ASHP winter performance and cost to run

3 months cost and performance for our air source heat pump. How did it cope with -5ºC outside temperatures? How much did it cost us to run it over the 3 months? All these questions and more are covered in the this video.
JMR Heating & Energy Ltd: jmrheatingandenergy.co.uk
Open Energy Monitoring (OEM) website: heatpumpmonitor.org
Our installation on OEM website: emoncms.org/app/view?name=MyH...
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🔴 Setup:
4.0kW solar array, installed Sept 2011, 16 x 250w Sanyo HIT-H250E01 panels
- 3.8kW SMA Sunny Boy inverter
2.34kW solar array, installed Oct 2019, 6 x SunPower Maxeon 3 390w panels
- 2kW Solis Mini inverter
Tesla Powerwall 2 (Gateway 1), installed Dec 2018
Vaillant 7kW aroTHERM+ heat pump
Vaillant uniSTOR 200ltr tank
Hyundai Kona 64kW, delivered 1st July 2019 - Dec 2021
Tesla Model 3 AWD Performance, delivered 28th Sept 2019
Renault Zoe 22kW, delivered 5th Jan 2022
myenergi eddi, installed July 2019
myenergi zappi v1, installed Dec 2018
myenergi harvi x 2
myenergi hub
myenergi iOS app
Kaifa MA120 SMETS2 smart meter
Based in Rushden, East Midlands, UK
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[@markbrice2928]

Hi John Thanks for the update, we had a Vissmann Vitocol150- A151 fitted on the 6th December 2023 this is a 16kW unit. Based on the last 75 day we have achieved a SCOP of 4.49 after using 1,564kWh of power to achieve 7,030kWh of heat which is split roughly 82% / 18% heating / water. The best day being yesterday we achieved 6.07 against the lowest average of 3.24 on the 16th January. The main thing we have found is that the house is comfortable all day rather than the old days of oil where we only heated the house in the morning and the evening.

[@johntisbury]

Good to hear Mark. 100% agree on comfort levels, the heat feels much nicer as it’s low and slow, unlike the peaks and troughs from our old gas boiler. Controls make a huge difference to effective but also maintaining a stable indoor temperature

[@markbrice2928]

@@johntisbury also looking forward to Kirk Hill.

[@dahur]

This will be my 2nd year of being net zero. In 2021 I had a Rheem Prestige 5 ton heat pump installed, along with a new air handler and propane backup furnace. It's 21 SEER, and 11 on the heating side. Here in southern New Mexico USA, I also have 12.4 KW solar array. I don't know for sure how much power it uses because my solar makes a lot more electricity than I use. The first year, I had the lock out temperature set to 20 degrees F. We got down to the teens a few times and I ended up using about 20 gallons of propane for the year. Two years ago, I lowered the lockout temp to 15, and we never got that cold, so it never called for any propane backup.. The heat pump has no trouble heating, or cooling my 2200 sq ft home. I also have a Rheem heat pump for hot water, and a Samsung heat pump clothes dryer. I think heat pumps are the way to go.

[@johntisbury]

100% agree on heat pumps being the way to go. They work magically and efficiently doing both hot and cold. Great to hear about your journey too and that the propane backup is getting less use.

[@andrewdeans2179]

Thank for info I am looking forward to get air source heat pump and will get open energy fitted info Great cheers

[@johntisbury]

Thanks for watching Andrew. OEM has been so useful, I look and refer to it daily. Rarely use the Vaillant app.

[@EVPuzzle]

Really good to have this data helping confirm your system is working as you expect . Its a complex system with cycles and flowrates bit i guess if you sont look at the data it seems simpler😂 Great to see it perform so well over winter

[@johntisbury]

Thanks Nigel. It does take time to know what to look for and what good looks like amongst the data. We are really pleased with the installation and its performance.

[@EVPuzzle]

@@johntisbury I'm sorry of envious of all that extra data and visibility of your COP values

[@johntisbury]

@@EVPuzzle data is king as we both know.

[@anthonydyer3939]

I’m watching your video as I’m getting my heat pump installed! My propane supply is disconnected so I suppose my house is technically “fossil free” now (though the tank still needs to be dug out and removed). Wood burner is excellent for temporary duty. Very interesting to see your performance stats between cold and mild days.

