Most gas appliances need a chimney or flue to remove the fumes. They make sure that the fumes from the gas appliance are not mixed with the fresh air you need to breathe.

Gas appliances need air to burn safely. With enough air, gas appliances produce carbon dioxide and water in safe amounts, which are normally taken away by a chimney or flue. However, a gas appliance will produce carbon monoxide if there is too little air or the chimney or flue is blocked.

Carbon monoxide gas is highly poisonous both to people and animals. It is difficult to recognise because it has no colour, smell or taste.

The danger signs from a gas appliance are stains, soot or discolouring around the top of a gas fire or at the top of a gas water heater or boiler. A conventional gas appliance should have a normal blue flame – not yellow or orange.

The symptoms of carbon monoxide poisoning are similar to those caused by other illnesses, such as colds or flue. However if you suffer from unexplained headaches, chest pains, muscular weakness, sickness, diarrhoea, stomach pains, sudden dizziness when standing up, or general lethargy after using a gas appliance, stop using it, report the fault to us and go to your doctor.

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