I’m spending a fortune running a heat pump in my build! Please HELP 😫

[SteamyTea]

@damspt

 

Does that price on your charts include the daily charge and VAT?

 

4 quid a day seems quite low to me, mind you, yesterday I used 6 kWh, and I had a light frost on the car this morning (only one at work that did, but then I start earlier than the idle buggers).

Your chart shows a higher usage during the evening, are you doing a lot of cooking and clothes washing/drying.

A faulty fridge can burn though quite a bit of juice, check it to see if it constantly running (touch it and feel the vibes).

 

Much warmer when I left work half an hour ago. South West wind now. So cold snap is over.

 

This is what it was like earlier.

Not much difference in temperature, but windier, and from the North, which is rare down here (we had snow in Bodmin).

 

 

 

[SteamyTea]

8 minutes ago, Beelbeebub said:

kwh

Oi, kWh.

[Kelvin]

24 minutes ago, JohnMo said:

Not sure why you think the electric consumption is high. Assume you are all electric etc.

 

Our house seems to use about 20kWh without the heat pump.

 

 

Ours is about the same. 

[JohnMo]

10 minutes ago, Kelvin said:

Ours is about the same. 

Glad I'm not the only one

[MikeGrahamT21]

I go into panic if I’m spending more than £4 a day 😬 but then I think that’s more part of being a Yorkshire man! 

[SteamyTea]

2 minutes ago, MikeGrahamT21 said:

but then I think that’s more part of being a Yorkshire man! 

Some say that a Cornishman is like a Yorkshireman with all the generosity squeezed out of them.

[marshian]

1 hour ago, JohnMo said:

Not sure why you think the electric consumption is high. Assume you are all electric etc.

 

Our house seems to use about 20kWh without the heat pump.

 

59 minutes ago, Kelvin said:

Ours is about the same. 

 

Blimey - we've never hit that sort of base line on Electric - 3 loads of washing, some with tumble drier (some with dehumidifier) and a load thro the  dishwasher and we peak at 16 kWh in a day

 

Average daily for the year is 9.5 kWh but typical base number is around 7 to 8 kWh and I regard that as above average 

[marshian]

1 hour ago, Beelbeebub said:

Just for perspective our gas heating has shot up during this cold snap (shock!) 

 

We were sub 50kwh a day then the cold snap hit and we are more like 100kwh plus - and that's with a log burner going to take the edge off things. 

same here from average of 25 kWh per day to over 70 

 

[marshian]

2 hours ago, damspt said:

I’ve noticed that it’s been since Monday (17/11) that we have been using a lot of electricity, I’m not sure if it’s a coincidence but our new fridge came on that day ( same as the previous one but had to be changed due to a fault ) 

 

HDD data for my house by day

 

 

Raw Data below - I scaled the total kWh per day by dividing by 6 (so 25% or the other two (HDD and kWh per HDD get lost at the bottom

 

Either way weather gets colder energy usage goes up or house gets colder - choice we have to make in winter (or a choice we don't get to make)

 

Date	HDD	kWh/HDD	kWh Scaled	Total kWh
07/11/2025	3.6	4.34	2.60	15.6
08/11/2025	4.6	3.30	2.53	15.2
09/11/2025	6.9	3.77	4.34	26.0
10/11/2025	5.0	4.43	3.69	22.2
11/11/2025	5.3	6.60	5.83	35.0
12/11/2025	2.8	5.21	2.43	14.6
13/11/2025	3.9	2.02	1.31	7.9
14/11/2025	5.8	1.94	1.87	11.2
15/11/2025	6.7	4.33	4.84	29.0
16/11/2025	8.4	4.50	6.30	37.8
17/11/2025	11.4	4.19	7.95	47.7
18/11/2025	13.1	3.99	8.72	52.3
19/11/2025	12.4	5.17	10.68	64.1
20/11/2025	15.2	4.61	11.68	70.1
21/11/2025	14.0	4.94	11.53	69.2

[JohnMo]

16 minutes ago, marshian said:

Average daily for the year is 9.5 kWh but typical base number is around 7 to 8 kWh and I regard that as above average 

Think the trouble is

MVHR on 24/7

Treatment plant compressor on 24/7

All water by well so UV steriliser on 24/7, plus intermittent lift pump use

The lowest steady state electric load is about 330W. So that's about 8kWh before we do anything else.

