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Boiler not working? Here's (probably) why and how to fix it

If your boiler's not working and it's given up the ghost, it could be something so basic you seem silly. Or, something so severe, you could be left with a silly bill. Let's hope it's not the latter.

If your boiler is broken.

So is your will.

So are your dreams.

So is your home.

As such. You’ll want the cheapest fix or the cheapest new boiler replacement

Read our quick guide:

What to do if your boiler is not working - free fixes

When you discover your boiler isn’t working, it can be incredibly frustrating.

Thankfully, there are some basic checks you can do to attempt to fix your boiler problems for free. In this guide, we will take you through some common boiler problems and troubleshooting steps, hopefully allowing you to fix your boiler online.

However, some problems require a professional, so if in doubt consult the assistance of a registered Gas Safe Engineer. They will be able to diagnose your boiler issues and repair them quickly and safely.

So, here are (some surprisingly) common issues – which are free and easy to fix. Closely followed up by more sinister and costly reasons why your boiler isn’t working (that requires an engineer).

(Looking for a new boiler? Check out our summary of the best boiler brands).

Common broken boiler problems (with free and easy fixes)

Fix a Broken Boiler (For Free)

There are a variety of reasons why your boiler may not be working; common examples include the boiler pressure being too low or too high, a power cut, gas supply issues, a faulty pilot light, a frozen condensate pipe, faulty internal components or a more complex issue.  

Read our quick guide:

And if you're just curious to see how much a new boiler will cost complete this quick questionnaire to find out for free.

#1 - Check the boiler is switched on

Turn Boiler OnAn absurd and seemingly patronising statement at first, but, boiler installation companies up and down the UK are relentlessly earning call out fees for customers who haven’t realised their boiler has been switched off – sometimes at the mains.

It can be human error, or perhaps you switch off appliances whilst sleepwalking but one of the most common causes are power cuts.

Your boiler probably hasn't broken, so switch the bugger on.

Cost: Free


Want an exact price on a new boiler? Use our boiler quote calculator (no personal details needed).

#2 - Have you paid your gas bill, or does the gas meter have credit?

Broken Boiler Pay Your Bill

Another silly reason at first glance but understandably common. People take boilers for granted and aren’t always acutely aware of the corresponding gas bill.

If you don't pay your energy bills, your boiler won't work. Simple.

Perhaps you upgraded to Netflix HD last month sending you tumbling beyond your overdraft. Or, it’s just the energy companies fault. The scumbags.

Either way – do check.

The good news is that combi boiler is much cheaper than the likes of immersion heaters, so it's not all bad. 

Curious to know which boiler brand performed worst? Find out in our report of the worst boilers

#3 - Boiler not working? Check for low pressure

Top Up Boiler Pressure

Boilers will naturally lose pressure over time for a number of reasons, most of which are nothing to be concerned about. If your boiler's not working, and it's simply low on pressure, you'll be back up and running in no time.

Read how to breath new life into a broken boiler that's losing pressure.

It’s super easy – one check and one tap turn. 

Have you had a boiler quote yet? Use our calculator to get an instant new boiler quote. 

How to check if your boiler's not working because of pressure issues
Glance at your boilers pressure gauge – the clock-like feature staring at you like a cyclops from the front of your boiler. When the boilers off, its arrow should point to the green zone – around 1 BAR.

Your boiler pressure being too high is also a thing.

How to fix your boiler's pressure issues
We recently published an article about boilers losing pressure - it'll tell you how to fix it.

#4 - Boilers pilot light may have gone out / not catching

To ignite the gas and deliver heat and hot water, the boilers pilot light (basically a tiny internal flame) will need to be alight when your boiler is active, in order to burn the gas.

Sometimes this flame will go out, whether caused by sudden drafts or wandering spirits trying to make contact.

Broken Boiler Pilot Light

In older boilers, you’ll be able to check this by peering through the casing to visually check on the boiler flame. If it’s out, you should try restarting/resetting your boiler. If the boiler is still not working, you'll need to call (and pay) a heating engineer (sorry).

#5 - Check your condensate pipe (winter conditions only)

Boiler Broken Frozen Condensate

Your condensate pipe travels from your boiler, to (usually) the nearest outside wall and is where excess liquid caused by condensation from your boiler is deposited outside.

This small amount of slowly dripping water is naturally vulnerable to freezing in cold weather. 

