Harnessing America's heat pump moment • Hacker News Board

Re: Harnessing America's heat pump moment

#181

Post by cycomanic » Sat, Oct 25, 2025, 1:49 AM UTC

VWWHFSfQ wrote: post #42

mithr wrote: post #26

Electricity costs are a big factor in this, imo. Rates for my northeast town increased by ~25% in 2024 and are going up by another ~10% this year. It's a hard sell to spend a large amount of up-front money (even after rebates, which decreased this year) to convert to a system that will cost you more than you pay today, and may not work as well in cold weather (every heat pump company I talked to suggested keeping my…

A heat pump just makes no sense whatsoever for me in my northeast town. The electric bill alone would outpace the old propane bill, not to mention installation. And it won't even work during some of the coldest winter weeks when you _really_ need it to work. Maybe I would consider it if I was in, like, Nevada or somewhere.

I don't know what sort of heat pump systems are common in the US, but Sweden (and AFAIK Norway and Finland as well), are probably >%80 heat pump for single family homes (most apartments are community heating at least in the larger cities). So it's absolutely now problem to run a heat pump even if it is very cold outside, but if you want to improve efficiency in areas that are super cold you can drill into the ground for a heat sink (those are called Bergvärme in Sweden).

Regarding cost, in most of the countries I've lived in a large fraction of the cost in the gas bill was the distribution cost. So once you switch to a heat pump, you also switch to electric cooking and even if heating with electricity would be significantly more expensive you would still win. Is that different in the US?

Re: Harnessing America's heat pump moment

#182

Post by throw0101a » Sat, Oct 25, 2025, 1:51 AM UTC

sokoloff wrote: post #171

throw0101a wrote: post #167

Earlier quoted context omitted.

Here's a Trane/Mitsubishi unit that has a COP of (at least) 3 at -13F/-25C: * https://ashp.neep.org/#!/product/156605/7/25000/95/7500/0///... An LG unit with 2.4 at -4F/-20C: * https://ashp.neep.org/#!/product/29688/7/25000/95/7500/0///0 Searchable database of cold climate air source heat pumps (ccASHPs): * https://ashp.neep.org/#!/product_list/

Correct (and thanks for the link to that unit). Though it’s worth noting that that first 2 ton rated unit is putting out 0.5 tons (6k BTU/hr) at that temp and rating. That’s not going to be particularly helpful for a structure that needed 24k BTU/hr during warmer temps, meaning the owner of the unit is likely mixing in a lot of 1.0 BTUs to meet the heat loss at -13°F.

> Though it’s worth noting that that first 2 ton rated unit is putting out 0.5 tons (6k BTU/hr) at that temp and rating.

I just did a quick search for "all" units and sorted the result list/table by COP@5F. If one was actually shopping/designing a solution then a more nuanced search criteria would be used.

Further, you'd probably want to do a (US ACCA) Manual J calculation to first determine how much energy is needed (j = joules)

* https://www.youtube.com/@HomePerformance/search?query=manual...

Then the (US ACCA) Manual S (select) to figure out your equipment:

* https://www.youtube.com/@HomePerformance/search?query=manual...

One can lookup the 1% (or 0.4%) of coldest/hottest days for your area, which would help determine what one actually has to typically worry about:

* https://ashrae-meteo.info/v2.0/

* https://www.airequipmentcompany.com/2021/what-does-design-da...

Re: Harnessing America's heat pump moment

#183

Post by smnrchrds » Sat, Oct 25, 2025, 1:52 AM UTC

Merad wrote: post #111

blahedo wrote: post #33

People are reluctant to install them because they don't work as well as the good old boilers we'd be replacing. I'm not saying they can't, and I'm not saying that there are zero models out there that work. But in practice, a lot of us that have interacted with heat pumps have the specific experience that they get anemic as the temperature goes down and eventually become unable to do much of anything. I live in the mi…

I have to agree. I've spent about 2/3s my life in houses with heat pumps and the last 5 years with a gas furnace (the rest being wood heat as a child). Mostly in Western NC and Eastern TN near the mountains, so chilly but not extreme cold. Heat pumps work, but they aren't nearly as _pleasant_. You can write essays about the efficiency of heat pumps, how lukewarm air works just fine to warm the house, how heat pumps a…

I have never had a heat pump, so I wasn't aware of this shortcoming. Could you please explain a bit more how different it is with heat pump compared to furnace?

