Home Improvement

Boiler Gas Leak: Signs, Causes and Solutions

Image source: Yevhen Prozhyrko / Shutterstock.com

Gas leaks are a home emergency, no matter where they’re coming from. If you notice signs of a gas leak, you should act as soon as possible. But what are the symptoms of a boiler gas leak, how can you avoid it, and what can you do in case you have one? Don’t worry, the Fantastic Services team has your back on this one! In this article, you’ll have all your questions answered.

Table of Contents:

This article is for all of you who:

  • Live in a property with a gas boiler;
  • Want to be prepared for a sudden boiler gas leak;
  • Wish to prevent carbon monoxide leaks.

Signs of a boiler gas leak

If you’re suspicious about a gas leak, look for the following signs:

  • Black stains on or around your boiler. On the boiler, or maybe on the ceiling above it, black stains mean that a leak is coming from your flue.
  • A faint smell. Carbon monoxide is odourless, but manufacturers mix it with other gases, so people can smell a leak and be warned.
  • Condensation in the boiler room. Carbon monoxide doesn’t cause condensation, but if your boiler doesn’t vent properly, it will mist the windows. Exhaust gases won’t leave your house, and this will result in carbon monoxide to be unleashed.

Causes for a boiler gas leak

The main cause for a boiler gas leak at home is usually a poorly fitted, or a badly maintained gas hose that leads into your boiler or from around the seal. The best way to avoid such a situation is to make sure that you get your boiler installed by a registered Gas Safe engineer in the first place.

Another cause for the issue can be faulty boiler parts with damages from general wear and tear and hard water deposits. There’s nothing you can do about those, but it will help if you have your boiler regularly serviced by a Gas Safe engineer. You can also consider the idea of investing in a boiler and central heating cover plan.

Did you have a boiler gas leak?

You might need a new boiler.

Add a valid postcode e.g. SE1 2TH

How to fix a boiler gas leak

Repairing a boiler gas leak is not hard, but it’s not recommended to be done by a non-technician. Don’t risk it and simply leave this task to the professionals. Here is what a certified engineer can do for you:

  • Identify the source. The first step is to identify the source of the gas leak. The most common culprit of this problem is the circulator. Another part that can cause a problem is the pressure relief valve. Or a leaking pipe connection.
  • Check the circulator. The circulator or the circulating pump moves hot water around your heating system. If it’s leaking, the solution is to replace the seal.
  • Check the pressure relief valve. The pressure relief valve can leak because of excess water in the system expansion tank. Draining the water fixes it. If the expansion tank doesn’t have any extra water then it could be a leakage in the valve itself, caused by sediment deposits.
  • Remove the sediments. The pressure relief valve should be opened and cleared up of any sediments. This can be tricky if the sediments are deposited too deeply inside. The cleaning procedure might have to be repeated a few times. If the valve can’t be cleaned completely, it has to be replaced.
  • Check for faulty pipes. Sometimes it’s a faulty pipe. A reliable technician can track the pipe to find the exact point of the gas leak. Then they will apply an industrial-strength adhesive to cover the leak.

How to prevent a boiler gas leak

There are many things you can do to prevent a gas leak at home. The obvious one is to have carbon monoxide alarms in your residence. They will detect the leak immediately and you’ll have an engineer visit your home in no time. 

However, taking extra care for your boiler and other gas appliances will prevent the leak from happening in the first place. For this, make sure that all your gas appliances are fitted by a registered professional. You can schedule regular checks for wear and tear and ensure your appliances are serviced regularly.

And if you live in a rented property, check if you have all of the gas safety documentation.

Do you need a professional boiler repairman?

Are you experiencing a boiler gas leak or other boiler issues? How old is your boiler? It could be time to replace it with a newer model. Whatever the case, a home needs to have a properly working boiler and heating system. No matter the kinds of issues you may have, you can be sure that the professional boiler engineers from Fantastic Services will always answer your call and help you in your time of need! Get in touch as quickly as you can!

Visit the main website for price rates for our professional boiler technicians!


  • The most common signs of a boiler gas leak are usually the smell, blackened spots on or around the boiler and condensation on the windows;
  • A gas leak occurs when  some of the parts of your boiler are poorly fitted or have become faulty due to wear  and tear or hard water deposits;
  • The most common fix is to replace whatever part is causing the issue, or in some cases, replace the entire boiler unit with a newer model;
  • It’s mandatory for every residence to have a carbon monoxide alarm to quickly inform for a possible gas leak;
  • You can prevent a gas leak by servicing your gas appliances regularly;
  • Every boiler repair procedure should be performed by a certified Gas Safe technician!u


Have you ever had to deal with a boiler gas leak? How did you fix it? Share your experience with us in the comments!

3 2 votes
Article Rating
Notify of
Inline Feedbacks
View all comments
Would love your thoughts, please comment.x