only lose about 1.5Kw at that ambient temperature. With this example the heat pump can only run for 50% of the time. A volumiser can help to lengthen the cycles as there is more water in the system to heat up and cool down.

[@Mistah_john]

v interesting. it is a shame in our society that if you have money to invest on heat pumps, solar, house batteries, electric cars etc then you can reduce your bills and make use of cheap overnight tariffs etc while the poorer of society are stuck, perhaps in rented accomodation with poor insulation and paying through the nose for energy the government need to do more to ensure houses are properly insulated, both for landlords and new builds. good housing = better health = more productive population

[@hughrattray9354]

Thanks for your comment. I agree the government must do more to bring the benefits to all in society. I feel it is much better to invest in the housing infrastructure to bring people out of fuel poverty rather than making extra payments for fuel continually. To me it is terrible that new houses are still being built with poor insulation standards and being fitted with gas boilers. It is so short sighted. The housing lobby is very strong and they constantly succeed in postponing higher standards. I also feel there is a role for those of us who can afford it to invest in this new energy efficient technology. By doing so we will bring the cost down for others.

[@JamesRattray]

Heat Pumps currently have £7.5 grants. No matter your income bracket, these grants are significant and really should be considered before they disappear. There are also insulation grants for the less well off too, here is a link I found www.gov.uk/apply-great-british-insulation-scheme

[@JamesRattray]

There is also the ECO4 scheme aimed at lower income groups www.ofgem.gov.uk/environmental-and-social-schemes/energy-company-obligation-eco/homeowners-and-tenants/faqs-domestic-consumers-and-landlords

[@TimHodgesofEdinburgh]

Excellent video. I'm about a year behind you and doing the measurements during this cold spell to determine the heat loss of my house. Currently looks to be about 4kW and I have 8mm microbore. One question I have is that you measured a heat loss of 3kW yet you selected a heat pump capable of 9kW. If I've understood correctly, the issue with oversizing the heat pump is that you get cycling with significant loss of performance. So why is a 9kW heat pump not considered oversized for a 3kW demand?

[@hughrattray9354]

Thanks for your comment. You will have to work out the flow rate for 8mm pipe, I have 10mm. Regarding your question on sizing, it is a very good question. The truth is my heat pump is probably a little over sized for the way we live most of the time, with the house partially occupied, but I have sized it for a full house. The 3Kw need was with several of the bedrooms set on frost protection levels. We will have a full house over Christmas so I will have a good chance to see how the output is then. Ideally heat pumps would be able to modulate further than they do now.

[@HeatGeek]

Your scop figures between the two systems will settle over time

[@hughrattray9354]

Thank you - I will record the two sources of data over the next few months.

[@davidscott3292]

What will cause that to happen over time?

[@barrydoherty636]

Great video, well done.

[@barrydoherty636]

My worry with these heat pump systems, there is a lot of equipment to go wrong and or service.

[@hughrattray9354]

@@barrydoherty636 it is basically refrigeration technology. We have two fridges and two freezers which we have had for 15 years or so with no faults. I think the technology is very robust.

[@davidstorm4015]

Regarding the Vaillant App. performance figure vs. the independent figures, you should be aware that Vaillant are alone in using a different calculation for COP and SCOP than anyone else uses. The independent figures will be correct, the Vaillant ones are likely to be over-stated. Vaillant state 'Environmental Yield', rather than 'Total Energy Generation', this is because Vaillant are excluding from that Environmental Yield any energy production that is a direct result of electricity input and they deduct the electricity used before applying this formula. This skews the figures. COP and SCOP should always be total heat produced by the heat pump, divided by total energy consumption (of all system components). Because you have a separate heat meter and electricity meter dedicated to your heat pump, the figures from those are the only ones you can trust to be correct, ignore what the Vaillant app. is telling you

[@hughrattray9354]

Thanks for your thoughts. I have confidence in the heat meter set up so that is what I trust and will use. The underlying information on the heat output and the electricity used from Vaillant is very similar to the Openenergy system. It is just the calculation that is wrong. Have you seen any justification for their calculation?

[@kevatnorthfield]

In the winter months, we pay about £260 a month. Everyone with a heatpump installation never actually states the new bill total. For each month. Why is that.

[@hughrattray9354]

I cover, in detail, the cost of running my heat pump in the video "12 months performance microbore heat pump" which you can find on this channel. The cost analysis is at about 17 minutes into the video. The cost depends on the tariff you use and also whether you have solar power and or a house battery. I found that for all tariffs a heat pump with the level of performance of mine would have considerable savings over gas. In my case I have an EV tariff, solar panels and a battery and my energy bills over the year are close to zero.

