Have you noticed your boiler is leaking? It can be alarming, but it's important to find out what's causing the leak. Before you skip straight to buying a new boiler, though, there may be a simpler (and cheaper) way to fix the issue at hand.
We’ll take you step-by-step through the possible causes of a leaking boiler, as well as the remedies needed for each potential issue. However, bear in mind it's most likely not something you should try to fix yourself – whatever the cause, we strongly recommend calling out a Gas Safe Registered Engineer to have a look at the issue. For a broader look at boilers, see our gas boiler guide.
How To Check if Your Boiler is Leaking
To check if your boiler is leaking water, you should look for stains around the boiler that would suggest a build-up of moisture. If you do find any water on or near the boiler, you should dry the boiler using a cloth and wait to see if the moisture collects again. If it does, you can be certain that there is a leak.
Boiler leaks aren’t always obvious, though - but luckily, there are ways to spot a subtler leak. For example, your boiler may lose pressure rapidly, leading to it cutting out. To see if a leak is the cause of this, check your water meter reading before and after a three-hour period of no use. If the reading has changed, you likely have a leak. However, there may be other causes of a boiler losing pressure, which you can read about in our guide.
A cost spike in your monthly water bills for no known reason is a strong indicator that your boiler is leaking, too, as is rust or mould near your boiler or pipes.
What To Do If Your Boiler is Leaking
If you notice that your boiler is leaking, you should follow our advice outlined below before making any decisions. We’ve also outlined some ways that you can reduce the chance of this happening, such as getting your boiler serviced regularly.
Identify Where the Leak is Coming From
As a first step, it's important to identify if the leak is actually coming from the boiler, to ensure the real cause of the problem can be addressed. If the boiler is close to a washing machine, dishwasher or sink, it’s possible that the escape of water is coming from one of these devices instead. If you can see water leaking from the boiler itself, check the pressure and only switch the boiler off if there’s a problem.
As it’s likely there is pipework around the boiler, you should start by running a cloth around the pipework near to where the puddle of water is forming and see if you can identify the leak. It’s possible that there is just a small leak from the pipe, which would be an easy fix.
Once you’ve established that the leak is definitely coming from your boiler, it’s time to identify the cause.
Check the Boiler Pressure
Your boiler will have a pressure gauge on the front of it, either in the form of an analogue gauge or a digital panel. Most boilers should have pressure between 1 and 1.5 bar when the central heating is off. When your boiler is on, it will go up slightly, but it should still be around this range. If the gauge is way above this level (say, 2 bar or higher), this could cause a leak. Boilers have pressure relief valves to protect them from high water pressure and are designed to leak if the pressure gets too high.
You can discover whether your boiler pressure is too high by checking the tundish. The boiler tundish has a clear window, through which you will see dripping if the pressure is too high. See our tundish guide to learn more about this clever boiler component, where it is, and how to examine it.
What To Do If Your Boiler Pressure is Too High
If your boiler is indicating it’s at high pressure, the first thing you should do is check your filling loop, which is often a piece of tubing curved round on itself with a valve at each end. The filling loop is used to fill your system with mains water, and once the correct pressure is reached, the valves should be turned off. However, if they’re left on, that can cause high pressure, so make sure they are fully off.
The easiest way to reduce water pressure is to bleed a radiator. Monitor the pressure of the boiler and stop when it’s back to normal. If the leaking has stopped, you may have fixed the issue – but keep an eye on it. A faulty expansion vessel can also be linked to high pressure, so if bleeding your radiator doesn’t work, you may need to call out a Gas Engineer.
What To Do If Your Boiler Pressure is Too Low
Low boiler pressure is also an issue that you may come across, but there is an easy fix. To solve the issue, your boiler system will simply need repressurising, which is best done by a Gas Safe Registered Engineer. Having low boiler pressure won’t damage your boiler and isn’t dangerous, but will affect the efficiency of your heating system, likely leading to higher costs.
Our guide to understanding why your boiler is losing pressure can help you to spot and resolve this issue.
Check the Temperature
If your boiler’s temperature is too high, water will drip from the temperature control valve. This is one of the simplest boiler issues to solve by reducing the temperature via your boiler’s thermostat. Read our guide to boiler thermostats to learn more about boiler temperature control.
However, there may be an issue with your boiler thermostat in which it gives the wrong reading and causes overheating. A key sign that this has happened is kettling, a shrill sound that indicates the water in your boiler has turned to steam. See our kettling guide to understand more about this issue and how to tackle it.
