A heat pump is a system that can be used to make hot water (optimally maximum 45°C). There are 2 possible types of heat pumps:
- Air / water heat pump: the heat pump draws energy from outside air for making hot water ( Ideal 45°C , maximum 55°C )
- Water / water heat pump: the heat pump draws energy from water (eg groundwater or process water from an air washer) for making hot water (Ideal 45°C, maximum 55°C)
The efficiency of a heat pump is expressed in the COP value (Coefficient of Performance). The COP coefficient indicates how much electrical energy is needed to generate thermal energy. With a COP of 4, for example, this means that 1 kWh of electricity is needed to generate 4 kWh of heat.
The COP of a heat pump generally increases when the temperature of the medium from which the energy is extracted becomes shorter than the temperature to be made on the other side of the heat pump. For example, when energy is extracted from groundwater (Temperature 11°C) at a water / water heat pump and water heat is made from 45°C, the net COP is approx. 4. When the temperature of the source, where the energy is withdrawn, becomes higher (eg process water from an air washer: Temperature 18°C) then the net COP rises to 5. This is the reason why an air washer is extremely interesting as a source of energy for a heat pump: energy is available all year round from a high temperature level.