[@colin4685]

Just a quick pointer. At the start of your video I see the tesla charger is blocking access to your gas meter box.... not very smart.

[@bordersw1239]

That would depend on if his gas meter is still connected.

[@colin4685]

@bordersw1239 still need access to a capped supply. Which is most likely compression stop end which needs to be accessible.

[@hughrattray9354]

Thanks for the comment. The gas meter has been removed and the pipe is capped. I aim to get another Powerwall now.

[@DGT73]

The more time it spends on heating the higher the SCOP, passive houses have very low SCOP.

[@hughrattray9354]

The heat loss from Pasive houses is so low I have seen it suggested you don’t even need a heat pump and you just have a small amount of direct electrical heating instead.

[@DGT73]

@@hughrattray9354 yes , with MVHR too

[@stephenbrown9998]

Try 1800s end terr

[@SusanPhillips-r4u]

Very selective on data shown. I wanted to see power consumption on coldest days. Where did you fit that massive water tank. You have to run a heat pump all day.

[@hughrattray9354]

I have made my real time heat pump available to everyone as I want to be completely open. I suggest you have a look yourself on heat pump monitoring, the link is in the notes with the video.. My set-up is the one in Newport. On the right of the listing there is a graph symbol click on that and you can see the monitoring system real time. I think there are about 100 heat pumps on there that you can look at including ones in Scotland. So power consumption for the coldest day (after the video was made), 2nd December, where the temperature was between -5C and 1C, exceptionally cold for us. The heat pump consumed 25.8Kwh of electricity to produce 67Kwh of heat with a COP of 2.6. 8 Kwh was at the rate of 7p. You should be able to see all this data yourself on the monitoring site I mentioned. Let me know if you have any trouble with that. Re the tank. If you look at the video at 4min 16 secs you can see I had a tank with my gas system and at 9.47 in the video you can see the new tank in a similar position. Heat pumps are designed to be run most of the time with less hot radiators. Because we and the house never get cold we are much more comfortable and also peak temperatures can be reduced.

[@SusanPhillips-r4u]

@@hughrattray9354 Thanks for the comprehensive reply. I think the issue is you've shown how to do it properly. Replacing a 26kwnboiker with a 8kw heat pump is impressive . All down to your insulation I suspect. The issue is I nearly had a free one installed and rejected it. A 12 kw heat pump to replace a 25k oil boiler made no sense to me and I realised then, the house has to be expertly insulated and air flow controlled to make it work. The large rads put me off and I did not buy into the CoP of 3:1 if it has to be run all day Vs just an hour in the morning and evening with our oil boiler. Our solution is we've connected our rayburn to our oil boiler as we have loads of free wood. We also have solar and batteries so our energy bills for the whole house are now under £500 a year. Good luck, but I won't be getting a heat pump until the installers have your level of knowledge and it's outrageous really that they are just thrown in. One last question-how much is your Heat pump maintenance?

[@hughrattray9354]

@@SusanPhillips-r4u I must admit I don't know what the maintenance cost is. I expect it to be similar to my gas boiler. I get a 7 year warranty from Vaillant.

[@SusanPhillips-r4u]

@@hughrattray9354 That's because they were a valiant approved installer. Otherwise the warranty is 2 years. I've heard maintenance is £200 per year.

[@jacquelinebrunder2384]

10mm pipes are minibore not microbore. I've had two homes heated with 400% COP air/air heat pumps now and they are great in the spring and autumn but the huge problem comes in with the colder weather. Designing for -2DegC isn't going to cut it in a bad Winter. I designed my systems to work down to 5DegC at which point I switch over to using a stove and that has turned out to be a far cheaper way of doing it. Also using 7p electric and a heat store only works if not everyone is doing that. If people are forced to install these units, that are highly inefficient at lower temperatures, we are going to end up with that 7p electricity price rising massively as people struggle to maintain their temperatures and of course if electric cars are also charging at such times in the night we are going to need a massive upgrading of the grid to be able to cope. Why are these issues never raised and never costed in for the long term? People used to consider the wider society and think 20 years ahead at least before doing things such as installing twice the heat pump size required so denuding the electricity network for everyone else than if you simply fit a cheap stove to use when it gets really cold. My brother has just had one of these systems fitted to his super insulated new home and I told him they had completely oversized the heat pump, so making themselves more money, and he said they know what they are doing. When the actual installer came and saw that my brother had two stoves in the house he said that my brother should complain as the system has been massively oversized given he planned to use the stoves for heat in the coldest weather. Heat pumps are great for heating your home cheaply only in Summer when you don't usually need it heated or if you don't have any mains gas supply and that is 20 years experience of living with heat pumps through many cold Winters in Scotland speaking. Undersize the heat pump and get a wood/coal burning stove and get some lovely CO2 into the air to green the planet some more.

