When is duct cleaning worth it?
Good reasons to book a clean: you can see dust blowing out when the system starts, you've renovated or sanded floors with the system running, something has been living in the roof, you've moved into a house with no history for the ducts, or a smell turns up every time the fan does.
Weaker reasons: a flyer saying ducts are due. We haven't found any official guideline on how often household ducts should be cleaned, so be wary of anyone selling it on a fixed schedule.
Older Canberra homes: rule out asbestos before anyone opens a vent
WorkSafe ACT says Mr Fluffy loose-fill asbestos insulation went into more than 1000 Canberra homes between 1968 and 1978-79, and fibres were found in some heating and cooling ducts and vents. Homes that were affected must carry a safety tag on the meter box and switchboard, so look there. If you find one, or you're not sure about your home's history, don't clean, open or disturb the ducts, and get advice from WorkSafe ACT first.
Check these before you pay for a clean
The return air filter. It sits behind the large return air grille and catches dust before air goes back to the heater or air conditioner. A clogged one can cause real trouble. Seeley's technician guide for its ducted gas heaters names a dirty return air filter among the common causes of overheating faults.
The unit itself. On a ducted reverse cycle system, a musty smell may be coming from the indoor unit rather than the ducts. Mitsubishi Electric's operating instructions say dirt or dust inside an air conditioner may cause an unpleasant odour, encourage mould or clog the drain, and to have the dealer inspect it.
The ducts' condition. Cleaning won't fix a duct that's crushed, split or disconnected in the roof. If one room is weak, have the runs inspected, and see our page on ducts, vents and filters.
What a proper duct clean looks like
An inspection first
The cleaner looks at the outlets, the return air path and, where it's safe, the duct runs, and asks about the age of the home. In older Canberra homes, the asbestos question comes before any tools come out.
Safe access to the roof space
WorkSafe Victoria warns that workers fall through plaster ceilings, and tells them not to step on ceiling materials, to lay crawl boards across the joists and to use battery-powered lights. Expect a cleaner to come prepared for that.
Each duct and outlet cleaned
Grilles come off and are washed, and each run is cleaned in a way that suits flexible ducting. Ask what method they use and how they avoid tearing the inner liner.
Filter and grille done
The return air filter is cleaned or replaced and the grille washed, so fresh dust isn't pulled straight back in.
A report on what they found
Damaged runs, loose joins, poor insulation or signs of pests should be pointed out, with photos, so you can decide what to fix.
Who should do it
A duct cleaning specialist does the ducts and outlets. Anything inside a gas heater is a job for a licensed gasfitter, so it makes sense to line the clean up with the heater's service, which Energy Safe Victoria says is due at least once every two years. Anything that touches the refrigerant in a reverse cycle system needs an ARC licence.
Daikin suggests a licensed technician looks over an air conditioner at the start of every summer, with a tune-up that includes inspecting the ductwork. If your ducted technician spots a problem at that visit, that's a good moment to book a clean.
What you can clean yourself
You can
- Wipe or vacuum the outlet grilles you can reach from the floor.
- Clean or replace the return air filter the way your manual says, with the system switched off.
- Keep rugs and furniture off floor vents so dust isn't pushed in.
- In Canberra, check the meter box and switchboard for a Mr Fluffy tag before you touch any vent.
Leave to a licensed installer
- Cleaning inside the duct runs.
- Anything in the roof space or under the floor.
- Cleaning inside the heater or the indoor unit.
- Any work on a home that may have asbestos.
Warning signs on a duct cleaning offer
- A quote and a booking date before anyone has looked at your system.
- Health promises that sound too good, with no detail on what's actually being removed.
- No questions about the age of the home, in Canberra especially.
- Walking on ceiling plaster or working in the roof without crawl boards.
- An offer to top up the aircon's gas while they're there. The ARC says topping up before the system is tested and leaks are fixed is illegal.
- A push to replace the heater without showing you the fault.
What we'd do
Our take
We'd clean the return air filter and the outlet grilles first, and only book a duct clean when there's a real reason. When we did, we'd want a specialist who inspects before quoting, asks about asbestos in an older home, brings crawl boards and gives a written report. If the ducts turn out to be damaged rather than dirty, we'd have them repaired instead of cleaned.
