Top 10 Common Boiler Problems and How to Fix Them

How to fix boiler problems

Now has got to be the worst time of year for your boiler to start acting up but it does happen, particularly with older models.

Here’s a list of the ten most common boiler problems and how to fix them before you’re left shivering any longer.


No heating or hot water

This is a big one, after all it is winter and you really need your central heating to work.

This could be because of a broken diaphragm, airlock or thermostat or low pressure levels. First of all try to rule out problems like thermostat faults or pressure levels with the advice below.

If that doesn’t work then you may need to call out a Gas Safety registered professional who can handle any internal faults or broken parts.


Loss of pressure

When the pressure drops too low, this could stop your central heating functioning properly. This might happen because of a water leak in the system or a pressure release valve may need replacing. It sometimes happens after recently bleeding radiators.

You can sometimes solve this problem yourself by taking a look at instructions in your boiler manual as it usually involves simply releasing a valve. However, if you’re unsure or this happens regularly then you might want to call out a professional who can take care of this for you instead.


Frozen condensate pipe

Condensing boilers have a condensate pipe which removes acidic water from the boiler. It usually runs outside and therefore runs the risk of it freezing over.

A lot of boilers have a warning notification if this pipe freezes over to help you identify the problem. It’s usually a simple case of using warm water to thaw the pipe out.


Radiators don’t heat up

If your radiators have cold patches it could be one of two things. If the cold patches are at the top, it’s most likely you’ve got air pockets. In this case you’ll need to bleed your radiators to remove the air so that they will heat evenly.

If the cold patches are at the bottom, it could be a build-up of sludge in your system. A plumber may need to help you flush the system out.

Thermostat problems

If you’ve got a problem with your thermostat this could mean that you’re losing accuracy or that the heating is not coming on/going off when you want it to. It could be time to replace it to see if this solves your heating problems.



This is when lime scale or sludge builds up on your boiler’s heat exchanger and restrict the flow of water. This can result in overheated water that steams and boils (hence the kettle-like sounds).

A professional can help you identify the source of any strange noises. In the case of kettling, they may descale or flush the system of any sludge or replace broken parts where necessary.


No pilot light

This could be a number of things. A broken thermocouple could be stopping the gas supply, a draught might be blowing the light out or there might be a deposit built around the light. Any internal fault like this is better handled by a professional who is Gas Safety registered.



One of the most common causes of this is a broken internal component such as a pump seal or pressure valve. In each of these cases, a professional can diagnose the problem and provide replacement parts.


Boiler switches itself off

This could be down to low water pressure, a broken thermostat or a lack of water due to a closed or blocked valve. If the problem can’t be solved with any of the above tips then it’s one for a professional to take a look at.


Strange noises

If your boiler is starting to make some unusual noises, it could be the sign of an internal problem. One possibility is that there’s air in the system. It could also be a sign of other problems such as kettling or low pressure. Older models may also have pump failure responsible for the noise.

You might be able to solve this by tackling low pressure and build-ups or you could replace your boiler with a newer model which will cause you less hassle in the long run.


If you’re having boiler problems, we provide servicing and new boiler installations. We are a Worcester Bosch Accredited installer which means we’ve been approved by the UK’s leading manufacturer of boilers. We can also offer up to 10 years warranty on any Worcester product we install.

If you would like a quote for a service or a new boiler, don’t hesitate to contact us on 0151 605 0881.