Common Boiler Problems: Take care of your boiler to help prevent problems from developing

Having said that, boiler issues can occur despite your best efforts and, of course, cause inconvenience to your entire household. Although some boiler problems do not require professional assistance, others will need the expertise of a Gas Safe registered engineer to get your boiler back up and running.

On this page, we’ve highlighted the 10 most common boiler faults and shared advice on the best course of action to take when these problems occur.

1) Boiler turns itself off

If your boiler keeps turning itself off, there are a number of things that could be causing it to do so. For example, it could be that the water pressure is too low or there might be air in the system. You may even have issues with the pump, thermostat or a frozen condensate pipe.

What you can do: The first thing you can check is your thermostat. Make sure the thermostat is in the on position and set above room temperature. If the thermostat is fine and it’s quite cold outside, it could be that your condensate pipe is frozen, so pour warm water onto it to allow it to thaw. You can also bleed your radiators to get rid of any unwanted air in the system. If you find that your water pressure is low, there may be work going on in your area so you’ll need to contact your water provider. Can’t identify the cause? Then it’s time to call out a Gas Safe engineer.

2) No heating or hot water

If only the heating or hot water is working and the other isn’t, it could be one of many things, such as low water levels, thermostat issues, broken airlocks, faulty diaphragm or problems with the motorised valve head.

What you can do: You can start by checking the thermostat and boiler pressure to see whether they are set correctly. If they are, we suggest you contact a Gas Safe engineer because it may be that your boiler needs a replacement airlock, diaphragm or motorised valve head.

3) Leaks and drips

Although the most common cause is a broken part, there are several issues that could cause your boiler to leak and drip. In some cases, leaks can be the result of a loose connection or even high water pressure.

What you can do: This is an issue that can only be put right by a Gas Safe engineer, and you must never attempt to fix a leaking boiler yourself.

4) Clanking, banging or tapping noises

When your boiler makes strange clanking, banging or tapping noises, this is known as boiler ‘kettling,’ which is often caused by a build-up of limescale in the heat exchanger. Alternatively, it could be that the boiler’s pump is faulty or there is just air in the system. This issue needs to be addressed right away because it can actually decrease your boiler’s efficiency and shorten its lifespan.

What you can do: You can try bleeding your radiators, as this may help to remove both air and limescale. However, we recommend you get in touch with a Gas Safe engineer who will not only be able to identify the cause quickly but also ensure the problem is rectified properly.

5) Pilot light keeps going out

The pilot light can be put out by a damaged seals, a deposit build-up or even something as simple as a draught but the most common cause is a broken thermocouple. A thermocouple is located near the pilot light and is basically a heat-sensitive device or sensor that is designed to measure the temperature in your boiler.

What you can do: First check that your gas stopcock is switched on and then see whether your other gas appliances are working. If you have issues with your other gas appliances, it’s likely that there is a problem with your gas supply, so you’ll have to contact your gas supplier. Not having any trouble getting your other appliances to work? Then you must speak to a Gas Safe engineer.

6) Condensate pipe has frozen

During winter and extreme periods of cold weather, a condensing boiler’s condensate pipe can freeze because part of the pipe runs outside to enable acidic water to go into a drain. If you have a modern condensing boiler, it will more than likely display a fault code to tell you that the condensate pipe is frozen.

What you can do: You can attempt to thaw the condensate pipe yourself by pouring warm (NOT boiling) water onto it. If the pipe is only frozen in a small area, you could try using a hot water bottle or a tea towel that has been soaked by warm water. But if you don’t like the idea of doing this yourself or you have tried these simple fixes and they haven’t worked, call a Gas Safe engineer for help.

7) Boiler is losing pressure

A boiler can lose pressure when there’s a leak in the system or because the pressure relief valve is damaged. When the pressure is too low, your boiler becomes less efficient and is unable to heat your home. It can also cause your boiler to switch itself off, leaving you with no heating and hot water.

What you can do: Look at the boiler’s pressure gauge to check whether the needle is below 1. If it is, you can re-pressurise your boiler. To check the correct pressure level for your boiler, simply refer to the manufacturer’s manual. If you aren’t confident doing this or have tried to re-pressure the boiler but it is still too low, get in touch with a Gas Safe engineer for assistance.

8) Radiators are only partially heating

Another common boiler problem is partially-heated radiators, where your radiators are warm at the bottom but cold towards the top. Common causes include a faulty pump or a build-up of air in the system, both of which will stop the hot water from circulating properly.

What you can do: The easiest way to remove trapped air from your system is to bleed your radiators if you feel comfortable doing so. Unfortunately, this isn’t always enough and you may find that your radiators need a power flush, which is best left to a qualified engineer.

9) Heating not coming on or switching off at the set time

This tends to be caused by a faulty thermostat, however, it could be something else entirely. It may even be that someone in your home has changed the heating or hot water on and off times on your thermostat without telling you, so you might find the fix is as simple as adjusting the settings.

What you can do: There are a couple of checks you should make before getting on the phone to an engineer including checking that the thermostat is in the on position and making sure it is set to your preferred time or schedule. The times could have been changed by a member of your household or the thermostat may have lost your preferred settings as a result of a power cut or the clocks going forwards or backwards. If your settings are still what they should be, it could be that the thermostat is broken or worn out and needs replacing.

10) Water is too hot

If you notice that your water is too hot, there could be an issue with your boiler’s thermostat or your cylinder’s thermostat. Water that is far too hot can scald your skin, as well as cause damp on ceilings or damage your central heating system.

What you can do: You must always call out a reputable engineer to check whether your boiler or cylinder thermostat is causing your water to be too hot. If the extremely hot water is only flowing out of your shower, then it might be a problem with your shower’s cartridges.

When Should You Replace Your Boiler?

Boilers usually last between 10 and 15 years, so if your boiler is around this age or older, you may want to consider a replacement. If all you seem to do is spend money on boiler repairs, then it’s definitely time to upgrade your boiler. Not only will a modern boiler be more efficient and save you money on your energy bills but it will also lower the risk of a boiler breakdown. When it comes to choosing a replacement, we recommend you opt for a boiler with a good reliability rating and one that comes with a lengthy warranty to give you complete peace of mind.