Most homeowners replace their furnaces every 10 to 15 years; and in a lot of cases, that's how long it's been since they've had an air duct cleaning.
According to the U.S. Environmental Protection Agency (EPA), you should consider scheduling an air duct cleaning if:
- There is substantial visible mold growth inside air ducts or on other components of your heating and cooling system such as your vents.
- Ducts are infested with vermin.
- Ducts are clogged with excessive amounts of dust and debris, and/or particles are released into the home from your supply registers.
The trouble is, you can't always see the particles and mold spores that are being released throughout the home - and when a contractor changes out your furnace, he or she isn't replacing the duct work, so anything previously trapped inside will stay inside. Also, when changing out furnaces, you run the risk of the replacement furnace blowing more air than the old one, which more forcefully pushes that debris out the first time it's turned on and then every time it cycles.
So ... should you schedule a duct cleaning when you're installing a new furnace?
The answer is: most likely.
In this instance, the best time to have your ducts cleaned would be while the old furnace is being removed, or at least before running the new furnace. Otherwise, you run the risk of an overabundance of debris blowing out of the vents upon start up.