Why you should regularly clean your home furnace ducts

“You would be surprised what we used to find in duct systems”

NAIT grad Tyler Phinney, owner of KTP MechanicalAir flow in a house can be obstructed in all kinds of ways. As Tyler Phinney (Refrigeration and Air Conditioning Mechanic '12) recalls, some are a little strange.

Today, Phinney owns and operates KTP Mechanical Services, based in Leduc, which installs and services heating, AC, hot water systems and more. But he started in the industry 20 years ago doing furnace cleaning.

The weirdest thing he found in a home floor vent during a job is not fit to publish on techlifetoday. The second weirdest … well, probably not either.

“You would be surprised what we used to find in duct systems,” says Phinney with a laugh. “A lot of people forget about the stuff they hide in them.”

More family-friendly items include golf balls, hockey cards and toys (that can make their way down to the furnace heating element and melt).

Phinney’s company doesn’t clean ducts, but he knows why it’s essential to keep them free of bizarre junk and all manner of dust and debris, and, just as importantly, he knows what it takes to do that properly.

Why ducts need to be cleaned


Ducts deliver heated or cooled air to every room in your home, and therefore to your lungs. “Dust and everything that collects in your duct work sits there until you get it cleaned,” says Phinney. “And you’re breathing that.”

In a way, your furnace is breathing it too. The furnance filter will catch some debris when it makes its way back around via the interior return air system, but it can only handle so much.

“If you have a dirty filter, it restricts the air flow to your blower motor,” says Phinney. That may mean less air moving from your furnace through the ducts, and therefore a less comfortable home.

How cleaning should be done


This is no small undertaking, taking anywhere from an hour-and-a-half to three hours, says Phinney, depending on the size of the house.

To start, a cleaner will insert a vacuum hose into the furnace above the heating elements (so as not to suck dirt onto them). Don’t be surprised if they need to cut a 10-inch (25-centimetre) hole into the duct work to do this; they’ll patch it up later. They may even remove the blower motor.

“When they’re vacuuming they’ll put covers over all of the vents so it’s really drawing the system tight,” says Phinney. Then they’ll go from room to room, opening vents and blowing air down to help the vacuum get all the dust and old hockey cards. They’ll clean vents and grills before replacing them. The return air system gets the same treatment.

Also, Phinney adds, “a good company will give everything a blow down: While they have the vacuum hose working they spray down the whole furnace so it takes all the dust off.”

How often ducts should be cleaned

Nikolaeva Elena/istockphoto.com

Phinney recommends cleaning ducts every three to five years. Opt for the lower end of the spectrum if you have animals or smokers in the house.

Similarly, if you’re moving into a new home, get a cleaning done if the builder didn’t, he adds. Ducts are like dustbins for construction dust and debris.

The best (or worst) time to clean


Know that the cleaner will be running a hose through the front door or a basement window for the duration of the job.

“If you’re doing it when it’s -20 C, it’s going to be cold,” says Phinney. “The furnace is going to be off and there’s going to be a major draft in your house.”

What it should cost


Expect to spend anywhere from $200 to $500. “It all depends on the size of your house and how many vents you have.”

How to find a good duct cleaning company

man looking into furnace duct

Phinney recommends that homeowners be cautious about great deals on furnace cleaning.

“There are so many scams out there. Especially on Facebook, there are companies offering $99 home duct cleaning. If you’re paying $99 and you know it’s going to take three hours to do it, things don’t line up.”

Vet companies via Google reviews, he adds, and the Better Business Bureau. Before anyone arrives, consider doing yourself a favour. Pop the vents and reach inside. You never know what you’ll find.

Keep your furnace filter clean

person installing new furnace filter

Dirt can negatively affect your blower motor in two ways. One: It can limit the flow of air it sends into the ducts. Two: It can collect on the fan blades. Both situations mean that motor works harder, decreasing furnace efficiency.

Regularly changing your furnace filter can lighten the load on the blower motor and keep your ducts cleaner. A standard one-inch filter, found in most homes, should be changed monthly, says Phinney. A four- or five-inch filter should last up to six months.

Banner image Petra Richli/istockphoto.com

Subscribe to receive more great stories every month

Find out more news about NAIT, stories about our alumni and their impact on their communities, and useful how-to content featuring our experts.

Sign up today »