Forced-air systems rely on ducts to carry warm air through the house. Ducts are notoriously leaky, and can raise heating costs 20 to 30 percent. Before installing a new forced- air furnace, have the contractor seal the duct system first. Do not hire a non-licensed contractor, no matter how inexpensive the estimate.
Asbestos leaves invisible, hazardous fibers.
Electric baseboard heating, however, may be an exception. The first step in assessing your furnace is an inspection by a licensed heating contractor. The U.S. Consumer Products Safety Commission and most furnace manufacturers recommend annual inspections to ensure safety as well as efficiency. If it's more than 10 years old, have it inspected annually. Grossman says that unethical contractors often use cheap, minimal inspections as a ploy to find a problem where no problem really exists.