On Mon, 07 May 2018 15:21:36 +0100, dpb wrote:

On 5/7/2018 9:08 AM, Jimmy Wilkinson Knife wrote:
...

Why on earth could an AC unit not run backwards? You just reverse the
pump. Every one I've seen in the UK (commercial and home) has been able
to do this. The controller usually has settings for heating, cooling,
or automatic. On automatic you can simply set a range (say 18 - 22C)
and if it goes over, it cools, if it goes under, it heats.

Those aren't "just" AC units; they're heat pumps specifically designed
and built to do so....an AC unit is just that; the condenser/compressor
connected in cool mode without all the other auxiliary arrangements to
operate in heat/cool mode.

How hard is it to make a motor run in reverse?

--
Two fish swim into a concrete wall. One turns to the other and says, "dam".