this post was submitted on 27 Oct 2024
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We had great heat pumps in Montana already. And if it gets insanely (-38f) cold, there's a resistive fallback mode. But I'd wager most places aren't gonna get to 38 below.
Not for much longer, at least.
I'm in PA and it doesn't get nearly as cold here, of course. We got mini splits in 2022 that can do -33f, I think. No resistive backup for us.
Mini splits are so, so nice.
Heat pumps don't work well (even the new ones coming from this article are only good to 15f) anywhere near that cold. Most are only good to about 25f. Anywhere they're installed that drops below freezing all have a backup heat system, whether or not it's a gas backup, or resistive electric backup.
Some large commercial heat pumps will got down to like 0 degrees F, but none of the residential ones do.
I am looking out my window at a heat pump in my back yard which is effective down to -15F. Your info is I think about 10 years out of date.
But is it effective , or work?
I understand heat pumps are really good now and do function at colder temperatures than we usually see, which is fantastic. However they get much less efficient as the temperature difference get bigger, meaning you’d have to size the appliance much bigger.
When I looked into this, in New England, HVAC companies were consistently telling me they’d work but not that effectively, and insist led on a new gas furnace as backup heat, as the cheaper option over sizing the heat pump enough to effectively keep the house comfortable
Short answer is yes.
I got curious and dug up the spec sheet. https://budgetheating.com/v/vspfiles/downloadables/BOVA36-60HDN1-M20G%20Technical%20Specifications.pdf So I overstated my particular unit. It's rated to -4F.
I live in a climate that gets under -4F a few times a year, so I also have an auxiliary furnace. I set the cutover temp very conservatively at 20F for last winter as it was the first winter using the heat pump, and I also heard people telling horror stories about $1000 electric bills in January.
While my winter electric bill is now larger than my summer bill, the increase in electricity spending is about half the decrease in gas spending. Looking back at the temperature record, my furnace turned on about 10 days last winter.
I've got the cutover set to 0F this year and we'll see how that impacts the balance.
It's also worth noting that my home was built in the early 70s and still has the original windows and insulation, so it's a long way from the ideal case.
As for your experience with HVAC technicians, I also met a few who clearly still thought heat pumps didn't work well enough, and others who basically recommended them to everyone. It really seemed to be a generational thing.
I have Hi2 heat pumps in a 100yo house with recently improved insulation, and it was just fine last year in -15F weather. No gas backup.
One family member has been talking to installers and they keep telling her that heat pumps can't work reliably, it's extremely frustrating.
I think you're forgetting ground source heat pumps. They'll work fine at -40 because they don't rely on air temperature.
Those are different and that's cheating. It's not what this article is referencing or talking about.
Cheating in what?
Geothermal heatpumps that gather the heat from underground below the frost line are different and much more time and space extensive than a regular heatpump.
They're literally all over the Alps and you've been lied to
Oh yeah? Link me one single residential heat pump from anywhere that works sub 0F.
Here
Their technical documents show that they are down to about 20% of their usual heat output at that lowest temperature so they need to be sized up accordingly. The reality for most folks in an area cold enough to require these is they have backup heat sources for the coldest days anyways.
Literally any decent heat pump has a COP > 1.0 down to around -20F.
Sorry I don't speak medieval, could you translate the temperature from 16th to 21st century?
I have run hest pumps down to -10F just fine in multiple homes.