[jstapels]

Maybe I'm missing something, but no matter how efficient a heat pump is, doesn't it have a limit on how much heat it can pump as ∆T increases?

Even here in western NY we occasionally have to deal with -10 F (-23 C) weather for a week and so that's a pretty big temperature delta if you want a comfortable 68 F (20 C).

Combine that with the fact that gas is still quite a bit cheaper per unit of energy than electricity (in my area) and a heat pump just doesn't make any sense.

The ability to have a single unit heat and cool is definitely nice, but without a geothermal-like ambient temperature to work with, I just don't see this working out, even with all the insulation in the world.

[thinkcontext]

Elsewhere in this thread fastbeef says "They're very common in Sweden and can easily warm an entire house even at -20 C [-4F]." So, it can work though at -10F you would probably need supplemental heat.

Of course in Sweden residential natural gas prices are almost 4 times what they are in the US so its a very different economic decision. Shows what a carbon tax can do.

https://www.statista.com/statistics/702735/household-natural...

[fastbeef]

Keep in mind that 1 kW worth of gas gives out 0.9 kW, while 1 kW of electricity entered into a heat pump gives out AT LEAST 3 kW of heat.

Also, no one uses gas for heating in Sweden. Very old houses down town use it for cooking only.

[patall]

Aren't you supposed (at least when you have a single house) to couple it with a geothermal energy so that your external temperature is always the years median of around 9 C?

[Yetanfou]

Geothermal or some other relatively stable source. If you live near a lake you can drop a water sling on the bottom and use that as a source, it is also possible to bury a sling in a field next to your house at a frost-free depth (2.5 m or deeper in the north of Sweden) and use that. In built-up areas with many houses using deep wells for heat extraction there have been cases of those wells freezing up, this can also happen if the system is under-dimensioned.