It operates on the principle that moisture and heat transfer will occur when there is a temperature and humidity difference between the two air streams. Fresh air and exhaust air are completely separated to avoid the transmission of any odor and moisture. The two air streams cross into the plate heat exchanger, and the energy of fresh air and exhaust air is exchanged through the plate, that is, the temperature is transferred from the hotter side to the colder side, and the humidity is transferred from the larger side to the smaller side, So as to recover the energy in the exhaust air.
