Combi Boiler Leaking – Here is Why?

Discovering that your boiler is losing pressure and combi boiler is leaking is one of those situations in life where you experience that sinking feeling in the pit of your stomach.

This could be a serious problem; this could be expensive; how will we keep the house warm in the meantime?

These are questions that explode in your head but are also relevant concerns that cannot be avoided.

As the leading leak detection company in the United Kingdom, we have dealt with thousands of leaks all across the country, and in this article, we walk you through the potential reasons why your boiler is leaking, and how to resolve the situation using a process of elimination. 

Boiler Pressure Guage

Why is my boiler leaking?

The first and most obvious question that you need the answer to is what is the cause of my boiler leak. The answer to this question will determine the extent of the problem.

In an ideal world, the pressure in your boiler is set too high, and the leak is simply a safety mechanism built into your boiler to reduce that pressure. We have a handy guide If you need to drain and refill your combi boiler.

Alternatively, the leaks inside your boiler may have caused irreparable damage to the components of the boiler, which may mean that you need a replacement boiler.

Let’s look at the steps you should take to identify your specific issue. 

What To Do When There Is Water Leaking From Your Boiler

Before beginning the investigation as to where the leak is coming from, you can do a few simple things to minimise the damage caused. If you can see where the water is dripping from, place a towel or saucepan under the drip to catch the water, preventing it from causing any further damage or staining. Another important task is to turn off the electricity supply to the boiler, which will remove the risk of electric shock and should help to reduce the risk of damage to the boiler itself. 

Causes of Water Leaking From Your boiler

Pipework Check

The first step anyone should take when faced with the prospect of a boiler leak is the pipework underneath the boiler itself. This is because the pipework underneath the boiler is far and away, the number one reason for leaks in your heating system.

Leaks in the pipework are usually caused by some type of corrosion. In essence, it is simple chemistry; the constant passing of water in conjunction with small metallic debris through copper piping will corrode the copper over time. Eventually, small holes will appear in the copper, which is where the water will escape causing the leaks.

Alternatively, if your boiler is relatively new, then the culprit is more likely to be poorly fitted joints. Surprisingly, a newly fitted boiler water leak is a common occurrence and not necessarily a sign of incompetent workmanship. If your boiler is newly installed, then contact the installer and ask them to return and resolve the issue.

If you can, look at the pipework and see if you can locate the exact source of the water drip. Use a piece of toilet roll to dry and absorb the water around the pipework, and then use your hands to feel for any new water appearing around the joints. Any leak under the boiler will require a gas-safe gas engineer to resolve the issue. Repairing pipework or a boiler cannot be regarded as a DIY job, so get in contact with a gas-safe engineer as quickly as possible. 

Too much pressure?

Thermal Imaging Central Heating Leakage Detection Edinburgh

Your entire boiler and heating system utilise pressure to circulate the water around the house, delivering heat to every part of your home. It is sometimes easier to think of pressure as water, so when the pressure is too high, it essentially means that there is too much water in the system.

You will find a pressure gauge on a combi boiler that tells you exactly how much pressure is currently in the system. Ideally, the gauge should be around 1 bar within the green area. If the gauge is reading higher than the green area, then that indicates that you have an over pressurised boiler. Reducing the pressure in the boiler is a quick and straightforward process known as bleeding the system.

If you have recently topped up your system, check that the filling loop located underneath the boiler is firstly closed. Look for a metal silver Flexi-pipe which will normally be connected to two pipes by black taps. The taps should typically point to the left when they are closed. You can move the taps slightly and watch what happens to the pressure gauge. If it rises, ensure the taps are completely turned to the left to ensure no further water enters the system.  

Bleed The Radiators

The next step is very simple, requiring a radiator key that can be purchased at any DIY store. Locate the nut on the end of the radiator and turn it slowly using the key. Initially, you should hear air escaping from the radiator. Keep the valve open until water starts to escape. This will reduce the pressure in the system and hopefully ensure that the gauge on the boiler returns to the green area. 

Corrosion in Your Heating System 

Corrosion is the enemy of your heating system, and unfortunately, the older your system, the higher the risk is that your boiler has become corroded. In most cases, if there is evidence of extensive corrosion in your heating system, it is time for a new boiler. As a homeowner, the only way to check for corrosion of the boiler is by looking at it closely, if this is even possible.

Call a qualified gas heating engineer to come and inspect your boiler. If you are lucky, they may be able to replace the component which has been corroded, but in all likelihood, it might be a better long-term option to investigate the purchase of a new boiler. 

Heat Exchanger Developed a Fault

The heat exchanger is the most expensive component of any boiler. They are often susceptible to fail or crack in older boilers or low-quality boilers, irrespective of their age. Identifying a broken heat exchanger requires the expertise of a qualified gas engineer. Although it is possible to replace a heat exchanger, it is likely to be a false economy, and it will make more financial sense to replace the boiler rather than take a gamble. 

Leaks on Internal Parts

There are many seals in a boiler, which can be prone to decay over time. If and when these seals fail, water will leak out of them surprisingly fast in some cases. A heating engineer may be able to replace the seals, so it is worth getting a quote.

Is a Leaking Boiler Dangerous and What Should I Do?

If your boiler is showing obvious signs of leaking, then our advice would be to check the pressure in the system. If the pressure is exceptionally high, then follow our advice above to try and reduce the pressure, which in turn may solve the issue. For all other problems, where there is a physical leak, then the best advice is to contact a qualified heating engineer to come and investigate the problem. A boiler leak should always be treated as urgent and be investigated as quickly as possible. 

If you need to replace your boiler then this list of the leading boiler brands may be useful to you

Never Use Leak Sealer 

A leaking boiler can prove to be very expensive, which is why it can be tempting to search for a less expensive option. Many people are tempted to use a range of products known within the trade as leak sealers. Leak sealer is basically a glue, which sets when exposed to air. The theory is that you pour the product into your heating system, which is then circulated.

As soon as the leak sealer finds the leak, it is exposed to air, hardening it and sealing your leak. Unfortunately, there can also be air in your radiators or air valves in the boiler, which can become damaged when the sealant hardens. In our opinion, using leak sealer could potentially turn into a costly quick fix, and we strongly advise against it. 

How Can ADI Leak Detection Help? 

Not all leaks are immediately visible to the naked eye, but if the pressure in your system drops rapidly within a 24 hour period, there is clearly an issue. The problem is that there could be a very small leak somewhere in the system. ADI are the original leak detection specialists in the UK, call us today on 0800 731 3843