Carbon monoxide detector: where to install it and how to choose one
The carbon monoxide detector should be installed at breathing height (approx. 1.5 m), near bedrooms, and never right next to the fireplace or stove — there it would only measure the appliance, not the room.
The carbon monoxide detector should be installed at breathing height (approx. 1.5 m), near bedrooms, and never right next to the fireplace or stove — there it would only measure the appliance, not the room.
We inspect flues and combustion appliances all year round, but carbon monoxide is not a flue problem — it is a problem with what happens inside the room when something goes wrong with combustion or smoke evacuation. A properly installed detector is the only way to know before it is too late, because the gas is odourless and invisible.
Why you need one even if your chimney is inspected every year
An annual inspection greatly reduces the risk, but it does not eliminate it: a bird can nest in the flue between visits, renovation work in the apartment above could accidentally block a shared outlet, or a very windy night could cause a temporary backflow of gases. The detector is the safety net for everything that can happen between one inspection and the next.
Where to install it (this is what is almost always done incorrectly)
- At breathing height, around 1.5 metres above the floor, not on the ceiling or at floor level — carbon monoxide mixes well with the surrounding air and does not accumulate at the top like smoke.
- Near sleeping areas: a hallway next to the bedrooms is the most recommended location, so the alarm wakes you if there is a problem at night.
- At a reasonable distance from the combustion appliance — not right next to the fireplace or boiler (it would only measure the air immediately around the appliance, not the room), and not so far away that it fails to cover the risk area. As a guide, between 1 and 3 metres from the appliance is usually a good balance.
- At least one per floor if the home has several levels and combustion appliances on more than one of them.
Which type to choose
Always look for EN 50291 certification, the specific European standard for domestic carbon monoxide detectors — a generic “smoke and gas” detector is not enough. Battery-powered models are available (easier to install in any home), as are hard-wired or mains-connected models with backup batteries, which are more common in new installations. For an existing home, an EN 50291-certified battery-powered detector is the most practical option.
Maintenance and service life
The sensor in these detectors degrades over time, even if the batteries are new: most manufacturers state a sensor life of around 5 to 7 years, after which the entire unit needs to be replaced, not just the batteries. Check the manufacturing date (usually marked on the casing) and test the button once a month.
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We check the draught and combustion and advise you where to place your detectors.
Frequently asked questions
Does a carbon monoxide detector sound the same as a smoke detector?
No, they use different alarm patterns specifically so you can tell them apart, although both are loud and intermittent. Familiarise yourself with the sound of each one.
Do I need a CO detector if I do not have a fireplace, only a gas boiler?
Yes. Any combustion appliance — boiler, water heater, gas stove or wood-burning stove — can produce carbon monoxide if combustion or smoke evacuation fails.
What should I do if the CO alarm goes off?
Ventilate immediately by opening doors and windows, leave the home with everyone inside, and do not go back in until a professional has inspected the installation.
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