Flue Installtion Guide for a Gas Furnace

Using a tape measure, determine the distance between the chimney and gas furnace to see how much piping is needed. Measure the flue pipe outlet opening on the chimney.

Purchase the piping at a home improvement store. Buy single-wall, galvanized piping and single-wall, galvanized elbows that match the flue pipe outlet size for your chimney. Follow the piping regulations for your location.

Connect the galvanized piping together that run the length of the chimney’s internal part, while wearing gloves. The piping has one crimped end on each side. Connect the crimped end to the next piece of pipe’s noncrimped piece. If piping needs trimming, use metal-cutting shears, and then crimp one end of the piping with a pipe crimper.

Secure the pipe connections by screwing sheet metal screws into the piping at each connection area. Secure each connection with four to six screws.

Slide the flue into one end of the chimney’s opening. Have an assistant stand at the chimney opening’s other end. Once the flue piping is visible, have the assistant grasp the piping and hold it in place. The piping should be about 2 inches longer then the chimney. For an exact length, refer to your area’s code regulations.

Connect the piping to the chimney by using flue-fixing straps, screwing one end into the flue and the other end into the top plate on the chimney.

Install a stainless steel or aluminum chimney flue liner once the flue is in place.