Gas safety at home: what to check, and what to do

Carbon monoxide: the one you cannot smell

Carbon monoxide has no colour, no taste and no smell. It is produced when a gas appliance burns fuel incompletely — a blocked flue, a cracked heat exchanger, a boiler that has never been serviced. It kills people every winter, and the early symptoms are easy to mistake for flu.

Warning signs on the appliance:

• A lazy yellow or orange flame where it should be crisp and blue.
• Black or sooty marks on or around the appliance.
• Pilot lights that keep blowing out.
• Excessive condensation in the room.

Warning signs in the people: headaches, dizziness, nausea, breathlessness and tiredness that get better when you leave the house and come back when you return. If that pattern sounds familiar, treat it seriously.

Fit an audible carbon monoxide alarm to BS EN 50291 in every room with a gas appliance. They cost very little. Test it monthly and replace it at the end-of-life date printed on the casing — the sensor expires whether or not the battery does.

Find your stopcock before you need it

The single most useful two minutes you can spend on your house. The stopcock turns off the water to the whole property, and you do not want to be hunting for it at two in the morning with water coming through a ceiling.

• Most commonly under the kitchen sink.
• Also worth checking: downstairs cupboards, the utility room, under the stairs, or a small covered hole in the path or pavement outside.
• Turn it off and on once a year so it does not seize. A seized stopcock is useless.

Know where the gas emergency control valve is too

It is next to your gas meter, with a handle that sits in line with the pipe when it is on and across the pipe when it is off. Check you can reach it, and that nothing has been built in front of it since you moved in.

Before winter

• Book the service in late summer. Boilers fail when they are asked to work hard. Finding the fault in September beats finding it in January, and every engineer's diary is empty before the first cold week.
• Run the heating for twenty minutes. Even in August. It flushes out the "it worked fine last year" surprise.
• Bleed the radiators that are cold at the top, and check the boiler pressure afterwards.
• Check the outside flue is clear of leaves, nests and anything stacked against it.
• Check the condensate pipe. If a white plastic pipe runs from the boiler to outside, it can freeze and shut the boiler down on the coldest night of the year. Lagging it is cheap.

Things never to do

• Never let anyone who is not Gas Safe registered work on gas. It is illegal, it voids your insurance and it is how people get hurt. Ask for the card.
• Never block an air vent. They are there because an appliance needs the air to burn safely. Boxing one in or taping it over is dangerous.
• Never use a gas cooker to heat a room.
• Never ignore repeated boiler lockouts. The boiler is protecting itself from something. Resetting it over and over hides the fault, it does not fix it.

If you rent

Your landlord must have every gas appliance and flue safety-checked every 12 months by a Gas Safe registered engineer, and must give you a copy of the record within 28 days of the check or at the start of the tenancy. If you have not seen one, ask. There is more detail in our guide to the landlord gas safety certificate.