Should I boost my heat pump during off-peak periods? - Will it save me money?
ฝัง
- เผยแพร่เมื่อ 30 มิ.ย. 2024
- If you have a heat pump heating system then you'll likely be running it for a good chunk of the day, including overnight. On a standard tariff you'll probably want to drop the set point temperature overnight so that you're not spending more money than you need to by keeping the house warmer than it needs to be while you're asleep. But what if you have a time of use tariff with a cheap overnight period, like Octopus Go or Intelligent Octopus Go? Would it save you money by doing extra heating during cheap off-peak times? I decided to build a simple theoretical model of heating and heat loss in a spreadsheet to see if I could work it out. Brace yourselves, it's going to get nerdy.
Grab a copy of the G-sheets spreadsheet here (once open go to "File: Take a copy" and save to your own Google Drive):
docs.google.com/spreadsheets/...
Our home system summary:
6.8 kWp solar array split E/W
5 kW Gen 2 GivEnergy hybrid inverter
14.7 kWh GivEnergy batteries
A2A heat pump heating/cooling system
Myenergi eddi hot water diverter
Fiat 500e EV
00:00 Introduction
03:26 Downloading the spreadsheet
04:24 How the model works
18:49 Model assumptions and simplifications
26:04 Estimating your house heat capacity
30:18 Demo 1 - constant heating
32:38 Demo 2 - high thermal mass house (block work walls)
42:51 Demo 3 - low thermal mass house (timber frame)
48:33 Demo 4 - milder weather
50:07 Demo 5 - taking it to the extremes
53:22 Summary and closing thoughts
Please note that Tim is not a professional consultant, just an enthusiastic amateur, so cannot reply to requests for advice or opinions on specific systems or green investment opportunities. Thank you for your understanding.
Support the channel and get £50 of credit by switching to Octopus Energy using my referral code:
share.octopus.energy/cute-qua...
Or buy us a coffee:
www.buymeacoffee.com/timandkat
![[MIRRORED] LISA - ROCKSTAR 🎸 MV version #LISA #BLACKPINK #ROCKSTAR](http://i.ytimg.com/vi/-U58DuCCtZk/mqdefault.jpg)
I think the green answer is simpler than you imagined. The green transition biggest obstetrical is the morning and afternoon peak of electricity. Reducing your usage during those times eases the transition to a renewable grid. Like you said pricing gives you the answer.
Take a look at the follow-up video I did after this one where I answer that question more comprehensively. It is pretty much as you say, but nice to see it actually calculated with proper values for reassurance.
Hi Tim, very interesting thought design and explanation. However when I have discussed it with her indoors, I got this reply 😊
We have never had the heating on over night.
We like it cold at night and most days have the window in the bedroom on the clip.
If there is any noise during the night to heat the house, you will hear it (so will the dog)
You find it difficult to sleep at night in the summer if it is hot.
You don’t need math to work out it’s not for us.
Tim, thank you but I have been told we are not doing this by the Boss 😊
Well, you are absolutely free to heat your house how you choose! But in any case I'd recommend not heating the bedrooms overnight even if you do heat the rest of the house, so I agree about that point.
Haven’t watched the whole thing but I run ours (and DHW) during the 6 hour intelligent period as it’s so cheap.
We use less during the day due to this but overall energy consumption does increase, however, costs go down quite a bit too.
Environmentally though, night energy is almost always considerably ‘greener’ so it doesn’t necessarily follow that increasing consumption means a larger footprint.
These are indeed all points I make in the video! I'm having a think about how I can calculate the relative green-ness of the different strategies as it's doable but not trivial. I suspect it's marginal in either case.
I already have the data to answer the green-ness question, just need to work out how best to do the calculation:
th-cam.com/video/bMA2uudMgsQ/w-d-xo.htmlsi=dkyHA7FlPfehq0T5
@@TimAndKatsGreenWalk I think of it this way.
Night time ‘loading’ means I don’t need a bigger battery to avoid any peak usage (or as much).
