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

02 December 2020 | Aimee Tweedale

There’s nothing worse than a boiler giving up the ghost on a cold day. If your boiler isn’t working, don’t panic. There might be a quick fix you can try before calling out a heating engineer. 

First, before you do anything else, answer these three simple questions:

  1. Is the boiler switched off? (We know, it sounds silly – but engineers do often get called out to see boilers that aren’t turned on at the mains!)
  2. Has there been a power outage? (If so, read our guide to what to do in a power cut.)
  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 run through some everyday boiler problems, how to fix them, and when to call a professional. Let’s get your heating up and running again!

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

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My boiler timer’s not working

One common boiler issue is finding that the timer isn’t working. This tends to happen to older boilers.

Some symptoms of boiler timer problems include:

  • 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 symptoms of a different problem. Confusing, we know. 

If you think there’s a problem with your timer, try this:

  • Make sure the heating, hot water, and power supply are all switched on: it’s always worth checking the basics first. 
  • Check the time: your boiler could be showing the wrong time for a few different reasons – for example, maybe it didn’t go back for daylight savings. Follow the instructions in your boiler manual to make sure the time is correct.
  • Next, check the thermostat: is it really your timer that’s the problem, or is it struggling to communicate with your thermostat? Try changing the settings to see if that helps. 
  • Reset the boiler: find out more about how to reset your boiler by reading our guide.

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. Find out more about how to use a boiler timer here.

Does your pilot light frequently blow out, or are there sooty stains around any of your gas appliances? This could indicate a carbon monoxide leak. Carbon monoxide poisoning is lethal. Read our guide to find out how to spot a leak, recognise symptoms of carbon monoxide poisoning and what to do. This guide could save your life

My boiler has stopped working in cold weather

Boiler problems are especially frequent (and especially irritating) in the winter. This could be because of the cold weather messing with your pipes, or it could be another fault related to your heating being on more. 

To protect yourself from seasonal boiler problems, it’s a great idea to insulate your pipes. Read our guide to insulating your home here. 

If you have a condensing boiler, and you find it’s not working on a cold day, it might be because the condensate pipe has frozen. This is the pipe that takes waste water outside. If there’s a blockage, usually the boiler will tell you via an error code (or you’ll be able to hear a gurgling noise). You can thaw out the troublesome pipe by pouring hot water on it, or even applying a hot water bottle. Read more about how to do this in our guide to defrosting a frozen condensate pipe.

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

My boiler is working, but there’s no hot water

If there’s no hot water coming out of your taps, the first thing to do is check:

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

If everything looks in working order, there could be a problem with your hot water controls (which direct hot water to your taps or radiators). 

I have hot water, but my radiators are cold

If your heating isn’t kicking in when it should, remain calm! The first thing to do is check all the same steps outlined 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: this means your boiler isn’t broken.

Instead, your radiators probably just need to be bled. Follow this handy step-by-step guide on how to do that.

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Why is my boiler making noises?

Has your boiler decided to make its presence felt by whistling, gurgling, or even making banging noises?

This can be due to a few different problems, including:

  • Low water pressure: try fixing this by repressurising your boiler – more on how to do that here.
  • Air trapped in the heating system: try bleeding your radiators. What else could cause air in your boiler system? It’s usually down to rusty, blocked pipes, or a leak. Call an engineer if you keep having problems. 
  • Debris or build-up: if your boiler is blocked by limescale or sludge, it will need to be cleaned out by a professional.
  • Boiler pump not working: if you have a faulty pump, you’ll need to call a professional to fix it. 

Why won’t my boiler fire up?

There could be a number of reasons why your boiler isn’t firing up when it’s supposed to. Before calling an engineer, check the below:

  • Is there a problem with the power or gas supply? Has a fuse tripped?
  • Is the boiler thermostat not working?
  • Is the timer not working, or has it reset to an incorrect time?
  • Is the pressure too low or too high? (If you’re not sure, read our guide on how to check your boiler’s pressure.)
  • Has the condensate pipe frozen?

If all looks okay, it could be a problem with your boiler’s pump, or your boiler fan may not be working.

Why does my boiler keep cutting out?

There are few things more frustrating than a boiler that fires up just fine, but then keeps switching itself off. 

Usually, this is down to pressure problems. 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 above, and it still keeps cutting out, you probably have a faulty part.

The pilot light on my boiler isn’t working

Older boilers will have a pilot light, which is the little flame inside the boiler that shows it’s active. If the pilot light on your boiler isn’t lit, you may have a problem – but it also might have just gone out by accident.

How can you tell if the pilot light has gone out? If it’s a few years old, your boiler may have a small inspection hole for you to check if the flame inside is still lit. Most newer boilers will simply display a flame on the boiler control panel. 

If the light has gone out, try this first:

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

Still no dice? Then it’s time to call a plumber.

I reset my boiler but it’s still not working

Have you tried resetting your boiler, but you’re still having trouble?

Unfortunately, a reset doesn’t fix most common boiler problems. It just reboots the system once the fault has been addressed. So unless you’ve managed to find and fix the issue, you may need to call a Gas Safe-registered engineer.

Always check the fault or error code on your boiler’s display – this should tell you what’s wrong. If you’ve been through all the fixes on this page and still nothing is working, then it’s time to get a professional to take a look.

Thinking of getting a new boiler? Read our guide to combi boilers and how much they cost to install. 

Common radiator problems and how to fix them

Is your boiler not the problem after all? If you’re having central heating issues, try these fixes.

My radiator is leaking

Leaky radiators are a pain, but they can often be easily fixed. 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: firstly, try fully closing the radiator valves. Still leaking? Read this guide to repairing your radiator valve at home. 
  • If the leak is coming from the spindle: the ‘spindle’ is the shaft on your radiator valve. If it’s leaking, try tightening the gland nut with a spanner.
  • If the leak is coming from the gland: the ‘gland’ is the hexagonal nut at the bottom of the radiator valve shaft. If the leak is coming from there, you could try tightening the valve, or replacing it altogether. Read this guide which explains how. 
  • If the leak is coming from the body of the radiator: sadly, this means that you’ll need to replace the whole thing. If you have a conventional boiler system, you can take the temporary measure of covering the radiator with sealant. Before doing this, isolate the radiator by closing the valves on either side.

Still got a leak? As always, if these quick fixes don’t work, it’s time to call a plumber.

Why is my radiator whistling?

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

Why is my radiator ticking?

Just like clocks, radiators often make ticking sounds! But this only happens because the metal is expanding and contracting as it heats up and cools down.

It might take you by surprise sometimes – but it’s nothing to worry about.

Why is my radiator making banging noises?

Clanking, gurgling, banging, and other more angry sounds can be a sign that your radiator has air trapped inside it. 

Try bleeding the radiator to let the air out, and the sound should go away.

As always, if the noises don’t stop, or even get worse, there’s no harm in calling out a professional to take a look. And if you think it might be time to replace your boiler altogether, see our guides to the costs of repairing or replacing your boiler, and how long it takes to fit a new boiler.

To avoid an emergency, it’s a good idea to have regular boiler check-ups. With our boiler cover, a network of Gas Safe engineers will help make sure your central heating system stays up and running. From £15 a month, you’ll get:

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Over time, a new, more energy-efficient boiler could save you money. Find out about boiler replacement with OVO. And find out all about condensing boilers in our comprehensive guide. 

You can get an A-rated, award-winning boiler from CORGI HomeHeat (which is part of the OVO family). Want to know more? Visit MyOVO and check out the offers from CORGI.