[@johntisbury]

Great to hear Anthony and I'm sure you will be happy with it. We are delighted with ours and its efficiency to date especially given the performance constraints around copper and plastic micro-bore we have in our installation.

[@glyn1782]

Hi John a great honest review, as usual that’s what I like about your vlogs honest and genuine every bit of detail included unlike others.The electric consumption of the heat pump is very good compared to gas . Two questions do you think another battery is worth it for the little peak power you would consume for 6/7 months of summer it will probably only be used very little. Second on the EOM site some users have a black line for in door temperature I just wondered if that is a separate piece of kit you have to purchase ? Looking forward to your solar battery and car stats take care Glyn 👍👍👍

[@johntisbury]

Thanks for watching Glyn. The second battery point is a good one, looking at the stats for peak usage no. However, to get such a low usage means a daily plan and vigilance to obtain it. A second battery would free up that somewhat inconsistent forecasting and planning. At the same time we will upgrade the Gateway from Gen 1 to Gen 2 which has full off-grid capability and backup reserve features. Currently we have no off-grid facility. In addition we are getting a couple of A2A units for air conditioning in the glass studio so again a second battery will ease the strain with that and allow us to pull 10kW house load rather than the 5kW at present. We often find that with the heat pump running on cold days and cooking we nudge the limits of the 5kW that having 1 Powerwall can deliver. I too have seen the indoor temperature too and did wonder myself how they have achieve that. I believe it's via MODBUS but I'm not really too well versed to advise. A good place to look is the OEM forums. community.openenergymonitor.org/t/welcome-to-openenergymonitor-faq/8/2

[@glyn1782]

Thanks John the back up gateway and powerwall is brilliant I can say for sure.Last summer on many occasions on a very sunny day I was charging both ev one on zappi pulling 7.2 kw and granny charger on other pulling 2.8 kw when cloud cover the zappi rampted down to 1.4 kw granny carried on obviously up and down all day with NO grid draw . Powerwall app showed no peak grid draw in all of 2023 but octopus billed me for 3.6 kw over all of 2023. The cold weather we just had my powerwall charged at 5 kw at 11.30 every night to full then just sat there until 5.30 before discharging unlike many other batteries. We have had probably 75 power cuts some minutes some hours gateway performed perfectly and uninterrupted solar in power cut until battery full then it just alters the frequency and turns your inverters off until battery down to 90% then inverters start again and the cycle continues. So now I have learned to put the car on charge in a power cut ie 1.4 and let it ramp up and down ‘

[@johntisbury]

Good idea on car charging during a power cut to make space for solar.

[@Jaw0lf]

Thanks for the figures, my ASHP used 311.24kWh for November 2023, 517.72kWh for December 2023 and January 2024 was 710.76kWh, maintaining 18c all day with 2c drop overnight. Still looking into the open energy monitor and looking an expensive but wanted add on!

[@johntisbury]

Thanks for your stats. OEM is essential if your a data geek and want to improve your heat pump’s efficiency

[@OH2023-cj9if]

Still more expensive than my gas boiler heating to 23c between 5 and 9pm, then dropping to 20c overnight and 21c from 6am to 9am. The only time it's off is if no one is in during the middle of the day, but on all day at weekends! Considering the cost to replace my lovely efficient gas boiler, I could put that money in a savings account and use the monthly interest to reduce the gas bill. If electric was cheaper, I would change over. The only people saying heat pumps are cheaper to run seem to be the type that were scammed in to fitting £10k+ solar and battery systems and found they wasted a lot of money for negative returns. At least they can provide a bit of power each day. Is it worth all the expense? No! It's a hobby to some, something to spend savings on.

[@Jaw0lf]

@@OH2023-cj9if I am off grid as concerned to mains gas so LPG costs were going crazy. So a massive saving and we are home pretty much all day so keep the home at a steady temperature. Funny thing is in general, solar does not cover much in the winter, when the ASHP is used. However in the colder but sunnier days we can use solar to run the ASHP. I have never had free gas to my boiler when I had it. I also Offset a lot of my electricity cost by use of my battery, so pay just 7.5p per kWh for a lot of my use. I don't believe anyone was scammed to fit solar or battery as they do shrink your monthly bills. Payback will be over years and a nice investment in the home. I now pay £90 per month for all of my heating, cooking home use and around 10,000 miles per year in my EV. It can and does work. Biggest thing is being on the correct tariff.