In all but the coldest days (-3c or less during the day) I rarely touch the grid during the other ‘peak’ 18 hours.
Thats def cheaper, and I’m assuming cleaner too. But I have nothing to specifically back that up.
Also means the battery can stay at the size it is, I guess reducing the ‘construction impact’.
@@ElectricVehicleMan yes, that's a good point about using the battery to effectively use off-peak power for your heating all day. That definitely will make it greener (and cheaper) overall.
I turn off heating at 9pm, increase the flow temps by +10 during my Go period, and turn it off between 430-9am.
With UFH this works well for us, as it gets brighter I might even have enough solar by 9am to cover the heat pump occasionally.
Fairly certain it saves us money, your modelling helps to confirm that 😊
So I should fill my house with thermal mass. A few pallets of breeze blocks in every room. Sorted. Interesting calculations. Cheers.
Our interior walls are aerated concrete already. The thermal mass for aerated concrete is not that high, hence their U-value. Better to use concrete blocks....but spread them out to increase surface area!! Don't tell the wife!! 😂😂😂😂
Build some book cases out of them.
Hi Tim, thanks for the video and spreadsheet work. Did you get any heat loss calculations from your A2A installer? Most don't and we did not. At some point are you able to show your system ie where fitted, where trunking runs etc. for interest. Great work! 😊
No, I did my own heat loss calculation using the Heat Punk tool I mentioned. And I already have you covered regarding the install video 😉
th-cam.com/video/PIgrN9uJfHY/w-d-xo.htmlsi=Tf-Qc7aPSxvbct8c
It is also worth noting that you will be helping reduce the price of electricity for everyone by using off peak electricity. Flattening the grid usage lowers the price of electricity. Too complicated to explain here but if you understand how single rate tariffs work then you will get the idea.
Yes indeed. I'm quite familiar with how electricity prices work having worked for EDF for a number of years in my past. Load shifting is certainly helpful in many ways, as you describe.
Hi Tim, great video and really interesting findings. I imagine a box of air might be similar to a conservatory.
Probably not far off.
a 12% saving is pretty decent. Although personally I’d veto upstairs being that warm overnight for sleep comfort :)
Agreed, I made that point at the end of the video too.
I think this boils down to whether your overnight temperature loss is more or less than off-peak price differential. i.e. if you start the night 10 degrees warmer than outside and end 5 degrees warmer, you've lost half of any energy you added - but if off-peak power is a quarter of the day rate, you still come out ahead.
Anyway, I can't believe an hour of spreadsheets was so interesting - great job!
Haha! I'll take that. Yeah, I knew it was going to be a long one when I started recording but wasn't expecting it to be nearly an hour. That is officially my longest video to date. I'm curious to see how many folks make it to the end.
Interesting. We have had our ASHP (air to water) for 2 years later this month, so will be able to give some real world running cost figures as we changed strategy this year.
The installers set the system up with a 55 degree flow temp which was what the MCS design said (SCOP 2.85 - which I now know isn’t great) and advised running it 24x7. We started with that but after the house being uncomfortably hot overnight and 80 and 65kWh consumed in 2 nights we changed to just running the heating during the day. Conscious that the heat pump was gentler and lower heat than the previous oil boiler we ran it for longer, trying 4pm-midnight, 12pm-midnight, etc. Consumption was a more reasonable 20-30kWh in autumn/spring and 50-60 in winter, with more on bitterly cold days.
Last summer I read articles where others had tested their LG ASHP in different scenarios and concluded that ‘long, low and slow’ was the least energy solution. The crux of the logic was that if you didn’t heat the house overnight and only heated it in the day has we were doing) then as you were running the heating over a shorter period, for you to achieve the target house temp it in a shorter period, it’d take a higher flow temperature and as heat pump efficiency drops with increased flow temperature, this would use more electricity overall.
And so this winter we’ve taken that advice and run our heating 24x7 but during the night with a setback temperature of 2.5 degrees.
