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Boiler Not Working: 6 Common Problems and How to Fix Them

If you’ve just found that your boiler is not working, you are probably in a bit of a panic. After all, a boiler breakdown means no hot water and no central heating, so keeping warm, washing, and lots of other everyday tasks suddenly seem insurmountable.

In this guide, we’ll walk you through several possible reasons why your boiler stopped working. We’ll also explain when repairs are justified, when a replacement may be due, and what is the best way to get a new boiler.

Boiler not working

If your boiler stopped working, the first bit of advice is this: don’t panic. A lot of common boiler problems are far more minor than you might think, and some may even have a quick, DIY fix.

That said, before we go any further —  any inspections or fixes that involve the boiler’s internal components, or the property’s gas connections, must be handled by a Gas Safe engineer. 

If your boiler is not working because of a major failure, we’ll help with boiler quoting and delivery service that can get a new boiler installed and working as quickly as the next day.

In a Rush? Here’s a Summary of Boiler Breakdown Causes

If you don’t have time to read the entire guide, you can use the links below to jump right to the boiler problem you’re experiencing.

  1. The boiler is not on
  2. There’s no gas supply
  3. Low boiler pressure
  4. Thermostat is set too low
  5. Pilot light is out
  6. Frozen condensate pipe

Boiler Not Working — Worst Case Scenario

The chances are that your boiler stopped working because of a relatively minor issue. But before we start to detail a few fixes you can try, here’s what you can do if your boiler really is beyond repair.

Boilers do have a lifespan, and many people don’t know that their boiler is dying until it’s dead. This creates a big problem, as a boiler’s sudden demise means an abrupt end to hot water and central heating. This makes life difficult for everyone, especially elderly people and children. You’ll have to replace a broken boiler as soon as possible — unless you have comprehensive boiler care coverage that includes replacement of irreparable boilers.

So, what are your options?

You can try calling a local plumber to install a new boiler. You might get lucky and find one with the time to do the job. But, with the number of plumbers in decline, they are getting busier, so finding a plumber to come and repair a boiler ASAP is a thankless task.

It is possible to buy a boiler online, but in no circumstances should you try and install it yourself. Boilers run off gas or LPG, and so only Gas Safe heating engineers can install them.

So, if your boiler stopped working suddenly, your best path to a prompt replacement is to get an online boiler installation quote from Heatable.

How Heatable Can Install Your New Boiler Next Day

Heatable are an online boiler installation company. The founders felt there was a market for a fast online boiler quotes and installation, so they started an online installation service with minimal overheads and next-day install options. Here’s a quote we got from them for a brand-new Worcester Bosch Greenstar 4000 combi boiler — you can get your own by filling in their quick, anonymous questsionnaire.

Worcester Bosch Greenstar 4000

Why Is My Boiler Not Working?

In the troubleshooting guide below, we will detail some of the most common possible reasons a boiler stopped working and suggest potential fixes. So, if your boiler doesn’t work, ask yourself the following:

1. Is the boiler switched on?

It might sound like a stupid question, but it’s amazing how often plumbers are called out to fix a boiler that’s just not switched on.

Most boilers have a mains power source, and if this has been switched off, accidentally or on purpose, the boiler will stop working.

Power cuts can be another issue. A power cut can trip the fuses in your house or simply switch your boiler off, leaving it off until you manually switch it back on.

The Fix:

Check that your boiler is switched on, the main power source is connected, and none of your fuses have tripped. Also, check the setting on your boiler timer — an incorrect setting may also stop your boiler from working.

2. Has your gas supply been interrupted?

If your gas boiler is connected to the mains gas supply, it’s dependent on this gas connection to work. If there is a problem with the mains gas supply, or insufficient gas pressure, your boiler will stop working.

Obviously, you should not mess with mains gas yourself unless you are a qualified Gas Safe engineer.

However, there are some simple ways you can find out if there’s an issue with the gas supply.

The Fix:

Check other gas appliances in the house to see if they are still working. These could include a gas hob or a gas fire. Alternatively, check your gas supplier’s website — they should detail any service issues there.

You could also contact their customer support team and ask why there’s no gas supply. For example, a common reason your gas supply is off is falling behind on your payments.

