Air Source Heat Pumps work using similar technology as the ground source heat pumps, but using the outside air as its energy source. In the UK and Ireland, the outside air temperature rarely goes below -3°C. The heat or energy moves from hot to cold (2nd law of thermodynamics) and the refrigerant in the heat pump boils at very low temperatures of -30°C so the difference between the outside air and refrigerant create the energy that flows into the heat pump.
Domestic customers receive a £2500 grant up front, plus they receive annual RHI payments at 5.6 pence per unit (kWhr) for seven years.
The RHI payment for a domestic biomass boiler is typically between £1000 and £2000 per annum. This equates to an impressive average grant income of £13,000 at the end of the 7 year period.