man adjusting water [ressure on boiler -

10 common boiler problems (and how to fix them)

October 18, 2019

Issues with your boiler? Consult this guide before calling in the repair professionals – it may be a simple problem that can be fixed in an instant. ..

Central heating season is upon us, but if you’re one of the few brave souls who hasn’t turned up the thermostat this autumn yet, it’s worth checking your boiler to ensure its still in good working order after the summer months to make sure you’re not left to the mercy of the cold weather when you do need it.

If you find that your boiler isn’t functioning properly when you do turn it on, it might not always be necessary to have to call out an engineer to repair it. There are many common boiler problems that you can tackle yourself before having to book in a service.

Consult these tips from David Holmes, founder of the Boiler Guide, as to whether your boiler problem is something you can fix yourself, whether you need a professional, and whether your issue could be dangerous and need urgent attention.

1. No heating or hot water

If your boiler is not providing any heating or hot water there are lots of potential causes such as a faulty thermostat, valve failure, airlocks or low water pressure. Therefore, you may be able to get it going again by refiring it or increasing the water pressure (it should usually be between 1 and 2 bar), but if neither of these work it’s best to find a Gas Safe engineer to diagnose the problem.

2. Boiler is leaking

A leaking boiler needs to be looked at by a Gas Safe engineer as it is likely that there is a loose connection, faulty component or corrosion. It may have been caused by high water pressure, but it will still need to be fixed by a professional as a water leak can be a safety concern.

3. Boiler is noisy

Boilers can make a range of different noises from gurgling, vibrating and banging to a whistling or ‘kettling’ noise. The most common reason for a noisy boiler is that limescale has built up on the heat exchanger but it could also be caused by a drop in water pressure, trapped air, a blockage in the system or a pump failure.

Check the water pressure level, make sure the external condensate pipe has not frozen and caused a blockage and try bleeding the radiators to release any trapped air which could be the cause. If none of these steps work, the system may need to be flushed with specialist chemicals by a heating engineer to remove blockages and limescale.

boiler guide bleeding radiator -

Image: Boiler Guide 

4. Radiators aren’t heating up

If your radiators are not heating up properly, e.g. they have cold patches, don’t heat up at the bottom or generally don’t get very hot, you may be able to sort this out yourself. When radiators are not heating up fully there may be pockets of trapped air inside preventing the hot water from filling the radiator. You can remove this air by bleeding the radiators. Not sure how to do this? Check out our guide to bleeding a radiator.

If they are cold at the bottom but hot at the top it’s likely that sludge and debris has settled at the bottom which will need to be flushed out by a professional heating engineer.

5. Heating is coming on/switching off at the wrong times

It sounds simple, but have the clocks move forwards or backwards? This may explain why your boiler is not running to schedule. Try turning the boiler off and restarting the system but if this doesn’t work, the thermostat may need replacing by an engineer.

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6. Boiler turns itself off

Boilers are equipped with automatic safety mechanisms which cause the boiler to shut down when it detects certain issues like low water pressure, problems with the gas supply, a faulty part or a blockage in the system. Check the water pressure, bleed the radiators and make sure that there are no issues with the gas supply before calling an engineer.

7. No pilot light

You will need to contact an engineer for this one. If seals are damaged, there is as faulty flue bringing in a draft or deposits have built up in the system the pilot light may be being blown out. It can also be caused by a faulty thermocouple which monitors and reacts to the boiler’s internal temperature.

man adjusting water [ressure on boiler -

Image: Boiler Guide 

8. Boiler keeps losing pressure

If it seems you are always needing to increase the water pressure, there may be a leak or a faulty pressure valve in the system which needs to be checked by an engineer. This will not only be irritating buy will be making your heating more expensive to run.

9. External condensate pipe has frozen

In cold weather the condensate pipe outside can freeze which causes a blockage and this may cause the boiler to shut down for safety reasons. You can often fix this by yourself by pouring warm (not boiling) water over the pipe. Consider insulating the pipe to prevent it from freezing again.

10. Emergency boiler problems

If you can smell gas there may be a leak. If your gas meter is easy to access, turn off the gas supply, open the windows and doors, evacuate the building and call the Gas Emergency Service on 0800 111 999. DO NOT switch any plugs on or off, create any sparks and do not smoke or use your mobile phone in the property as you could cause an explosion.

If the pilot light is orange or yellow (not blue) the boiler is not burning the fuel away completely and may produce carbon monoxide (CO). We can’t see or smell CO gas, but breathing it in can quickly cause us to become seriously unwell leading to permanent brain damage or even death.

Early symptoms of CO poisoning are very much like the flu, including headaches, dizziness, nausea and vomiting, confusion, tiredness, pain in the stomach and/or difficulty breathing.

Black stains around or on the boiler could also indicate a leak and damaged, rusty or corroded pipework (including green discolouration on copper pipework) should be inspected by a Gas Safe engineer ASAP.

If you notice black stains, a yellow or orange pilot light and/or you may be experiencing CO poisoning symptoms, evacuate the property and call 0800 111 999.

For more information about Boiler Guide, visit


A message from the editor:

Let us help you create the home of your dreams! Get ideas & inspiration from Good Homes every month, delivered direct to your door. Visit to sign up for the weekly Good Homes newsletter. Meet the Good Homes team at Ideal Home Show and be inspired by our on-trend roomsets.

~ Karen Walker, Editor, Good Homes