[datatrashfire]

It's not that it's more energy efficient than AC per se, just that running it in reverse to move heat into your house is much more energy efficient than using electricity to generate heat compared to electric resistance heat.

Relative to gas, it's going to be competitive when the ambient outdoor temperature is > 40 degree Fahrenheit, but probably more expensive depending on utility rates where you live.

[thraway3837]

If I rephrase what you said to make sure I understand it correctly: Cooling costs would be the same as AC units and heating would be cheaper or same depending on the cost of Gas. Would that be correct?

[Schroedingersat]

Generally. Depends a bit on climate, choice of heat pump, and relative energy costs.

A ground loop can make cooling cheaper too, as can upgrading to newer more efficient compressors.

[thraway3837]

Thank you! Also sounds like heat pumps come with multi or infinite stages akin to a CVT to be able to run at any speed for the heating or cooling demands. Rather than legacy units that are only On or Off.

Down in the comments, sounds like MA has good incentives, but not seeing other states. CA is banning new gas installations, so I assume heat pumps are the only way for new developments

[Schroedingersat]

> Also sounds like heat pumps come with multi or infinite stages akin to a CVT to be able to run at any speed for the heating or cooling demands. Rather than legacy units that are only On or Off.

Yeah, kinda. They can convert the incoming power to dc then back to ac at a different frequency so they can run at any speed. This cuts the energy losses from start-stop.

Less related to heat: It also has a neat side effect that it's a very simple change to make them run directly on solar with no (separate) inverter (and with no AC->DC step). On top of being more efficient even with AC->DC->AC this means in hot climates the energy used for cooling is used more efficiently, and the inverter on the solar array doesn't need to be as big (if you're getting full noon sunlight you probably want the AC on).

[pxmpxm]

I don't believe there is a municipality anywhere in the US where heat pump heating will be cheaper than nat gas on run rate basis.

[datatrashfire]

I actually used https://www.ncei.noaa.gov/products/land-based-station/us-cli... for my city to develop a model for the cost of btus from either method throughout the year and the heat pumps cope at that hourly temperature, and it was slightly cheaper for heat pump for the entire year. But I also live in a marine influenced climate in the west with low electricity rates.

[pxmpxm]

Whereabouts did that actually work? I can't think of a west coast locale where electricity is actually cheap and you get anything remotely resembling a winter.

I can see places like coastal california where you're on AC virtually year around and maybe need a day or two of heat.

[seanmcdirmid]

> I can't think of a west coast locale where electricity is actually cheap and you get anything remotely resembling a winter.

Eastern Washington? 10 cents kWH in Spokane.

I don’t know if any coastal Californian locale that needs AC for more than one or two weeks a year. Even in LA you can get by without AC.

[datatrashfire]

Yes! It could be more expensive too, the real kicker is utility costs and how cold your climate gets.