Home made heat pump

[adam2]

A refrigeration engineer whom I know has been experimenting with heat pumps, at very little expense as they have access to redundant equipment.

They have installed two heat pumps, one is air source and the other is ground source.
The ground souce heat pump collects heat from the soil in the front garden and pumps this into a large hot water tank at about 40 degrees.
This is used to heat coventional central heating radiators, but very over sized in order to emit enough heat at the low temperature.

The other unit collects heat from extracted air at about 20/25 degrees and heats the same hot water tank as the first unit.

Initial results are most encouraging with electricity consumption being about 10 to 20 KWH a day in cold weather.

I have my doubts about the general use of heat pumps on account of the costs and complexities involved and the likelyhood of expensive repairs.
In this case however the system is home made and most worthwhile if no value is put on the time spent tinkering.
They also have the advantage of a 3 phase electricity supply.

The next project is a higher temperature heat pump to reclaim the heat in waste water and use this to heat domestic hot water to a useful temperature.

[RenewableCandy]

Is the 40 degC water in a sealed system? Otherwise they might be at risk of Legionella and the like? Just a thought. Classic "salvage engineering", mind

[adam2]

Yes the water at 40 degrees is in a semi sealed system, with a feed and expansion tank. The water is treated with biocide.