The flow temperature is lower as a result, it’s 48 degrees not 55. Average daily consumption Oct-Jan 1st is 24kWh but I need to wait for the full winter period to make a meaningful comparison. Definitely notice that on very cold nights the heat pump can use 30kWh overnight and I’ve seen 90kWh in a full day, which is not dissimilar to what it was before in winter.
My leaning is towards this is a better strategy as the big benefit we notice is that the house is comfortably warm all the time.
Cost wise almost certainly cheaper even on the very cold days as we’re doing some of the heating on cheaper rate electricity
Yes, absolutely, lower flow temperatures will give better CoP so running longer and slower should work out better for A2W, I agree. Very interesting that you're able to compare these different strategies with large amounts of data. I've switched to overnight heating now so will be building up my own comparison dataset for a future video too.
Can you get bigger radiators? That would allow lower flow temperatures for the same hearing effect and better COP efficiency.
Hi Tim, thanks for the effort you've put into this information. I have a two unit A2A ASHP which I installed three years ago primarily as air conditioning for my very hot bedroom but it's working like a champ heating my living room. With the living space a comfortable 20degrees, some of the heat leaks into the rest of the house and I find that I don't have to have the gas heating on at all except when it is below 5 degrees outside. With the house in two zones, I had to treat my house as one very small house with poor insulation to get the toy model to work (the rest of the house is about 12-14 degrees).
As such, it seems that most of the overnight heat leaks away and it would cost me more overall to run the heating overnight on the low tariff. That said, I got good agreement with my real world energy use and battery savings - costing about £2.20 a day to heat my living space. (the rest of the house is a similar 480m3). Combine a cold bedroom with an electric blanket = great nights sleep 🙂
My personal green walk has dropped combined gas and electric household kW from 13300 to 4000 pa. Keep up the good fight. Jon
Nice, that's great to hear. I've got a much more complicated version of the spreadsheet which I'll be showing shortly but it's gratifying to hear that this simple version has some benefit. Sounds like you've had great success reducing your energy usage, good stuff.
Great bit or work there, I have thought it would help. Also it's good to be toasty warm in morning when getting up.
Also I was thinking to add a larger volumiser to the air to water.
Thank you. It's nice to see the effect of different strategies without having to run loads of tests in real life. Hopefully the model is close enough to reality that it's useful, despite the simplifications.
I think as we push for more renewables, we have to accept some wastage of energy, so using spare/cheap overnight, even if use slightly more in total is probably the best scenario. Great video.
Yes, that's a fair comment. The ideal would be to store as much of that excess as possible and of course in some ways doing extra heating overnight is a form of storage, it could be argued.
I reckon Kat would vote for the boost option. The morning house temperature looks far more comfortable.
The air actually heats up a bit quicker than the model suggests, as it assumes the walls heat up at the same rate, which isn't what happens in reality, so it's not quite as bad as it looks!
I do find that I have longer showers when I wake up and it's bloody freezing which is a waste of energy
Hi Tim, I found this to be a brilliant structured approach and I will use the spreadsheet to apply to our house and send you the feedback. We have an A2W LG Therma heat pump and a TESLA Powerwall 13.4kWh. Battery. We are at the opposite end of your current strategy … we run the heat pump and charge the battery at full pelt on Octopus Intelligent Go between 11.30pm and 5.30am at 7.50p per kWh. BUT we don’t use the heat pump at all during the peak period (30p per kWh) during the day, relying on the house thermal mass, cavity block work with 100mm insulated cavity. Currently we are using 35-40 kWh each day at a normal total cost of £2.50- 7.50 per day with a per kWh unit cost of c£0.10p - £0.12p) on average. We have a very gentle slope down in the internal temperature during the day. I am unsure whether the HP wizards out there would regard this as heresy? But it works practically. Many congratulations on your TH-cam output . it’s very easy to understand and I follow it continually.
Well, I'm very glad you liked the video! I'm impressed that you're able to do all your heating overnight. I'm not sure we could quite manage that! As long as you're comfortable that's the important thing.
