What happens on duct cleaning day: timing, prep and each room

A house duct cleaning takes about 1.5 hours and a condo takes about 45 minutes. A technician protects the floors and corners, photographs the system, seals the registers, connects a truck-mounted vacuum to the main trunks, cleans every supply and return and the trunks themselves, then cleans the furnace J-channel, blower and base before closing up and photographing everything again. You get the before-and-after photos by email. This post covers how to prepare, what happens in each part of the house, and what to expect once we leave.

How long it takes

Where a house lands in the 2 to 4 hour range depends on the number of registers, how many furnaces there are, how dirty the system is, and whether you have added a dryer vent, HRV or humidifier cleaning. We work 7 days a week from 6:00 AM to midnight, so early and evening slots are available.

Prep checklist

None of this is difficult, but each item saves time on the clock and keeps the crew out of your closets.

• Clear access to every register. Move furniture, rugs and anything stacked on floor registers. Wall and ceiling registers need a clear spot for a step ladder. Every supply and return gets cleaned individually, so a blocked one gets skipped or delays the job.
• Clear the furnace room. We need to reach the furnace from the front and sides to open the blower compartment and cut the trunk access points. Storage leaning against the plenum or trunk lines has to move.
• Contain pets. The truck vacuum is loud, doors are open to the driveway, and there is a hose running through the house. A closed room or a visit to a neighbour is best.
• Have a new filter ready. The old filter comes out during the furnace steps. Have a new one in your furnace's size on hand so it can go in at the end. In a condo, the same applies to the fan coil filter if your unit has one.
• Parking for the truck. The vacuum stays on the truck and the hose runs from it into the house, so the truck needs to park close to the door nearest the furnace. If you have permit parking or a shared driveway, sort that out the day before. For a condo, let the concierge or property manager know a contractor is coming with equipment, and book the service elevator if your building requires it.

You do not need to turn the system off ahead of time or cover anything; that is part of the first step.

What we do, grouped by where in the house

Our 12-step process is listed in order on the process page. Here it is by location, in plain language.

At the door and around the house (steps 1 to 3)

Arrival and protection. Corner guards go on wall corners the hose will pass, and floor mats go down along its route. Pre-inspection and photos. The technician opens a return and a supply, photographs the trunk interiors and the blower compartment, and notes anything unusual, such as a disconnected run or water staining. These are the "before" photos. If the system is cleaner than you expected, this is where we say so. Sealing the registers. Every supply and return register is covered. This matters more than it looks: with all openings sealed, the truck vacuum pulls air through the whole duct system from one point, which is what creates the suction that carries loosened dust out instead of into your rooms.

In the basement or furnace room (steps 4, 7, 8, 9, 10, 11)

Connecting the vacuum. An access opening is cut into the main supply trunk and the main return trunk, and the truck hose is connected. From this point the system is under negative pressure for the rest of the job. Main trunk cleaning. The long rectangular trunks along the basement ceiling are cleaned with contact brushes, compressed air and the vacuum's suction working together. Return trunks are usually the dirtiest part of a system. Furnace J-channel. The channel where the filter sits collects anything that gets past or around the filter; it is brushed and vacuumed. Blower and furnace base. The blower compartment is opened and the blower wheel and housing are cleaned, then the base of the furnace cabinet where debris settles. This is the part of the job most "per-vent" cleaners skip, and the part a CMHC fact sheet said "has been shown to make some difference in duct air flow." Benefect sanitizing. Benefect, a botanical disinfectant, is applied. Sealing the access points. The openings cut for the vacuum are closed and sealed so the trunks are tight again.

Room by room (steps 5 and 6)

Each supply vent. Working one register at a time, the technician removes the cover, runs a compressed-air tool down the run toward the trunk, and the vacuum pulls what it dislodges out through the truck. The cover goes back on and the next one is uncovered. Each return vent. The same, on the return side, where hair and heavier debris collect. You will hear the compressor and the hose; you will not see dust in the room because the system is under suction.

Back at the furnace (step 12)

Post-inspection and photos. The same spots photographed at the start are photographed again. Your new filter goes in. The technician walks you through the photos, reinstalls any covers, and packs the mats and corner guards. If you booked add-ons, the dryer vent, HRV, humidifier or bathroom exhausts are done in the same visit.

Condo day, in 45 minutes

A high-rise suite has a fan coil or wall unit instead of a furnace, and short duct runs, so the job is smaller and the equipment is portable. The technician lays mats and wears shoe covers, covers the registers, and disables the system during cleaning. A portable vacuum and compressor are set up at the wall unit, each vent is flushed, and the coil or wall-unit return is vacuumed. Bathroom exhaust fans are cleaned, and the dryer vent is cleaned from inside the suite and from the balcony side if that is accessible. Benefect is applied to the wall unit, and if you have a filter ready it goes in. The condo duct cleaning page covers what is included in the flat fee.

After we leave

The before-and-after photos are emailed to you. Compare them yourself; the US EPA's standard for a finished job is that "you should not be able to detect any debris with the naked eye," and the photos are how you check that. Run the system normally. There is nothing to air out and no restriction on using the furnace or air conditioning afterwards.

The guarantee is "Love it or don't pay." If the photos do not show the difference you were promised, say so before you settle up. For pricing by home size, see the residential duct cleaning page, and to pick a date, use the booking page.

Frequently Asked Questions

Do I need to be home during the cleaning?

Someone needs to let the technician in, show them the furnace and registers, and be reachable for the photo walkthrough at the end. You do not need to follow the crew around.

Will there be dust in the house afterwards?

No. The registers are sealed and the system is under suction from the truck vacuum for the whole job, so loosened dust travels out to the truck rather than into the rooms.

Do you cut holes in my ducts?

Yes, small access openings in the main supply and return trunks to connect the vacuum. They are sealed closed as step 11, before the post-inspection.

Should I buy a filter before you arrive?

Yes. Have a new filter in your furnace's size ready and we install it at the end of the job. The same applies to a fan coil filter in a condo.

Can you clean a house with two furnaces in one visit?

Yes. Each additional furnace is $200 on top of the base price, up to three furnaces, and the visit runs longer because each is a separate duct system.

What if you find the ducts are not dirty?

The pre-inspection photos come first. If there is nothing worth cleaning we tell you then, before any work starts.