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To clarify, in the US, there are two commonly used HVAC heat pumps:

- A/C units, which can only cool a room but can’t heat it up

- Heat Pumps, which typically do both.

What’s particularly frustrating is that the only thing that separates one from the other is the inclusion of a $20 reversing valve[1], and some software that can use it.

[1] https://en.m.wikipedia.org/wiki/Reversing_valve

Well, that and you tend to split heat pump systems instead of pumping around warm air to pick up efficiency. And the design of the condensers, etc, is a little different for efficiency and to cope with e.g. condensation outside.

The AC unit can do heating if you just run the pump in the opposite direction. It is just a feature the manufacturer did not bother to install/wants extra money for (it is literally a single $20 part for the valve).

Obviously they are not the most efficient heaters as they are not designed for it but they would still work.

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