Updated: 5th December, 2024
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If you have noticed a leak coming from your boiler, it is important to work out the cause and get it fixed quickly to avoid any further damage being done to your home and heating system.
If you have noticed a leak coming from your boiler, it is important to work out the cause and get it fixed quickly to avoid any further damage being done to your home and heating system.
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In this guide, we will be looking at some of the most common causes behind a leaking boiler and what you should do if you have found a leak.
There are several reasons why water may be leaking from your boiler, and the root cause can usually be determined by identifying where the water is coming from.
Below is a list of the most common places where a leak can come from:
In most cases, the pipes immediately beneath the boiler are to blame for a boiler leak.
This is because, over time, pipes and other components inside your boiler can start to corrode, creating small holes that water can escape from, resulting in a boiler leak.
If just one part of the central heating system has become corroded, then you will only need to have that part replaced to solve the issue.
However, if multiple parts inside the boiler have corroded, it will likely be beyond repair, and you will require a new boiler.
If your boiler is new and has recently been installed, then corrosion probably isn't the issue here but rather a poor installation job by the engineer.
This doesn't necessarily mean that it is entirely their fault. Still, if this is the case, the installation company should send someone out as soon as possible to resolve the issue and make sure everything is secured within the boiler as it should be.
This is why you must use a reputable boiler company with qualified Gas Safe Registered engineers for all services.
If your boiler pressure is too high, you may find that water starts to leak from it as the boiler attempts to release some of the excess pressure to avoid imploding.
An easy way to tell if your boiler pressure is too high is by reading the gauge.
If the needle points anywhere above 2, your pressure is likely too high and must be lowered to between 1 and 2 (or the green section).
To do this, you should first try bleeding your radiators to release some of the pressure.
If this doesn’t fix the issue, please refer to your manufacturer’s guide and follow the instructions on what to do.
Sometimes, in lower-quality boiler models, the heat exchanger can fail, crack or become damaged.
Without a qualified Gas Safe Engineer, it can be incredibly difficult to tell if the issue is due to a faulty heat exchanger, however, if this is behind the boiler leak then you would be looking at a very hefty repair bill due to the high cost of the replacement part.
That’s why we would recommend getting a higher quality boiler replacement instead, as this will be greater value for money and less likely to break down in the future.
Over time, parts of your heating system will see some wear and tear.
This can sometimes mean your joints and pipe connections become loose due to the water repeatedly expanding on heating and then contracting on cooling.
To fix the leak, try tightening the joints and pipe connections.
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Boilers are fitted with a temperature control valve (TCV) which monitors the temperature of the water within the boiler to 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.
To lower the temperature of the water from your boiler, locate the adjustment needle on the thermostatic expansion valve.
Turn the adjustment needle one 45º anticlockwise to decrease the temperature. Each 45º turn is equal to one degree.
The boiler pump is designed to push water around your heating system; however, if the pump isn’t sealed correctly, water can escape causing a leak.
If you notice water coming from your boiler pump, you will likely need to reseal it or replace it.
An overflow pipe leads from a water storage tank or cistern inside your home to the outside.
When an overflow pipe is dripping or running with water, one of the most common causes is a problem with a float valve.
Float valves are found in toilet cisterns, cold water tanks, central heating feed, and expansion tanks.
It’s the component that controls the water level and consists of a metal or plastic arm with a plastic ball on the end that floats on the water.
If the float valve is damaged or there’s a puncture in the plastic ball, it must be.
To do this, shut the water supply off and drain the cistern.
Remove the float valve and purchase a new one from your local DIY store. Then, reinstall it.
Yes, a leaking boiler is indeed dangerous and should be addressed immediately. When a boiler is leaking water, it not only indicates a malfunction within the system that can worsen over time but also poses several risks.
Firstly, the water leakage can lead to electrical short circuits, which are hazardous. Secondly, the continuous loss of water from the system can cause the boiler to operate inefficiently, leading to higher energy consumption and increased costs.
More critically, a leak might result in the boiler pressure dropping too low, hindering its ability to operate safely and effectively. In severe cases, a leaking boiler can also cause structural damage to your property through water damage, promoting the growth of mold and damp. Therefore, if you notice your boiler leaking water, it's essential to turn off the system and contact a qualified professional immediately to prevent potential dangers and further damage.
If you still can't find the cause of a leak in your boiler, your best bet is to turn off your water and get in touch with a local Gas Safe Engineer immediately before any more damage can be done to your property.
The heating engineer should then be able to identify the cause and recommend either a fix or a new boiler.
If this is the case, you can make replacing your boiler much quicker and easier with iHeat.
