Energy recovery ventilator: means for defrosting heat exchanger medium

Abstract

In an energy recovery ventilator (ERV) for exchanging indoor air with outdoor air. The ERV having a housing including first and second input ports, and, first and second exhaust ports, and a heat exchanger core. The ERV further having a first blower for drawing indoor air into the ERV through the first input port, through the heat exchanger core and out the first exhaust port, and a second blower for drawing outdoor air into the ERV, through the second input port, through the heat exchanger core and out the second exhaust port. A means for defrosting the ERV is taught having a first bypass from the first exhaust port to the first input port and second bypass from the second exhaust port to the second input port. Dampers close the first exhaust port and the exhaust port when defrost of the heat exchanger core is needed. To defrost the heat exchanger core, the dampers close, closing the first and second exhaust ports, air passes through the bypasses and recirculates through the heat exchanger core, upon the heat exchanger core being defrosted the dampers open. While defrosting the blowers are set to high speed to increase the waste heat from the blower motors and to increase air circulation. A re-humidifier is incorporated to transfer the moisture to the dry outside air being provided to the building. As the heat exchanger core is defrosted moisture from the heat exchanger core is collected by the re-humidifier, the re-humidifier converts the moisture to steam and provides the steam to the second input port second embodiment of the above described invention provides bypasses from the first exhaust port to the second input port and a second bypass from the second exhaust port to the first input port.