Gas emergency guidance
My carbon-monoxide alarm is going off — what to do
Carbon monoxide poisoning kills around 30 people a year in the UK and hospitalises many more. Symptoms — headache, dizziness, nausea, confusion — feel like flu. A working audible CO alarm is your only reliable warning inside the home.
Do this right now
A sounding CO alarm means carbon monoxide has reached a dangerous level. CO is odourless, colourless and can be fatal within hours. Get everyone out first, ask questions later.
- 1
Get everyone outside into fresh air immediately
Take children, pets and anyone showing symptoms out first. Do not stop for phones or bags. Don't send anyone back in to 'check the boiler'.
- 2
Open windows and doors on your way out
Ventilation dilutes CO fast. Prop the front and back door open as you exit if it is safe to do so.
- 3
Turn off any gas appliances you can safely reach
Only if the appliance is on the way out and easy to isolate — boiler off at its fused spur, hob knobs to off. Do not go hunting for switches upstairs.
- 4
Call 0800 111 999 from outside
The National Gas Emergency Service handles CO incidents 24/7 for free. Tell them your alarm has triggered and if anyone has symptoms.
- 5
Seek medical attention if anyone feels unwell
Headache, dizziness, drowsiness, chest pain, confusion or unconsciousness after being in the affected building — call 999 or attend A&E immediately and tell them you suspect CO exposure.
- 6
Do not re-enter until an engineer says it's safe
The emergency service will ventilate, take readings and identify the source. Only re-enter when they confirm safe levels.
Do NOT do these
- Do not assume it's a false alarm — a properly certified CO alarm (EN 50291) does not go off for no reason.
- Do not ignore symptoms because 'it's probably a bug' — CO poisoning mimics flu.
- Do not go back in to open more windows once you are out.
- Do not restart the suspected appliance to 'see if it does it again'.
- Do not remove the alarm's batteries to silence it — treat the trigger as real.
- Do not sleep in the property that night unless it has been formally made safe.
Once the property is made safe
After the National Gas Emergency Service has attended and issued their paperwork, a Gas Safe registered engineer needs to make the follow-up repair before the gas can be turned back on. Only book us after the immediate emergency has been handled.
- The emergency engineer will identify the source (usually a faulty boiler, fire, cooker, flue or blocked chimney) and disconnect it with a warning notice.
- The affected appliance must be repaired or replaced by a Gas Safe registered engineer before use — we service, repair and replace boilers, fires and cookers across Greater Manchester and Rochdale.
- Replace any CO alarm that has actively alarmed — most manufacturers advise replacement rather than reset after a real trigger.
- Book a full flue and combustion check on every gas appliance in the property, not just the one that triggered the alarm.
KJ Plumbers promise: £50 fixed diagnostic, transparent written quote before any work, and if we can't fix the fault we diagnosed the £50 is refunded. All gas work carried out only by Gas Safe registered engineers — ask for the card on arrival.