Carbon monoxide testing on ducted heaters: why every 2 years matters
What CO is, how it builds up in old units, what we test for on a service, and why this isn't a corner you can cut.
Carbon monoxide is the colourless, odourless gas that kills a couple of Victorian families every winter. It comes from gas heaters that aren't burning cleanly, cracked heat exchangers, blocked flues, spider webs in the burner. You can't see it, smell it, or feel it building up. That's why we CO-test every gas heater we service.
What actually happens on a CO test
We run a two-stage test. First, an atmospheric test, the ducted unit runs on its normal cycle while we measure CO in the return air with a calibrated analyser. If we get any reading above 30 parts per million we're already investigating. Above 100 ppm and the unit is red-tagged on the spot.
Second, a flue-gas test at the burner. We measure O₂, CO and combustion efficiency straight from the burn. A healthy ducted gas heater sits under 100 ppm CO air-free and above 78% combustion efficiency. Anything worse means the heat exchanger or burner needs attention.
Why every 2 years
Ducted gas heaters accumulate dust and lint in the burner over time, spider webs form in the flue draft diverter, and heat exchangers develop micro-cracks from thermal cycling. All three fail slowly, you don't notice degradation until it's dangerous.
The Australian Gas Association recommends CO testing every 2 years. Insurance companies increasingly ask for the CO test report on rental properties. And the difference between a 25-year-old ducted heater that's safe and one that's leaking CO into the house is often just one skipped service.
What we charge
$280 + GST for a full gas heater service with CO test. Includes:
- Visual inspection of the unit, ductwork and flue
- Burner clean, ignition check, gas pressure test
- Full atmospheric and flue-gas CO test
- Written report with all readings, for insurance or landlord records
If we find CO above the limits, we red-tag the unit and give you options: fix (heat exchanger swap, flue clear, burner replace) or replace. We don't upsell, if it's fixable we fix it.
Book a service before the cold snap and we can usually get you in within a week.
Fixed-price, no obligation, VEU rebate applied at the quote.
We usually reply within 12 hours. Free 20-minute site check for bigger jobs.
