Heat pump kwh usage as sole source of home heat

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B4Xt3r
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Heat pump kwh usage as sole source of home heat

Post by B4Xt3r »

Hi Guys,

I'm curious if anyone else would share their experience.
  • I'm on the border between climate zones 5/6, https://basc.pnnl.gov/images/iecc-climate-zone-map
  • Based off last years electrical bills before heat pump install I'm guessing that the heat pump is using somewhere between 45 and 50 kwh/day
  • A best estimate of temp delta (inside to outside) is ~+35 F (think 65 F interior with 30 F exterior)
  • Heating roughly 1900 square feet total with a single exterior unit with four interior heads
  • Home was built in the 60s but is well insulated for it's age
That works out to a daily usage of ~0.00071 kwh/deg F /sq ft (= 47.5 kwh/(+35 F*1900 sq ft)), as a way to normalize out the interior set points & sq footage size.For other people with heat pumps, how does that usage compare to yours?

Few other items just for sharing:
  • I was able to maintain mid sixties interior temperature when exterior temperature was just below 0 F, but I doubt that it had much more capacity, and went with the smallest system quoted
  • I run a setback overnight
-b4xt3r
rossington
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Re: Heat pump kwh usage as sole source of home heat

Post by rossington »

B4Xt3r wrote: Thu Jan 30, 2025 3:43 pm Hi Guys,

I'm curious if anyone else would share their experience.
  • I'm on the border between climate zones 5/6, https://basc.pnnl.gov/images/iecc-climate-zone-map
  • Based off last years electrical bills before heat pump install I'm guessing that the heat pump is using somewhere between 45 and 50 kwh/day
  • A best estimate of temp delta (inside to outside) is ~+35 F (think 65 F interior with 30 F exterior)
  • Heating roughly 1900 square feet total with a single exterior unit with four interior heads
  • Home was built in the 60s but is well insulated for it's age
That works out to a daily usage of ~0.00071 kwh/deg F /sq ft (= 47.5 kwh/(+35 F*1900 sq ft)), as a way to normalize out the interior set points & sq footage size.For other people with heat pumps, how does that usage compare to yours?

Few other items just for sharing:
  • I was able to maintain mid sixties interior temperature when exterior temperature was just below 0 F, but I doubt that it had much more capacity, and went with the smallest system quoted
  • I run a setback overnight
-b4xt3r
Looks as though you need more heating capacity than you currently have.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill.
mgensler
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Re: Heat pump kwh usage as sole source of home heat

Post by mgensler »

We have 4 cold climate Fujitsu one to one heat pumps in zone 4th a total of 4 tons installed. We sized them based on our gas usage of the old furnaces and then subtracted the estimated improvements in air seal and insulation. We don't have comparative numbers to yours but overall our electric usage dropped 2-3% and our gas dropped to zero after we installed them. The house is much more comfortable, the humidity in the winter is 10% higher, and we were able to remove the two humidifiers.
skp
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Re: Heat pump kwh usage as sole source of home heat

Post by skp »

I live in zone 5b and have an all electric 2100 sq foot house. We have always had a heat pump. My budget electric monthly is 188 dollars but we do have a rather large swimming pool that sucks electric in the summer. Not sure if that is helpful or not. There is no natural gas where I live so I don’t have a choice. It has been an unusually cold winter but we have had no problems keeping our indoor temp at set
Last edited by skp on Fri Jan 31, 2025 8:48 am, edited 1 time in total.
dbr
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Re: Heat pump kwh usage as sole source of home heat

Post by dbr »

We installed mini-splits for air conditioning in a hot water radiator gas heated house in zone 6. A supplementary benefit is the fraction of days we need to turn on gas heat is reduced in spring and fall. An extra low temp system usable below 0F might have been a choice, but those systems in the original mini split design for air conditioning still stop working at the coldest temperatures we experience (-20F to -30F).

I don't have usage figures for gas but obviously they have gone down and electric has gone up as far as heat is concerned. Note electric can also include electric resistance baseboard heaters. Heat pump efficiency always exceeds resistance heating even when it is not optimal.
aerofreaky11
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Re: Heat pump kwh usage as sole source of home heat

Post by aerofreaky11 »

S. VT, last month I was a little over 1000 KW. This is for a super insulated/low ach (sealed) 1500 ft2 camp. Mitsubishi Hyper Heat 2 head unit. It was -0 f several nights in fact, it was below -14 the advertised low end of functionality of the unit for a couple of days.

The number would be higher, except for a vacation which sit the thermostat at 55 for my h of the month.
beardsicles
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Re: Heat pump kwh usage as sole source of home heat

Post by beardsicles »

I'll see if I can pull a couple year's data out of my energy monitor, but it's definitely cheaper in Minnesota at this point.
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Re: Heat pump kwh usage as sole source of home heat

Post by Pops1860 »

This thread has been moved to the "Personal Consumer Issues” forum. Moderator Pops1860
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Topic Author
B4Xt3r
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Re: Heat pump kwh usage as sole source of home heat

Post by B4Xt3r »

Yesterday I looked back on my manual J & the "part load" portion of a data sheet for my exterior heat pump & they seem to match up with the 45-50 kwh/day number from my electric bills. Seems in the ball park then.
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B4Xt3r
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Re: Heat pump kwh usage as sole source of home heat

Post by B4Xt3r »

rossington wrote: Fri Jan 31, 2025 5:39 am
B4Xt3r wrote: Thu Jan 30, 2025 3:43 pm Hi Guys,

I'm curious if anyone else would share their experience.
  • I'm on the border between climate zones 5/6, https://basc.pnnl.gov/images/iecc-climate-zone-map
  • Based off last years electrical bills before heat pump install I'm guessing that the heat pump is using somewhere between 45 and 50 kwh/day
  • A best estimate of temp delta (inside to outside) is ~+35 F (think 65 F interior with 30 F exterior)
  • Heating roughly 1900 square feet total with a single exterior unit with four interior heads
  • Home was built in the 60s but is well insulated for it's age
That works out to a daily usage of ~0.00071 kwh/deg F /sq ft (= 47.5 kwh/(+35 F*1900 sq ft)), as a way to normalize out the interior set points & sq footage size.For other people with heat pumps, how does that usage compare to yours?

