Abstract: An integrated heating unit operates in a first heating mode, in which the heat of combustion gases is transferred to return air, and a second heat recovery mode, in which the heat of exhaust air is transferred to fresh air. The heating unit of the present invention utilizes the same heat exchanging unit and fans to transfer the heat from the combustion gases to the return air and to transfer heat from the exhaust air to the fresh air. The exhaust air is recovered from a select group of rooms, e.g. kitchens and bathrooms. A secondary heater can also be provided in the integrated unit in the form of a fireplace for providing an alternate or an additional source of the combustion gases.

Abstract: A defrost system for a heat recovery ventilator/energy recovery ventilator (HRV/ERV), uses the interior space supply air of an integrated fan coil for defrosting a HRV/ERV core without creating negative pressure in the interior space, which wastes energy, without need of an external fifth port from which to draw defrost air from the interior space, which increases costs, and without re-circulating exhaust air into the interior space. During the defrost cycle, automatically controlled dampers close off the fresh air and exhaust air inputs, and exhaust output, and circulate supply air through the heat exchange core and into to the living space.