@@TimAndKatsGreenWalk I think the main secret is the level of our initial decisions on insulation in our new house I designed myself. 100mm insulation in the cavities and 150mm in the floor plus two aluminium skinned blankets in the loft …. One vertical and another horizontal with HD taped seams. We moved from an 1880 very cold country mansion and built the new house in the garden.Wd are now expecting our annual bill for heating and elec to be c£600 for a 2500 sq ft detached house. We have 3.8k of solar and two EVs Niro and C4. Plus Zappi and EDDi. However I think our best investment monetarily is the rainwater harvesting system ….. moved our water costs from >31500 in the old house to
@@regaldridge4248 you clearly did a great job! We don't have any plans to build our own house at present, although it's something we've considered. Maybe one day.
@@regaldridge4248Sorry was your water £1500? You have a typo in your post I think.
Hi Tim,
I already do this with my hot water - setting the DHW for the heat pump to 50°C overnight during the cheap rate and then setting it to 40°C during the day on a timed schedule - so it only comes on at night unless I use loads of hot water during the day and it dips below 40°C. It normally at most stores a 10°C top up of 3.45 kWh x 7.5p = 26p as opposed to 97p if done at day rate so saves 71P. It also uses less energy because the average temperature is heading towards 45°C instead of the former constantly maintained 50°C. Once a week it sets to 60°C for the Legionella via the heat pump rather than the immersion heater which only cuts in if the heat pump can't quite manage 60°C (all done at cheap rate).
Yes, I'd definitely always heat hot water during the cheap rate (I do this too).
Hi Tim, as I have previously said, my ASHP drops to 16c overnight and 18c all day. A second layer is used to keep warm, but if I heat the house another couple of degrees it is too warm. I have also moved all the DHW to heat at cheap rate, also using the ASHP instead of my Eddi in the Summer months as it uses far less energy and means I can export more! I wouldn't sleep very well if I warmed the property overnight.
Yes, indeed, it'd be best to exclude the bedrooms from any overnight boosting, for sure. Not sure how possible that is with most A2W systems but it's something we can do with our A2A system, thankfully.
I'm currently working on taking the spreadsheet a little further with half hour outside temp inputs and heatloss calcs, and also variable COP depending on heat power & outside temp.
Same. It gets quite complicated quite fast.
Great topic, I have an ASHP (air to water) and I boost the temperature overnight to 22C at 0400hrs to have a nice toasty morning, and I think it works (being on Octopus Agile, my normal constant daily temp is 20C)
Good stuff, glad to hear that works well for you. I'm performing my own experiments now so hopefully I can prove it works for our situation too in due course.
Tim, thanks for a great video. This is a question I've been playing around with for a year or so. Context: Nibe S1255 GSHP in a recently renovated stone-built cottage (high thermal mass), with moderate-good insulation; UFH downstairs; oversized rads upstairs; no solar or battery...yet!. Used as a holiday let - and unfortunately holidaymakers expect it to be HOT! I've been running the pump hard from midnight - 5am, low until 4pm, mid-point from about 4pm - 10pm and low till midnight. It's kept the cottage toasty warm (22C - 24C) throughout the cold snaps but...cost an arm and a leg! We're currently with British Gas Electric Driver (8.95p midnight - 5am; 30.131p day rate) so, I've just been comparing costs if we switched to Octopus. Here's the results (average cost per day between 20/12/23 and 20/1/24):
British Gas ED: £13.23
IO Go: £12.62
Agile Octopus: £8.94
Agile Octopus with 70% of peak load shifted: £8.17
Agile Octopus using long term average rate: £12.16
Octopus Cosy: £14.98
Octopus Cosy with 70% of peak load shifted: £13.75
Food for thought!
