Boiler not working? Here’s what to do if yours breaks down

If your boiler isn’t working, don’t panic. There might be a quick fix you can try before calling out a heating engineer.

But before you do anything else, check for the warning signs of a carbon monoxide leak. Does your pilot light frequently blow out, or are there sooty stains around any of your gas appliances? Read our guide to find out how to spot a leak, recognise symptoms of carbon monoxide poisoning, and what to do.

If you have a working carbon monoxide detector, or if you’ve checked everything in the above guide, then move on to these 3 questions:

1. Is the boiler switched off? (It might sound obvious – but engineers do sometimes get called out to boilers that aren’t turned on at the mains.)
2. Has there been a power cut? (If so, read the power cut section on our emergencies page.)
3. Are you late paying your gas and/or electricity bills?

If the answer to all of the above is ‘no’, then keep reading. We’ll go through some everyday boiler problems, how to fix them, and when to call a professional.

In a hurry? Watch our Senior Engineer Rich Laniyan talk through the most common boiler problems and how to fix them – all in under 3 minutes:

If your boiler timer isn't working

A faulty timer is a common issue, especially in older boilers. Some signs of timer problems are:

• The heating isn’t automatically coming on when it should be
• The boiler is working, but the radiators are cold
• The boiler won’t fire up at all

The tricky thing is, all of these issues could also be signs of a different fault. To fix or rule out a problem with your timer, try this:

• Make sure the heating, hot water, and power supply are all switched on.
• Check it’s showing the right time. If you need to change it, follow the instructions in your boiler manual.
• Have a look at the thermostat – it might be struggling to talk to your timer. Try turning the temperature settings up or down to see if that helps.
• Reset your boiler.

If you try all these steps and nothing works, it’s time to call in a professional. They can tell you whether your timer needs replacing, or if there’s something else going on.

If your boiler has stopped working in cold weather

Boiler problems are more common in winter. This could be the cold weather affecting your pipes, or because your heating is on more.

To help prevent boiler problems in winter, it’s a good idea to insulate your pipes.

If you have a condensing boiler, and you find it’s not working on a cold day, the condensate pipe might have frozen. This is the pipe that takes waste water outside.

If the pipe is blocked with ice, the boiler will usually tell you with an error code (or you’ll be able to hear a gurgling noise). You can thaw out the blocked pipe by pouring hot water on it, or even by holding a hot water bottle against it.

Still not warm enough in the house? Try bleeding the radiators to let any trapped air out of your heating system.

If your boiler’s working, but there’s no hot water

The first thing to do is check:

• The hot water is switched on
• There’s no issue with the power or gas supply
• There’s nothing wrong with the thermostat or timer

If everything looks like it’s working, there could be a problem with your hot water controls. These send the water to your taps or radiators. Call an engineer if it looks like this is the case.

If you’ve got hot water, but the radiators are cold

Heating not starting up when it should? The first thing to do is follow the same steps we listed above – hot water, power, gas, thermostat, and timer.

Next, feel every radiator in the house. If just one of the radiators is even slightly warm, it’s good news: your boiler isn’t broken.

Instead, your radiators probably just need bleeding. And you can follow our step-by-step guide on how to do that.

If your boiler is making noises

If your boiler’s started making whistling, gurgling, or even banging noises, it could be down to a few different problems:

• Low water pressure. Try repressurising your boiler.
• Air trapped in the heating system. This is usually caused by rusty or blocked pipes, or a leak. Try bleeding your radiators, and call an engineer if you keep having problems.
• Debris or a build-up. If your boiler is blocked by limescale or sludge, it will need to be cleaned out by a professional.
• A faulty boiler pump. If your pump isn’t working, you’ll need to call a professional to fix it. 