Few other items just for sharing:
  • I was able to maintain mid sixties interior temperature when exterior temperature was just below 0 F, but I doubt that it had much more capacity, and went with the smallest system quoted
  • I run a setback overnight
-b4xt3r
Looks as though you need more heating capacity than you currently have.
99% design temp out here is ~0F, so I'm not too worried. (I can always put another one to one heat pump somewhere if I need.)
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snackdog
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Re: Heat pump kwh usage as sole source of home heat

Post by snackdog »

I don't have a breakdown on our heat pumps, but our total electricity usage works out to $0.00099 kwh/F/sq ft. If heat pumps are 80% of our electricity usage, that falls to $.00079/khw/F/sq ft. Same as yours.

Hope this helps.
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ETK517
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Re: Heat pump kwh usage as sole source of home heat

Post by ETK517 »

Yikes. Only +35 degrees? Is that based on your preferred indoor temps or the unit’s abilities?
Crimsonandclover
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Re: Heat pump kwh usage as sole source of home heat

Post by Crimsonandclover »

Not sure if you are looking for recommendations, but suggest you eliminate setback during the winter months. Setback at night means that the heatpump is trying to recover home temperature during the coldest time of the day outside. Heat pumps are the least efficient at lower temperatures. A setback under these conditions may increase electrical cost rather than leaving tstat at a constant temperature.
Just my 2 cents!
BreadandButter
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Re: Heat pump kwh usage as sole source of home heat

Post by BreadandButter »

We have a similar home with regards to age, size, and insulation, but heat mostly with gas, plus one room with electric resistance heat. I did a heat loss calculation when I was looking at possibly changing to a heat pump. Our heating load at a 35 degree differential is about 356,000 BTU/day, which would be the heat pump equivalent electric draw of about 36 kWh/day.
We have a rambler, which is less efficient than an equivalent sized 2 story house. We do have a nice southern exposure which helps on sunny days. Our actual energy use is a bit less than the heat loss calcs predict. The appliances and people seem to generate about 5 degrees of heat.
Legoman666
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Re: Heat pump kwh usage as sole source of home heat

Post by Legoman666 »

~3020 sq ft conditioned space in Cincinnati. 1976 construction, R14 in the walls, walkout basement that's finished and conditioned.

We have solar so I have access to a lot of data. However, we have 3 EVs so I had to cherry pick data from days where no charging occurred. Our baseline usage on a day with no HVAC usage and no charging is 35kWh. So subtracting 35 from the total usage should yield the HVAC usage (more or less). With that in mind, I made this graph for you.

Image

Exponential because the heat loss increases with the temperature difference, and because the heat pump efficiency decreases with the outdoor temperature.

normalizing to a 65F day requiring no heat, we use 0.00046 kWh/delta from 65F/ sq ft. Seems reasonable compared to yours.
Last edited by Legoman666 on Sat Feb 01, 2025 9:02 am, edited 1 time in total.
MtnTravel
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Re: Heat pump kwh usage as sole source of home heat

Post by MtnTravel »

B4Xt3r wrote: Thu Jan 30, 2025 3:43 pm
[*]I was able to maintain mid sixties interior temperature when exterior temperature was just below 0 F, but I doubt that it had much more capacity, and went with the smallest system quoted
We have a ducted Mitsubishi HP with electric heat strips as a backup. We have about 2,600 sqft above ground plus a finished basement. The house is very well insulated.

I loved the HP during the summer, but I'm not so sure in the winter. The blower purposely runs 24/7 so the house is a constant temperature, which is nice, but you can't fluctuate temp very much or the HP can't keep up.

For example, I like it cold at night. With our old gas furnace, we'd set it at 63 during the night and then it would slowly warm to 68 by the time we got up. The gas furnace had no problem doing that, but the HP can't do that without using a ton of energy and relying on the heat strips.

That being said, a constant 65 with the heat pump feels about the same as 68 with a traditional furnace since the temp is more even with a HP, but I would bet that the HP couldn't keep our house at a constant 70 or 72 in the winter (which is what a lot of people apparently keep their house at).

Maybe in a very small house the ducted HP could keep up, but in ours it can't (I think we have the largest system). If I went with a HP again, I'd get a separate unit for upstairs and downstairs, or ideally get a mini split so you don't have to heat the whole house all the time.
Crimsonandclover wrote: Sat Feb 01, 2025 8:10 am A setback under these conditions may increase electrical cost rather than leaving tstat at a constant temperature.
This is my experience as well. As noted above, with a ducted HP you really can't vary the temps much or it uses a lot of energy.
ETK517
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Re: Heat pump kwh usage as sole source of home heat

Post by ETK517 »

Fascinating discussion given other heat pump threads here express incredulity at any mention of performance issues. 65 degrees is not warm enough for me during the evening (more like 68-70), yet I also prefer to sleep cold (I usually turn the heat down to 58, though it rarely gets that cold). I also tend to heat my house to 70 or 72 in periods of extreme low temperatures because it just feels colder inside due to drafts and the like. Sounds like a heat pump is not a good solution in that case.
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B4Xt3r
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Re: Heat pump kwh usage as sole source of home heat

Post by B4Xt3r »

Legoman666 wrote: Sat Feb 01, 2025 8:42 am ~3020 sq ft conditioned space in Cincinnati. 1976 construction, R14 in the walls, walkout basement that's finished and conditioned.