Very interesting. You may also be interested in an update to this spreadsheet that I'll be publishing this week. It deals with Cosy much better as well as adding in the CO2 calculation and other various features to make it more "accurate", especially when combined with battery storage. I've not done a version for Agile but if you don't have battery storage that won't matter as you could use the Go version just as easily. Hopefully the video will be out by Wednesday and it's only 26 mins this time!
I started doing this too, for similar reasons but less directly. It was so my PV batteries would last longer during the day at the stored off peak rate.
This has led to savings as well as a much more comfortable house.
While A2A is very responsive and can heat the air rapidly, it can be quickly absorbed by the house thermal mass leading to less comfortable spiky temperatures.
Yes, indeed, low and slow is the way to go regardless of the heat pump output method. We've been running the overnight experiment for a week now and it has indeed resulted in a more comfortable house first thing in the morning. I'll be doing a full breakdown of the comparison in due course once I've got a decent amount of data using both methods.
I have a ground source heat pump, with underfloor heating up and down. I am on the cosy tariff, I only run the heating during the two three hours cheap rate, the house is nice and warm.
That's good to hear. The cosy tariff is an interesting proposition, but with the battery and EV I decided Go would work better for us overall.
@@TimAndKatsGreenWalk It would be interesting to see your simulation adapted to Cosy hours. Like @andrewgateway I use my ASHP to heat up my house (A2W) during the two off-peak periods and drop to a setback temperature a couple of degrees lower during the day and 3 degrees lower at night (until the 4-7am cheap rate). I use Tado TRVs on my radiators to keep bedroom temps low at night and just heat up downstairs. I also have a battery, so Cosy means that ALL of my electricity usage is at cheap rates - my bills are lower than your figures. My only difference from you is that I can't charge my EV from home, as I don't have off-road parking...
I’ve got the octopus cosy tariff. So get a cheap rate between 4 and 7 am, and another cheap rate between 1 pm and 4 pm. it doesn’t go quite as low as the one you’ve got, but it works well for heat pumps
Yes, that is a good tariff. We have an EV too (and battery and solar) so I decided Go was best for us over the Winter instead. It's good that Octopus has those options.
We have wet underfloor downstairs and radiators upstairs with ashp and home battery. We boost the underfloor to 21.5 overnight and then it's toastie in the morning. We can usually get through most of the day on the battery depending on temp outside so our bills are less than using the gas we swapped from two years ago. Having an EV is the gateway drug to cheap electricity.
That's excellent, great to hear. Yup, I certainly wouldn't go back from EV, solar, battery, and heat pump now.
Hi Peter, if we did that in my house, I’d be sleeping naked, with no sheets!
When we refurbished the house 12 years ago we put a ton of insulation around each room so if the doors are closed we can maintain 16 degrees in the upstairs yet have 21 downstairs. Now the kids have left we can keep the cost down .
Hi Tim just to let you know we heat our lounge/diner with A2A from 2.30am to 5.30am this keeps it warm enough for everyone to have breakfast and off to school/work when it is below 5 degrees we sometimes supplement this with a 400w halogen heater when we get up The A2A then comes on again at around 3.00pm to heat the whole house and goes off about 6.00pm If we didn’t use the off peak electricity our 9.5 Kw battery wouldn’t last long we are a family of four and have high usage. I am now waiting to fit the IHP Mixergy tank to help reduce this. Thanks for the video although sorry to say all the figures are beyond me ha ha
I'm glad you've got a strategy that works for you. I hope the iHP helps too, it's an interesting piece of kit, for sure.
Very informative 👍
Just a quick question
We use octopus go and have 18kw of battery storage with a 3kw output inverter.
What is the usage in kwh for the heat pump if used continuously. As I don’t want to be dipping in to the off peak tariff.
Thanks
Well that depends on a lot of things (it may be a quick question but it's not quick to answer). You'd have to grab a copy of the spreadsheet and set it up for your own house to work it out. If you're asking about our heat pump, you can see that in the video, I explain how many kWh the heat pump uses over the day (although it depends on the temperatures etc.).
