Posted By: WillInAberdeenWhy would an underfloor grid of refrigerant pipes need different maintenance than the equivalent grid of hot water pipes?

Because the consequences of a refrigerant leak are much more serious than the consequences of a water leak.

I diy fitted a Hitachi 2.5kW (output) aircon around 9 yrs ago, used almost entirely for heating. Re cold feet, it is installed at just above skirting level, with a couple of bookshelves in front to conceal it. These need moving every 6 mths/yr for access to clean the air filter. I also brush the outside screen clear every year or so, and that's it. The books get a bit dusty too.

The only problem has been a whine from the outside fan motor last year which was sorted with a pair of new ballraces - a little awkward to fit as the motor casing was glued on, but I was spurred on by the quote of £235 for a new motor vs. £10 or so for the races.

An earlier post said that ASHPs are no good for poorly insulated houses. That might be true if you want it to do the whole job, but in my heat-leaky old house it works in tandem with a LPG CH boiler, reducing our gas consumption very significantly.

Our DHW is via immersion, or there's the possibility of firing up the old Rayburn in the kitchen in the event of a long power cut. I toy with the idea of heating the water by fitting a heat exchanger in the thermosyphon output pipe of the Rayburn and passing the hot 'refrigerant' through that. Should be able to get the tank up to about 50C, and guaranteed not to boil without any controls. Not so great if cooling is wanted, so a valve to divert the flow would be needed.