We have solar so I have access to a lot of data. However, we have 3 EVs so I had to cherry pick data from days where no charging occurred. Our baseline usage on a day with no HVAC usage and no charging is 35kWh. So subtracting 35 from the total usage should yield the HVAC usage (more or less). With that in mind, I made this graph for you.

Image

Exponential because the heat loss increases with the temperature difference, and because the heat pump efficiency decreases with the outdoor temperature.

normalizing to a 65F day requiring no heat, we use 0.00046 kWh/delta from 65F/ sq ft. Seems reasonable compared to yours.
^Does that graph already have your 35 kwh subtracted out?
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B4Xt3r
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Re: Heat pump kwh usage as sole source of home heat

Post by B4Xt3r »

MtnTravel wrote: Sat Feb 01, 2025 9:00 am
B4Xt3r wrote: Thu Jan 30, 2025 3:43 pm
[*]I was able to maintain mid sixties interior temperature when exterior temperature was just below 0 F, but I doubt that it had much more capacity, and went with the smallest system quoted
We have a ducted Mitsubishi HP with electric heat strips as a backup. ...
Crimsonandclover wrote: Sat Feb 01, 2025 8:10 am A setback under these conditions may increase electrical cost rather than leaving tstat at a constant temperature.
This is my experience as well. As noted above, with a ducted HP you really can't vary the temps much or it uses a lot of energy.
Are the heat strips controlled by the Mitsubishi HP or are they separate?

From both my installer and my energy auditor, I've heard that HPs are more efficient running constantly at lower set point, but my understanding of the actual data from the part load chart for my Mitsubishi hyperheat, with no electric heat backup strips) leads me to do the setback.

Data is on pg 72 of the pdf available here: https://www.sgtorrice.com/ASSETS/DOCUME ... EERING.pdf. Examples with exterior temp 2F:
  • interior 70 F producing 42k btu (maximum), calculated COP 2.5
  • interior 70 F producing 20k btu (50% of maximum), calculated COP of 1.9
  • interior 60 F producing 52k btu (maximum), calculated COP of 3.3
  • interior 60 F producing 12k btu (25% of maximum), calculated COP of 1.9
I'm wondering if the "don't do a setback" advice is for heat pumps that have resistive strips which fire up nice and hard when trying recover. For a cold-climate heat pump. I can't back it up with data, so far.
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B4Xt3r
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Re: Heat pump kwh usage as sole source of home heat

Post by B4Xt3r »

ETK517 wrote: Sat Feb 01, 2025 7:30 am Yikes. Only +35 degrees? Is that based on your preferred indoor temps or the unit’s abilities?
The +35 degrees is just a best guess of a monthly avg.

(At -2F exterior recently, it was maintaining +66 F inside for a +68F delta -- but that was just one day out of the month.)
Legoman666
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Re: Heat pump kwh usage as sole source of home heat

Post by Legoman666 »

B4Xt3r wrote: Sat Feb 01, 2025 10:10 am
Legoman666 wrote: Sat Feb 01, 2025 8:42 am ~3020 sq ft conditioned space in Cincinnati. 1976 construction, R14 in the walls, walkout basement that's finished and conditioned.

We have solar so I have access to a lot of data. However, we have 3 EVs so I had to cherry pick data from days where no charging occurred. Our baseline usage on a day with no HVAC usage and no charging is 35kWh. So subtracting 35 from the total usage should yield the HVAC usage (more or less). With that in mind, I made this graph for you.

Image

Exponential because the heat loss increases with the temperature difference, and because the heat pump efficiency decreases with the outdoor temperature.

normalizing to a 65F day requiring no heat, we use 0.00046 kWh/delta from 65F/ sq ft. Seems reasonable compared to yours.
^Does that graph already have your 35 kwh subtracted out?
Yes
Legoman666
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Re: Heat pump kwh usage as sole source of home heat

Post by Legoman666 »

Since I couldn't resist, I went through and put the cooling data in there too. The temps are the average daily temperature, not the high. The scatter in the y axis for similar temps is almost certainly due to sunlight as our living room/kitchen has a wall that is almost all windows that face NW.
Image
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B4Xt3r
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Re: Heat pump kwh usage as sole source of home heat

Post by B4Xt3r »

Legoman666 wrote: Sat Feb 01, 2025 11:17 am
B4Xt3r wrote: Sat Feb 01, 2025 10:10 am

^Does that graph already have your 35 kwh subtracted out?
Yes
So I guess you're doing a bit better than me :D in terms of usage.
MtnTravel
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Re: Heat pump kwh usage as sole source of home heat

Post by MtnTravel »

B4Xt3r wrote: Sat Feb 01, 2025 10:29 am Are the heat strips controlled by the Mitsubishi HP or are they separate?
The heat strips are controlled by the HP. There was another thread on here with more info, but the controller is apparently programmed to kick on the heat strips if the HP doesn't raise the temp to the set point within 1 or 2 hours (or something like that). I have the Mitsubishi cold climate heat pump, but if it's in the 20s or low 30s outside and I set the stat to 64 and I want it at 66 when I wake up, it is not able to warm the house up 2 degrees in 2 hours so the heat strips will inevitably kick on. Again, this wouldn't be an issue with mini splits, but only on the ducted systems.

