Gas·18 Sept 2026 · 3 min read
By Mohammed Miah, Gas Safe registered heating engineer
An annual service catches most problems before they become dangerous, but a gas appliance can develop a fault in between services too. These are the signs worth acting on straight away rather than waiting.
Watch for these
- A yellow or orange flame instead of a crisp blue one, gas should burn blue; yellow can mean incomplete combustion and carbon monoxide risk.
- Soot or dark staining around an appliance, on the wall, the appliance casing or the flue.
- Increased condensation on windows near the appliance, more than you'd normally expect.
- Pilot lights that keep going out, or are difficult to relight.
- A smell of gas that comes and goes, even faintly, particularly near an appliance rather than a joint or meter.
Don't wait if you notice any of these
None of these on their own necessarily means an emergency, but all of them mean the appliance needs looking at rather than monitored. If you smell gas strongly, follow the emergency steps: turn off the supply if safe to, ventilate, avoid flames or switches, and call the National Gas Emergency Service on 0800 111 999. For anything less urgent, book an engineer in rather than waiting for your next scheduled service.
