Air to water heat pumps make use of the latent energy from outside air by converting it into heat that can be used with a typical wet heating and hot water system.
The heat pumps use the constant energy from the air with a refrigerant circuit to boot temperatures for the provision of heating or hot water.
The refrigerant meets the outdoor air in the evaporator (heat exchanger) of the outdoor unit. The air is drawn through by a fan on top of the heat pump. The liquid refrigerant absorbs free energy from the air and evaporates in the process, being led into the compressor. Here, the pressure is increased and the vapour’s temperature reaches approximately 100oC. This gas is led into the condenser where is meets the water from the heating system and, when the warm gas is cooled by the circulating heating water, it changes into a liquid. Energy is emitted in this process to the heating system or hot water. The refrigerant, now a liquid, goes through a drying filter that collects any moisture in the system and passes through a sight glass, used to check the level in the system. The refrigerant continues to an expansion valve where the pressure is lowered causing the temperature to drop, causing it to change to a vapour again. This completes the refrigerant circuit.
Control units:
A sensor is installed on the outside, north facing wall of the property enabling the heat pump to regulate the heating in the property depending on the outdoor temperature.
This control can be supplemented with a room sensor providing information to the control unit about the room temperature to ensure that the pump gives the best possible energy savings.
The air to water heat pump will work well with either underfloor heating or radiators in the property.
The cost of installing an air to water heat pump is significantly lower than a ground source heat pump that requires trenches or boreholes. It is a self contained unit that needs simply connecting to the mains electricity supply and the wet heating system.
