Is your boiler leaking water? Finding the cause and fixing it quickly is crucial to avoid damage to your heating system and home. Read on to discover common causes of boiler leaks and potential solutions.
All boilers can sometimes leak, leading to further problems if left unsolved.
Water leaks can negatively impact your boiler’s function and efficiency by affecting water levels and system pressure.
They can force the boiler to work harder to maintain temperature and pressure, increasing energy use and reducing efficiency.
Hot water and heating account for over 50% of your energy bills annually, so fixing leaks can help improve efficiency and save you money.
But what are the causes of a boiler leaking water, and what can you do to fix it?
This guide explores the common causes of boiler water leaks and some potential solutions.
Boiler Leaking Water Quick Takeaways:
- Boilers can leak water due to high pressure, corrosion of components, high temperature, loose joints, a faulty heat exchanger, or failed seals.
- You should immediately solve a boiler leak problem to prevent it from worsening and damaging your boiler or property.
- Sometimes, you can do a quick DIY fix if you’re confident. However, it’s usually best to leave leak repairs to the professionals, especially if they involve internal components.
- You can prevent your boiler from leaking water by getting it serviced annually by a Gas Safe registered engineer.
Are you wondering which boiler manufacturers performed best? Check out our best boiler brands guide for the full rundown, and if you are trying to determine who the best boiler installation company is, check out our Warmzilla and Boxt reviews.
Common Reasons Why a Boiler Might Leak
Boiler water leaks can occur due to various reasons and you can usually determine the root cause by identifying where the water is coming from.
Here are some common reasons why your boiler may be leaking water:
Leaking Pressure Valve
One of the most common issues with boilers is pressurisation. The relief valve will leak if the boiler pressure exceeds the recommended settings.
Excessive pressure can cause the pressure relief valve (PRV) to try and release some of the water in the system to bring the pressure back down to a comfortable level.
The recommended boiler pressure is 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 can try to lower the pressure.
Refer to your boiler’s manual for the normal pressure settings and set the boiler to these settings using the pressure filling taps.
If the boiler does not stay within the recommended settings, ensure that the filling loop taps are closed on the boiler.
You can also try to lower the pressure within the system by bleeding the radiators using a radiator key and a container to catch any water that comes out.
However, if these steps don’t help reduce or maintain the boiler’s pressure, limescale or other system debris may have found its way inside the boiler, causing blockages and subsequently increasing the pressure.
In such cases, you must call a Gas Safe registered heating engineer to flush and clean the boiler system.
Further reading:
Boiler Leaking from the Temperature Valve
Another cause of a leak could be water coming from the temperature valve, which can be caused by the water’s temperature being too high within the boiler.
Boilers are fitted with temperature control valves (TCVs), which monitor the boiler’s water temperature and prevent it from getting too high.
If you notice your boiler leaking water from the temperature valve, the boiler temperature is likely too high and could result in scalding water coming out of your taps.
Again, this is something that will require a professional to investigate and lower the temperature of the water.
Leaking Boiler Pipe Joints
Water leaking from the pipes in a new system installation could indicate a fault.
Even with proper installation, the joints in the new boiler pipework can leak when they’re not fitted correctly.
Small leaks are very common in new boiler installations, as it can be challenging for installers to identify potential leaks during installation. You may only spot the leak when there’s a puddle.
In such cases, you must call the company or sole trader engineer who performed the installation. They can investigate and fix the leak by tightening the joints and pipe connections.
Ensure you only allow a Gas Safe registered engineer to install and work on your boiler.
Corrosion
If you notice water leaking from under the boiler unit, it can be a sign that the pipes under the boiler or other components have corrosion damage.
You should deal with such leaks urgently, as the corrosion can spread and require replacing the entire system or boiler.
Corrosion occurs over time as the water and metallic debris within the system combine and naturally corrode the copper piping. This eventually leads to small gaps that allow the water to leak.
The older the boiler or system, the more likely you are to have issues with corrosion.
If the corrosion hasn’t spread further than a single pipe or valve, simply replacing the corroded part will resolve the issue.
You should call a Gas Safe registered engineer when you notice leaking underneath the boiler to help prevent corrosion from spreading throughout the system and leaving it beyond repair.
Did you know your boiler’s efficiency can impact the energy it uses and, ultimately, your heating bill costs? Check out our guide to the best condensing boilers to learn more.
You may also find our review of the best eco-friendly boilers of interest.
Leaking or Faulty Heat Exchanger
The heat exchanger is an important part that allows your boiler to heat cold water.
It can sometimes fail, crack, or become damaged, especially in older and low-quality boiler models.
