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Safety · Indoor Air QualityCarbon Monoxide Detector Installation
Carbon monoxide detector installation is a twenty-minute job that most Ontario homes are legally required to have done, and it is worth doing properly: the right alarm, in the right place, at the right age — and a combustion test on the furnace, water heater or fireplace it is actually watching.
Ontario requires a carbon monoxide alarm adjacent to the sleeping areas of any home with a fuel-burning appliance, a fireplace, or an attached garage. That covers almost every house in Burlington, Oakville and Hamilton, including all-electric homes that happen to have a garage on the other side of a bedroom wall. The rule has been in force since 2014 and applies to owners; our note on Ontario's carbon monoxide detector law covers the details and what applies to rental units.
The thing homeowners are most often surprised by is that alarms expire. The electrochemical sensor inside degrades whether or not it has ever seen carbon monoxide, and manufacturers print an end-of-life date or a manufacture date on the back — most units are rated for seven to ten years. An alarm from the last renovation is not a working alarm because the test button still beeps; that button tests the horn and the battery, not the sensor. When we are in a basement for a furnace visit, checking the date on the back of the alarm takes ten seconds and it is one of the more useful things we do.
Placement matters as much as the alarm. Carbon monoxide mixes with room air rather than sinking or rising sharply, so a hallway alarm outside the bedrooms at any convenient height works — but it should not be crowded against the furnace or water heater, where normal start-up puffs cause nuisance alarms, or in a dead-air corner, or right beside a bathroom door where humidity shortens sensor life. Manufacturers publish exact clearances for their own model, and we install to those. A second alarm near the mechanical room is a good idea in a home with a chimney-vented appliance, as long as it is far enough from the draft hood. Filtration and ventilation sit under indoor air quality; the alarm is the one item Ontario actually requires you to have.
Standard residential alarms are built to a threshold standard: they are deliberately slow to sound at low concentrations so that transient, harmless readings do not empty the house. That is the right trade-off for most people, but it does mean a chronic low-level source — a slightly back-drafting water heater, a fireplace with a partially blocked vent — can run for months under the alarm's trigger point. That is why the alarm is only half the answer, and the other half is putting an analyzer in the flue. If your alarm has already sounded, read what to do when a carbon monoxide alarm goes off before you do anything else — leave the house first, then call from outside, and our 24/7 line is answered at the same price at any hour.
Book an alarm check and a combustion test when
- You cannot find a manufacture or replace-by date on the back of your alarm, or it is more than seven years old
- There is no alarm on the bedroom level, or the house has an attached garage and no alarm near it
- The furnace, boiler or water heater vents into a masonry chimney rather than a plastic sidewall pipe
- You have headaches, nausea or drowsiness that improve when you leave the house
- Soot marks, rust streaks or a loose connection are visible around a vent pipe or draft hood
How it works
We note every fuel-burning appliance, the attached garage, where people sleep, and where the existing alarms are and how old they are.
Alarms mounted to the manufacturer's clearances, batteries or hardwired connections done properly, and each unit tested. Combination smoke and carbon monoxide units where they suit the location.
A combustion analyzer in the flue gives an actual carbon monoxide reading on the furnace and water heater, plus a spillage check at the draft hood. Numbers go on your invoice so next year has something to compare against.
Common questions
How many alarms does my house need?
At minimum, one adjacent to the sleeping areas. In practice we suggest one on each storey and one near the mechanical room in a house with a chimney-vented furnace or water heater — carbon monoxide from a basement appliance can reach a third-floor bedroom long before a single hallway alarm at the other end of the house responds.
Battery, plug-in or hardwired?
All three are acceptable if they are certified and within their service life. Hardwired interconnected alarms suit a large or multi-storey house, because one sounding sets all of them off. Sealed ten-year-battery units are the simplest retrofit where there is no wiring. Plug-in units with a battery backup are fine but end up unplugged more often than people admit.
Can my furnace actually produce carbon monoxide?
Any appliance that burns gas produces some, and a healthy one sends all of it up the vent. Problems come from a cracked heat exchanger, a blocked or disconnected vent, or a house pulled so negative that the flue reverses. Can my furnace leak carbon monoxide explains each path, and a cracked heat exchanger is the one we rule out first with an analyzer rather than by eye.
Do you check this during a regular service visit?
Yes. A furnace tune-up at $120–$250 includes flue-gas carbon monoxide readings and a vent inspection, which is a more sensitive test than any household alarm. If the readings are unsafe we shut the appliance down and tell you exactly why in writing.
Why did my alarm go off when nothing seems wrong?
Either it detected something real that has since cleared — a brief back-draft on a windy day, exhaust drifting in from an idling car in the garage — or the sensor has reached end of life and is producing false alarms. Both are worth a visit. Never reset and ignore it, and never assume a repeated alarm is faulty just because you feel fine.