Missing carbon monoxide alarm: what it is, how serious, what it costs

Carbon monoxide, or CO, is a toxic gas you cannot see or smell. It comes from anything that burns fuel: a gas or oil furnace, a fireplace, a wood stove, a gas water heater, and a car running in an attached garage. The alarm, « avertisseur de monoxyde de carbone » in a French report, sounds when it detects it, before the level becomes dangerous.

A house needs one as soon as it has a fuel-burning appliance or an attached garage. An all-electric house with no fireplace and no attached garage generally does not.

Yes, it is a safety issue, and it is cheap to fix. When a report notes that alarms are missing in a house that needs them, I put it under “Fix first”: they go in before moving in.

It is even more pressing if the report also mentions a problem with how combustion gases are vented, at the furnace or the chimney for example. Recent building rules require them in houses with a fuel-burning appliance or an attached garage, and some cities also require them in existing houses: check your municipality’s bylaw.

Installing carbon monoxide alarms: $150 to $400 for one floor, $600 to $1,400 for every level that needs one. A battery or plug-in model, you can also put up yourself.

If the report suspects combustion gases are spilling back into the house, have the venting evaluated first: $200 to $550.

These are ballpark figures for Quebec, to be confirmed with quotes.

1. Which fuel-burning appliances did you see: furnace, fireplace, stove, gas water heater?
2. Are there carbon monoxide alarms, where are they, and are they still within their service life?
3. Did you see signs of poor venting: rust, soot or heat marks around an appliance?

Does your report mention carbon monoxide alarms? Upload it: in five minutes, I tell you what comes first, what to have checked and what to ask the seller.

Generally near the bedrooms, so it wakes people up. Follow the manufacturer’s instructions and your city’s bylaw for how many and where.

It has a limited life, often 7 to 10 years depending on the manufacturer. The replacement date is printed on the device. A smoke alarm does not detect carbon monoxide, except combination models.