[marshian]

2 minutes ago, JohnMo said:

Think the trouble is

MVHR on 24/7

Treatment plant compressor on 24/7

All water by well so UV steriliser on 24/7, plus intermittent lift pump use

The lowest steady state electric load is about 330W. So that's about 8kWh before we do anything else.

 

My overnight electricity usage is pretty much 0.3kWh as a background - it's just the day time increase isn't that large unless there is a reason - like laundry, dishwasher, oven etc

[JamesPa]

2 hours ago, damspt said:

I’ve noticed that it’s been since Monday (17/11) that we have been using a lot of electricity, I’m not sure if it’s a coincidence but our new fridge came on that day ( same as the previous one but had to be changed due to a fault ) 

Its nothing to do with 'your' fridge, its to do with the fridge outside which was delivered by the almighty (other explanations for the natural world are available) around the same time.  Its warming up at the weekend and consumption will drop back down again.  

 

However you heat your house its going to consume a lot more when its -1 than it will most of the time, typically twice as much!  With an ASHP the relationship is a bit exaggerated, but it evens out over the season.  Did you watch your consumption daily in your previous house/with your previous heating, I'm guessing not.

Edited yesterday at 19:57 by JamesPa

[Kelvin]

23 minutes ago, JohnMo said:

Think the trouble is

MVHR on 24/7

Treatment plant compressor on 24/7

All water by well so UV steriliser on 24/7, plus intermittent lift pump use

The lowest steady state electric load is about 330W. So that's about 8kWh before we do anything else.

This although we have two UV sterilisers, the treatment plant compressor does switch off and on, borehole pump although that probably only runs once a day, control panel

for that, our water is pumped into the house. Other half wfh so there’s three screens, and a laptop. I also have a bunch of networking stuff and Starlink consumes a bit. We’re np about 450W background load. It was higher but have put everything on standby when idling or off overnight. 

[marshian]

3 minutes ago, JamesPa said:

Its nothing to do with 'your' fridge, its to do with the fridge outside which was delivered by the almighty (other explanations for the natural world are available) around the same time.  Its warming up at the weekend and consumption will drop back down again. 

 

Exactly - My house heat loss is calculated to be 4.0 kWh at -2.4 Deg C OAT

 

So if we have 24 hrs of -2.4 Deg C (or that as a average over the whole day) I can realistically expect to use 96 kWh for space heating plus another 5 kWh for HW requirements if I run the heating 24/7 

 

Reality is those days are maybe just a handful of days a year rest of the winter time it's somewhere between 2 and 7 deg C 

[SteamyTea]

1 hour ago, marshian said:

Raw Data below

I re-charted your data in a more suitable way, but as I do not know what Heating Degree Days (HDD) base temperature you used, was it 15.5°C as that is the usual UK default, I suspect it is not giving a true picture, as at 1 HDD, your house has no base load.  15.5°C is really a reflection of our shoddy housing stock and crap heating systems.

At 3 HDDs, and 3°C is a typical house temperature above OAT when there is no heating on, your daily, non heating, load seems to be about 10 kWh.

Adjusting the base HDD temperature, and with a full years (or more is better) worth of data, should show you the DHW usage and any parasitic loads.

I have found that HDDs are not very good for homes like mine that have E7 heating as during the shoulder months it is too easy to have an overheated house.

I also have a secondary issue in that half the time my house does not draw anything from the grid, this skews the numbers if I try an calculate it at the hourly level to reduce the effects of the overheating issue.

Where HDDs work well is in offices that are fully climate controlled i.e. very stable internal temperature.

[marshian]

6 minutes ago, SteamyTea said:

I re-charted your data in a more suitable way, but as I do not know what HDD base temperature you used, was it 15.5°C as that is the usual UK default, I suspect it is not giving a true picture, as at 1 HDD, your house has no base load.  15.5°C is really a reflection of our shoddy housing stock and crap heating systems.

At 3 HDDs, and 3°C is a typical house temperature above OAT when there is no heating on, your daily, non heating, load seems to be about 10 kWh.