That's the biggest frustration for me as someone who likes it cold at night. Maybe it's the size of our house (which isn't that big by modern standards), but the HP does not work well unless it's set at a constant temp throughout the day with maybe one degree of fluctuation. In the summer it's fantastic.

We have comparatively cheap electricity where I am in the winter, and I've seen a spike in our utility bill since we got the heat pump vs. our 10 year old gas furnace. That's all down to gas vs. electric prices, and it could be cheaper if gas prices suddenly went up. If you have solar, it's a non issue.

Long story short, definitely do your research before diving into a ducted heat pump, especially without solar.
Last edited by MtnTravel on Sat Feb 01, 2025 4:09 pm, edited 1 time in total.
WGP3
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Re: Heat pump kwh usage as sole source of home heat

Post by WGP3 »

What is the r-squared value for that curve?
Legoman666 wrote: Sat Feb 01, 2025 11:45 am Since I couldn't resist, I went through and put the cooling data in there too. The temps are the average daily temperature, not the high. The scatter in the y axis for similar temps is almost certainly due to sunlight as our living room/kitchen has a wall that is almost all windows that face NW.
Image
Wwwdotcom
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Re: Heat pump kwh usage as sole source of home heat

Post by Wwwdotcom »

Legoman666 wrote: Sat Feb 01, 2025 11:45 am Since I couldn't resist, I went through and put the cooling data in there too. The temps are the average daily temperature, not the high. The scatter in the y axis for similar temps is almost certainly due to sunlight as our living room/kitchen has a wall that is almost all windows that face NW.
Image
Thanks for the chart, I'll need to make one for myself soon. Out of curiosity, is your heat pump a modern one with higher efficiency below freezing?
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B4Xt3r
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Re: Heat pump kwh usage as sole source of home heat

Post by B4Xt3r »

MtnTravel wrote: Sat Feb 01, 2025 4:02 pm
B4Xt3r wrote: Sat Feb 01, 2025 10:29 am Are the heat strips controlled by the Mitsubishi HP or are they separate?
The heat strips are controlled by the HP. There was another thread on here with more info, but the controller is apparently programmed to kick on the heat strips if the HP doesn't raise the temp to the set point within 1 or 2 hours (or something like that). I have the Mitsubishi cold climate heat pump, but if it's in the 20s or low 30s outside and I set the stat to 64 and I want it at 66 when I wake up, it is not able to warm the house up 2 degrees in 2 hours so the heat strips will inevitably kick on. Again, this wouldn't be an issue with mini splits, but only on the ducted systems.

That's the biggest frustration for me as someone who likes it cold at night. Maybe it's the size of our house (which isn't that big by modern standards), but the HP does not work well unless it's set at a constant temp throughout the day with maybe one degree of fluctuation. In the summer it's fantastic.

We have comparatively cheap electricity where I am in the winter, and I've seen a spike in our utility bill since we got the heat pump vs. our 10 year old gas furnace. That's all down to gas vs. electric prices, and it could be cheaper if gas prices suddenly went up. If you have solar, it's a non issue.

Long story short, definitely do your research before diving into a ducted heat pump, especially without solar.
Ok, thanks for the perspective. We have a "multi split" with multiple heads attached to one external unit.
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Re: Heat pump kwh usage as sole source of home heat

Post by Legoman666 »

WGP3 wrote: Sat Feb 01, 2025 4:08 pm What is the r-squared value for that curve?
Legoman666 wrote: Sat Feb 01, 2025 11:45 am Since I couldn't resist, I went through and put the cooling data in there too. The temps are the average daily temperature, not the high. The scatter in the y axis for similar temps is almost certainly due to sunlight as our living room/kitchen has a wall that is almost all windows that face NW.
Image
0.84
Wwwdotcom wrote: Sat Feb 01, 2025 4:21 pm
Legoman666 wrote: Sat Feb 01, 2025 11:45 am Since I couldn't resist, I went through and put the cooling data in there too. The temps are the average daily temperature, not the high. The scatter in the y axis for similar temps is almost certainly due to sunlight as our living room/kitchen has a wall that is almost all windows that face NW.
Image
Thanks for the chart, I'll need to make one for myself soon. Out of curiosity, is your heat pump a modern one with higher efficiency below freezing?
Yes, it's from 2022. Mitsubishi. COP 4.1 at 47F, 2.3 at 17F, 2.0 at 5F.
Legoman666 wrote: Sat Feb 01, 2025 8:42 am
normalizing to a 65F day requiring no heat, we use 0.00046 kWh/delta from 65F/ sq ft. Seems reasonable compared to yours.
I had an error in calculating this, the correct value is 0.00062 across the full range of temps.
ondarvr
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Re: Heat pump kwh usage as sole source of home heat

Post by ondarvr »

ETK517 wrote: Sat Feb 01, 2025 9:09 am Fascinating discussion given other heat pump threads here express incredulity at any mention of performance issues. 65 degrees is not warm enough for me during the evening (more like 68-70), yet I also prefer to sleep cold (I usually turn the heat down to 58, though it rarely gets that cold). I also tend to heat my house to 70 or 72 in periods of extreme low temperatures because it just feels colder inside due to drafts and the like. Sounds like a heat pump is not a good solution in that case.
It depends on how the system is set up. I put mine in several years ago, it was before the current popularity of them. If you use two systems and slightly oversize the total capacity, then warming things up quickly isn't a problem, neither are the very cold or hot extremes. Most of year I only use one system, but sometimes if I want to warm or cool the house quickly i turn on both. And below about 15-20F I'll run both to eliminate some cold spots in the house.