The heat exchanger is an internal boiler part. Therefore, a fault with this component isn’t something you’ll be able to diagnose yourself, as it involves taking off the boiler’s cover and looking inside.
You must call a Gas Safe registered heating engineer to investigate and diagnose the issue.
Unfortunately, the heat exchanger is one of the most expensive components in a boiler. If it is the culprit, you’ll likely face a hefty repair bill.
Should the heat exchanger cause your leak, discuss the costs involved with the heating engineer.
In some cases, it may be more economically viable to replace the whole boiler instead, depending on the boiler’s age.
Leaks from Seals on Internal Parts
Seals on internal parts of the boiler or heating system can sometimes fail due to wear and tear, causing leaks.
High pressure can also cause seals to fail and water to leak.
A Gas Safety registered heating engineer can check the condition of the seals during an annual service.
However, if leaks start between service times and you notice water dripping inside the boiler unit, call a heating engineer to check things out safely.
Small sealant issues can be solved relatively cheaply, while more substantial seal issues may require you to look for a new boiler.
Got a common boiler problem? Check out our quick fix guide for boiler lockout, ignition faults, PCB faults, faulty diverter valves, and boiler timer issues.
Overflow Pipe Leaking
An overflow pipe transports excess water from a home’s water storage tank (or cistern) to outside the home, avoiding flooding.
If you notice a leak from an overflow pipe, the cause is likely a fault with a float valve within the water tank.
The float valve controls the water level and consists of a plastic/metal arm along with a plastic ball at the end of the arm that floats in the water. Float valves are also found in toilet cisterns, expansion tanks, cold water tanks, and the central heating feed.
The float valve moves up and down with the water level to switch the cold water feed on and off. The tank’s water level should be an inch below the overflow pipe.
If the float valve isn’t operating correctly, the cold water feed may not be properly switched off, causing excess water overflow.
It is best to call a heating engineer to confirm the source of the problem and, if necessary, replace the float valve.
Is a Boiler Leaking Water an Emergency?
You should solve a boiler leak problem immediately to prevent it from worsening.
A boiler leaking water indicates a malfunction in the system, which can pose several risks to the boiler and your property.
Continuous water loss can cause your boiler to operate inefficiently, increasing energy consumption and energy costs. The pressure can also drop too low, preventing the boiler from operating effectively and safely.
In severe cases, and depending on the boiler location and how far the water has spread, leaks can cause structural damage to your property through water damage, including walls or ceilings.
How Can You Fix A Boiler Leaking Water?
Sometimes, you can do a quick DIY fix if you’re confident. However, it’s usually best to leave leak repairs to the professionals, especially if you suspect an issue with an internal component.
If you suspect a loose joint is leaking, you can attempt to fix it. You can dry off water from the leaking joint using a cloth and try to tighten it.
You can also seal up small leaks using a special additive. Add it to the central heating system, and it will automatically seal the holes as it circulates. However, adding them isn’t always straightforward, and they may not fix the issue.
If you still cannot find the cause of the leak in your boiler, your best bet is to turn off your water and contact a local Gas Safe heating engineer to identify the cause and recommend a fix.
How Can You Prevent Boiler Leaks?
The best way to prevent your boiler from leaking water is to get it serviced annually by a Gas Safe registered engineer.
Annual boiler servicing is an essential part of boiler ownership and maintenance. It’s usually a requirement of the boiler warranty and can ensure the trained professional can identify and fix potential issues before they develop into major repairs.
An annual service allows preventative maintenance and helps keep your boiler running safely, reliably, and efficiently.
If your property is located in a hard water area, limescale can contribute to leaks. Therefore, you can have scale inhibitors fitted to reduce the amount of limescale entering the boiler.
Fitting a magnetic filter can be a long-term solution for removing debris from the heating system before it can build up.
You can also consider flushing your heating system to remove limescale and debris and help reduce the risk of corrosion.
Boiler Leaking Water Summary
A boiler leak can result from several factors, including component corrosion, high boiler pressure, a faulty heat exchanger, loose joints, and high temperature. It’s important to identify the source of the leak and address it promptly to prevent further damage to your home and heating system.
Sometimes, you can do a quick DIY fix if you’re confident. However, it’s usually best to leave leak repairs to a qualified Gas Safe registered engineer, especially if you suspect an issue with an internal component. Arranging an annual boiler service can also help prevent boiler leaks by allowing a professional to identify and fix potential issues before they develop into major repairs like leaks.
Further reading:
- Smell of gas from boiler.
- Boiler leaking water.
- Boiler lockout.
- Boiler PCB faults.
- How to fix a faulty diverter valve.
- Compare BOXT boiler prices.
Sources and References
- https://energysavingtrust.org.uk/advice/boilers/