A frozen condensate pipe will lead to a blockage, meaning the excess water has no escape route and your boiler will shut down upon detecting this. It's a surprisingly common cause of a boiler that's not working.

How to fix a frozen boiler that's not working
Gently pour warm water over the frozen condensate pipe until the frozen water has melted away.

After you’ve tackled that – reboot your boiler.

How to (try to) prevent
Checking regularly on the pipe is helpful, but may be something you easily forget to do. 

Instead, wrapping the external part of the pipe in foam or cloth to prevent future freezing is recommended.

Want an exact price on a new boiler? Use our boiler quote calculator.

#6 - Boiler does not respond to thermostat? 

Faulty Thermostat

Like Governments blaming immigrants and the poor for their shortcomings, boilers are often held accountable for the failings of their controllers.

If you’re privileged enough not to have to physically approach your boiler to switch it on, you should check if it’s actually your timer that’s not working. Your boiler might be working just great.

How to check if your boiler's not working because of a faulty thermostat:

  • Check it’s switched on with a full charge or working batteries
  • Ensure that the temperate is turned up to the level you require
  • Check your Wi-Fi connection if applicable with the boiler thermostat
  • Run over the time settings, making sure no ‘vacation modes’, stand-by options or unnoticed daily schedules have been set.

How to fix a boiler thermostat not working

  • Replace the batteries in your thermostat
  • Clear any settings and restore to manual operation
  • If all else fails, refer to the thermostat manual

Want to save money and energy on your heating bills? If so, you should consider installing one of the best smart thermostats.  

Common issues for a boiler that's not working (requiring an engineer and £££)

Fix a Broken Boiler (Costly)

#1 - Pressure issues (due to faulty parts)

Boilers require pressure to be maintained within a certain range since it allows the hot water to circulate around your system.

A loss of pressure will result in an inadequate amount of water running through your boiler that will, in turn, struggle to provide heat to your home – or enough hot water, obviously.

Too much pressure and your boiler won’t have time to thoroughly heat the water – amongst other issues, like putting internal parts under pressure and causing leaks.

Culpable boiler parts include; expansion vessel, pressure release valve and the heat exchanger. These are all too often heartbreakingly expensive repairs that are much more likely to lead you down the new boiler route.

How to check if your boilers not working because of a leak
Refer back to the trusty pressure gauge on your boiler; it shouldn’t be under or above the green zone whilst the boiler is switched off and never in the dreaded red zone.

If it is, switch the boiler off.

How to fix a leaking boiler that's not working
A qualified Gas Safe heating engineer will need to strip the boiler down and inspect all possible parts – replacing them where possible.

Boiler over 10-years old with a faulty part? Gently massage the idea of a new boiler into your thoughts. You’ll thank yourself later.

Boiler not working and the repair going to cost you an arm and a leg? Save your last two limbs and upgrade to a hot new boiler with a 10-year warranty and mind bogglingly low monthly payments.


Want an exact price on a new boiler? Use our boiler quote calculator (your fixed price will appear on screen).

Read our new boiler costs guide to get a better idea of boiler costs and if you are interested in paying monthly, check our boilers on finance guide. 

#2 - Leak in the boiler, or heating system

Boiler Not Working (Leak)

Leaks within the boilers internal parts or around the heating system (pipework) aren’t just bad for your carpets and floorboards.

They’ll cause a loss in pressure that we’ve already established is a boiler killer.

How to check
Look for patches of water and drips directly underneath your boiler (within the case if you can) and also check the pipework throughout your house, particularly around the joints/bends in the pipes.

How to fix
You’ll need a boiler engineer to give your system a once over and either replace any faulty parts or secure any leaks in pipework that can be repaired.

If it’s an internal boiler part that’s failed, you may well be better off upgrading to a new boiler rather than falling into the trap of eternal repairs.

Boiler not working during the financial low of your life? Typical. Get a new boiler now – and pay monthly, with no interest!.

#3 - Boiler not turning on (no power to boiler at all)

If your boilers not turning on to the point where it appears utterly dead with no sign of life. It’s likely an electrical issue.

Most commonly a boiler not turning on will be caused by a busted PCB (circuit board) and could set you back a few hundred pounds.

How to check
The age-old off and on again at the mains power is your only real play here. You’re going to need an engineer to diagnose the issue.

If your boilers not working at the same time as your TV, kettle, lights and washing machine – get calling your electrical provider.

