a/c & heating unit with no outside unit

[hard-work]

This is probably outside the experience of most on this forum. I believe these are taking off in flats. Many dump heat from the apartment into a preheat DHW cylinder or electric thermal store, which sound efficient enough. Anyone had any direct experience of them?

 

[muggles]

Not A/C, but I've fitted a cylinder connected to MVHR for hot water preheat in a barn conversion. Seems ok at the moment but they've not had a winter with it yet

 

[hard-work]

That appears to be an in-duct air to water heat exchanger reclaiming heat in air that would normally be dumped to outside. Low grade heat usually but OK for DHW preheat.

Some A/C & Heating units dump heat into a DHW preheat cylinder which can get quite hot. Then the performance of the a/c diminishes. To cool the preheat cylinder/condenser, if DHW is not drawn off, hot water in the cylinder is dumped into the drain, cooling the cylinder by cold mains water. This costs in water bills of course and I am pretty sure many water authorities would not allow it.

A reversible heat pump could do heating by extracting heat from the pre-heat cylinder. But again it can be too cold needing a mechanism to prevent temperatures that are too low, so needs heating by elements, or switching over to air heating elements for space heating.

Versions of a/c & heat without outside air condensing units are becoming popular in London flats. Many new builds have not gas in them.

 

[Gasguru]

Good luck saving any money...repair bills often exceed savings.

 

[hard-work]

It is not for me. The cost of UFH and the rest can't be too much different in installation costs, but this will have a/c as well. A quality unit, Mitsubishi, Panasonic, etc will be reliable enough.