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Why Is My Boiler Leaking Water

A boiler is an appliance that we take for granted but just like all other appliances, they can develop problems over time and that can be a concern. One of the main problems that can occur is a boiler that is leaking water and for homeowners, that can be a bit of a worry.

There are several reasons why a boiler might begin leaking water but one of the most important things you can do is to take action immediately as this will prevent further damage. It might be corrosion or poor installation and even pressure that can cause a water leak. Whatever the reason, it will need solving rapidly to ensure your boiler gets back to full working order.

It’s important that you opt for a reputable installer even if you are tempted by a cheaper quote. This is because you could pay for making the wrong decision further down the line as you’ll need to rectify problems that are associated with a bad installation. If you opt for an installer that understands the process, has high standards and knows the products they install, you’ll benefit in many ways.

So, the aim of this article is to identify the common causes of a leaking boiler, how the leak can be stopped and how to prevent the problem.

Common Causes Of A Leaking Water

When you come across a boiler that is leaking, you’re going to need to find out where it is leaking from. Then, once you have done this, you’ll be able to identify the reason why the leak has occurred.


This is one of the most common reasons for a leaking boiler. Corrosion is going to affect the pipework that forms part of your system, If corrosion is affecting a single component such as a heat exchanger then essentially, it would only be this that would need replacing. However, if the corrosion goes further through the system then you might need to think about replacing your boiler.

Checking for corrosion is a relatively simple task and it just a case of inspecting the pipework and the other parts that make up your heating system. However, if the leak looks as though it is coming from inside the boiler then you should not do anything else as you will need a professional to take a look at it. They will have the ability to open up the system and assess the damage before making an informed decision about how to solve it.

High Boiler Pressure

A central heating system can leak because of the pressure relief valve discharging water consistently from the system. The common cause of this is that the pressure in your boiler is too high. To check whether this is the case, you can take a look at the pressure gauge on the boiler. This is commonly found on the front of the boiler and has a small needle that indicates the current pressure level of your system. Most boilers should be operating at a level of around 1.4 bar.

There are several things that you can do to help overcome the problem of a leaking boiler caused by high pressure. The first thing you can do is to bleed your radiators to relieve the pressure. However, you should ensure that the boiler filling loop has been firmly closed before you undertake this task. This can be checked by ensuring that black taps are perpendicular to the pipe. If they are facing the same directions then the filling loop will be open.

Leaking Heating Pump

This is not a hugely common issue but it can prove to be a difficult problem to detect if you are not familiar with the way in which boilers operate. If you have an old boiler system then the seal around the heating pump can become damaged due to elements moving around the system. It could also be caused by high pressure as this will place strain on the seals located around the heating pump. Therefore, if the problem is not fixed then the leak will continue to occur.

This is a job that needs to be rectified by a professional as it will require a Gas Safe Engineer to undertake the job, so doing it yourself is not an option. There’s a risk you could cause further damage to the boiler and components but there is an increased risk of invalidating your warranty causing further problems.

Loose Joints On Pipework

This is another problem to identify as it often doesn’t take too much time or effort to find. Just like all other appliances around the home, your boiler is susceptible to wear and tear and over time, this can cause damage. As hot water and cold water passes through the system, the pipework is constantly expanding and contracting. However, corrosion could also cause leaking pipework as well as poor installation, however, the joints in your pipework can show the earlier signs that your boiler is leaking water, so it is worth ensuring that you keep an eye out for leaks.

If you have leaking joints, then this is not something that you are going to be able to rectify yourself and so, you will need a professional on-site to fix the issue. So, make sure you use a reputable installer to ensure that they carry out the repair efficiently and correctly.

Poor Installation

While most of the problems discussed are based on faulty components or faulty pipework and even high pressure but often, these problems are caused because of a lack of quality in the way in which the installation has been carried out.

When the time comes for you to replace your boiler, it’s vital that you use a service that is well-regarded and recognised than those that offer a cheap service because you will get what you pay for. So, it is worth paying more when it comes to installation as this is more likely to ensure you benefit from a better level of service and quality.

Can I Use My Leaking Boiler?

While this might seem obvious to some, you have to stop using your boiler if you spot a leak as this can cause more problems and make the leak worse. If you spot a leak, make sure you isolate your boiler by turning it off and ensure the water supply is cut off too. Once you have done all of this, you will then be in a position to speak with your professional to seek out advice and guidance.

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