The 12kW Air to Water Heat Pump was chosen because we have no depth of earth before hitting rock here in Ratooragh, so the prospect of a major expense drilling a well influenced our decision.
It works like a big air conditioner in reverse, using a heat exchange system to take heat from the air and transfer it into our big Buffer Tank to be used in the under floor heating. We usually have the temperatur of the Heat Pump set at 30 to 35degs C which is usually sufficient. A normal boiler/radiator system has to heat the water to about 75degs C to work properly, so underfloor heating is much more efficient.
The only time there is a problem is when the air temperature stays below +5deg C, and the system becomes less efficient. This is because it gets iced up and spends some time each day de-icing automatically. Fortunately, living so close to the sea, we have a very temperate climate, so very rarely have this problem.