EXHAUST AIR HEAT PUMPS
Exhaust air heat pumps collects energy form the exhaust air of the property. The exhaust air is extracted from the kitchen and the bathrooms and brought to the heat pump via ductwork. The exhaust air heat pumps come with an integrated hot water cylinder. Better Planet install the whole system, including the duct work, in some cases including supply air ducting as well. These systems are mainly used for flats and other smaller properties which are not suitable for other types of heat pumps and where air quality is an issue.
As with all types of heat pumps, it is important to specify the right size (kW) heat pump. For this a room by room heat loss assessment of the property is required. A heat pump produces less hot water than a boiler and the lower temperature it can operate at, the more efficient the system is. Therefore, the overall efficiency of the heating system requires heating distribution (underfloor heating, radiators or fan coil units) which can deliver comfortable room temperatures at low operating temperatures.
The maximum capacity of an exhaust air heat pump is around 5 kW which means that they are mainly used for flats and small bungalows. The system contributes to the ventilation of the property by removing air from kitchens and bathrooms. It is therefore most relevant for new, airtight properties.
All exhaust air heat pumps require ducting. For smaller units, only extract ducting is required while for bigger units both supply and extract ducting is required. In the latter case, the system is effectively a heat pump and MVHR in one system.