Get a free, fixed quote on a brand new A-rated boiler today!
For more information and advice, check out the rest of our handy boiler guides in our blog.
Selecting the right boiler brand is pivotal for ensuring efficiency, reliability, and longevity in home heating. Among the myriad of options, brands like Vaillant, Viessmann, Alpha, Ideal, and Worcester Bosch distinguish themselves with innovative technology and customer satisfaction. Below is an in-depth comparison of these brands, focusing on their standout models and unique industry positions.
Brand | Standout Model | Energy Efficiency | Unique Features | Environmental Impact |
Vaillant | ecoTEC Plus | A-rated | Eco-friendly, quiet operation | Reduced carbon emissions |
Viessmann | Vitodens 100-W | A-rated | Compact design, smart compatibility | Low emissions technology |
Alpha | E-Tec Plus | High efficiency | Compact, cost-effective | Energy-saving operation |
Ideal | Logic Plus | A-rated | User-friendly, easy installation | Efficient energy use |
Worcester Bosch | Greenstar i | A-rated | Robust build, smart controls | Eco-conscious design |
Vaillant's eco-friendly ethos shines in their ecoTEC range, particularly the ecoTEC Plus and ecoTEC Exclusive models. These boast top-tier energy efficiency and reduced carbon footprints. They're known for quiet operation and user-friendly controls, making them a harmonious blend of performance and environmental responsibility.
Viessmann's Vitodens series, especially the 100-W and 200-W, are hallmarks of high-efficiency and technology. These models feature compact designs and stainless steel Inox-Radial heat exchangers for durability. Advanced features like smart thermostat compatibility offer enhanced control and user convenience.
Alpha Heating Innovation's E-Tec range, particularly the E-Tec Plus, offers a fine balance between affordability and quality. Notable for their impressive energy efficiency and compact size, these boilers are suitable for various home types, making them an ideal choice for straightforward, efficient heating solutions.
Ideal Boilers, especially the Logic Plus range, are lauded for their reliability and value. These boilers stand out with their efficiency, user-friendly interface, and compactness, favoured for their ease of installation and maintenance. They come with comprehensive warranties, offering peace of mind and reliability.
A leader in the market, Worcester Bosch is synonymous with quality and reliability. The Greenstar range, including models like Greenstar i, Si, and CDi, is known for its efficiency and robust build quality. These boilers blend innovative features such as smart thermostat compatibility with user-friendly controls, making them a top choice in many homes.
Boiler leaks can be a real headache, especially when they lead to bigger problems like inefficiency or damage to your heating system. While some leaks can be repaired, a severe issue might mean it’s time to consider replacing your boiler. In such cases, understanding the new boiler cost is essential to make an informed decision about whether to repair or upgrade.
The cost of a new boiler typically includes two parts: the price of the boiler itself and the installation by a qualified engineer. Both are critical to ensuring your new system runs safely and efficiently. At iHeat, we aim to take the stress out of this process, offering straightforward solutions. On average, a new boiler installation ranges from £1,845 to £3,500, depending on your specific requirements.
Installation Type | Price (inc VAT) | |
Combi to combi swap | £1,845 | |
System to combi conversion | £2,499 | |
New boiler install | £2,899 | |
Back boiler to a combi | £3,299 | |
System to system | £1,945 |
A leaking boiler can be caused by several issues, such as a faulty pressure valve, loose joints, corroded pipes, or even excessive pressure in the system. Identifying the source of the leak is crucial, as small issues can escalate quickly if left unaddressed.
If water is leaking from underneath your boiler, it might be due to internal components like the heat exchanger, pump, or connections failing. Corrosion or damaged seals are common culprits. It’s best to turn off the boiler and contact a professional to avoid further damage.
A leak from the relief valve often happens when the system’s pressure is too high. The valve is designed to release water to prevent damage, but if it’s happening frequently, it may indicate a faulty valve or pressure imbalance that needs fixing.
Turn off your boiler immediately to prevent further damage or safety risks. Check the pressure gauge and see if it’s above the recommended level. Avoid trying to fix internal components yourself—call a Gas Safe Engineer to diagnose and repair the problem safely.
This could be a sign of expansion and contraction causing stress on worn-out seals, or it might indicate an issue with your system's heat exchanger. Leaks that only occur when the heating is on often suggest pressure-related problems within the system.
Yes, a leaking boiler is less efficient because it may struggle to maintain pressure, leading to increased energy consumption. Over time, this inefficiency can result in higher energy bills and even more expensive repairs if the issue isn’t resolved quickly.
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