How do I check for carbon monoxide risk at home?

Carbon monoxide gives no warning through the senses at all, which is why it depends entirely on equipment and on recognising a symptom pattern rather than a smell.

Safety

What you'll need

• Audible CO alarm certified to EN 50291
• Service records for every fuel-burning appliance

Step by step

1. List every fuel-burning appliance.Gas boiler, gas hob and oven, gas fire, wood burner, open fire, oil boiler, portable paraffin or bottled gas heater, and any solid fuel stove. Anything that burns produces CO if combustion is incomplete.
2. Fit an audible alarm, not a colour patch.Certified to EN 50291 with an audible siren. The black-spot cards do not wake anyone and are not a substitute. This is the single most important step here.
3. Place it correctly.At head height, roughly one to three metres horizontally from the appliance, not directly above it. Not in a cupboard, not behind furniture, and not immediately next to a window or a draught.
4. Put one in every relevant room.Each room with an appliance, and in rooms where people sleep if a flue passes through. One alarm in a hallway does not protect a bedroom.
5. Test it monthly and note the expiry.Press the test button monthly. Sensors expire — typically seven to ten years — and the date is on the casing. An expired alarm reads as working and detects nothing.
6. Read the flame.Gas should burn crisp blue. Yellow or orange lazy flames indicate incomplete combustion, which is what produces CO. That is a stop-using-it-and-call-an-engineer sign.
7. Look for staining and soot.Black or brown marks around an appliance, on the wall above it, or on the casing. Also excessive condensation on windows in a room with an appliance.
8. Check the pilot light behaviour.A pilot that keeps blowing out, or a boiler that repeatedly locks out, can indicate a flue or ventilation problem. It is worth reporting rather than repeatedly relighting.
9. Keep vents and flues clear.Air bricks, wall vents and flue terminals outside. Blocked ventilation starves combustion of oxygen, which is exactly how CO is produced. Never block a vent serving an appliance.
10. Service appliances annually.Gas Safe registered for gas, OFTEC for oil, a competent sweep for solid fuel. Chimneys and flues need sweeping according to the fuel — at least annually for wood.
11. Never bring outdoor burners inside.Barbecues, camping stoves, generators and patio heaters. This includes a cooling barbecue moved into a tent, garage or porch, which kills people every year.
12. Learn the symptom pattern.Headache, dizziness, nausea, breathlessness, confusion, tiredness. The tell is that it affects several people or pets in the household and improves when you are out of the house.
13. Know exactly what to do if the alarm sounds.Everyone out, doors and windows open on the way if you can do it without delay, do not go back in, and ring 0800 111 999. Seek medical advice for anyone with symptoms.
14. Check it in rented and holiday accommodation.Landlords in England must fit an alarm in rooms with a fuel-burning appliance. Holiday lets and caravans are worth checking yourself, and a portable alarm is inexpensive.

Tips

• Audible alarm to EN 50291. The colour-change cards are not a substitute and do not wake anyone.
• Blue flame good, yellow or orange bad. It is the one visual check anyone can do today.
• Check the expiry date on the alarm casing. An expired sensor still lights up and detects nothing.

Common mistakes

• Relying on a colour-change indicator card — It requires someone to be looking at it, and it will not wake a sleeping household. Only an audible certified alarm does that.
• Bringing a cooling barbecue indoors — Charcoal releases carbon monoxide for hours after cooking. Moving one into a tent, garage or porch for warmth or shelter kills people every year.

If it doesn't work

Questions people ask