[@michaeld5888]

The air quality from a stove is not too good though. Getting kiln dried wood under the laws will help but how many people are going to even bother about that. Plus a cheap stove does not exactly hint at efficient combustion. My village whilst even on the gas mains stinks of wood smoke especially with the inversion layer we get with a cold clear sky keeping it all near the ground. This is very like the diesel campaign where CO2 was the only factor and the dire effect of particulates on health entirely ignored. Now people with diesels are not welcome in the town but wood burners the thing. There is just no logic in all this. Wood burners currently produce more particulates than traffic in the UK and imagine what the air quality will be like if this solution is taken on as the alternative to all the gas boilers currently in use.

[@JamesRattray]

Jacqueline, You might be interested to see what other people are getting from their heat pumps at low temperature. We have just produced a video on the Open Source Energy Monitor system, where you can find live information on the performance of heat pumps. Hope it is of interest kzbin.info/www/bejne/pp3Veqylqaisfqs

[@SandhyaPai-q1r]

when will you visit India again ? We are waiting on your videos on wildlife

[@JamesRattray]

Yes, I can't wait to return to India. My big project at the moment is refurbishing our home. So sadly I will not be going this year.

[@v_0]

Why did you go for a 7kW heat pump when your own data shows 3kW maximum loss? You could have had a much better efficiency, SCOP of 4.5 - 5!!! kzbin.info/www/bejne/oamudqtnr5VjY5Y

[@hughrattray9354]

Good question. I failed to mention that the gas usage was when the house was not fully occupied. When it is the power required is close to 7kw. I am very happy with the HP I installed. See my latest video on it after 1 year.

[@v_0]

⁠fair enough. Even partially heated 3kW, with your upgrades, I’m surprised you’re at 7kW still. You seem extremely knowledgeable so who am I to question you 😂!!! Your video is very helpful, so thank you for putting it out there.

[@hughrattray9354]

​@@v_0to be honest I think the smaller heat pump would have been fine too so it is hard to know which would have been the best choice.

[@iareid8255]

Insulation is the factor that reduces heating cost. It is irrelevant whether that heating is gas, oil or electricity. There is a significant error in stating the efficiency of heat pumps because it invariably is based on electrical units consumed. This fundemental error gives heat pumps a false perception of being efficient, which they are not. What should be used is the fuel required to provide the electrcity that a heat pump requires and that is significantly more than that what which is consumed. My view is that gas boilers are more efficient when such losses are taken into consideration. Science has it that no device is 100% efficient.

[@JamesRattray]

Thanks for your comments: I agree with you completely on the insulation point. People often link the cost of insulation with heat pumps but, as you say, it will save you money whatever your heating. Everyone should improve their insulation unless their property is already well insulated. Regarding your points on efficiency, the majority of the electricity in the UK is from renewable sources or nuclear (from national grid website). For this energy it is much more efficient to use a heat pump than any other form of electrical heat. However, even for electricity produced from gas it is better to use a heat pump than burn the gas in a boiler. A combined cycle gas generator has an efficiency of around 60%, and even if you assume a 10% transmission loss, 55% of the raw energy will be delivered to a customer. A heat pump can achieve a SCOP of 4 meaning that for 1Kwh of raw gas the heat pump will deliver over 2Kwh of heat (4 x 0.55). A gas boiler is typically around 85% efficient so 1Kwh of raw gas will produce 0.85Kwh of heat. I accept you point that it is strictly incorrect to use the term efficiency to explain the performance of a heat pump. The fact is though that a heat pump can achieve a SCOP (seasonal coefficient of performance) of 4 in the UK. That means it can use 1Kwh of energy to produce 4Kwh of heat. We plan to produce another video on my system showing the huge energy savings that the heat pump has resulted in for me.

[@cliffwhite2812]

Why not include real money figures? Why concentrate on kwh and COP when these figures are unimportant compared to £££?

[@joewentworth7856]

Kwh and sCOPs let you workout costs and emissions. But you can't work them back the other way as prices are far more variable. But no harm in having both .