Without watching the technical part of your video I would think a lot of this will depend on internal thermal mass versus hear loss. I don't currently have a house with an ASHP. In a previous house which did have an ASHP I found that because of the high thermal mass and good insulation, the lag in temperature rise over 4-6hrs could well be saving cost. This was in France where the differences between day and night rates are less. I never did the calculations because we were never there full time but if I were to own a house again with an ASHP I would certainly look deeper into your modelling.
Yup, watch the technical part 😉
You are missing the fact that heat pumps usually use much less power if you keep a stable temperature. You need to add cop to your spreadsheet.
I did. Watch the next video. But brace yourself first.
I'm so glad to live where they don't muck with time of use billing. In addition to considering a castle, maybe you can convince the wife that an indoor pool would be an economical addition.
Time of use tariffs are very beneficial if you take the time to consider them carefully. Not sure why you'd not want that option available if it provides so many benefits.
By the way, time of use tariffs are available everywhere, even where you live, you just haven't looked by the sounds of it. Just because they exist doesn't mean you're forced to use them if you don't want to.
REAL example ....
We use our underfloor heating is a heat store. We load it up the heat pump on agile tariff - ca. 22:30-06:00 and have cut bills (at least 33% but aiming for 50%), improved comfort to the "standard" run it 24 hrs. It isn't optimum as I don't get full control - I'm trying to optimise for cost rather than energy.
However cost is a pretty good proxy for "green". Heat pump is off from 07:00 to 22:30 so plenty of wind power consumed and avoiding the gas and coal times. In fact helping balance the system for others who don't have the choice.
Lose about 1.5 deg in building (23.5->22) each day. Nice to wake up to a toasty house and do exercises (fewer strained muscles) and go to bed when cooler (as human body prefers).
This degree of comfort is the real bonus. The 24hr running scenario on std tariff, was at 20 deg because it was so expensive. Colder and cost more.
Very good. Yeah, price is a good proxy for green-ness. I did a follow-up video to calculate the carbon impact too and it does indeed work out both cheaper and greener doing the overnight boost. We've now been doing that strategy for a few weeks and it seems to be working well.
@32:50 you have an annotation saying that with A2W you may get a better CoP and lower running cost for longer at a lower flow temperature.
This is also true of A2A as well, just it's less obvious. The "maintaining the room temperature" output is less than the "need to heat up the room" output. So you may find that the former is 50C, when probing the temperature from the internal unit, so the "leaving it on all day" strategy will likely use less electricity than the sheet suggests. It's a shame A2A is so much harder to monitor COP compared to A2W.
Yes, it's annoying that there isn't more data available from our A2A units. Even so, I'm now running our overnight heating experiments so hopefully will have some real world data to show to compare the two strategies at some point soon.
Haven't watched the video yet so apologies if this is covered, but it would be interesting to combine the power usage data with anticipated grid CO2 emissions to see how that works out. Emissions could be lower overall even if more power is consumed, if the grid is cleaner at that time.
Ignore, got to 42m and you covered this. Thank you.
As it happens I've already started to work on that particular addition to the model (it's not covered in this video although I do mention it). Hopefully I'll have a follow-up video to explain my findings soon (just as soon as I can work out the best way to include battery storage in the calculation, as that can make a big difference too).
I do this in Summer for cooling. I cool the house around 4am and I don’t even have off peak pricing.
Fair enough.
Question. Would the COP not need to be a dynamic field? I could be wrong, but are heat pumps not more efficient at a more steady temperature and less efficient when 'ramping up' (the car speeding to 70mph analogy)
By heating up during your off peak hours, you might get slightly lower COP at that time but for the rest of the day your cop would be better as you're simply maintaining that temperature.
So with the in mind, heating during your off peak hours is better from as you're pre-heating AND maximizing the COP.
FYI. Im 20 minutes into the video, its gteat btw, but thats all i have time for (apols if this is addressed later in vid)
Well, like I said, it's a toy model, it has a lot of simplifications. I could certainly make it a lot more complicated but I don't think it would hugely affect the result. It's a case of choosing when to stop adding features.
can you replicate anything like the castle example but using a ‘normal’ house multiplier and adjusting only the heat loss to simulate additional insulation?