Re: Harnessing America's heat pump moment

#184

Post by cycomanic » Sat, Oct 25, 2025, 1:53 AM UTC

crgwbr wrote: post #106

doctorhandshake wrote: post #98

Earlier quoted context omitted.

The notion that heat pumps don’t work at low temperatures hasn’t been true for years. I think you may be surprised to find that just about any heat pump you look at has good efficiency down to very low temperatures.

That’s true, but still doesn’t always make heat pumps the most cost effective choice to operate. For example, last winter I paid an average of $0.24/kWh for electricity vs $0.05/kWh for natural gas. Even if a heat pump had a perfect 4.0 COP all winter, gas would be ~15% cheaper. Electricity prices really need to come down before it will be viable for everyone.

Does your 0.05/kWh include the distribution costs? The thing to do once you go to heating with gas is to just switch completely to electricity and turn off gas. In my experience (admittedly not in the US, but several other countries) distribution cost often more than double the $/kWh for natural gas (especially if you only heat part of the year).

Re: Harnessing America's heat pump moment

#185

Post by whateveracct » Sat, Oct 25, 2025, 1:58 AM UTC

throw0101a wrote: post #152

Loughla wrote: post #101

Earlier quoted context omitted.

Define low temperatures. Mine struggles if it gets below 30, and might as well not exist below 10. They're not great at low temps.

> Mine struggles if it gets below 30, and might as well not exist below 10. They're not great at low temps. What percentage of the (US) population gets temperatures like that? That's generally mostly IECC Zone 7 (though cold snaps in Zone 6) can happen: * https://basc.pnnl.gov/images/iecc-climate-zone-map ASHRAE—an HVAC organization—has data on the coldest and hottest days for areas so that you can design things for…

> What percentage of the (US) population gets temperatures like that? That's generally mostly IECC Zone 7 (though cold snaps in Zone 6) can happen:

A lot? e.g. Chicago gets it every year

Re: Harnessing America's heat pump moment

#186

Post by glxxyz » Sat, Oct 25, 2025, 1:58 AM UTC

bluGill wrote: post #50

When I replaced my furnace a couple years back I asked for a heat pump - a previous house had it and it worked great. Turns out my contractor didn't ask the right questions and so mine only works to 25F - it still outputs heat below that, but not enough to keep my house warm and so I use the backup furnace a lot more than I want to. A previous house the heat pump was sized to work to 14F. They make them that will wor…

I'm amazed at these prices, I replaced a propane tank + furnace with horizontal loop ground source for $40k Canadian (+ tax, but government rebate matched that). It's almost paid for itself in about 6 years, I gave more detailed numbers in another reply.

Re: Harnessing America's heat pump moment

#187

Post by glxxyz » Sat, Oct 25, 2025, 2:02 AM UTC

estimator7292 wrote: post #67

WorldMaker wrote: post #60

Earlier quoted context omitted.

The strength of your heat pump shouldn't be outside surface temperature, but underground aquifer temperature. Those two temperatures are related but not as directly as they seem. A good aquifer in certain cavernous regions of the US might stay about 55 degF year round, regardless of outside surface temperature. 55 degF is still below what a lot of people want their home to be year round so a heat pump still has to su…

You're talking about geothermal heat pumps which are far less common than air-to-air heat pumps because they are far more expensive. These are entirely disjoint concepts.

The prices when I looked weren't that different- it was about C$30k Canadian for air source and C$40k for ground source (which I went with).

Re: Harnessing America's heat pump moment

#188

Post by glxxyz » Sat, Oct 25, 2025, 2:06 AM UTC

twothamendment wrote: post #121

ssuds wrote: post #76

Earlier quoted context omitted.