[@davidelks7684]

Hi John. Many thanks for all the detailed figures and facts herein. You mention you have one battery already, and might benefit from another - what capacity do you have, and how many additional kWh might you consider increasing to? I looked to see if I could understanding how/when peak rate electricity was being called upon - can you shed light on this at all? Second point - is the COP for heating your hot water typically lower due to the need to heat hot water to a higher temperature than you heat the radiator water to?

[@johntisbury]

Thanks for watching David. We have 13.5kW battery storage, looking to double it to 27kW. I look at my bills (retrospectively) as peak/off peak is shown in 30 min time slots and the Tesla Powerwall app (realtime) to see what’s happening when we are peak rate. Second point, exactly that.

[@eliotmansfield]

I think the openenergy monitoring is essential with heat pumps as it’s the only way to know what it’s doing in the real world

[@johntisbury]

I do agree with you. It's not for all folks it has to be said. However, if you want to maximise efficiency and know what's happening with your system then I'd say it's essential too.

[@oswaldconsultancyltd3150]

Well done John. Very interesting. I’m designing/sizing my own hp. Probably Vaillant. I’m interested in open loop control /full weather compensation and how you get in when the sun heats your sunny room. I have similar. KBO.

[@johntisbury]

Thanks for watching. Solar gain can be a blessing and a problem. If you have too much solar gain then you can set the controls for the heat pump to take into account the indoor room temperature and place the controller in that room or location where the sun falls. It still does weather compensation but also blends in the data from the room thermostat.

[@oswaldconsultancyltd3150]

Thank you John. I didn’t know you could “blend temperature measurement with weather compensation”. Thank you for the info.

[@johntisbury]

On the Vaillant aroTHERM+ there's 3 settings for Room Temperature Modulation : Inactive (not used and uses pure 100% weather compensation with no room influence), Active (adjusts flow temp based on current room temperature), Expanded (Adjust flow temp based on current room temperature but also activates/deactivates the zone)

[@peterjones6640]

John will you be doing an update on your PV performance during the winter?

[@johntisbury]

Yes, it’s next on my to-do list. A 3 month update.

[@johntisbury]

Peter, video now live of solar PV performance during winter and for 2023 kzbin.info/www/bejne/oXayhKKera6crbcsi=-cpwAKdIZScH5QQI

[@peterjones6640]

@@johntisbury Thank you John, I watched it yesterday. Useful background for when hopefully I build my new house .

[@davidgordon773]

Hi John. I’m about to get my heat pump. I’m interested to know what size storage battery you have . You are clearly on Intelligent Octopus Go, as am I. I have 6kw of solar and a 9.5 kw of battery and wondering if this will run the majority of my heat pump usage. I’m finding it difficult to get my head around it all. I read recently about the new Cosy tariff with its three cheaper rate windows. Although a higher off peak rate there is the opportunity to charge the battery three times in a day as opposed to the once with Go. The proposed heat pump is 8 kw Daikin by the way.

[@johntisbury]

Hi David, it can be tricky to forecast how much you need. During the last heating season 2023/24 we found that on cold winter days, circa 1 - 2ºC the battery lasted till around mid morning. We have a 13.5kW Tesla Powerwall. We've now added a second Powerwall brining us up to 27kW of battery storage, even that won't last all day. You should find your 9.5kW will suffice on average winter days of 10ºC or so. It's when it drops below 5ºC that heat pumps start using more electricity. Our 7kW Vaillant used 35kWh over 24 hours on days when it was 2ºC outside.

[@davidgordon773]

@@johntisbury thank you John for your prompt reply. The extra battery capacity certainly looks to be a good option. Thank you.

[@johntisbury]

@@davidgordon773 go have a look on heatpumpmonitor.org if you've not done so already. You can find comparable setups. There's Daikin installs on there and hopefully ones with a similar house size. It will give you some real world data of usage.