You sure can, just change the heat loss number. Although the heat loss would have to be a tenth of a typical well insulated house, so a huge amount of extra insulation.
What is your impression on Tepeo heating system. the idea is that Tepeo will store the heat during off period and any excess will be used by battery. The advantage is that you end up installing small battery as there is some storage happening in Tepeo
It all comes down to efficiency. The ZEB stores heat using electricity with at best 100% efficiency (some heat will leak out but if it's installed in your house you'll make use of that heat anyway), whereas a heat pump will give you 300+% efficiency. In my opinion that makes heat pumps unbeatable and should be used in preference to any other system unless it's not possible to do so for practical reasons. The ZEB has its place in that context, however, so I absolutely appreciate that it'll be preferable for some folks.
That was fun - thinking now about moving into a castle.
Definitely. Although I suspect the heat loss would be higher than the 7 kW I used in my examples.
Hi Tim,
As always thanks for the video. I have been using your savings spreadsheet, thank you. But I can’t find historical data for the basic tariff for comparison. I contacted Octopus but they said they don’t publish it which is a shame. We are in the East Midlands. It would be nice to get it right rather than guessing.
If you do a search for Octopus tariffs there should be a list of historical ones somewhere. At least I'm sure I've seen one.
Yeah, here it is:
octopus.energy/tariffs/
@@TimAndKatsGreenWalk Thanks Tim, I had looked at that before, will have to have a deeper dive. Strange that Octopus said they don’t publish it.
In your model would the floor mass of underfloor heating be beneficial for A2W by heating the floor overnight.
Very probably, yes (although worth doing real world tests to be sure).
Interesting video, I do think you are being over Conservative with your heat capacity multiplier for a timber frame house. I live in a new build house in Scotland which is timber and only lose approx 2degC over night without heating so think my number would be closer to 100 I think
Well, exactly, this is why you tune that number to match your house. I just picked a number half of what I found for our own house as an example.
If you’ve got some logging temperature sensores (possibly from the A/C units) then you should be able to work it out pretty quickly…
Work what out in particular? Not quite sure what you mean.
7kw is a lot for a home 2 years old are you sure at that figure, my 100yr home is 6.6kw heat loss at -2 @ 21 rooms & 20 bedrooms,
avg gas used in 7 days is 100kwh gas with a knackered boiler @ room temps above & avg out door temps of 2.5 this week
have you tried setting the heating to example of 18 that would deliver 20 room temps with the fan set to low and ASHP in eco mode
i did find my air to air was used the same kwh to run 24/7 with the setting above used rather than 6-8hrs a day
the heat pump ran in 24/7 mode at 480w avg until the temp was satisfied
We have extremely large windows (too big, really), so that pushes the heat loss up a lot.
Most of our units are set to 18 on the lowest fan setting. In the smaller rooms that gets them to 20+, in the hall that gets it to about 18.5. That works well for us. I'm now experimenting with running them overnight too.
29kWh for spacing heating! How big is your house? We heat a 4 bed house using a A2W heat pump including hot water (250L tank) and induction cooking, and our total electricity use is 30kwr at -6oC.
It's not a competition, you know.
Indeed it isn't but 29kwh for space heating @5oC, kinda leaped out of the data as a very high figure without all the other consumption added to the figures. How did you do energy wise during the cold snap to -6, -7oC?
@DMFPERFORMANCE I pointed out that the model ignores solar gain, heating from appliances, and people, so will be higher than real life. It's all there in the video, including the size and heat loss for our house.
You're more than welcome to grab a copy of the spreadsheet and set it up for your own house, of course.
And I'll be showing a lot of my own real world data in a future video once I've got enough data using the overnight boost strategy to compare to what I used to do before. You'll have to wait for that one if you're interested in the gory details of our heating demand stats.