Gas Fire Won't Light

What's happening?

A gas fire lights in stages. A small pilot flame or an electric spark ignites first. A flame supervision device, a thermocouple or an oxygen depletion sensor, then proves the flame is safe and lets gas through to the main burner. Where it stops tells you the fault. Nothing at all points to the supply: the gas tap, the meter, a battery or the remote. A click with no pilot means a blocked pilot jet or no gas reaching it. A pilot that lights and goes out when you let go of the knob is the flame supervision device not getting enough heat. A pilot that holds but the main burner will not light points at the control valve or a blocked burner. And a fire that lights then dies minutes later is its own fault, since it can mean the flue is not clearing. Open-flue fires in living rooms are one of the commoner places for carbon monoxide.

What usually causes it?

• Flat batteries in the igniter or the remote handset or receiver
• A gas tap, appliance valve or the meter turned off or out of credit
• A dirty or partly blocked pilot jet, from dust and lint
• A weak or worn thermocouple or flame supervision device
• An oxygen depletion sensor tripping because the room or flue is not getting enough air
• A blocked flue or chimney, from debris, soot or a bird's nest
• A faulty control valve, piezo igniter or remote receiver

Is it dangerous?

Yes, more than most appliance faults. Repeated attempts to light a fire that will not catch can release unburnt gas into the room, and a flue that is not clearing can put carbon monoxide into it. Stop after two tries, open a window and wait several minutes before trying again. If you smell gas, do not touch any switch. Leave the property and call the National Gas Emergency Service on 0800 111 999 (0800 002 001 in Northern Ireland).

Can I fix it myself?

Change the batteries in the igniter and the remote. Check the gas tap on the fire is open and that other gas appliances work, which shows gas is reaching the house. Check prepayment credit. Follow the manufacturer's lighting sequence exactly, holding the control in for the time stated, not longer. That is all. Anything inside the fire, the pilot, thermocouple, jets, burner and valve, is gas work that must be done by a Gas Safe registered engineer.

When should you call a gas engineer?

Call a Gas Safe registered engineer if the fire still will not light after batteries and two careful attempts, if it lights and then goes out, if you can see soot or yellow flames, or if you have a headache or the CO alarm sounds. Do not use the fire until it has been checked. Landlords must keep gas appliances safe and checked.

What will the gas engineer actually do?

• Check the gas supply and working pressure at the fire
• Clean or replace the pilot jet, thermocouple, flame supervision device or igniter
• Test the control valve and burner for correct operation
• Check the flue is clear and draws, and the room has the ventilation it needs
• Test the oxygen depletion sensor where fitted and for any spillage of fumes
• Light the fire to the manufacturer's sequence and confirm a steady blue flame

Who fixes this

• Gas fire installation and service
• Gas appliance repair

What it usually costs

Gas Fire Installation Cost

£750

Questions people ask

Sources & References

1. HSE: domestic gas safety, homeowner FAQs
2. HSE: carbon monoxide awareness FAQs
3. Gas Safety (Installation and Use) Regulations 1998
4. NHS: carbon monoxide poisoning