Also, a more efficient furnace may necessitate the installation of a metal sleeve called a flu liner inside your brick chimney. In fact, many city codes now require flu liners with new furnaces. Older, inefficient furnaces lose a lot of heat up the chimney, keeping the chimney warm and dry. More efficient furnaces send less heat up the chimney, and the cooler air in the chimney condenses moisture, which corrodes bricks and mortar. Choosing a reputable and honest contractor is the most important decision you'll make regarding your furnace.
Contractors rely on loyal customers.
Good contractors keep them. Heating and cooling contractors are licensed by the state. If you're considering several contractors, call your city's mechanical inspector. The inspector can tell you if the city has had complaints about a company. Beware of companies that cold-call, offering specials on cleaning or maintenance.