A novel ventilation heat pump system.

The move towards improving building air-tightness to save energy has increased theincidence of poor indoor air quality and associated problems, such as condensation onwindows, mould, rot and fungus on window frames. Mechanical ventilation heat recoverysystems (MVHR) combined with heat pumps offer a means of significantly improving indoorair quality as well as providing heating and cooling required in buildings.This paper is concerned with the testing and performance of a novel ventilation heat pumpsystem developed for the domestic market (1,2,3). The novel system uses revolving heatexchangers which both impel air and transfer heat. Low grade heat recovered from theexhaust air is upgraded by a heat pump and used for heating the fresh supply air. Theprototype system has a heating coefficient of performance (COP) of up to 5 and an averagesystem COP of 2.5 over a range of conditions. The system typically provides 2kW of heatingfor air supplied at 250 m/hr. The system can also be used for cooling by switching the airflows over the evaporator and condenser. The prototype system requires very littlemaintenance and is compact and energy efficient.