[@robinedwards218]

I've watched John's video a few times now and as a bit I'm a bit of a geek(background mainframe systems programmer many years ago) I'm kicking myself. I tried to change my spots with this, but apparently leopards cant get stripes. I decided to be hands off non-geek. I didnt get an OpenEnergyMonitor and wish I did. Vaillant Arotherm+ 10kW installed to replace combi. Vaillant tank added and radiators cascaded getting four new big rads and throwing away three for a total of 17 installed. Anyway all of that was OK. Install was week of 11/3/24 and went pretty well. What I'm missing is the fine detail of data to be able to tune the system. The target was 4.49SCOP with design flow temp of 41C. So far we're sitting 3.8 for the month (myVAILLANT app). I've gradually moved the heat curve from 1.1 down to 0.90. Last night I dropped it to 0.80 and today we have a COP of 3.9. Advice: get OEM if you can, because you can't un-geek. Question (if you're looking at this John) were you planning on running dhw cycle at different times depending on season? I guess with your decision to go to second Powerwall that becomes less of a question. I'd trying to think through avoiding export to grid if I can benefit.

[@johntisbury]

Hi Robin, agree with you about Open Energy Monitoring. My recommendation is get Open Energy Monitoring if you want to understand your heating system and be able monitor its performance. For DHW I’m running it at the warmest part of the day 1pm - 2pm. That may change as things progress with the 2nd Powerwall.

[@robinedwards218]

Thanks John. I guessed the second Powerwall would change thinking on things such as DHW time. With 'only' one I'm a bit tight on capacity. BTW, somebody told me that you get a small discount on a second, have you heard that? I think I'm stuck on fitting an OEM in retrospectively. The guys did a great job with the install but there is a very short length of pipe between it coming through the wall and it being split to CH and DHW, definitely not long enough for adding the Bad decision on my part I think, I guess it will take me longer to tune the system without the data from OEM.

[@johntisbury]

@@robinedwards218 Agree with you that having 1 Powerwall it is a bit tight to use for DHW, ASHP and general household use. This was the main trigger for getting a second one. There's no discount for getting a second, although all home storage batteries now attract 0% rated VAT so it's kind of a discount. Local installers may offer incentives but it's not a Tesla driven marketing campaign. Be careful on the placement of the heat meter if/when you go down the OEM route. They are very sensitive to turbulent flow near bends, valves and pipework constraints. They require lengths of straight pipework to function correctly. Installation manuals give minimum distances to bends etc, along with vertical/horizontal dos and don'ts.

[@joewentworth7856]

Your open energy show flows below 40. So something must be limiting not just weather comp. But you say you needed to change the wc number from 0.4 to 0.6 . Exactly what I had to. I found .4 is a flat curve where as having 0.8 but with a target room temp of 19. Gives a steeper curve. So the warm weather flow is similar to .4 at a high room target. But the flow if boosted on the colder days and with bit of fiddling I got a setting that is set and forget. With a good scop. I also notice you do legonella at 4 am. I guess to get cheap rate. But as you mention its more energy efficent to run at the warmer part of the day. Finally! You say you might need another battery, I wonder if agile octopus would be an option. Much shorter peak for your existing battery to run through. But the low rate not as low. Needs number crunching. But another battery is a significant cost.... Great content.

[@johntisbury]

Thanks for watching Joe and the points you raise are good ones. Let me respond to your points / questions one by one. 1. Legionella setting. The setting defaults to 04:00, if you notice on the video of the sensoCOMFORT screen the Anti-leglo. day:off. This means we don't run a Legionella cycle. Most people don't need to run it to be fair unless you don't turn over your water volume frequently or have it set to a very low temperature. Heat Geek has done a great in depth video on the subject: kzbin.info/www/bejne/pXvIqpaVmKx8g7csi=IM-xCg8bPoqqGFsN 2. We have decided on a second battery to ease the daily chimping of weather apps, solar forecasting websites, decisions on whether to charge not to charge etc. Whilst it's kinda fun second guessing the weather and solar forecasts it gets a bit frustrating at times when we have to pull from the grid at peak rate due to a poor decision based on the data at the time. With a second battery we will have 27kWh of battery storage and hopefully, with the DNO approval being positive, we will be able to export and get paid for it at saving sessions run by Octopus Energy. Currently we have no export option in place. I've been on Agile previously and whilst it was good it added another task for the day ahead forecasting. As we don't have an even daily routine for electricity usage it's tricky to apply the Agile tariff as a set and forget approach. 3. The heat curve as its name suggests is a curve. The 0.4 curve will only achieve a 40ºC flow temp only when it gets down to -15ºC with a room temperature setting of 20ºC. At 5ºC outside temperature the 0.4 heat curve will produce 30ºC flow temperature water. There is nothing limiting the flows other than pure weather compensation. If a home has lots of solar gain then pure weather compensation may not react quickly enough and certain rooms may overheat. This is where the option to include the sensoCOMFORT room thermostat comes into play by placing it in the warmest room and moving from inactive to active mode for Room Temperature Modulation. As you point out getting the right heat curve is a bit of trial and error but once you find the sweet spot for your house then it should be a set and forget. We are still in the learning stage as it's our first winter with an ASHP. Mick Wall has written a comprehensive article on the subject which is well worth a read if you have time: energy-stats.uk/vaillant-arotherm-weather-curve-information/

