Super high efficiency - how heat pumps perform in Autumn

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When you are paying close attention to heat pump performance you start to notice when it is the most efficient, and the times when we start to need heating as the weather gets cooler each autumn starts to see super high efficiency. This is partly because the weather is still quite mild, but cool enough to need heat. This autumn we have seen weeks where our efficiency has been above 400% and an average of 376% between 22nd September and the end of November.
Now we are in a cold snap, the efficiency has definitely dropped and you can tell it is winter. But before we hit winter, we see big savings linked to the heat pump, in both costs and CO2.

[@alanmcguinn]

Love hearing your perspective Tom. Definitely one of my favourite KZbinrs!

[@TomBray-LowCarbonLifestyle]

Hi Alan, thanks so much for commenting! Really appreciate the support Tom

[@1943L]

It all sounds good Tom, making my 20 year old gas boiler look sick. Big changes ahead.

[@TomBray-LowCarbonLifestyle]

Great to hear!

[@terryrigden4860]

Very informative, thank you. Our heat pump gets fitted after Christmas, I'm really looking forward to not burning gas anymore. If we save money it's a bonus

[@TomBray-LowCarbonLifestyle]

Fantastic Terry, thrilled to hear that. What kind of heat pump will you be installing? How did you find the installer? Interested to hear how you get on! Hope it won't be too much of a change / disruption installing during winter!

[@DavidAspden]

County Durham / Northumberland is castles and wind turbines at most turns. I'd argue that if you look at the generation capacity locally the two counties are carbon neutral most days. Gross oversimplification ofcourse. The irony of it happening in an area devastated by the demise of coal is too much to handle.

[@TomBray-LowCarbonLifestyle]

Hi David, I suspect you are right, if you look at the national grid stats the North East is often some of the lowest CO2 electricity - carbonintensity.org.uk/. We also have the Hartlepool Nuclear Power station nearby. I sometimes say - move to the North East, reduce your emissions! Imagine if the attacks on North East industry in the 80s/90s had come with investment in green technology... There is the school of thought that flooded mines give an opportunity for extracting heat, a couple of successful projects already in the North East using the mines for heating. Not the solution everywhere but could be some opportunities across the North East Thanks for the comment Tom

[@oncomingdrizzle]

I really love your videos and all the data you present is brilliant and you've inspired me to make a plan for our small 1900s Victorian terrace. But there is a definite Dad telling you "Don't Touch The Thermostat!!" vibe to it as well which I just picked up on and had a chuckle about. I will definitely be that person looking at the COP and optimising to the nth degree when we get round to getting ours in (a year or two away; insulation first),

[@TomBray-LowCarbonLifestyle]

Hello - thanks for your kind comment! And pleased that you might be able to make a plan for your house. Would love to hear how you get on! Thanks Tom

[@Loopyengineeringco]

Great easy to understand video, thanks! Similar story with my house, but we went from a 40 year old back boiler which was probably less than 70% efficient, and getting similar figures now. Just managed to hook all my 3rd party data into heatpumpmonitor, it's a really great tool to keep an eye on systems and levelling expectations 👏👌

[@TomBray-LowCarbonLifestyle]

Thank you for commenting! I suspect going from an old boiler means you could be saving loads! Which is yours on heatpumpmonitor? I wish I was more competent with this stuff as I suspect I could get ours onto there. Have a Sontax heat meter and we have been connected remotely to a research project that has now ended, so I suspect we could send data elsewhere without much work… out of my expertise just now!

[@DMFPERFORMANCE]

I have the same 5KW Aerotherm+ and the cop is crazy efficient at the moment. According to the app, I use 5kwh of electrical power to generate 29kwh of heat. It's brilliant. We have our unit 390mm in front of the end of a conservatory with metres of clearance either side so its optimum. The COP if I calculate correctly is 29/5=5.8. I'm elated.

[@TomBray-LowCarbonLifestyle]

That's fantastic. I don't use the Vaillant app as we don't have a gateway installed as part of our system so can't compare but this week we have had a COP over over 4. I think the mild weather is helping! Anything over 5 is extremely high efficiency! Thanks for the comment and engaging with the video Tom

[@nickflynn666]

Average working gas boiler efficiency in the UK is 80%. You only get over 90% with a new gas boiler and large modern radiators and underfloor heating, both or which will allow you to run your gas boiler at low flow temperatures.

