The S&P have been engineered & designed to improve indoor air quality by reducing excess humidity or other contaminants during the winter time, and replacing this air by fresh filtered air from the outdoors. Ideal for use in cold climates where home heating is essential, the HRV or ERV Series ventilators use one motor to exhaust stale room air and another motor to bring fresh outdoor air back into the house. The technology of a plate heat recovery core is that it transfers warm ambient air from one airstream to the other without mixing the air streams for maximum efficiency and comfort. During colder seasons, the units heat recovery core (polypropylene core) will reclaim the heat from the outgoing stale air and use this heat to temper the incoming fresh air, which reduces the cost of effectively ventilating the home during winter. This process is reversed in the summer months.