[@billyt9921]

As I understand it - for every KWh going in in electric, he's getting almost 4 out. Which looks fantastic. However, electricity is currently 4 times the cost of gas per KWh. So I cant work out how air source heat pumps male financial sense. There's the co2 I suppose - but the science is far from settled on that. Plus an awful of electricity is generated thru fossil fuels, so. It sure that's really too valid either. And renewables are falling a long long long way short.

[@joewentworth7856]

​@@billyt9921you are right currently they are not about saving huge sums if any. They are absolutely about reducing co2. Even with current fossil use on electricity in uk a heat pump reduces co2 emissions to 25% to 30% that of a gas boiler. As the grid moves to net zero the co2 benifit of hp grow. C02 is well proven to be a major cause of climate change and is disputed by very few credible scientists. I hope in the coming years a combination of industry growth and gas/electricity ratio closing the finances will tip to being an overall cheaper option to gas, so those who are not interested in helping the environment can make the change for there wallet.

[@JamesRattray]

@@joewentworth7856 We have just produced a video on the Open Source Energy Monitor system, as there was a lot of interest in where you can find live information on the performance of heat pumps. Hope you find it of interest kzbin.info/www/bejne/pp3Veqylqaisfqs

[@topgazza]

Impressive scientific study. But that’s the problem. It’s all baffling and complicated for the average person. I have spoken to four plumbers and all of them refused to install because I have microbore. This is a common experience for others I know. Many homes have concrete floors so any changes require digging out floors and replacing flooring. Massive extra expense. Frankly this is yet another attempt at convincing the sceptical with a biased set of info. Cost is extreme for most houses. It’s a con and another rip off

[@hughrattray9354]

Yes plumbers seem to operate very much by custom and practise and so it will take a lot to change attitudes. I found those that advocated replacing all plumbing could not explain why in engineering/ mathematical terms. I have a friend who also has microbore pipes and he is having a heat pump installed in a couple of weeks. That will provide another data point and I will see if he is willing to do a video on his system.

[@topgazza]

@@hughrattray9354 Hugh, I do tend to agree with that view. But none of them were luddites and were all committed to the, dodgy in my view, theory behind heat pumps. But two of them carefully explained why the flow rates would not produce the expected efficiency. I don’t have the option to fit 22mm pipe to improve that. Concrete floors etc. I don’t want 8 ft high rads in living spaces or the wall space to fit extra rads. With all due respect whenever I see vids like this they are not typical house installs and never show anything but fairly straight forward installs. Houses built since, say, 1985 have this issue where microbore is installed. The installation cost is prohibitive and it would have nice to see how much yours cost and the payback period. It’s not enough to cheer any supposed carbon saving. At the end of the day your typical household simply can’t afford it One guy suggested underfloor heating which is a good idea but not at the £20k quoted So for me the whole thing is only relevant for specific house types and not the majority of

[@JamesRattray]

@@topgazza For me it all starts with insulation, no matter what system you use. This will reduce the running costs of all heating systems. Talking of heat pumps, we installed our first heat pump back in 2009 in the Cairngorm National Park in Scotland, one of the coldest parts of the UK. We lived in a 1860s coach house and stable block. The installer of the heat pump was an engineer, not a sales man. He would not even consider selling us the heat pump until we had insulated all the external facing walls on the inside of the house. Our joiner, removed the skirting boards, and applied 60mm PIR board with plaster board. Before replacing the skirting boards and redecorated. It totally transformed the house, even before the heat pump was installed. So forget heat pumps, concentrate on insulating all your outward facing walls, on the inside of the house. There are grants about to help those in the lower income groups in our society. We should all start with insulation.

[@hughrattray9354]

If you live in the West of England or East Wales I could recommend and installer that you might get more joy from. Best of luck with whatever you decide to do. @@topgazza

[@topgazza]

@@JamesRattray I have a 1989 detached with a loft conversion circa 2002. Full spec roof insulation, full cavity wall insulation, new double glazing this year. UPVC Outside doors. Not really anything I can do. I do get your point. I am an ex electrician so familiar with house types of all kinds and age My humble opinion is that older houses with floor boards, either cavity or externally able to have insulation are suitable for heat pumps. More modern houses with concrete floors and microbore are not. Unless you have £15-20k before any grant. Simply not viable for the majority of the population. Especially with payback running into multiple decades. Then they’re the usual maintenance costs. So for me it’s all about house structures. And what would be achieved ? Cheaper energy costs ? Maybe but only if you exclude installation costs. It’s simply not viable for the majority of households both in costs and practicality. Great for those like yourself, no issue there with me. But like EVs it’s only for the few and a lot of those will be virtue signalling because they can afford it. It would have been handy if you had shown your total costs against a new boiler and also that payback time

[@waynekerrr9027]

My combi boiler was fitted by my son.. £1200 fully fitted....heat pumps waste of cash

[@JamesRattray]

I think everything has its place. Great to have a practical son. Thanks for sharing your thoughts with us.

