Carbon monoxide and wood burners: stay alert
Any fire that burns wood or solid fuel makes carbon monoxide (CO). A sound stove, a swept chimney and enough air carry it safely away. When something goes wrong (a blocked flue, a leaking seal, not enough ventilation) it can spill into the room. You can't see or smell it, so a working CO alarm in the room is your warning.
Why stoves can produce carbon monoxide
Carbon monoxide forms when fuel burns without enough oxygen. In a stove that's normal, and the chimney's draw takes the gases up and out. Trouble starts when that draw is weakened or blocked:
- A chimney that needs sweeping, or one blocked by soot, tar or a nest.
- A damaged flue liner, door rope or seal letting gases out into the room.
- Too little air for the stove, for example after a room has been draught-proofed.
- Smouldering fires from wet wood or a stove turned right down.
The warning signs
Signs around the stove that something isn't right:
- smoke coming into the room when the door is shut,
- a fire that won't draw or keeps going out,
- soot or staining around the stove, the flue pipe or the register plate.
If your alarm sounds, follow the fire callout at the top of this page: open windows, let the fire die down, get out, and call the Gas Emergency or a professional.
What guards against it
- A CO alarm in the room with the stove, positioned as its maker says and checked with its test button as often as the manual says. Replace it at the age on its label. Our CO alarm checklist takes two minutes.
- A swept chimney. See how often to sweep.
- Dry fuel. Logs at or below 20% moisture burn hotter and cleaner. See log moisture content.
- A properly installed stove. A HETAS-registered installer checks the flue and the room's ventilation before fitting.
- Sound seals. Check door ropes and glass seals each year. See rope seals.
The rules on alarms
Whether a CO alarm is legally required with a stove depends on where you live and when the stove was fitted, and the rules differ between England, Wales, Scotland and Northern Ireland. See do I need a CO alarm with a wood burner? Whatever the rules say, fit one.
FAQs
Can a wood burner give off carbon monoxide?
Yes. Burning wood always makes some carbon monoxide; the chimney normally carries it away. A blocked or damaged flue, poor seals or too little air can let it into the room.
Where should a CO alarm go with a wood burner?
In the same room as the stove, positioned as the alarm maker's instructions say.
How often should I check a CO alarm?
As often as its manual says, using the test button, and replace it at the replace-by age on its label.
What should I do if my CO alarm goes off?
Open windows, let the fire die down, get out, and call the Gas Emergency or a professional. Don't relight the stove until it's been checked.