Do I Need a Carbon Monoxide Detector?

Where carbon monoxide comes from

Carbon monoxide is a product of incomplete combustion. Anything that burns a carbon-based fuel can produce it, and the danger arises when the combustion is incomplete, the venting fails, or the appliance is used somewhere it should not be.

CPSC attributes more than 200 US deaths a year to carbon monoxide produced by non-automotive consumer products. Portable generators are a large share of that, and heating appliances make up much of the rest.

The reason 'I have no gas' is not an answer is that most of the list below is not a gas appliance.

The sources that catch all-electric homes out

Any one of these means you need CO detection.

• ◆An attached garage. Starting a car and letting it run to warm up — even with the door open — puts exhaust into a space that shares walls, a ceiling and often a door with your living space. This is one of the commonest residential CO events and it does not need the engine to run long.
• ◆A fireplace or wood stove. Wood is a carbon fuel. A blocked or partially blocked flue, a closed damper, or a stove with a corroded pipe puts combustion products into the room. Gas fireplaces and decorative gas log sets are the same hazard with a different fuel.
• ◆A portable generator. The single biggest acute risk in this list. People run them in garages, in basements, on porches and under open windows during outages, and the outage is exactly when the alarm's battery backup matters. Generator CO safety.
• ◆A shared wall, floor or ceiling with another dwelling. In a duplex, a townhouse, a terrace or an apartment building, your neighbor's failing furnace or their car in a shared garage is your problem. You do not control their appliances.
• ◆A charcoal or gas barbecue used too close to the house, or brought inside or into a garage for warmth or shelter from rain. A grill that has stopped flaming still produces carbon monoxide, which is how most of these fatalities happen.
• ◆A camping stove, patio heater or unvented space heater used indoors. Every year, and it is always during a cold snap or a power cut.

The one case where the answer is genuinely no

A detached, all-electric home with electric heating, an electric water heater, an electric range, no fireplace or wood stove, no attached garage, no generator, and no history of anyone bringing a grill or a camping stove indoors — that house has no carbon monoxide source, and a CO alarm in it is not answering a real risk.

We are saying so plainly because the alternative — telling everyone they need every device — is how a site loses credibility, and because the honest version is more useful. If that is your house, spend the money on smoke alarms instead: the smoke alarm roundup is where it does more good.

Two caveats worth keeping in mind even then. First, houses change: a wood stove, a gas conversion, a generator bought after an ice storm, a garage built on. Second, if your local code or your lease requires CO alarms regardless, that requirement governs — verify locally.

What a CO alarm is not a substitute for

An annual appliance service. The alarm tells you the appliance has already failed. A professional service of every fuel-burning appliance and every flue, once a year, is what stops it failing — and it is the step households skip because nothing visibly goes wrong when they do.

A swept chimney. A blocked flue is one of the classic mechanisms, and a chimney sweep is cheaper than the alternative.

Not using combustion appliances indoors. No grill, no camping stove, no unvented heater, no generator, ever, inside any part of the building including a garage with the door open. An alarm is a backstop for a mistake, not permission to make one.

A gas detector. A CO alarm does not detect natural gas or propane leaks — different hazard, different sensor. CO detector vs smoke detector explains why sensors do not cross over.