It gets down to -10F and up to +113F where I live, my system covers that temperature range comfortably. I do frequently light up the wood stove when it gets down to around 0F because wood heat is just so darn comfy.
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B4Xt3r
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Re: Heat pump kwh usage as sole source of home heat

Post by B4Xt3r »

Legoman666 wrote: Sat Feb 01, 2025 8:10 pm
WGP3 wrote: Sat Feb 01, 2025 4:08 pm What is the r-squared value for that curve?

0.84
Wwwdotcom wrote: Sat Feb 01, 2025 4:21 pm
Thanks for the chart, I'll need to make one for myself soon. Out of curiosity, is your heat pump a modern one with higher efficiency below freezing?
Yes, it's from 2022. Mitsubishi. COP 4.1 at 47F, 2.3 at 17F, 2.0 at 5F.
Legoman666 wrote: Sat Feb 01, 2025 8:42 am
normalizing to a 65F day requiring no heat, we use 0.00046 kWh/delta from 65F/ sq ft. Seems reasonable compared to yours.
I had an error in calculating this, the correct value is 0.00062 across the full range of temps.
That makes me feel a bit better about my usage :D. Your original number was like 50% lesser than mine, but the updated number is only 13% less.
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Re: Heat pump kwh usage as sole source of home heat

Post by noco-hawkeye »

Added solar at the end of 22, added a heat pump in spring of 23 (and also a HE gas furnace). In zone 5.

We run the heat pump at anything above 30F, and have house temps from 62-66 in the winter. House is 3500 sq ft and built in 2000.

I think we see something like 500-800 extra kwhr / year with the addition of the heat pump. It's tough to say since they were both added at around the same time. I think over all the house is more comfy and I think we are saving some money and more eco friendly. But it's not a slam dunk / obvs decision.
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Re: Heat pump kwh usage as sole source of home heat

Post by CloudNine33 »

I’m heating 7,000 sf of finished space for about $5/day ($0.10/kwh) with an air source heat pump. When I switch to the propane furnace it’s at least triple the daily cost. New build, very well insulated home. 5 degrees last night and house is toasty warm.
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Epsilon Delta
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Re: Heat pump kwh usage as sole source of home heat

Post by Epsilon Delta »

MtnTravel wrote: Sat Feb 01, 2025 4:02 pm That's the biggest frustration for me as someone who likes it cold at night. Maybe it's the size of our house (which isn't that big by modern standards), but the HP does not work well unless it's set at a constant temp throughout the day with maybe one degree of fluctuation. In the summer it's fantastic.
You can zone a heat pump system. You could probably get the bedroom a couple of degrees cooler by adjusting vents and keeping the door closed. Better but more costly would be a second thermostat, zone valves etc. to actually control the temperature.

If you want a large temperature difference you might need to weather strip the bedroom door or even add insulation to interior walls.
prioritarian
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Re: Heat pump kwh usage as sole source of home heat

Post by prioritarian »

Our heatpump heats/cools ~1950 sq feet and our usage only went up by ~15 kWh/day over the last 12 months. We also insulated and air-sealed our house which likely had a huge impact on our energy use. We were paying $220 per month to heat our house with fracked gas last Dec (house purchase in 2023).
Last edited by prioritarian on Sun Feb 02, 2025 12:00 pm, edited 1 time in total.
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Re: Heat pump kwh usage as sole source of home heat

Post by prioritarian »

MtnTravel wrote: Sat Feb 01, 2025 9:00 am This is my experience as well. As noted above, with a ducted HP you really can't vary the temps much or it uses a lot of energy.
Our experience is diametrically different. Our energy use went down enormously when I turned off the "follow me" feature on our Ecobee thermostat that continuously activated heating due to cat movement during the "away" and "night" periods. Our winter schedule: 59 when away, 66 when home, and 63 at night.
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Re: Heat pump kwh usage as sole source of home heat

Post by THY4373 »

ETK517 wrote: Sat Feb 01, 2025 9:09 am Fascinating discussion given other heat pump threads here express incredulity at any mention of performance issues. 65 degrees is not warm enough for me during the evening (more like 68-70), yet I also prefer to sleep cold (I usually turn the heat down to 58, though it rarely gets that cold). I also tend to heat my house to 70 or 72 in periods of extreme low temperatures because it just feels colder inside due to drafts and the like. Sounds like a heat pump is not a good solution in that case.
I maintain 73 (downstairs) and 72 (upstairs) via heat pump no problem. Downstairs I do cut over to natural gas backup around 27-32 degrees (vary it based on gas vs electric costs at time) as that is where gas becomes cheaper for me. The big set back is more of a problem (unless you go with a fossil backup like I have). I also like to sleep in cold so I just close all the registers in my bedroom which keeps it about 5-10 degrees cooler which works for me. I personally am a big fan of dual fuel.
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Re: Heat pump kwh usage as sole source of home heat

Post by ETK517 »

THY4373 wrote: Sun Feb 02, 2025 12:08 pm
ETK517 wrote: Sat Feb 01, 2025 9:09 am Fascinating discussion given other heat pump threads here express incredulity at any mention of performance issues. 65 degrees is not warm enough for me during the evening (more like 68-70), yet I also prefer to sleep cold (I usually turn the heat down to 58, though it rarely gets that cold). I also tend to heat my house to 70 or 72 in periods of extreme low temperatures because it just feels colder inside due to drafts and the like. Sounds like a heat pump is not a good solution in that case.
I maintain 73 (downstairs) and 72 (upstairs) via heat pump no problem. Downstairs I do cut over to natural gas backup around 27-32 degrees (vary it based on gas vs electric costs at time) as that is where gas becomes cheaper for me. The big set back is more of a problem (unless you go with a fossil backup like I have). I also like to sleep in cold so I just close all the registers in my bedroom which keeps it about 5-10 degrees cooler which works for me. I personally am a big fan of dual fuel.
In my climate (NYC metro) this would mean I’d be running two heating systems 3-4 months a year just to sustain comfortable indoor temps. I can’t imagine that the cost of maintaining and eventually replacing two independent heating systems offsets the savings, if any, of a heat pump. The registers thing doesn’t work for me - I want it warm when I wake up and before I go to bed at night, but cool overnight. This is something any other modern heating system can handle without issue.