Check the Pipe Joints
When boilers are initially fitted, all of the joints and pipes will be sealed. It’s likely that over many years of wear and tear, these joints will loosen thanks to the constant expansion and contraction of the water heating and cooling or from the seals rotting over time.
See our guide ‘How Long Does a Boiler Last’ for more tips on maintaining your boiler through the years.
Check for Corrosion
Another potential reason your boiler is leaking is corrosion, which can build up in your heating system’s pipes and feedback into your boiler. This is likely to be an issue that occurs the older your boiler is and isn’t something you will need to worry about if your boiler is relatively new. This corrosion can build up and damage the rubber seals joining two pipes, so if you suspect a leak, checking these seals may help you get to the bottom of the problem.
If one component or pipe of your boiler is corroded, the one part will need replacing by a Gas Safe Engineer. However, if multiple parts are corroded, your boiler may need to be replaced entirely. See our advice on replacing an old boiler to help with this.
Was Your Boiler Installed Properly?
If your boiler is leaking despite being brand new, it’s likely it was poorly installed. To fix this, contact a qualified Gas Safe Engineer to service or even reinstall your boiler.
Is a Leaking Boiler Dangerous?
If your gas boiler is leaking water, this won’t pose a direct threat to your health in the same way a gas leak would, but it’s still important to fix it as soon as possible. Leaking water could cause electrical components to short circuit. If left untreated, or if the leak is significant, water could also cause extensive damage to your home and furniture, such as damp spots forming and warped flooring. This can also cause mould and fungus to grow, which can damage your health.
How Do I Know if My Boiler is Leaking Gas?
A gas boiler leaking water is a cause for concern and needs attention. If your boiler is leaking gas, however, the situation is even more urgent.
Signs of a gas leak include:
- A foul odour similar to rotten eggs or a musty smell
- A hissing sound from your boiler or pipes
- Plants or dirt outside being blown around as though by wind (if the leak is outside)
- Bubbles in wet areas of the home
- Plants dying
- Brown, black or burnt-looking areas on your boiler
- More condensation than usual on your windows
If you notice these signs, contact a Gas Safe Engineer immediately to prevent issues such as carbon monoxide poisoning. If you are exhibiting symptoms of carbon monoxide poisoning, see a doctor as soon as possible. Symptoms of carbon monoxide poisoning are:
- Headache
- Sickness
- Dizziness
- Fatigue
- Stomach ache
How to Prevent a Boiler Leaking
The number one way to prevent your boiler from leaking is through regular servicing. Servicing allows a Gas Safe Engineer to catch and deal with any issues that your boiler has before they escalate, including replacing faulty or old parts before they can cause problems.
Boilers should be serviced once a year by a qualified engineer to ensure that small issues are nipped in the bud before they worsen. If your boiler is still under warranty, any repairs should be free of charge. Having your boiler checked annually is often a condition of the warranty and so if your boiler hasn’t been serviced in the past year, you might have to pay for any repairs.
Another way to prevent leaks is by handling debris buildup. This can be done through either a limescale flush or by installing a magnetic filter.
If your boiler is leaking despite your proactive approach, you should turn off your boiler as soon as you spot the issue. This will stop water from escaping and causing further damage to your home. Turning off your boiler in this situation will also allow for safer inspection, whether you decide to try and identify the problem yourself or call a professional to fix the issue.
The final step to preventing a leaking boiler is to fix any problems that have popped up, no matter how large or small. If there is only a small crack in the rubber seals or a slight build-up of pressure, for example, you should address these issues as soon as possible to prevent them from worsening.
Is it Time to Upgrade Your Boiler?
If your boiler is over 15 years old, it is more likely to suffer from problems, so it could be time for an upgrade.
At Ideal Heating, we offer a range of boilers that are designed to work efficiently and effectively, ensuring you can enjoy a warm home all year round. We also offer a several-year warranty (length varies subject to model) to ensure that you’re not left out in the cold, should a problem arise.
Take a look at our combi boiler range, for example - we have now released the Logic 2 Max, the latest version of our Logic Max Combi Boiler, which you can read about in our guide.
If you do decide it’s time to replace your boiler, our guide to how long it takes to fit a boiler can help you to understand the process further, while our guide to preparing your home for boiler installation will help you to ensure the process goes smoothly.
Browse our boiler selection or contact one of our Gas Safe Engineers to keep your home heating running smoothly. For more information and advice, bookmark our blog or follow us on social media.
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