How Often Should You Clean Your Air Ducts in London, Ontario?

The standard recommendation from NADCA (the National Air Duct Cleaners Association) is to have your air ducts professionally cleaned every 3 to 5 years. For most London, Ontario homeowners in a typical detached house with no pets and no major renovations, that's a solid baseline.

But "typical" covers a lot of ground. Your actual cleaning frequency depends on your home, your household, and a few London-specific factors worth knowing about.

Frequency by Household Type

London-Specific Considerations

Older Housing Stock

London has a significant inventory of homes built in the 1960s through 1980s. Older duct systems — often galvanized steel, sometimes with fibreglass duct board — can accumulate decades of buildup that doesn't get disturbed by regular HVAC operation. If you bought an older London home and haven't had the ducts cleaned, there's a reasonable chance they haven't been done in years, or ever.

London neighbourhoods like Old North, Wortley Village, Byron, and Westmount have a high proportion of these older homes. If you're in one of them, the 3–5 year baseline might not apply — especially if you're the first cleaner in the chain.

London's Climate and Furnace Use

London, Ontario gets meaningful heating season — roughly October through April. That's 6–7 months of continuous forced-air circulation per year. More run time means more air (and everything in it) moving through your ducts. London's proximity to Lake Erie also means more humidity swings than inland cities, which can affect what clings to duct walls.

Gas Furnaces

Most London homes use natural gas forced-air heating. Gas furnaces are efficient, but they move a lot of air — which is good for comfort and bad for dust migration. If your furnace filter is a standard 1-inch filter (vs. a high-MERV media filter), more particulate gets past it and into the duct system. Higher-MERV filters reduce duct contamination and may let you stretch your cleaning interval a bit.

Signs You Need a Cleaning Now — Regardless of Last Date

Timing isn't everything. These are signs you may want to book sooner than your schedule says:

• Visible dust puffing from registers when the furnace starts: A small puff on startup is normal. A visible cloud is not.
• Dust settling rapidly on furniture: If you're dusting every few days and it's still coming back, your duct system may be redistributing debris.
• Reduced airflow from some registers: Partial blockages — often from debris, collapsed flex duct, or disconnected sections — reduce room-by-room airflow.
• Musty smell when the furnace runs: Can indicate biological growth in the duct system, though this isn't always the cause.
• Allergy or asthma symptoms that improved when you were away from home: If you feel better at work or on vacation, your indoor air quality may be the variable.
• Visible mould at a register: This warrants immediate attention — not just cleaning, but assessment of why moisture is present.

What a Professional Cleaning Actually Does

Professional duct cleaning involves more than a vacuum on a duct. A proper NADCA-standard cleaning uses negative air pressure (a powerful truck-mounted or portable unit) to put the whole duct system under suction, then agitates debris loose with rotary brushes or compressed air whips so it's captured — not just redistributed.

Here's what a full cleaning covers:

• Supply and return ductwork throughout the home
• Main trunk lines
• Furnace air handler and blower compartment
• Evaporator coil (if accessible)
• All supply and return registers (removed, cleaned, replaced)
• Optional: dryer vent cleaning (often done at the same visit)

Budget 2–4 hours for a thorough cleaning in a typical London home. Larger homes with more registers or older duct systems take longer.

What About Dryer Vents?

Dryer vents are a separate system from your HVAC ducts, but they're worth mentioning here because they're often cleaned at the same visit. The general recommendation for dryer vents is annually — more often if you do a lot of laundry or notice the dryer taking longer than one cycle to dry a load. Lint buildup in dryer vents is one of the leading causes of house fires in Canada. It's quick to add to a duct cleaning appointment.

Is DIY Duct Cleaning Worth It?

There are consumer-grade duct cleaning kits — brush attachments for drills, shop-vac nozzles — that can dislodge some surface debris from accessible registers. They're better than nothing, but they can't create the negative pressure system needed to actually extract debris from deep in the duct network. And without that suction, you risk loosening material that then gets recirculated through the system.

For a meaningful cleaning — the kind that actually improves air quality — professional equipment is necessary. The cost difference between a DIY attempt and a professional cleaning isn't large enough to justify the compromise.

How to Choose a Duct Cleaner in London

London has a range of duct cleaning companies, from established HVAC firms to seasonal operators. A few things to look for:

• NADCA membership or certification (Air System Cleaning Specialist, or ASCS) — the industry's standard credential
• Negative pressure equipment — ask if they use truck-mounted or portable negative-pressure systems, not just vacuums
• Before-and-after access to your ducts — a reputable company won't refuse to let you see what they're removing
• Written quote that itemizes what's included — watch for bait-and-switch pricing where the quoted price excludes registers, supply lines, or the furnace compartment