Just seems like an immature technology to me, or one that is suited to Europe where folks expect a lot less from their HVAC than your typical American.
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Re: Heat pump kwh usage as sole source of home heat

Post by Epsilon Delta »

ETK517 wrote: Sun Feb 02, 2025 1:26 pm The registers thing doesn’t work for me - I want it warm when I wake up and before I go to bed at night, but cool overnight. This is something any other modern heating system can handle without issue.
No it's not. A highly insulated house (e.g. a Passive house) will not cool down over night.

The existing system is not a spec.
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Re: Heat pump kwh usage as sole source of home heat

Post by MtnTravel »

prioritarian wrote: Sun Feb 02, 2025 11:58 am
MtnTravel wrote: Sat Feb 01, 2025 9:00 am This is my experience as well. As noted above, with a ducted HP you really can't vary the temps much or it uses a lot of energy.
Our experience is diametrically different. Our energy use went down enormously when I turned off the "follow me" feature on our Ecobee thermostat that continuously activated heating due to cat movement during the "away" and "night" periods. Our winter schedule: 59 when away, 66 when home, and 63 at night.
What kind of heat pump do you have? My understanding is that the Mitsubishis have to have the Mitsubishi controller, so you can't use a Ecobee.
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Re: Heat pump kwh usage as sole source of home heat

Post by prioritarian »

MtnTravel wrote: Sun Feb 02, 2025 7:06 pm
prioritarian wrote: Sun Feb 02, 2025 11:58 am

Our experience is diametrically different. Our energy use went down enormously when I turned off the "follow me" feature on our Ecobee thermostat that continuously activated heating due to cat movement during the "away" and "night" periods. Our winter schedule: 59 when away, 66 when home, and 63 at night.
What kind of heat pump do you have? My understanding is that the Mitsubishis have to have the Mitsubishi controller, so you can't use a Ecobee.

Panasonic INTERIOS 2.5 Ton.
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Re: Heat pump kwh usage as sole source of home heat

Post by THY4373 »

ETK517 wrote: Sun Feb 02, 2025 1:26 pm In my climate (NYC metro) this would mean I’d be running two heating systems 3-4 months a year just to sustain comfortable indoor temps. I can’t imagine that the cost of maintaining and eventually replacing two independent heating systems offsets the savings, if any, of a heat pump. The registers thing doesn’t work for me - I want it warm when I wake up and before I go to bed at night, but cool overnight. This is something any other modern heating system can handle without issue.

Just seems like an immature technology to me, or one that is suited to Europe where folks expect a lot less from their HVAC than your typical American.
You completely misunderstand the tech. It is not two completely different systems it is one system. Basically I have the same setup as somebody who has AC. You have a gas furnace with and AC coil. Except in my case the AC is a heat pump so it can work summers and winters. The marginal cost is fairly nominal since basically you are mostly just paying for an extra reversing valve in the condenser and a slightly more sophisticated thermostat. In my case the marginal cost was negative since I got a tax credit for installing an efficient heat pump (I also got a tax credit and utility credit for installing a 97% efficient gas furnace). In fact with the tax credit it would have made sense to install the heat pump even if I only used it for AC. And this tech isn't even new my current system installed last year replaced a similar system that was over 30 years old and still going (it was just noisy and ineffecient). In my neck of the woods heat pumps have been common since the 1980s and often with fossil backup. The savings is considerable for me since I am south of you and most of our winter is where the heat pump is often 30%-50% cheaper than natural gas (at 32 and above). I can also adjust the cutover to NG based on my utility rates. In NYC your electric rates are much higher than I pay (I don't know about NG so a heat pump might make no sense). I also like having redundant heat sources. It isn't an immature tech it is one that doesn't work for everybody. For me I get amazing comfort and great savings. YMMV.
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Re: Heat pump kwh usage as sole source of home heat

Post by ETK517 »

THY4373 wrote: Mon Feb 03, 2025 8:35 am
ETK517 wrote: Sun Feb 02, 2025 1:26 pm In my climate (NYC metro) this would mean I’d be running two heating systems 3-4 months a year just to sustain comfortable indoor temps. I can’t imagine that the cost of maintaining and eventually replacing two independent heating systems offsets the savings, if any, of a heat pump. The registers thing doesn’t work for me - I want it warm when I wake up and before I go to bed at night, but cool overnight. This is something any other modern heating system can handle without issue.

