This means that one-half of the volume of air in the house is changed every hour. At such a low rate, indoor air pollution caused by cigarette smoke, radon gas, formaldehyde gas, combustion gases from stoves and heating systems, and cooking odors can be a health problem. The unit is connected through ducts to all rooms in the house. About 70 percent of the heat contained in the outgoing air is recycled by the heat exchanger. Preheated fresh air is supplied to bedrooms, the living room and family room.
Stale air is removed from kitchen, bathrooms and laundry areas.
Locate both supply and exhaust vents in or near the ceiling of each room. Undercut doors about 1 inch to provide circulation between rooms when doors are closed. In addition to continuous low speed operation, blowers are controlled by variable speed control switches located in kitchen and bathrooms to provide increased ventilation rates when cooking or after showering. Ventilation also includes the type of heating system installed. In the STS house, electricity, natural gas or propane can be used for supplemental heating.