If your boiler won’t fire up

There could be a few reasons why your boiler isn’t firing up when it’s supposed to. Before calling an engineer, answer these questions:

• Is there a problem with the power or gas supply? Has a fuse tripped?
• Is the boiler thermostat working as it should?
• Is the timer working, and is it set to the right time?
• Is the pressure too low or too high?
• Has the condensate pipe frozen?

If all of that looks OK, it could be a problem with your boiler’s pump, or your boiler fan might not be working.

If your boiler keeps cutting out

It can be frustrating when your boiler fires up, but keeps switching itself off. Usually, this is because of problems with pressure. Check your boiler’s pressure gauge, then repressurise and reset the boiler to see if that helps.

If you’ve run all the usual checks listed just above and it’s still cutting out, you probably have a faulty part. At this point, it’s best to call in a professional.

If the pilot light on your boiler isn’t working

Older boilers will have a pilot light – the little flame inside the boiler that shows it’s active.

If it’s a few years old, your boiler might have a small hole so you can see the flame inside. Most newer boilers will just show a flame symbol on the boiler control panel.

If the pilot light on your boiler isn’t lit, it might have gone out by accident. Or it could mean there’s a bigger problem.

If the light has gone out, try this first:

• In older boilers, you should be able to reignite the flame yourself. Check your boiler manual for more instructions.
• If you have a newer boiler, try resetting it to see if the light comes back on. Here’s our guide on how to reset your boiler.

Still no luck? Then it’s time to get a professional to take a look.

If your boiler isn’t working after you’ve reset it

Resetting your boiler doesn’t always fix the problem. If it’s still not working after you’ve checked the error code and been through our fixes, call in a professional engineer.

Thinking of getting a new boiler? Find out more and get a boiler quote.

Common radiator problems

Maybe your boiler isn’t the problem after all. Here are some common issues with central heating, and how to fix them.

If your radiator is leaking

Check where the leak is coming from by running tissue paper over the whole thing, then try the following:

• If the leak is coming from the valve, try closing it fully. Still leaking? Read this guide to repairing your radiator valve at home.
• If the leak is coming from the spindle (the shaft on your radiator valve), try tightening the gland nut (the hexagonal nut at the bottom of the radiator valve shaft) with a spanner.
• If the leak is coming from the main part of the radiator, you’ll need to replace it. Or if you have a conventional boiler system, you can cover the radiator with sealant. This isn’t a long-term fix, but if you want to give it a try, you’ll need to isolate the radiator by closing the valves on each side.

If your radiator is whistling

Whistling noises coming from your radiator can be a sign that the water flow rate is too high. Try turning the radiator valve on fully, and hopefully that’ll quieten things down.

If your radiator is ticking

Radiators can often make ticking noises that sound a bit like a clock. But this only happens because the metal is expanding as it heats up, and shrinking as it cools down. It might sound strange – but it’s nothing to worry about.

If your radiator is making banging noises

Clanking, gurgling, and banging sounds could be a sign that your radiator has air trapped inside it. Try bleeding the radiator to let the air out.

If the noises don’t stop or if they get worse, then you should call a professional to take a look.

Preventing problems with your boiler

Getting regular boiler check-ups is the best way to keep it running smoothly. With our boiler cover, you get a yearly service – as well as access to Gas Safe engineers, unlimited callouts, and a 24/7 emergency helpline. We can even repair an existing problem through Home Recover.¹ All you have to do is pick the plan that works for you.

Or if you think it’s time to get a new boiler, we’ve got a guide to help you with that too.

Get a boiler, plumbing, heating, or electrics repair with Home Recover

At OVO, we want to be there for you in an emergency – whether you’ve got cover or not.

If something goes wrong with your boiler, plumbing, or electrics, we’ve got you. With Home Recover, we’ll fix it for free for OVO customers (or £79 if you get your energy elsewhere) when you take out our Complete cover plan.²

Our experienced, independent network of engineers is already trusted by over 200,000 UK homes³. And with our 24/7 emergency helpline, we’ll help you get up and running again as soon as possible.