[@TomBray-LowCarbonLifestyle]

Hi Nick, I suspect you are right, I tend to use a high efficiency figure to compare against to make sure people don't suggest I am biased, but at 80% efficiency. If I compare against 80%, I would be saving £80 this autumn on the agile tariff, or £40 on standard tariffs. It would be great to get gas boilers working at low flow temps! Tom

[@user-ry7yg2hk7i]

Highest efficiency for boiler when made hot water is 85%, and best gas boiler obtain max. 90% for both heat and hot water. Plus it consumes even more electricity especially for high efficiency. You obviously saved more carbon dioxide than you calculated.

[@jeanh9641]

That was great presentation. Your enthusiasm shines through. I am in the bery early stages of getting ashp. Waiting for Octopus survey. I feel the cold and need the room temperature to be at least 20 degrees Celsius. Thank you for sharing your personal experience of living with a heat pump. It gives me more confidence to press ahead.

[@TomBray-LowCarbonLifestyle]

Hi Jean, thanks so much for commenting and kind words. Sorry it has taken me a while to get back to you. Pleased to hear you are looking into a heat pump, I hope the process goes well. I would be keen to hear about your experience with Octopus. There is a someone near me in Durham who has just had an installation with them, that appears to have gone well. Hope you are able to navigate the process ok! Thanks Tom

[@AndyKennedy]

Thanks for sharing this, pulled the trigger on Octopus' heat pump scheme and just waiting for installation now, it's reassuring that even after hours and hours of research over the months before committing, that people are finding ways to make them even more efficient - have you ever thought of doing a rundown of everything you've done over the years on yours in simple terms and showing people how? I know I'd watch it in a years time! Keep up the good work.

[@TomBray-LowCarbonLifestyle]

Hi Andy, well done on taking the step with Octopus, would love to hear all about your experience. The closest thing to a run down on the changes I’ve made is this video kzbin.info/www/bejne/pqLSdpadpq2XfLMsi=OHiq6hJoQsBgoJHu It’s all about getting the flow temperature down as low as possible, and to help with that, minimise the set back overnight. When is yours being installed? What heat pump are they putting in? Hope it all goes well! Tom

[@AndyKennedy]

@@TomBray-LowCarbonLifestyle June. Think you've maybe just answered a question of whether I should get the bathroom radiator exchanged too then as they said that one's optional but ideally they'd want to take out a nice grey towel rail for a full white radiator 😭

[@AdamNoble-cj2he]

Hi Tom, big up the north-east. I'm a Gateshead lad originally but am now up in the highlands. Durham is a great spot. I've been watching your videos since we had out Vaillant 12kw heat pump installed in April. We have loved having it so far. I'm curious about how you have tweeked your since having it for a few years? I'm trying to make the most of our octopus cosy tariff and boost the heating during the cheaper periods and keep the setback 2 degrees less during the other periods. The weather for the past week where we live has probably averaged -5 or so. I've noticed a massive increase in our energy useage being around 50-80kwh daily. That seems a lot?? I can't seem to find anyone to compare with. This does include charging our 10kw energy battery during the cheap period as well. What temperature to you have your dew set to? Sorry for rambling, just wanting to be as efficient as possible. For context we're in a 5 bed detached kit house built in 1989 so reasonable insulation. Cheers

[@TomBray-LowCarbonLifestyle]

Hi Adam, come on the NE! Although I can understand the move up to the highlands, maybe one day for me...! The tweaks I have made have been all about driving down the weather compensation curve, running the heat pump for as long hours as possible and minimising the set back. I would say that running a heat pump like this doesn't really work with Octopus' smart tariffs as you are wanting to deliver heat all the time rather than boosting during the times of low costs. I do make sure our hot water is only generated outside the peaks. Our usage for the last week or so in Durham has been around 25-30 kWh per day, we are in a 3 bed terrace and temps haven't been quite as low as -5°C but this has been a big jump on the rest of Autumn. 80 kWh in a day is a lot but bigger, with more surface area to lose heat could make sense, but I suspect you are better insulated than us... What is your weather compensation curve set to? How big is your hot water tank? We could book in a call one day to compare settings on the Vaillant controller? Thanks Tom

[@gregevans8939]

Tom... you may want to look at how much space there is for the outdoor unit to get rid of all that cold air... I can't see the space properly in the video... but you don't want the unit sitting in a pile of cold air... makes it work harder for the gain.

