[kenmacd]

There are systems (like the sanco2) that use an indoor/outdoor pump.

> This sounds terrible for efficiency in winter, as you will need to reheat the room

Sure, but lots of people have some point of the year they want cooling.

Even during the heating season it's only worse if you're heating the living space with something _worse_ than what you're using to heat the hot water. If you have a heat pump for room heat then you're moving heat from outside, to in the house, to in the water heater.

If you're heating the room with electric then in the winter it's no different than using an electric water heater (100% efficient).