VENTILATION SYSTEM

摘要

The present invention relates to an apparatus for ventilation systems which include an element for the transfer of heat from warm exhaust air (taken from inside a building) to cooler exterior fresh air which is drawn into the building. The present invention in particular provides an apparatus whereby, during a defrost cycle, interior a ir may circulate through both of the fresh air and exhaust air paths for delivery back into the building, i.e. the warm interior air, used as defrost air, may be able to circulate from the interior of the building into the ventilation apparatus and back to the interior of the building. The apparatus can thus use interior air as defrost air while diminishing or avoiding the creation of a negative air pressure in the building.