[@john-eo1ns]

Rich man's toy, he says it all gas is 4x cheaper than electricity and he is relying on cheap electric during the early hours to justify his purchase. What happens if the Government changes the goalposts on cheap electricity. Oh and he also needs the solar and batteries. Don't be conned by these virtue signalling signalling videos I am saving the plant. This is way beyond the budget of the average working person.

[@JamesRattray]

There are all sorts of grants available many only aimed at the less well off. The Eco 4 scheme is aimed at those on benefits from what I can see. There are also grants for insulation for the less well off. www.ofgem.gov.uk/environmental-and-social-schemes/energy-company-obligation-eco/homeowners-and-tenants/faqs-domestic-consumers-and-landlords

[@john-eo1ns]

​@@JamesRattrayJames I do not believe the co2 in the atmosphere causes global warming, therefore any new technology should not be forced on the populace, nor existing technology phased out by political decisions. To me any transfer to new technology happens naturally by market forces, eg videos, mobile phones, vinyl to tape to CDs to downloads etc. The science is corrupted and used as evidence to force change by politicians. If your house is now highly insulated I would watch for black mold, no draughts to let moisture escape a hidden hazard and consequence of this new religion.

[@hughrattray9354]

Octopus energy and some other installers are offering to install a heat pump without any charge to the customer for smaller properties without too many complications. In other words they can install the heat pump within the grant money offered by the government.

[@john-eo1ns]

@@hughrattray9354 Hi Hugh, so we have a government driven agenda, why don't they offer the fit gas boilers without any charge? You are an intelligent guy surely you can see co2 does not cause global warming the evidence is out there, but it is the basis for all life on earth, why do commercial greenhouse growers pump co2 into their houses at 1200ppm? Because the plants grow bigger, stronger, more drought resistant plus more pest resistant and produce a greater harvest, its because of rising co2 why with a rising world population we are able to produce enough food. If co2 falls below 120ppm that's it life over on earth no plants, yet our past history shows we have had levels in the 1000s rather than to much co2 we have intact a dearth at around 400ish. I have nothing against heat pumps however this technology should not be forced on the population by regulation nor stealth, nor by paid for biased science propaganda by a government to comply with an unelected body the WHO and UN etc.

[@BenIsInSweden]

​@@john-eo1ns You mean like they did with the Energy Company Obligation, and Boiler Scrappage Schemes? Y'know with the government "forcing" energy efficient condensing boilers on people. Not sure where heat pumps are being forced onto the population either to be honest.

[@UpsideDownFork]

Wow, this is an incredible video that I wish I had found before I started my journey! I had to learn so much of this the hard way! I'm also documenting my heat pump journey which also has microbore and a 7kW Vaillant Arotherm Plus! kzbin.info/aero/PLxiY5khGACu3S5XxEI8_bhkX6H8DOR2VW&si=-TxNtZx-YeF2WZ1C

[@JamesRattray]

You certainly have done a great job in sharing your experiences. When ever there has been change in history, there has always been those who rail against it. It would make a fascinating book if anyone was prepared to research the topic. There was a strong lobby against trains in the mid and early 19th century. Some people said the human body would disintegrate, if it travelled faster than 20 miles per hour. Also you would suffocate if you went into a tunnel on a train. So many early train travellers got off the train, to catch a horse and carriage, so as to bypass the tunnel just outside Bristol on the London to Bristol line. Heat pumps and electric cars has a similar bandwagon of change is bad sceptics.

[@UpsideDownFork]

@@JamesRattray we can make a difference, one video at a time, but probably more important is the difference we can make with our friends, family and neighbours! Great to find another advocate!

[@hughrattray9354]

Great to see your journey too. I have put many hours into understanding the subject(as you say the hard way). The impact on friends and family has been significant. Several have already committed to heat pumps and others are very interested.

[@UpsideDownFork]

@@hughrattray9354 I love becoming a nerd about things but I look forward to the day where the heat pump market is mature enough to reliably serve any widow and get the right product, installation and setup. 👍

[@JamesRattray]

@@UpsideDownFork We have just produced a video on the Open Source Energy Monitor system, as there was a lot of interest in where you can find live information on the performance of heat pumps. Hope it is of interest kzbin.info/www/bejne/pp3Veqylqaisfqs