Air

Do I need a CO alarm and where do I put it?

Short answer

Yes, with every combustion appliance. Choose an alarm to EN 50291-1 and mount it on the ceiling, 1 to 3 metres from the appliance.

Explanation

Carbon monoxide (CO) forms during incomplete combustion. You cannot smell it. An alarm warns of acutely dangerous levels. Servicing the appliance and enough air supply prevent the problem itself.

Rules of thumb

• Standard: EN 50291-1. [SW-S27]
• Placement: on the ceiling, 1–3 m horizontally from the appliance, at least 30 cm from walls, not behind curtains or near grilles. [SW-S27]
• Have combustion appliances checked at least once a year. [SW-S27]
• With open appliances keep a grille or window ajar 24 hours a day, 7 days a week. [SW-S27]

Pitfalls

• Alarms usually sound only around 30 ppm; WHO advises at most 6 ppm over 24 hours. An alarm therefore does not protect against low, long-term exposure. [SW-S27]
• A CO2 meter is not a CO alarm. [SW-S27]

Search terms

These search terms are in Dutch; only terms that also find a topic in English are links.

koolmonoxide CO-melder EN 50291 geiser kachel

Read also

• Which smoke alarms are mandatory, and may they be smart?
• How harmful is a wood stove or open fire?

Sources

1. SW-S27 Voorlichting koolmonoxide: risico's verbrandingstoestellen — RIVM (GGD-richtlijn MMK koolmonoxide) (Reference date 2026-09-27)

Reference date: 2026-09-27 · Translated with AI from the Dutch original.