How Heat Pumps Work

Heat pumps operate on the same prinicpal as a refridgerator or an air conditioner, only in reverse. Rather than burning fuel to create heat, they are moving heat.

The heap pump contains a refrigerant type liquid which boils and evaporates at a low temperature of about 40 Degrees C. Within the pump a compressor increases the pressure acting on the evaporating liquid. The compressed refrigerant then transforms to a hot gas under this added presure. The hot gas passes through a condensor where the hightened temperature is extracted. The cooled gas then goes back through a valve where the pressure is released and it transforms back to liquid allowing the circuit to be repeated over and over.

The performance of a heat pump is measured using it's Coefficient of Perfomance (COP), which is the ratio of useful heat energy supplied by the pump to the electrical energy input. Heat pumps that are working efficiently are capable of producing 3-5 units of heat energy per unit of drive electricity, thus having a COP of between 3 and 5.