Gas cookers and unflued gas heaters use air during combustion and release water vapour and gases into the room - eg carbon and nitrogen oxides.
Inadequate ventilation of gas appliances can create a serious health hazard. Never install or use an unflued appliance in bedrooms, bathrooms or in caravans and marine craft. A flue is a ventilation pipe from the appliance to the outside.
Make sure your appliances are safety checked, installed by a licensed gas fitter and properly maintained to ensure they operate safely.
For advice about correct ventilation for outdoor appliances, see
Using gas safely outdoors.
On this page:
Safely using flued gas appliances Safely using unflued gas appliances Risks of carbon monoxide poisoning Protect your health and safety
Safely using flued gas appliances
Flued gas appliances have fixed duct work, piping or chimneys to vent combustion products outside.
Regularly inspect your gas appliance. Discolouration or stains on the walls or on the appliance may be signs of a blocked flue. Make sure the flue is not obstructed or blocked and that there are no holes in the flue before using the appliance.
It's advisable to contact a licensed gas fitter to inspect and service the appliance before use.
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Safely using unflued gas appliances
When installing and using unflued appliances adequate ventilation is required to prevent:
- the appliance from running poorly and the rooms becoming stuffy
- water vapour from condensing on cold surfaces which can lead to mould growth on walls and ceilings
- irritation to people who suffer from respiratory problems.
- build up of exhaust gases that could be harmful to your health
When an unflued appliance is installed, permanent vents must be fitted in the room. A licensed gas fitter or equipment supplier will advise on the size of the heater and vents required for the room.
Never seal doors, windows, skylights or ventilation grilles while an unflued appliance is being used.
Gas instantaneous water heaters must not be installed in bathrooms or rooms with limited ventilation unless they are of a room sealed type. This type has a flue that is partitioned to provide both air to the appliance while separately expelling the exhaust gases.
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Risks of carbon monoxide poisoning
If gas doesn't burn properly carbon monoxide is produced. Carbon monoxide is a colourless, odourless and tasteless gas which is very poisonous. The human body doesn't recognise its presence and it can kill you before you know it's there.
Incomplete combustion of gas can be caused by faulty or dirty appliances, insufficient ventilation or if the wrong gas type is being burnt. Signs of incomplete combustion include:
- an acrid smell and irritation to the eyes
- yellow or orange flames rather than blue flames (except for decorative fires that display this colour flame)
- soot or yellow/brown staining around or on the appliance
- pilot lights that frequently blow out
- increased condensation inside windows.
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Protect your health and safety
To avoid problems with your gas appliances and to protect your health and safety:
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More information
On this site
Reporting gas leaks
Installing gas appliances