Learn all about combi boilers in our what is a combi boiler guide. 

How to fix
If your PCB board has gone into the long night then it’s going to need a costly replacement.

Hopefully, though, you’ll get away with a faulty fuse or another less expensive repair.

Is your boiler working but not providing hot water?

No Hot Water From BoilerA boiler not working that still provides heating is a brave boiler indeed.

But it definitely has a faulty part, and it’s probably the diverter valve.

The aptly named diverter valve diverts the water to either your radiators, hot water outlets or both – depending on what you’re demanding from it.

Here's some help if you've got no hot water from your boiler.

How to fix
Your diverter valve is going to need replacing, or you’re going to need a new boiler.

Is your boiler making a lot of noise? Find out why in our noisy boiler guide. 

Is your boiler working but your radiators aren’t getting hot?

Boiler Working Not Radiators

This is unlikely to be your boiler not working.

Over time, heating systems – pipes and radiators – become congested with metallic debris and congealed dirty water.

This causes blockages within the system, that can lead to a number of problems, such as cold spots and some radiators not heating up like they used to.

You'll know you've got a sludge issue if your radiators are cold at the bottom. That's the most common.

On a side note, and much rarer instance, your boiler may not actually be powerful enough for your home's needs. Read more about which size boiler your homes needs.

The fix?
A heating engineer is going to need to flush your system – probably a power-flush to cleanse the pipework and radiators of debris and bad vibes. It’s the spa break your boiler deserves.

As a preventative measure, you should also invest in the installation of a magnetic boiler filter. 

Treating yourself to a new boiler? Heatable fit an Adey Pro magnetic boiler filter, as standard with every new boiler installation. We even throw in a chemical treatment for your radiators. 

Want to have your boiler moved to a different location? Check out our cost of moving boiler guide.

Still not sure which boiler is right for you? Check our guide all about the main types of boilers

Common issues, for common boilers that don't work

Worcester Bosch boiler not working

Worcester Bosch Boiler Not Working

Common reasons your Worcester boilers not working & Worcester Bosch boiler error codes:

Worcester Bosch Fault Likely Error Code
Pressure too low/high A1, CE 207, H07, 224V, 1017W, 2970B
Pilot light issue (not lighting) EA, F7, FA, EA227, F7 228, FA306
Heat Exchanger error 2963 B, 2964 B, 2966 B, 2967 B
Fan Fault C6, T2, C6 215, C7 214, C1 264

Vaillant boiler not working

Vaillant Boiler Not Working

Common reasons your Vaillant boilers not working & Vaillant boiler error codes:

Vaillant Fault Likely Error Code
Pressure too low/high F.24, F.12, F.22, F.73

BAXI boiler not working

BAXI Boiler Not Working

Common reasons your Baxi boilers not working & Baxi boiler error codes:

BAXI Fault Likely Error Code
PCB (circuit board) error E100, E167, E168, H.02 - 02, 4-5 Green Flashes
Pressure too high/low E28, E119, 117, 118, 119
Pilot light error E128, E129, E384

Ideal boiler not working

IDEAL Boiler Not Working

Common reasons your Ideal boilers not working & Ideal boiler error codes:

Ideal Fault Likely Error Code
Fan defect F3
Low water pressure F1
PCB (circuit board) error F9, L9, F8, L8

Boiler still not working? Here's how you can get the best deal

How? Without boasting, buy from us.

Use this clickable form to get a fixed price on the screen instantly. 

We're an online, nationwide boiler installation business with 500+ 5 star reviews from a shed load of happy customers.

Fixed Online Boiler PricesBecause we're online, our overheads are low which means we pass those savings on to our customers, ensuring they're always getting the best deal on a new boiler.

Plus, because of the volumes that we install, we're able to access exclusive warranty lengths from our partner boiler manufacturers. For example, we can offer 10 years of protection on the Viessmann 050-W range, whereas your traditional installer can only offer you 7. Boom.

To get the best deal on a new combi boiler, answer some quick online questions and we'll give you an instant fixed price.


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Heatable is registered in England and Wales No. 08804726 (VAT No. GB205805920 ). Trading address is 1 Station Road, Great Sankey, Warrington, Cheshire, WA5 1RH. Heatable acts as a credit broker (not as a lender) and offers credit products through a panel of lenders. Heatable is authorised and regulated by the Financial Conduct Authority (reference no. 805259).

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