If you receive gas bills and pay on time, your gas provider should contact you about any payment issues and offer a variety of support services if you’re struggling to keep up with payments. Cutting off supplies is always a last resort for them. So, call your gas supplier and ask them to reconcile your gas meter readings with the bills you’ve paid to see if there’s been an error.

If your gas provider is not helpful, you can always talk to services like Citizens Advice for support with payment issues.

Having your supply cut is a far more common problem for those who use prepayment meters. If you use one of these, check you have enough credit on your meter and if not add some. This should get your gas supply back fast.

Either way, if gas supply is the problem, you’ll have to wait for your gas provider to resolve the issue; then, your boiler should start to work again.

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3. Is your boiler low on pressure?

In most scenarios, low boiler pressure points to a leak somewhere in the system. If your boiler pressure gauge reads below 1 bar, you should be on the lookout for a leak in the boiler or the central heating system. Unfortunately, filling up the system is only a temporary solution for boiler issues with low pressure — as long as the leak persists, your boiler will continue to lose pressure, and may even stop working if it drops too much.

The Fix:

If your boiler doesn’t work and you’ve found that the water pressure is too low, you should look for obvious signs of a boiler leak and attempt to fix it. Once you’ve fixed the leak, you can top up the system via the filling loop and restart the boiler — the pressure issue should be gone now, and the boiler should operate without any problems. If the leak persists, however, you should call a Gas Safe engineer to investigate.

If your boiler pressure is too high, the boiler may also stop working. You can read more about this problem in our guide here.

4. Did you set your thermostat high enough?

If your heating hasn’t come on, it could be that your thermostat isn’t set high enough and your boiler isn’t getting the call for heat. It’s not a problem with your boiler, and the fix is simple — raise the temperature setting and see what happens.

The Fix:

Simply switch your thermostat to a higher temperature setting and see if your boiler fires up.

5. Has your pilot light gone out?

All boilers contain a pilot light, which is a small internal flame that allows the boiler to ignite. If your boiler stopped working, or you’re stuck with a boiler not firing, the pilot light could be the culprit.

Sometimes, the pilot light can go out accidentally. Innocuous things like a strong draft can be enough, but once it’s out, your boiler will not work until you relight it.

Checking whether the pilot light is on is simple — it should be visible through a little window. Reigniting it is usually as straightforward as flicking a switch — check your boiler manual to see where it is located. If the pilot light still won’t light, unfortunately, you will need to call in the assistance of a Gas Safe registered engineer. There may be an issue with the gas valve that has cut gas supply to the pilot light.

The Fix:

Reignite your pilot light by using the reignite button. If this doesn’t work, you will need to call a heating engineer.

6. Do you have a frozen condensate pipe?

If the weather outside is wintery, this can cause the water in your boiler’s condensate pipe to freeze.

This pipe usually connects your boiler to the nearest exterior wall and thus expels the condensate liquid.

So, if you’ve got a frozen condensate pipe, this excess water has nowhere to go. Your boiler will quickly detect this and stop working.

The Fix:

Luckily, this problem is easy to resolve. All you have to do is pour some warm water over the exposed end of your condensate pipe, and doing so should quickly melt any frozen liquid inside the pipe.  Next, reset the unit. Now, your boiler lockout should be cleared and the appliance should work without further interruptions.

Boiler Still Not Working? Consider a Replacement

If your old boiler breaks down often and is out of warranty, it may be time to consider purchasing a replacement boiler. The last thing you want to do is sink 100s of pounds into boiler repairs, only for the breakdowns to continue as the boiler ages, until, one wintry day, it gives up the ghost on you completely.

To get an idea of what replacement quotes might look like, we suggest you try Heatable. They’re a reputable installation company with great connections with the best boiler manufacturers on the market (including top system and combi boiler models from Worcester Bosch and Viessmann). You can get a fixed price boiler quote from them in 90 seconds, on your screen, by filling in an anonymous form


If your boiler has stopped working, it doesn’t mean the end of the world. Often the problem is very simple, and you can quickly resolve it yourself. Of course, if the issue involves the internal components of a gas boiler, you should always contact a Gas Safe heating engineer for assistance.

Did your boiler stop working for reasons not mentioned here? Or, do you have any other questions? Please leave us a comment below with the error codes you’re seeing and we’ll get back to you as soon as possible.

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