I just wrote a big thread yesterday responding to someone with similar concerns to yours ( https://bsky.app/profile/shreyassudhakar.com/post/3m3w3nra2h... ). Copying it here if it's helpful to other folks. FWIW, the challenges you are facing seem to be grounded in bad design and application, which happens more than it should and really sucks. We need to move the bar much higher for the contractors installing heat pum…

I'm in Northwest Montana. My ground source heat pump doesn't struggle until the highs outside are -20F (actual, not wind-chill). I have the backup heat strip, but the breaker is off. I don't know when it would turn on, I just wanted to know it wouldn't without me knowing it.

I'm in Canada at a similar latitude with ground source, resistance heating normally kicks in at about -25C (-13F) or so, just a few hours on the coldest nights, doesn't cost much. I could probably leave the breaker off too, I wouldn't mind it a degree or two colder.

Re: Harnessing America's heat pump moment

#189

Post by pfdietz » Sat, Oct 25, 2025, 2:14 AM UTC

prlambert wrote: post #54

blahedo wrote: post #33

People are reluctant to install them because they don't work as well as the good old boilers we'd be replacing. I'm not saying they can't, and I'm not saying that there are zero models out there that work. But in practice, a lot of us that have interacted with heat pumps have the specific experience that they get anemic as the temperature goes down and eventually become unable to do much of anything. I live in the mi…

Yes this is actually the worst – when open minded people get a heat pump for "the right reasons" and then have buyer's remorse. Completely backfires the transition. Do you have a ducted or ductless heat pump? Sounds like ducted, and if so that might be part of it too. The air cools down in the ductwork and if that's not accounted for - i.e. you reuse ductwork that was meant for a furnace – you run into issues like th…

When we had our ducted heat pump installed, we also had the ducts in the attic covered with extra insulation, as well as spray foam at the top of the foundation to seal that completely. This all really helped.

Re: Harnessing America's heat pump moment

#190

Post by throw0101c » Sat, Oct 25, 2025, 2:18 AM UTC

whateveracct wrote: post #185

throw0101a wrote: post #152

Earlier quoted context omitted.

> Mine struggles if it gets below 30, and might as well not exist below 10. They're not great at low temps. What percentage of the (US) population gets temperatures like that? That's generally mostly IECC Zone 7 (though cold snaps in Zone 6) can happen: * https://basc.pnnl.gov/images/iecc-climate-zone-map ASHRAE—an HVAC organization—has data on the coldest and hottest days for areas so that you can design things for…

> What percentage of the (US) population gets temperatures like that? That's generally mostly IECC Zone 7 (though cold snaps in Zone 6) can happen: A lot? e.g. Chicago gets it every year

>>> Mine struggles if it gets below 30, and might as well not exist below 10. They're not great at low temps.

>> > What percentage of the (US) population gets temperatures like that? That's generally mostly IECC Zone 7 (though cold snaps in Zone 6) can happen:

> A lot? e.g. Chicago gets it every year

[citation needed]

Per historical weather data:

https://ashrae-meteo.info/v2.0/index.php?lat=41.960&lng=-87....

It is warmer than -16C/3F at Chicago (O'Hare) for 99% of the time (i.e., except for 4 days a year), and warmer than -18.7C/-2F for 99.6% of the time (2 days).

ASHRAE are the folks that publish the heating/cooling standards that are used in building codes for estimate heating/cooling equipment capacities (Manual J) and selecting the right equipment (Manual S).

Here's a PDF with a lot of locations in the US and CA (and other countries further down), and if you look under the "Heating DB" column, you'll find very few US locations that have -30F under the 99% (or even 99.6%) sub-columns:

* https://www.captiveaire.com/catalogcontent/fans/sup_mpu/doc/...

So unless you're in AK, MN, or ND, long runs of temperatures colder than -20F/-30C don't happen too often. Of course if you have a leaky house with little insulation, you're throwing money out the window/door, so the first consideration for a good ROI is better air sealing and insulation.