Fires of London
9 Gas Fire Warning Signs You Shouldn’t Ignore
Has your gas fire changed? Use this symptom checklist to spot unsafe behaviour, know when to switch it off, and choose the right next step.
If your gas fire’s flame, smell, sound or heat output has changed, do not diagnose it yourself. Some characteristics are normal for particular models, but several gas fire warning signs mean you should stop using the appliance or take emergency action.
Use the checklist below to choose the safest response. Gas fire servicing and repairs should always be handled by a Gas Safe registered engineer qualified to work on gas fires.
Emergency information
Smell gas or suspect a gas leak? Call the National Gas Emergency Service on 0800 111 999.
If a carbon monoxide alarm sounds or exposure is suspected, leave immediately. If someone has collapsed or is seriously unwell, call 999 for an ambulance.
First, decide how urgent the symptom is!
You do not need to identify the fault. Recognise the symptom and take the appropriate action.
What You Notice
Gas smell, carbon monoxide alarm or illness
An unchanged, model-specific visual feature
Changed operation, soot or visible damage
Action level
Emergency action
Stop and arrange an inspection
Verify and monitor
What To Do
Leave, seek help and
follow emergency guidance
Switch the fire off and do not relight
it until checked
Check the manual and watch for changes
or other symptoms
“Monitor” never means continuing to use a fire you suspect is unsafe. Switch off a gas appliance suspected of being unsafe and leave it unused until a qualified engineer checks it.
Warning signs that mean you should act
You can smell gas
Domestic gas has a distinctive sulphur-like smell added to make leaks easier to detect. If your gas fire smells of gas, the source could be the appliance, its connection or elsewhere in the installation. Do not locate it yourself or relight the fire to see whether the smell returns.
Open doors and windows, turn off the gas at the meter if you know how to do so safely, leave the property and call 0800 111 999. Follow the emergency service’s instructions. Carbon monoxide is different: it has no smell, colour or taste.
The carbon monoxide alarm sounds or someone feels unwell
Carbon monoxide cannot be seen, smelled or tasted. Possible symptoms include headache or dizziness, nausea, stomach pain or vomiting, breathlessness or chest pain, unusual tiredness, weakness or confusion, loss of coordination or consciousness.
Leave the property immediately. If someone has collapsed or is seriously unwell, call 999 and ask for an ambulance. Otherwise, seek immediate medical advice and state that carbon monoxide exposure is suspected.
You see soot, black marks or heat staining
Carbon monoxide cannot be seen, smelled or tasted. Possible symptoms include headache or dizziness, nausea, stomach pain or vomiting, breathlessness or chest pain, unusual tiredness, weakness or confusion, loss of coordination or consciousness.
Leave the property immediately. If someone has collapsed or is seriously unwell, call 999 and ask for an ambulance. Otherwise, seek immediate medical advice and state that carbon monoxide exposure is suspected.
The flame looks different from its normal pattern
The key clue is not one universal “safe” colour but a change from the flame picture specified for your model. Unusually floppy, weak, unstable or uneven flames require attention.
Some decorative fuel-effect and flueless fires are designed to show yellow or orange flames. Compare your fire with its manufacturer’s instructions, not a boiler flame or an online photograph of another model.
The fire is difficult or slow to light
A gas fire that is difficult to ignite may take several attempts, light after an unusual delay or have controls that no longer behave normally. Follow the manufacturer’s standard lighting procedure once. If the fire does not light as expected, stop.
Repeated attempts could continue introducing gas. Do not improvise a lighting method or try to clean pilot jets or internal parts.
The pilot light or main flame keeps going out
A pilot that will not stay lit, a main flame that cuts out or a fire that switches itself off unexpectedly is giving you a warning – not an inconvenience to overcome. Do not keep relighting a fire that repeatedly extinguishes itself.
It starts making new hissing, popping or booming sounds
A faint, familiar flow sound may be normal. A gas fire making strange noises needs attention when the sound is new, louder, persistent or accompanied by delayed ignition, a smell or unstable flames. Note whether the sound occurs during ignition, normal operation or shutdown, then switch off the appliance and arrange an inspection.
The fire produces less heat or burns unevenly
Reduced heat at the usual control setting, an uneven flame distribution or a room that suddenly takes much longer to warm can signal a performance problem. Stop using it if low heat appears with soot, a smell, abnormal flames or repeated shutdowns.
There is more condensation or the room feels poorly ventilated
New condensation on nearby windows while the fire operates can be associated with incomplete combustion or inadequate airflow. Covered, blocked or altered vents are also concerning.
Never cover or block a permanent vent serving a gas appliance. Stop using the fire if condensation is new or excessive, particularly when combined with staining, headaches, unstable flames or stuffiness.
What might be cosmetic and what should not be dismissed?
Gas fires vary by model. Use the manufacturer’s instructions to understand your appliance’s normal flame picture, controls and permitted exterior care.
Observation
Yellow or orange flame
Brief first-use odour
Surface dust or marks
May be model-specific or cosmetic when…
It matches the manual and has not changed
It is non-gaseous, clears quickly and no other warning appears
Dust is on the cold exterior, or old marks
are unrelated to heat
Needs investigation when…
It is new, unstable or produces soot
It persists, worsens, smells like gas or occurs
with another symptom
Marks are new, spreading, cracked, melted or sooty
What to do after you notice a warning sign
- Stop using the appliance if the symptom could affect safety.
- Do not repeatedly relight it to reproduce the problem.
- Do not remove the fire front, adjust parts, move fuel effects or alter ventilation.
- Record what changed, when it occurred and whether it stopped when the fire was switched off.
- Photograph visible changes from a safe distance.
- Find the make and model without dismantling the appliance.
- Contact a Gas Safe registered engineer qualified for gas fires.
What will a professional check?
A professional gas fire inspection may cover:
- Whether the appliance is burning gas correctly
- The flame picture and ignition
- Relevant component condition and cleanliness
- Safety devices
- Ventilation and air supply
- The flue or chimney arrangement
- Signs of leakage, unsafe combustion or heat damage
- Whether servicing, repair, disconnection or replacement is appropriate
Do not wait for a second warning
You do not need to know the exact fault before stopping use. New, worsening or combined symptoms are signs your gas fire needs servicing or professional investigation. Take emergency action where required and leave internal checks and repairs to a qualified Gas Safe registered engineer.
Need a gas fire safety check?
Arrange an assessment with a Gas Safe registered engineer qualified to work on gas fires.
Call: 0208 952 6722
Fires of London Ltd
Your Fire& Flue Specialists
Gas fire servicing, repairs and safety checks in London
Call us: 0208 952 6722