Safety & Compliance
Carbon monoxide has no colour, no smell and no taste. It is produced whenever carbon-based fuel burns without enough oxygen, and with solid fuel that can happen for entirely mundane reasons — a partially blocked flue, a closed-down fire, an extractor fan pulling against the chimney.
The reason it is dangerous is that the early symptoms are indistinguishable from a winter virus, and people go to bed rather than opening a window.
What raises the risk
Every one of these is preventable, and most are picked up during a routine sweep and service.
- A blocked or partially blocked flue — soot, nest material or fallen debris
- A flue that has not been swept for a long period
- Inadequate room ventilation, particularly after draught-proofing or new windows
- A powerful extractor fan competing with the chimney for air
- Burning wet or unsuitable fuel, producing incomplete combustion
- Damaged appliance seals, a cracked firebox or a failed register plate
- Running the appliance with the air controls closed right down for long periods
Recognising the symptoms
Headache, dizziness, nausea, breathlessness, confusion and unusual tiredness are the common signs. The pattern is the clue: symptoms that affect several people in the household, that appear when the fire is lit, and that improve when everyone is out of the house.
Pets are often affected first, and a household where the animals are unwell as well as the people is a strong signal.
Alarms: where and which
Fit an audible alarm to the current British standard in every room containing a solid fuel appliance. Position it according to the manufacturer's instructions — typically at head height and a sensible distance from the appliance, not directly above it.
Test monthly. Note the expiry date: sensors have a finite life, usually stated on the unit, and an expired alarm is a decoration. Replace it rather than assuming it is fine because it beeps when tested.
If the alarm sounds
Act on it immediately and do not spend time looking for another explanation.
- Stop using the appliance and let the fire go out — do not add fuel
- Open doors and windows to ventilate
- Get everyone out into fresh air
- Call the emergency services or the gas emergency line for advice
- Seek medical attention if anyone has symptoms
- Do not use the appliance again until the flue and appliance have been inspected
Prevention through maintenance
Regular sweeping keeps the flue clear, which is the single biggest factor. A service checks the seals, register plate and firebox integrity that keep combustion gases where they belong. A draw test after sweeping confirms the flue is evacuating properly on the day.
We fit a carbon monoxide alarm as standard with every stove installation, and check for one during sweeping and servicing visits.
Frequently asked questions
Do I need a CO alarm if I only use the fire occasionally?
Yes. Occasional use is if anything higher risk, because infrequently used flues are the ones that get blocked or nested without anyone noticing.
Does sweeping guarantee there is no CO risk?
No, and nobody should claim it does. Sweeping removes the most common cause and lets us inspect the flue, but ventilation, appliance condition and how the stove is operated all matter too. The alarm remains essential.
Where exactly should the alarm go?
Follow the manufacturer's instructions for the specific unit — typically at head height, within a few metres of the appliance but not immediately above it, and away from windows and doors where draughts could affect it.
My alarm went off once and then stopped. Is that fine?
No. A single activation means CO was detected. Ventilate, stop using the appliance and have the flue and appliance inspected before lighting it again.
Keep the flue clear and the alarm current
Sweeping, draw testing and appliance checks — book a visit before the heating season.