Most furnaces are sold through contractors who are usually trained to install and repair the brands they sell. The contractor typically helps you choose the right-size unit for your home and will install it (and usually service it, too).

In the end, it's the contractor who will make the biggest difference in how well the furnace replacement goes. Ask friends, co-workers, and your local gas utility for recommendations (some utilities install and maintain furnaces themselves). Check the yellow pages for additional names.

Get bids from at least three contractors, especially if you don't have a strong personal recommendation for one company. Contractors who bid on your installation should show you proof of bonding and insurance, plus any required contractor's licenses. Check with your local Better Business Bureau and consumer affairs office for complaint records. It's a plus if technicians are certified by a trade organization, North American Technician Excellence or HVAC Excellence, to service residential heating and cooling equipment. These and other similar programs assess the technician’s knowledge of specific types of equipment and its proper service methods. We believe that a contractor who has made the effort to get certified and has practiced this trade and learned from several years of service and installation experience will be a better service provider.

Last of all, be wary of bids that are considerably below the others; the contractor may be cutting corners in ways that compromise the system's effectiveness. Once you select a contractor, ask for references and check them. Then check for any complaints with the Better Business Bureau before signing a contract.

Plan on having your furnace replacement done in the off-season, which for heating-and-cooling contractors is a small window in spring and fall. You'll have more time to choose a contractor and negotiate a price. Contractors can be more flexible when they don't need to respond to a backlog of emergency no-heat calls.