[@TomBray-LowCarbonLifestyle]

Hi Greg, thanks for the comment, the cold air is blown out the front and warm air drawn from around the unit. I doubt there is much mixing nor reduction in temperature of air taken into the unit. I doubt my installation is perfect. And others have commented that space for servicing is limited. Haven’t had a problem for the first couple of years. But something you don’t realise when first installed! Thanks for engaging with the video Tom

[@benetra]

Implicit new definition of autumn as a season: ends when snow is falling. Would be interesting to know which period you are referring to in this video. And if possible, get an indication of the average outdoor temperature.

[@TomBray-LowCarbonLifestyle]

Hi Benetra, I think I do mention in the video that this was between 22nd Sept and end of November, basically because I took some meter readings on the 22nd, and felt that December is the start of winter... it is fairly arbitrary and, knowing the cold spell we have had over the last 7-10 days, and the impact that has had on efficiency, it would be more transparent to do a follow up video with the reality of winter heat pump performance, which I will do! I don't have an accurate figure of temperature at my house over that period, but have an estimate through an app that tracks this, and the average temp has been 9.2°C over the time from 22nd sept to end of November. The point I want to make in the video is that heat pumps during the shoulder months, September, October, November, March, April etc perform incredibly well. They work a lot harder in December, January, February but still heat a house, and during this cold snap for us, with an efficiency / COP of just below 3. I will try to report all this at some point this winter..! Hope that is a helpful response? Tom

[@benetra]

@@TomBray-LowCarbonLifestyle Absolutely! Thank you!

[@71brp84]

Great to see you're still getting additional small gains in efficiency. Do you think it would be worth changing any of your rads to K3s so you could reduce your flow temperature? As an aside, I know it's not your primary motivator, but if you're doing cost comparisons using a smart electric tariff, you probably should also use a smart gas tariff to, eg. Octopus Gas Tracker.

[@TomBray-LowCarbonLifestyle]

Thanks for engaging with the video! It is great to keep getting small efficiency gains, and it may be worth putting in some K3s, although I was worried when we had the installation that they would be really big.... before I do that I would think about adding some rads to a couple of spaces (we have an electric rad in our under the stairs toilet... which was a bad decision from me 5-6 years ago... or increasing the size of the towel rail rad in the bathroom. I think a lot about buying a couple speed comfort fans to increase the output of a couple of rads and bring the flow temp down.... and it could be fun to make a video about them! I haven't really engaged with gas tracker, so not at the front of my mind, but fair point! Just checked the current prices... really cheap! And maybe makes gas heating much cheaper... And, yes, not my primary motivator! Thanks again for commenting. Tom

[@edc1569]

Smart gas tracker! I had no idea!

[@v_0]

I think the wider adoption is going to be sold on cost of use over anything green. You’re not mentioning the standing charge on gas as well which you can now easily avoid by switching to an induction hob. That said, if you’re using agile tariffs, you’ll be avoiding the less greener electricity. Lastly, you don’t talk about comfort! Lower flow temperatures being on for longer is so much more comfortable to live in. Not stuffy rooms.

[@TomBray-LowCarbonLifestyle]

Hi V_0 Absolutely agree! This video was mainly about efficiency around heat pumps, but I think I have mentioned the rest of your points in other videos on this channel! And comfort is one of the main points Thanks for engaging with the video Tom

[@iareid8255]

Tom, you cannot exchange the CoP figure for efficiency, unless you are comparing it with another electrically powered heating system. The true efficiency in pure terms is the amount of gas used to generate the electrcity that power your heat pump. I can assure you that this is significantly much more and I doubt if your heat pump is as effcient as a modern gas or oil boiler. My sort of ball park figure used to be about 30% efficiency between generation and consumer, but one problem I have with that is that ground source heat pumps are claimed to have a CoP of about 5. Now basic physics states that no device gives more than the energy supplied to it. (Electricity is not energy, by the way, it is an energy carrier) which means the very minimum amount of gas used to generate the electrcity is five times plus which makes the average air source heat pump (CoP of 3) around 60% true efficiency. The other answer is that maybe the way the CoP is calculated is flawed and gives an overly high figure.

[@UpsideDownFork]

I'm not sure exactly what your point is. The grid is continually getting greener. The change in the mix over the last 10 years is quite staggering. Yes, there are losses in burning gas to produce electricity which then powers an ASHP but there are also losses with transporting gas to homes to be burnt in 80-90% efficient boilers.

