You suffer, and the house suffers too, from excessive humidity. In winter you'll see it as running condensation on windows and window frames. You won't see it at work inside walls, where it can eventually cause serious structural damage.

Health problems are aggravated by the many solvents -- from paint, adhesives, furnishings, plastics, cleaning compounds, and carpets and underpadding -- which are trapped inside your house.

Allergies and respiratory conditions are aggravated by air borne pollution that includes tobacco smoke, pollen, dust, cat and dog dander, dust mites and combustion byproducts. The pollution level builds and builds all winter long -- and all summer long too, if you have air conditioning.

Although your home will not always require heating, the Clean Air Furnace's built-in Heat Recovery Ventilator works year-round to provide a constant stream of fresh air to every room of your house.