Gas Leak from Boiler? – What should you do?

Last updated: November 15, 2023

Do you smell gas from your boiler? What should you do if you suspect a gas leak?

If you ever smell gas that could possibly be escaping from your boiler, there could be a serious problem and therefore the situation should be treated as an emergency.

Leave the property immediately and call for help via the National Gas Emergency Helpline on 0800 111 999. Do not make the call inside the property.

Large gas leaks from your boiler or pipework can usually be detected via the sense of smell or a hissing sound coming from the gas equipment, however smaller gas leaks may only be noticed over a period of time by more subtle signs such as indoor plants drying out or more condensation than normal on the windows.

Other warning signs include a boiler’s pilot light continually being blown out or increased use of gas without a change of household habits.

In this post, we will be discussing what you should do if you ever smell gas coming from your boiler as well as other immediate dangers that boilers present.

What Should I do When I smell Gas from a Boiler?

A potential gas leak situation could present an immediate danger to life to all of the occupants of the property and surrounding areas and therefore prompt action would need to be taken.

If the smell of gas is ever detected from a boiler, you should:

  • Switch off the mains gas supply using the control valve at the meter. The position of the handle would be 90 degrees from the pipe to switch off the gas supply.
  • Extinguish any lit flames.
  • Open all doors and windows.
  • Do not use any electrical device or switches – including do not switch things off manually.
  • Do not make any sparks or use any flames such as lighting a cigarette or candle.
  • Leave the property immediately and call for help via the National Gas Emergency Helpline on 0800 111 999. Do not make the call inside the property.
  • Do not re-enter the property until it has been confirmed safe to do so.
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The helpline’s telephone operative will log the call, taking details of the emergency including:

  • The location of the suspected leak.
  • The approximate number of people within the suspected area.
  • Details of the smell such as the specific location.
  • Strength of the smell of gas and the caller’s contact details.

Depending on the prioritisation of the call, the callout duration is usually:

  • One hour should the mains gas supply not be able to be turned off.
  • Two hours if the mains gas supply has been turned off.

The helpline is free and available 24 hours a day. The telephone advisor will provide further advice regarding any further steps to make while awaiting emergency support.

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Seek Medical Assistance for Anyone affected

If gas has been inhaled by someone at the property or within the surrounding area and they start to feel unwell, medical advice should be sought immediately.

Symptoms of gas inhalation can include: feeling lightheaded, dizzy, nauseous, breathing difficulties or incurring a headache.

It is important to advise the medics that the person may have been exposed to carbon monoxide to ensure that the best course of action can be taken.

What Would Cause a Boiler Gas Leak?

Gas leaks can occur for a range of reasons. Some of the more common reasons include ill-fitted boilers, incorrect boiler maintenance, a malfunctioning printed circuit board that has failed to run safety checks or the boiler’s fan developing a fault and not pushing the dangerous gases into the flue and outside of the property.

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On a rare occasion, mains gas pipes into the property can also burst and create a leak or can be disturbed during local repair works.

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You may also find our review of the best eco-friendly boilers of interest.

What other Dangers do Boilers Present?

The gas itself has a smell that can usually be detected by the sense of smell, however, another dangerous gas that can be omitted from a boiler does not have a smell at all.

Carbon monoxide cannot be detected by the senses of smell or taste and therefore is deadly due to a lack of warning that the harmful gas is leaking.

The poisonous gas can enter a person’s bloodstream from inhalation causing the blood to stop carrying oxygen resulting in death within two hours.

On average there are 60 deaths a year from carbon monoxide poisoning within England and Wales as per the NHS data, and the most common cause of the poisoning is a faulty boiler.

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Therefore, due to the risks of such an occurrence, it is highly recommended that you fit your property with carbon monoxide alarms in order to alert the inhabitants should a carbon monoxide leak be detected.

These are relatively inexpensive but could save lives so it is well worth investing in these. They can be found in many retailers such as supermarkets and DIY/hardware stores like B&Q and Screwfix.

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Check out our complete guide to new boiler installation here if you are wondering about the best type of boiler for your home. 

How much may a new boiler cost? Are you considering converting from a conventional to a combi boiler? Use our boiler installation cost calculator to get an estimation.

Why Boiler Servicing is Important

Annual boiler servicing is very important to prevent the risks of gas and carbon monoxide leaks as the Gas Safety registered heating engineer should perform a number of tests on the boiler components to ensure they are safe as well as checking for any emissions of dangerous gasses.

Regular annual servicing also undertakes a monitoring task in order to keep an eye on the wear and tear of the parts, advising if a replacement is required before they become dangerous.

Therefore, boiler servicing is an annual preventative measure that homeowners can undertake to safeguard from fires, explosions and leaks.

Boiler Insurance

There is a range of insurance policies available in order to help spread the cost of annual servicing which may be useful to some.

Such policies may also cover the price of parts should fault or wear and tear be discovered during an annual service.

You may be able to use online comparison websites to help try and find you the best deal on these.

Boiler Gas Leak Summary

Gas leaks can be extremely dangerous and therefore if you ever smell gas coming from a boiler, immediate help should be called for via the National Gas Emergency Helpline.

Gas leaks are very rare however the best prevention is via booking an annual boiler inspection and service which should only be undertaken by a Gas Safety registered heating engineer.

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