As the heating goes back on across Oxfordshire, boilers, fires and stoves that sat idle all summer are suddenly working hard again. Carbon monoxide warning signs include headaches, dizziness and nausea that ease when you leave the house, plus sooty marks, a yellow or orange flame, or a pilot light that keeps going out. If you suspect a leak, get fresh air, turn off the appliance, leave the property and call the National Gas Emergency Service on 0800 111 999. Our heating engineers can then check the appliance.
Why carbon monoxide matters
Carbon monoxide (CO) is a poisonous gas with no colour, taste or smell. It’s produced when fuels like gas, oil, coal or wood don’t burn properly. A faulty boiler, a blocked flue or chimney, or poor ventilation can all let it build up indoors without anyone noticing. That’s what makes it dangerous, and why an alarm is so important.
Symptoms to look out for
Early CO poisoning is easily mistaken for flu or tiredness. Common symptoms include:
- Headaches
- Dizziness
- Feeling sick or being sick
- Tiredness and confusion
- Stomach pain
- Shortness of breath
Clues that point to CO rather than a bug:
- Symptoms ease when you go out and return when you come home
- Several people in the house feel unwell at the same time
- Pets seem unwell too
- Symptoms are worse when the heating or a fire is on
Warning signs around your appliances
Look out for:
- A lazy yellow or orange flame on a gas hob or fire, instead of a crisp blue one
- Black or brown sooty marks on or around a boiler, fire or flue
- A pilot light that keeps going out
- More condensation than usual on windows near an appliance
- A boiler that’s struggling, showing faults or making unusual noises
None of these prove CO is present, but each is a reason to stop using the appliance and get it checked.
What to do if you suspect carbon monoxide
- Open doors and windows
- Turn off the appliance if you can do so safely
- Get everyone, including pets, out of the property
- Call the National Gas Emergency Service on 0800 111 999
- Seek medical advice through NHS 111, or call 999 if someone is seriously unwell
Don’t use the appliance again until a Gas Safe registered engineer (or an OFTEC registered technician for oil) has checked it.
Where to fit a CO alarm
A carbon monoxide alarm is the only reliable way to detect the gas. Choose an audible alarm marked to BS EN 50291, and follow the manufacturer’s positioning instructions. As a general guide:
- Fit one in every room with a fuel-burning appliance, such as a boiler, gas fire or wood burner
- Place it typically 1 to 3 metres from the appliance, not directly above it
- Consider one in bedrooms and on landings
- Test it regularly and replace it when it reaches its end-of-life date
Landlords have specific legal duties on CO alarms. Our landlord gas safety certificate guide covers the rules.
Keeping homes in Oxford, Abingdon and Didcot safe this winter
The simplest protection is an annual service. During a service, the engineer checks combustion, the flue and the safety devices that help prevent CO problems. Older homes around Oxford and Abingdon, with open-flued fires and older boilers, especially benefit. Our post on what’s included in a boiler service explains what’s checked.
Frequently asked questions
Can a boiler leak carbon monoxide without any signs?
Yes. That’s why CO is so dangerous. A boiler can produce CO with no visible soot, no smell and no obvious fault. Annual servicing and a working, audible CO alarm in the same room are the two best ways to protect your household, especially as the heating starts working harder in autumn.
My CO alarm is going off. What should I do?
Treat it as real. Open windows, turn off fuel-burning appliances if safe, get everyone outside and call 0800 111 999. If anyone feels unwell, seek medical help. Don’t assume it’s a faulty alarm until the appliances have been checked by a qualified engineer.
Do gas hobs and cookers produce carbon monoxide?
Any appliance burning gas can produce CO if it isn’t working properly or the room is poorly ventilated. Never use a hob or oven to heat a room. If the flame on your hob burns yellow or orange, stop using it and have it checked by a Gas Safe registered engineer.
Get your appliances checked
If you’ve noticed any of these warning signs, or your boiler is overdue a service, give us a call on 01865 817 611 or drop us a message and we’ll come and check it’s working safely.