[@gregevans8939]

Iareid8255... the bit you're missing is that an ASHP (like Tom is talking about) takes energy from the electrical supply AND the air... this energy is then used to heat water, which is what gets circulated around the radiators. The COP is merely looking at the ratio of electrical energy used (because we have to buy it) and the useful heat energy that ends up in the property (because we're using it to heat the place !). The balanced equation is 1 part electrical + 4 parts heat from the air = 5 parts in the house. You're right about the overall efficiency compared to gas... A typical gas fired power station (which is the single biggest supply source we have right now) is about 50% efficient... less losses in the transmission network will lower this again. BUT those losses and inefficiencies are paid for by the power generators. If you wanted to look at an overall efficiency so that you can compare to a gas boiler... for ASHPs... it's something like 30% (generation/transmission efficiency) x 400% (being typical, and target COP) = 120% overall. This compares to a gas boiler at maybe 90% (assuming correctly installed and setup correctly with WC etc.).... So, ASHPs are still more efficient overall.

[@joewentworth7856]

If we had a 100% gas grid then hp would not be a great option. To me this is why heatpumps have only become meaningful in the last 10years. As electricity used to be so grubby.

[@UpsideDownFork]

@@joewentworth7856 yep, just need the political will to shift the levies now...

[@iareid8255]

Joe, in practice we have with regard to any extra demand on teh grid. Gas is what balances supply and demand, and as demand rises gas output rises. Renewables and nuclear give all that they have available all the time and do not contribute to the extra load that heta pumps and evs cause.

[@Cashclever]

Well that’s not like that for me I spent 8k on a heat pump took my boiler out my bills have rocketed and we are never warm….be warned before buying

[@TomBray-LowCarbonLifestyle]

Hi Cash Clever, it sounds like your system could be improved. Have you asked your installer to revisit? What kind of heat pump do you have? There is likely away to improve efficiency, our system is 18% more efficient this year than 2 years ago. All about minimising the weather compensation curve and flow temperature, and increasing heating times Happy to try and talk through if you wanted me to Thanks Tom

[@edc1569]

How have they rocketed? Electricity is 3 x the price of gas, a poor heat pump installation should give you a CoP of about 3, should be cost neutral.

[@Loopyengineeringco]

I'd immediately go through the official channels & get the installers back to rectify, before they disappear or the warranties run out: MCS exists for ensuring standards & there are other systems in place to root out cowboy installs. There are many ways you can mess up a heat pump install. Boilers are forgiving, heatpumps are not. Many of them aren't achieving good efficiencies purely because of wrongly specified components, bad commissioning, 3rd party controls and people not being explained how to use them most efficiently.

[@lharris828]

I am wondering about my tariff - Octopus Go. EV charging monthly, heat pump taking 20+ 30+ up to 40kWh per day in cold weather. It all works fine but is costing. 🤔

[@TomBray-LowCarbonLifestyle]

Hello - thanks for the comment, the cold does give a bit of a shock each year. My usage is similar - 25-30 kWh per day during this cold snap. I think in December and January last year our usage was around 25 kWh per day on average. If this is operating at a COP of 3 this would be 75+ kWh of gas to deliver the same heat, which would be costing an awful lot too! In terms of tariffs, the agile tariff from Octopus this week hasn't really helped in terms of cost, a few days I averaged over 30p per kWh, and over the last week it has been 28.5p per kWh on average. In the past I have been on Octopus Cosy too which is supposed to be designed for heat pumps and I am thinking of switching back to that, although the high costs between 4-7pm do appear to punish heat pumps a bit. I wonder whether, with EV charging and a heat pump, cosy could be a good step, or the tracker tariff... although I wonder whether it would be minimal impact compared to GO.... The website energy-stats.uk/ gives some great comparisons of all of Octopus' tariffs and you may find this helpful? Thanks Tom

[@lharris828]

@@TomBray-LowCarbonLifestyle Any particular high cost period could be offset via my 6kWh batteries, but only for a time. Currently they are flat by 08.30am!

[@CaptainProton1]

32kwh of batteries charged on Octopus intelligent at 7.5p kwh and they run 2,000 sqft of house with 2 x Air to Air heatpumps, house electrics, cooking and hot water. Average usage this month has been 8p kwh due to having to use grid a couple of times when battery ran out.

[@lharris828]

I have not been able to find the COP for our Daikin h.p. so it's not obvious to me how I estimate the overall effectiveness. I expect that all is fine but I would like to know!

[@edc1569]

@@CaptainProton1 Huuuuge battery :)