Leave the property and call the National Gas Emergency Service: 0800 111 999 from a safe location. Do not use flames or operate electrical switches or appliances. Open doors and windows if safe, and turn off gas at the meter only if you know how and can reach it safely. Do not enter a cellar. Follow the emergency service instructions; a quote form is not an emergency contact.
A smell of gas near the boiler is not a fault to troubleshoot yourself. Treat a suspected leak seriously even if the smell comes and goes, there is no fault code or the heating still works. The National Gas Emergency Service is the first call; a routine repair enquiry must not delay it.
Gas Safe registered 25 years in the trade 12 years running the business
Written by Chris Gill, C Gill & Son Plumbing & Heating ·
Why the emergency call comes before diagnosis
You cannot judge the source or seriousness of a gas escape by smell alone. Gas can travel from its source, and an odour near the boiler does not establish that the boiler is the only appliance involved. Do not remove the casing, look for a leaking joint or test another appliance to see whether gas is flowing.
Call 0800 111 999 from a safe location and follow the instructions you receive. Describe the address and what you have noticed without going back inside to collect model numbers. The emergency service deals with the immediate safety concern. An appointment with a heating engineer is a separate step, once the situation has been made safe.
Things not to do while a leak is suspected
Do not smoke, use a naked flame or operate electrical switches, sockets or appliances in the affected area. Switching something off can also create a spark, so do not try to make the situation safe by turning the boiler off at its electrical switch. Do not use the reset button or unplug equipment nearby.
Open doors and windows if you can do so safely, and turn off the gas at the meter only if you know how and can reach it safely. Do not enter a cellar or basement where gas may have collected. Leave the property and make the call away from the suspected leak. Keep other people away rather than asking someone to investigate on your behalf.
A gas smell is different from carbon monoxide
Carbon monoxide has no smell. A lack of gas odour therefore does not establish that an appliance is safe, and a carbon monoxide alarm must not be dismissed as a gas-smell issue. If an alarm sounds or carbon monoxide exposure is suspected, get everyone outside into fresh air and obtain urgent advice. Call 999 if anyone is seriously unwell or you suspect a medical emergency.
Headache, dizziness, nausea and breathlessness can have many causes, but possible exposure around a fuel-burning appliance needs to be taken seriously. Tell the emergency responders about the appliance and symptoms. Do not return to use the boiler simply because symptoms improve outdoors or the alarm later becomes quiet.
Intermittent smells still need attention
A smell that appears only when the boiler starts is not a reason to keep switching it on for comparison. Nor should an odour be attributed to a drain, paint or a nearby appliance without an appropriate assessment. Stop investigating and report the suspected gas escape; you do not need to be certain before making the call.
If you are unsure whether the smell is gas, explain that uncertainty to the emergency service. Do not rely on an internet checklist to rule it out. A recent service, a working display or a normal-looking pressure gauge does not override the immediate precautions. These visible signs concern different parts of the appliance and cannot establish gas tightness.
After the property or appliance has been made safe
The emergency attendance may result in the supply or an appliance being isolated. That does not necessarily mean a permanent appliance repair has been completed. Follow the instructions left with you, keep any written notice and do not reconnect, relight or reopen an isolated supply yourself. Ask clearly what needs to happen before anything can be used again.
For subsequent appliance work, use a Gas Safe registered engineer competent for the relevant task. Share the emergency service findings when you arrange the visit. Parts, testing and any further work depend on what has actually been identified; there is no universal repair that applies to every report of gas near a boiler.
Need it sorted? Book boiler repairs after safety advice
Once you have followed the emergency instructions, our boiler repairs page explains the next enquiry step for the appliance. The emergency boiler repair page describes how to contact Chris about a breakdown, but neither replaces the National Gas Emergency Service for a suspected leak.
Use the quote form for a follow-up repair request, including any notice or findings you were given. An online form is not an emergency reporting channel, and no attendance time is promised here. Keep the boiler out of use until the appropriate professional has confirmed it can be operated safely.
Covering Neath, Port Talbot, Swansea and the surrounding area.
Common questions
Boiler Smells of Gas: What to Do First FAQs
Clear answers before you arrange a visit.
Should I contact Chris first if gas seems to come from the boiler?+
No. Call the National Gas Emergency Service on 0800 111 999 first, from a safe location. Follow their instructions before making any ordinary repair enquiry, even if you believe you know which appliance is involved.
Can I reset the boiler to see whether the smell stops?+
Do not reset or run it again while a gas leak is suspected. Avoid electrical switches and appliances in the affected area, leave and contact the emergency service rather than testing the boiler.
Does a normal pressure reading mean there is no gas leak?+
No. The heating pressure gauge measures the water circuit, not whether gas is escaping. A normal reading, working heating or lack of an error message cannot rule out a gas safety problem.
Can the boiler be used after the gas smell has disappeared?+
Not simply because the odour has gone. Follow the emergency advice and any isolation notice. An appropriate professional must establish that the affected supply and appliance are safe before they are used again.
