What to check if your boiler is leaking water
A boiler that is leaking water isn’t a good thing and, if left, can lead to further problems. Sometimes it’s just a sign that a seal or a valve has developed a fault and can be relatively easy to repair, however when left alone, it can cause other components to rust and can even damage the electrical components within the boiler, which may lead to an expensive repair. Your best option when you notice a leak is to fix the problem quickly and prevent any future damage.
Below, you can find out how to determine a probable cause. Remember that if it’s not an obvious fix or you need to take the cover off to get inside the boiler, you should call a registered Gas Safe engineer to take a look and fix the issue for you.
How do I know if my boiler’s leaking?
It’s not always easy to spot when your boiler is leaking. However, there can be a number of telltale signs. The first thing you might notice is water pooling around the base of the unit or, if you’re dealing with smaller leaks, damp or discoloured areas near the boiler. Another common sign your boiler is leaking is a noticeable decrease in water pressure.
For this reason, it’s a good idea to monitor your boiler’s pressure gauge over a few days if you suspect a leak. In the case there’s a loss of pressure in the heating system but no leak from the boiler itself, then you should look for signs of leaks from your radiators, thermostatic radiator valves (TRVs) or hot water cylinder if you have one.
Inspecting the pipes and connections leading to your boiler is also sensible if a leak is suspected. Check for visible water droplets, corrosion or evidence of damp or mould near these pipes. We will discuss this in more detail below. Finally, if you’ve noticed a sudden increase in your water bills, this can also be the sign of a hidden leak. While significant leaks that impact your bill are unlikely to be caused by a boiler leak, it’s important to check.
Remember - if you do suspect a boiler leak, it's crucial to consult a professional plumber or heating technician to assess and repair the issue promptly. Water leaks can lead to significant damage and pose safety risks, so need fixing as soon as possible.
Why is my boiler leaking?
Before you can do anything with your boiler, you need to find out why it’s leaking, but this isn’t always easy. The first thing to do is find where the water is coming from, as this will give you a better idea. Below, we’ve listed some of the main causes
High boiler pressure
Have you ever noticed the pressure gauge on the front of your boiler? This is important as it tells you how much pressure there is in the system. Too little or too much pressure can cause a problem and so you should check the valve every now and then and add or remove water as required.
If your boiler is leaking, you should check the pressure gauge to see if the pressure is too high. If this is the case, it’s likely that the pressure relief valve (PRV) is trying to release some of the water in the system to bring the pressure back down to a comfortable level. The valve needle should be between one and 1.5 bar (usually shown on the gauge as a green zone). If the needle is higher than this, or in the red zone, you may need to bleed the radiators to release extra water.
Corrosion in your system
Corrosion can be a problem in older boiler systems as it can cause rust and other debris to build up within your radiators and pipework. As the water runs around the system, it can pick up this debris and return it to your boiler as well. The older the system, the more likely you are to have issues with corrosion. The only problem is, many people don’t know it’s there as it can’t be seen.
Corrosion can also break the rubber seals around the joint of two pipes, so water may be leaking through here. If the corrosion is on an individual component, a Gas Safe engineer will be able to replace this with ease. However, if the corrosion is widespread, then you may need to replace the boiler and central heating system completely. An engineer will be able to advise if a new system is required or if a new boiler and flushing the system would be adequate. If you have an old boiler, replacing it with a newer model could make your home more efficient and you could save money on your gas bills too.
Faulty heat exchanger
The heat exchanger is the part that allows your boiler to heat cold water, so it’s a very important part of the appliance. Unfortunately, a leak can be a sign that the heat exchanger is starting to decay. It’s not uncommon for this part to crack in some models over time, and it can be expensive to replace. This isn’t a problem that you’ll be able to diagnose yourself, as it involves taking off the cover of the boiler and looking inside. Therefore, you should call a Gas Safe engineer to check the issue for you. Some are more susceptible to corrosion due to the materials they are made from. The Stainless steel Inox-Radial exchangers used in our Vitodens 050-W models are super efficient.They are also corrosion-resistant and particularly durable, thanks to their high grade stainless steel material. We are so confident in their performance, Viessmann heat exchangers come with a 10 year warranty.
Is a leaking boiler dangerous?
A boiler that’s leaking water should be checked to ensure that the problem is solved quickly so it doesn’t get any worse.
How to fix a leaking boiler
Now that you know why your boiler might be leaking, you need to know how to fix the issue. Below we outline the steps you should take when it comes to fixing a leaking boiler.
Step 1:
First you should check the pressure gauge and if the pressure is too high, bleed some of your radiators to release a bit of water. This should help with the issue.
Step 2:
Next, you should see if the water is coming from around any visible pipe fittings or joints. To check, dab the area dry then wait to see if the water appears again. If it does, you can try turning the connector by just a quarter turn using a spanner to see if this tightening does the job. However, corrosion can cause seals to wear away, allowing water to escape. If this is the issue, you’ll need to get a suitably qualified heating engineer out to take a look at the seals and replace them where necessary. It may even be that a seal has come loose and just needs to be tightened.
Step 3:
If, after doing the above, you still cannot determine the issue yourself or need someone else to delve a little bit deeper into the problem, you should call an engineer. There are many excellent engineers who will give impartial advice as to the most cost effective solution to fixing your boiler leaking water.
How to avoid a boiler leak
As discussed above, boiler leaks can be caused by a fault or simple wear and tear to your boiler. In these cases, there is little you can do to prevent them. However, by conducting regular inspections for signs of corrosion, rust, or water accumulation around the unit, as well as scheduling annual services to ensure your boiler is professionally maintained, you can reduce the chances of a leak occurring.