[@Triune3]

That’s the difference in price on viessmann. They have ESBE Valve on their heat pump. Also the quality is spot on their product.

[@johntisbury]

Is that inside the heat pump?

[@AirCommodore64]

Hi. I see your heat loss report says 8.4kW and recommended a 7kW ashp. Have I read this correctly and why wouldn’t your ashp meet or exceed heat loss? Thanks.

[@johntisbury]

It's a good question. Many heat pumps will work above their stated rating. Vaillant aroTHERM+ 7kW can output up to 10kW with a 35ºC flow temp at 2ºC. At our design temp of 40ºC flow at -3ºC it can pull 8kW. So there's latitude there for it not to be underpowered.

[@AirCommodore64]

So your ashp should have excellent modulation as it doesn’t appear to be oversized.

[@johntisbury]

@@AirCommodore64correct.

[@johntisbury]

@@AirCommodore64 FYI over the past couple of days with slightly warmer temps it's been ticking along. Today for example from midnight to 11:00am it was ticking along using 570w energy usage with no cycling. Long and slow. Almost 12 hours of a constant run. Turning on is where the largest power draw is until it settles down.

[@Divinefemininemiracles]

Advice needed pls. I am in an old stone cottage on a hill, i have qualified for a grant for 2.8kwh solar a 12kw samsung ashp (no choice on make model its a gov /energy company grant) and my upstairs to be insulated but not downstairs.. currently on lpg tanked bulk with epc F hence why i qualified and low income.. im nervous about the running costs as this is a very old house and i have heard horror stories about the cost to run. Can anyone advise me on if to go ahead or not ? I also have a 5kw log burner but it's in an enormous inglenook so barely heats the living room .. thx

[@johntisbury]

Thanks for watching. Tricky to answer your question without some additional information. What is the heat loss for the cottage? This would have been completed when they specced the 12kW heat pump. What is the design flow temperature for the heating system, e.g. ours is 40ºC flow temp when it's -2.5ºC outside temp. Those two bits of information will impact your running costs and how hard the ASHP will need to work to keep the house warm. The lower the flow temperature the cheaper it will be to run the system. Are you having new radiators fitted? The solar array sounds very small, I guess you don't have much available roof space? A 2.8kW array will not offset your electricity usage costs by too much. It will certainly help and is better than not having anything - so that's a good thing. The second variable is which electricity tariff you are on. Heat pumps are efficient, much more so than gas boilers or LPG. Being on the right electricity tariff is very important as heat pumps are most efficient running low and slow, e.g. you keep them on all the time. We have ours set with Weather Compensation and it's technically 'on' 24/7, 365 days a year. It only actually turns on when the outside temperature drops below 16ºC with our setting. I don't know the cost of LPG to buy, however I suspect it's not cheap. Trying to heat a house with an EPC of F will be very expensive no matter what the fuel source as it will be like trying to heat a house made from Swish cheese with all its holes. With the installation improvements and the solar contributions you should find it more economical than LPG. However, that costs to run will be very much dependant on the design temperature of the system and your electricity tariff. The horror stories you have heard will be the edge cases. The majority of current installations are well done and heat pumps are certainly cheaper to run than gas, LPG or even wood burning stoves if you are having to purchase the fuel source. I guess the worry would be the reputation and professionalism of the companies who are carry out the work. Often they can cut corners, not do a good install as they are getting paid via the scheme rather than direct from a consumer. Worth trying to obtain references and see who else has had work done by them before pressing ahead. I have done a more details video on the installation of our heat pump, the design stage and the whole installation process. That might be worth watching to give you an idea. The design stage is the critical bit to get right.

