Most common boiler problems

Boiler problems can cause a significant headache, particularly during the winter months. From leaks to cold radiators, boilers can suffer from a wide range of issues if not serviced regularly. Fortunately, most of the most common issues are easy to identify and can easily be fixed by a Gas Safe registered engineer.

Below we have listed the top ten most common boiler problems across all types of condensing boilers.

One of the most common boiler issues is a boiler leak. Leaks can be a nuisance because not only can they cause water damage to a home, but water can also cause electrical components in and around the boiler to malfunction.

A leaking boiler can be due to a number of things:

• Excessive boiler pressure
• Corroded pipes or tanks
• A faulty Component
• Leaks from seals

A leak should always be treated as a serious issue. If you find a leak you should call a qualified heating engineer as soon as possible to investigate. Do not attempt to remove the boiler casing yourself to find the source of the leak.

Low boiler pressure can lead to cold radiators and a lack of hot water. Low boiler pressure can be identified on the boiler display panel, where either a digital or physical dial will show the level of pressure in the system. The most typical pressure level should be around 1.5 bars, with slight variance depending on the boiler manufacturer and model.

A boiler’s pressure can drop due to two main reasons:

• A leak in the system will result in not enough water being present in the system, consequently causing the pressure to drop.
• A bleeding radiator can also reduce system pressure.

Low boiler pressure can be fixed by repressurising the boiler. This involves opening the boiler filling loop to allow water to re-enter the system.

Check out our guide on repressurising a boiler to see the full list of steps to follow.

Another common boiler problem is kettling. Boiler kettling occurs when water is heated too quickly and reaches boiling point, causing steam to be generated and air to become trapped. The trapped air gives off a whistling sound, like a kettle.

Boiler kettling can be caused by limescale build-up, which slows down the flow of water in the system and causes it to heat up excessively. A faulty component on the appliance could cause the boiler to heat up water to higher temperatures than expected.

A boiler engineer will be able to inspect the system and identify the cause of the kettling. There is a solution to this problem which depends on the severity. Sometimes the noisy component can simply be cleaned using different methods, alternatively replacing the parts may be required.

A frozen condensate pipe is an issue that many people face during the colder months. Every condensing boiler has a pipe that transports waste water produced during the condensing process outside the property. If temperatures drop below freezing, the water in the condensate pipe can become frozen, forcing the system to shut down automatically as a precautionary measure.

The best way to fix a frozen condensate pipe is to pour warm water onto it to thaw it. This should allow waste water to exit the pipe, meaning the boiler can turn back on. For further detail on this, check out our guide on how to safely resolve a frozen condensate pipe.

If your boiler has left you without heat or hot water, there is definitely something wrong with the system. A boiler may stop providing central heating or hot water for several reasons:

• The boiler has become disconnected from the power, gas or water supply. These connections can be switched off accidentally or during a power outage.
• If the boiler pressure becomes too high or too low the system turns off automatically, causing a lack of heat and hot water
• Piping issues, such as frozen condensate pipes or airlock, can stop a boiler from functioning.
• Along with various safety features built into the appliances that would display other faults.

A lack of central heating and hot water can be down to any number of these things, so it’s always best to call a Gas Safe registered engineer to inspect the boiler and resolve the issue.

If left unserviced, a boiler may over time begin to randomly switch off. There are a number of potential reasons for this, including:

• Trapped air in the system
• Low boiler pressure
• High boiler pressure
• A faulty thermostat
• Debris and sludge building up in the pipes

If you notice that your boiler keeps switching on and off, it may be because of one of these faults. Depending on the severity, a qualified engineer will be able to say whether the problem can be fixed, or whether a new boiler is needed.

If you have an older boiler you may have a pilot light that needs to be constantly lit to light the larger boiler burner. However, over time the necessary parts for lighting the pilot switch can become faulty, such as the thermocouple.

If your pilot light keeps turning off, do not try to repair/replace this yourself. This would require taking off the boiler casing, which is illegal unless you are registered with the Gas Safe Register. Instead, first check that your other gas appliances are working correctly. If they are not, the issue might be with the gas supply itself.

If the other gas appliances are working correctly, there may be a faulty part, so call a Gas Safe registered engineer to resolve the problem. Newer boiler models are not built with pilot lights so do not suffer from this issue.

• Boilers can suffer from many problems, most of which should be resolved by a qualified boiler engineer.
• Boiler leaks should be treated as a serious issue and resolved as soon as possible.
• A lack of central heating could mean that the radiators need bleeding.
• Low boiler pressure can be caused by leaks and can be solved by opening the filling loop.
• Boiler kettling can make a lot of noise and sometimes requires the system to be cleansed or for a part to be replaced.
• Frozen condensate pipes can be thawed using warm water.
• A boiler may not respond to a thermostat if the thermostat runs out of battery or is placed too far away.
• A lack of hot water and central heating is usually a larger issue that definitely needs the help of a boiler engineer.
• If a boiler keeps switching off, an engineer will be able to say whether a part needs replacing or if the entire boiler needs to be replaced. Sometimes this is more cost effective.
• Boilers can make lots of strange and distracting noises, such as gurgling and humming.
• Never attempt to replace any parts yourself. An engineer is best to fix any issues safely.