Adjusting the base HDD temperature, and with a full years (or more is better) worth of data, should show you the DHW usage and any parasitic loads.

I have found that HDDs are not very good for homes like mine that have E7 heating as during the shoulder months it is too easy to have an overheated house.

I also have a secondary issue in that half the time my house does not draw anything from the grid, this skews the numbers if I try an calculate it at the hourly level to reduce the effects of the overheating issue.

Where HDDs work well is in offices that are fully climate controlled i.e. very stable internal temperature.

Base is 16.5 (once daily average temp falls below this heating is required - have a few years data that backs it up)

 

Base temp was worked out using on-line regression tool with 2 years of daily heating data (with HW/cooking energy usage removed)

 

it’s an 1980’s build that I’ve tried to bring kicking and screaming into a more insulated state - biggest issue is it’s shape - fundamentally it’s a T shape so a number of rooms have 3 external walls (north facing frontage being the worst areas for heat loss)

 

I was planning on re-running the regression tool after this winter to see if the most recent improvements have made any difference (loft insulation increased to 300 mm from a depth of 75mm to 150 mm)

[marshian]

21 minutes ago, SteamyTea said:At 3 HDDs, and 3°C is a typical house temperature above OAT when there is no heating on, your daily, non heating, load seems to be about 10 kWh.

JFYI No DHW energy usage is included in “total kWh” per day in data above

 

it’s not contributing to space heating so I remove it for HDD calcs - my target is 4.0 kWh per HDD - most of the time heating 24/7 I’m in the ball park (it does trip above when there are significant changes in OAT over a short period of time) 

[SteamyTea]

8 hours ago, marshian said:

JFYI No DHW energy usage is included in “total kWh” per day in data above

That will account for the negative usage then.

[Andehh]

We're using around £9 a day during this cold snap, but we do like a warm house! Without the ashp it's around £3 - 4 a day I think!

 

[Nickfromwales]

£6 / day, all in?

”Fortune”?

Ermmmmm……  

 

Try a week in my house and you’ll sleep well.

 

🤔😉

[dpmiller]

£6 is 10 litres of oil these days, which would run the average oil boiler for about 4 hours?

[Marvin]

Hi @damspt

 

There are so many considerations when discussing ASHPs.

Although I am not a fan of EPC's I would be interested to know what rating your house is.

If you look up your home on the EPC register it will tell you lots of things which are questions you would be asked here. For example:

Is your home rated A B or C.  The Floor area and the calculated kWh use per year for heating: If you divide the kWh by the floor area this will give you the amount of heating in kWhs per square metre floor area per year. 

 

From my own experience with our ASHP over the last few years we are satisfied with the results.

Our ASHP uses masses during cold weather but almost nothing during the rest of the time. 

We run at about 22 - 23 degrees C during the winter.

We also have a MVHR system and PV.

 

So when you compare our little bungalow to @Nickfromwales's home we would use kWh per year per square metre of floor. (don't do it Nick you would only be depressed😆).

 

Good luck

 

M

 

 

 

Edited 14 hours ago by Marvin
minor change.

[SimonD]

Worst day for us was Wednesday at about 65kWh including EV charging. Best day was yesterday with  30kWh which is total consumption, so about £8.5. On gas just heating would have been about £6.5 with no dhw.

[damspt]

On 21/11/2025 at 08:47, JohnMo said:

Are you on the correct tariff would be my first question. If you have a battery maybe, without suspect not.

 

Do you have a timer for DHW or is that for CH as well?

@JohnMo Yes, Agile tariff which seems to be the best by comparing with others. Please let me know what are the terms for DHW and CH as I'm new to this and have no idea what those initials are for. 

[damspt]

On 21/11/2025 at 09:04, Bonner said:

All depends on your insulation and air tightnesses levels but £6/day during this cold snap does not seem unreasonable, especially with 22/24 degree set points. My set points are 18/20 degrees but I do have a wood burner for the evenings. Do you have UFH, charging it when rates are low (overnight)?

@Bonner Hi, I had a professional snagger checking on my property and apparently the insulation is not bad at all, he did say the loft needed more insulation which then the builders added more. Not sure what UFH is, i'm sorry