Just seems like an immature technology to me, or one that is suited to Europe where folks expect a lot less from their HVAC than your typical American.
You completely misunderstand the tech. It is not two completely different systems it is one system. Basically I have the same setup as somebody who has AC. You have a gas furnace with and AC coil. Except in my case the AC is a heat pump so it can work summers and winters. The marginal cost is fairly nominal since basically you are mostly just paying for an extra reversing valve in the condenser and a slightly more sophisticated thermostat. In my case the marginal cost was negative since I got a tax credit for installing an efficient heat pump (I also got a tax credit and utility credit for installing a 97% efficient gas furnace). In fact with the tax credit it would have made sense to install the heat pump even if I only used it for AC. And this tech isn't even new my current system installed last year replaced a similar system that was over 30 years old and still going (it was just noisy and ineffecient). In my neck of the woods heat pumps have been common since the 1980s and often with fossil backup. The savings is considerable for me since I am south of you and most of our winter is where the heat pump is often 30%-50% cheaper than natural gas (at 32 and above). I can also adjust the cutover to NG based on my utility rates. In NYC your electric rates are much higher than I pay (I don't know about NG so a heat pump might make no sense). I also like having redundant heat sources. It isn't an immature tech it is one that doesn't work for everybody. For me I get amazing comfort and great savings. YMMV.
What am I misunderstanding? In my climate (as in many other posters' climates) you need a backup heat source in addition to a heat pump for cold weather. The backup heat is an independent system, whether a simple coil system or a preexisting heating system like hot water or steam radiators, electric baseboards, etc. That entails having two separate heating systems, though I suppose they can be integrated relatively seamlessly. You may be stating that the total number of HVAC systems remains the same because a heat pump also serves as A/C?
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Re: Heat pump kwh usage as sole source of home heat

Post by Valuethinker »

ETK517 wrote: Sun Feb 02, 2025 1:26 pm

In my climate (NYC metro) this would mean I’d be running two heating systems 3-4 months a year just to sustain comfortable indoor temps. I can’t imagine that the cost of maintaining and eventually replacing two independent heating systems offsets the savings, if any, of a heat pump. The registers thing doesn’t work for me - I want it warm when I wake up and before I go to bed at night, but cool overnight. This is something any other modern heating system can handle without issue.
Just seems like an immature technology to me, or one that is suited to Europe where folks expect a lot less from their HVAC than your typical American.
Yes American heat pump technology is (mostly) pretty basic. Japanese are way out in front, and there is now comparable European manufactured stuff.

US the HPs are mostly designed around the needs of high AC but limited winter heat. The South, broadly defined. Relatively few days below 32 F. And natural gas is generally pretty cheap, so an NG furnace is a simple heating solution (even if much less efficient).
where folks expect a lot less from their HVAC
Better to say "where the heating system is distinct from any air conditioning". Since European summers tend to be dryer (and cooler than large parts of North America) AC is less important. And you see a lot of room ACs in places like Italy or Spain (old houses and apartments).

Hot water heating systems predominate in Europe. So Air to Water HPs are relatively easy to retrofit (unless you need to increase both rad size and pipe size). Underfloor heating is also quite common and that works really well with the HP's principle of slow, even heat. The systems also tends to take care of Hot Water, too (so-called "indirect" systems where the same boiler heats both HW & rads).

It's in the US NE, for old houses and apartments, that you encounter HW systems (parts of Canada, too). Almost always in pre WW2 homes, I think.
There's also steam rads, which I have never actually encountered in Europe, knowingly, but may be present.
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Re: Heat pump kwh usage as sole source of home heat

Post by THY4373 »

ETK517 wrote: Mon Feb 03, 2025 9:23 am

What am I misunderstanding? In my climate (as in many other posters' climates) you need a backup heat source in addition to a heat pump for cold weather. The backup heat is an independent system, whether a simple coil system or a preexisting heating system like hot water or steam radiators, electric baseboards, etc. That entails having two separate heating systems, though I suppose they can be integrated relatively seamlessly. You may be stating that the total number of HVAC systems remains the same because a heat pump also serves as A/C?
You don't need a backup heat source in your climate as a cold climate heat pump could easily cover NYC. A cold climate heat pump didn't make sense in my area given I already had a gas supply. So I went with a non-cold climate heat pump with gas furnace to get the best of both worlds. To me to separate heat systems are two systems that are entirely separate. For example a wood stove and an oil burner furnace. In my case I have a single HVAC system that operates as one, with one thermostat. Once setup I don't need to pay attention to it as the thermostat controls which heat source I am using. There are no more major components in my system than a regular gas furnace/AC system. To me that is a single system (one thermostat, one AC/heat pump, one gas furnace that also acts as air handler in AC and heat pump modes). Two entirely separate systems to me are systems that do not coordinate with each other and require my intervention to cut over. Basically I have no more components in my system than a bog standard AC/gas furnace combination. The only real difference is I have four stages of heat. Two variable ranges for the heat pump, 60% gas furnace and 100% gas furnace (my gas furnace is two stage). The comfort of my new system is well ahead of the old one, it is not even close it is also significantly more efficient. But as I said if heat pumps don't work for you that is fine, they aren't right for plenty of folks but don't sell them short they can work extremely well and be extremely cost effective in the right use cases.
Last edited by THY4373 on Mon Feb 03, 2025 10:36 am, edited 3 times in total.
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Re: Heat pump kwh usage as sole source of home heat

Post by Epsilon Delta »

Valuethinker wrote: Mon Feb 03, 2025 9:52 am
It's in the US NE, for old houses and apartments, that you encounter HW systems (parts of Canada, too). Almost always in pre WW2 homes, I think.
There's also steam rads, which I have never actually encountered in Europe, knowingly, but may be present.
You'll find steam rads in various British stately homes and a few public buildings. Which are pretty much the only places you'll find pre-WW2 central heating in Britain. It's mostly the age of the system that matters and there are many more old heating systems in the US.

