Maintenance Checklist for Furnace Ductwork

Before turning on the furnace this winter, it may be wise to examine the status of the furnace ductwork. Furnace ductwork should be examined annually to ensure it is in proper working. Doing this routine maintenance on the ductwork is easy and allows the furnace to function at its optimal efficiency.

1 - Check for Leaks

Turn the blower within the furnace to its “on” setting and inspect the ductwork with a spray bottle full of soapy water. Lightly mist the ductwork, especially at the joints and look for excessive bubbling. Excessive bubbling means that air is escaping in that location because of a ductwork leak. In this case, turn the blower back off and paint the area with a sealing mastic. Use a rag to wipe the area dry afterwards.

2 - Check for clogs and blockages

If the ductwork is free of leaks, go to each of the vents and test the air flow through them. Make sure the vents are open and clean. If there is no or very little air flow coming through the ducts, and the inspection for leaks did not reveal any crushed or kinked pipes, then the ducting may be clogged. A clog can occur when dust, pollen or other debris builds up within the system. Worse case scenarios involve mold build up in these pathways. Mold can release spores into the air system that can make people sick. A professional ductwork cleaning crew should be called to clear any clogs in furnace ductwork.

3 - Look for Rust Spots

Rust spots often develop on furnace ducting that is also used as a delivery system for air conditioning in the summer. The condensation caused by the cool air inside of the ductwork reacting with the warm air outside of it can rust ductwork. If a rust spot is found, sand it down as much as possible and paint it with an epoxy based paint that is rated for high heat. Greater problems develop when the rust is inside of the ducting and cannot be seen from the outside. If sanding the rust down results in breaking through the ducting, or the rust within the ducting corrodes the wall of the ducting to the point where is breaking through, then it is easiest to cut out and replace that section of pipe. Once the ducting is cut through, try to look through it in order to see if there are other rust spots developing.