[@Divinefemininemiracles]

@@johntisburythx for that. I don't know what the heat loss is I can find out. My current electric tariff is variable with eon and is high but i could change. They seem like a pretty reputable company and yes they are increasing the radiators forgot to mention that but I am not sure exactly of which yet I have asked for specifics. They are also fitting direct ventilation system which again i have no choice it's part of the package. That's all I know thus far.. i will ask for references. Solar is 6 panels no battery. I have asked them to let me have an approx usage cost they said they will work out. I have pushed for downstairs insulation but the funders said no . The upstairs insulation is classed as room in roof as it has slopey ceilings everywhere. 🤔

[@johntisbury]

@@Divinefemininemiracles feels like you are asking the right questions. The Heat Loss figure and the ASHP design temperature will be 2 important pieces of information.

[@Divinefemininemiracles]

@@johntisbury👍ty

[@rdelhomme3016]

The length of pipe outside of the house (the warm side) is rather large. With 25 mm pipe, 40° difference water-ambiant air, loss is 45W per meter.

[@johntisbury]

All true, but no other option in terms of installation location.

[@rdelhomme3016]

@@johntisbury other option, to increase pipe insulation, is small cost, hight efficiency. Small is beautifull unless if we discuss insulation of the hottest spot.

[@arnovdmeer]

Heating domestic water in the afternoon gives you a better cop but with the nightly later its far better to heat up the water at night if you look at the real cost

[@johntisbury]

I guess it depends on what your heat pump is powered by. During the day ours runs on excess solar and/or battery. At night it will most always be from grid power albeit it at cheap rate. Cheaper for us during the day if costed out.

[@AndyJHiscock]

Great video. The energy bills look abotu the same as my whole house (gas and electric & charging) so for me no real benefit.

[@johntisbury]

Thanks for watching Andy. I always think it's tricky to compare usage against someone else's as there's just too many variables around lifestyle, family size, comfort levels in term of thermostat settings, typical daily routines and how much electricity / gas is used.

[@geoffmansfield2668]

I am now 72, and aware that I am loosing my ability to problem solve I.e. I’m moving from Geek to normal. The average person would not pick up the problems/finesse of the system, would not therefore achieve COP > 3 (Break Even Point for gas combi), and just say ASHP don’t work. How can the country (or me in a few years time) sort this issue?

[@johntisbury]

As the heating industry improves and installers become more aware of the remote monitoring systems available to them, the onus will shift from consumer to installer. We are still in early adopter phase.

[@geoffmansfield2668]

@@johntisbury I'd forgotten we are 'early adopters'. The 'Heat Geek' insurance scheme (for which you pay a premium) seems a good safety net for my senile years! The expense of it will put most normal people off; with the consequential result SCOP will not be what that could achieve, and the tabloids get more stories ☹

[@johntisbury]

I firmly believe as installer experience grows so prices will come down. Installs will be become quicker, more efficient and manufacturers will embrace innovative products and tools to aid this. In 3-5 years the industry will look very different I feel.

[@geoffmansfield2668]

@@johntisbury I wish I could be as optimistic as you. I have closely watched five year of new builds and conversions round here in West Yorkshire. Always gas boilers, never solar panels and just one ASHP. The working plumbers I talk to (challenge!) all have enough traditional work swapping out boilers for new combi ones, “cannot afford to go on courses” etc. If ten years ago, our pathetic Government had set a road map that forced all new builds to have ASHP (+ solar) from 2018, we might now have a small workforce with those skills. Liasse faire has been an excuse for atrocious leadership. Sorry John - rant over. P.S. love your work

[@johntisbury]

@geoffmansfield2668 you are not wrong. Lack of direction and consistent policy has slowed the UK transition down, helped by the fossil fuel industry and their pie in the sky hydrogen model for domestic home heating. The heating industry is pivoting to ASHPs, many of the heating engineers I follow have not fitted a gas combi in the last 12 months. Gas boiler installs will slowly reduce in volume and die, plumbers will either retrain, retire or move industry.