There are also plenty of modern hot water radiator systems in the NE US. Most of these use baseboard radiators. At least partly because most homes in the NE have basements and that makes ground floor baseboards easy to plumb.
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Re: Heat pump kwh usage as sole source of home heat

Post by Valuethinker »

Epsilon Delta wrote: Mon Feb 03, 2025 10:32 am
Valuethinker wrote: Mon Feb 03, 2025 9:52 am
It's in the US NE, for old houses and apartments, that you encounter HW systems (parts of Canada, too). Almost always in pre WW2 homes, I think.
There's also steam rads, which I have never actually encountered in Europe, knowingly, but may be present.
You'll find steam rads in various British stately homes and a few public buildings. Which are pretty much the only places you'll find pre-WW2 central heating in Britain. It's mostly the age of the system that matters and there are many more old heating systems in the US.

There are also plenty of modern hot water radiator systems in the NE US. Most of these use baseboard radiators. At least partly because most homes in the NE have basements and that makes ground floor baseboards easy to plumb.
Thank you. That is interesting.

I know one of those old houses. I am not sure when Central Heating was installed (pretty sure before WW2), but I don't think it is steam based (I would have to ask). What I do know is that it's almost never running, because of the cost of heating a large house (with heating oil). Never been so cold in my life.
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Re: Heat pump kwh usage as sole source of home heat

Post by ETK517 »

THY4373 wrote: Mon Feb 03, 2025 10:31 am You don't need a backup heat source in your climate as a cold climate heat pump could easily cover NYC.
This is contrary to the advice of licensed HVAC folks, my GC, and posters here, who have said their heat pump alone would struggle to maintain 65 degree indoor air temps. If you are not in the US then you may be unfamiliar with the typical systems that are installed here as well as expectations for US consumers as to indoor air temperatures.
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Re: Heat pump kwh usage as sole source of home heat

Post by Valuethinker »

ETK517 wrote: Mon Feb 03, 2025 11:10 am
THY4373 wrote: Mon Feb 03, 2025 10:31 am You don't need a backup heat source in your climate as a cold climate heat pump could easily cover NYC.
This is contrary to the advice of licensed HVAC folks, my GC, and posters here, who have said their heat pump alone would struggle to maintain 65 degree indoor air temps.
65 F indoors at what outdoor temperature?

Heat Pumps come (normally?) with backup strip heating. Essentially a Coefficient of Performance of 1.0. That should cope with pretty much anything a gas furnace can cope with. It's just an expensive way to heat your house if you have high electricity rates. You'd only not have that option fitted if you did have another backup source of heat.
This is contrary to the advice of licensed HVAC folks, my GC, and posters here, who have said their heat pump alone would struggle to maintain 65 degree indoor air temps. If you are not in the US then you may be unfamiliar with the typical systems that are installed here as well as expectations for US consumers as to indoor air temperatures.
They are US resident, I believe.

The thing is the higher heating performance heat pumps have barely appeared in the US market. They exist if you go with Japanese ranges, but (according to poster talzara) the US manufacturers have very few models. That's because the US heat pump market was Air Conditioning-led and grew up in the southern states.

Nearly 100% of new heating installations in Scandinavia are heat pumps.* So at least the climate of Wisconsin (unless you are on the Norwegian coast). Maybe colder.

https://www.carbonbrief.org/guest-post- ... ess-story/

https://www.cell.com/joule/fulltext/S25 ... 23)00351-3

What you are experiencing is the innate conservatism of the HVAC market -- there's been a lot of change, and "scientific revolutions proceed funeral by funeral" -- updating long experienced contractors will take a long time.


* they also have a lot of urban heat networks. However there are now installations to replace the gas or biomass fueled boilers there with very large heat pumps.

The vast majority of those HPs are now Air Source HPs. Ground Source/ geothermal HPs were much more common, but new installations tend to be ASHP (around 80% from memory).
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Re: Heat pump kwh usage as sole source of home heat

Post by ETK517 »

Valuethinker wrote: Mon Feb 03, 2025 12:08 pm 65 F indoors at what outdoor temperature?

Heat Pumps come (normally?) with backup strip heating. Essentially a Coefficient of Performance of 1.0. That should cope with pretty much anything a gas furnace can cope with. It's just an expensive way to heat your house if you have high electricity rates. You'd only not have that option fitted if you did have another backup source of heat.
65 degrees is not sufficient for me - that was what I've seen others say would be tough to maintain in very cold temps. I want my house to readily hit 70 in the winter. In the NYC metro climate, it needs to be able to do that at 0F outside (two weeks ago, the nighttime lows were single digits for 5+ consecutive nights). Since the primary justification for heat pumps is efficiency/cost savings, running an inefficient, expensive heat strip constantly defeats the purpose. In my particular use case, it was also not possible to install heat strips.

Your sources report that in Scandinavia, heat pumps are heavily supplemented not just by communal heat but also by wood and other electric heat sources:
Many homes continue to use wood stoves after having installed a heat pump as a study from the Oslo Centre for Research on Environmentally Friendly Energy (CREE) on heat pumps shows, albeit less frequently. This resulted in about a quarter less wood being used for heating in 2021 compared to 2010. The continued use of wood is at least in part a result of aesthetic and cultural preferences.

In Finland, heat pumps are often installed as an additional heating system complementing mainly electric heating.
There is a lot of talk of efficiency, but I didn't see much on the main measure of performance I care about as a consumer, which is reliable, comfortable indoor air temperatures without supplementation.

If there are much better heat pumps out there then I'm not sure why they're not coming stateside.
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Re: Heat pump kwh usage as sole source of home heat

Post by Epsilon Delta »

If a heat pump can only keep the house at 65 it's not a big enough heat pump. The simple solution is a bigger heat pump. Or two heat pumps.
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