Boiler Not Working? Common Boiler Problems & How To Fix

Boiler not working? Common boiler issues you can fix

Is your boiler broken? Don’t worry! Whether it’s not turning on, making strange noises, or leaving you with no hot water, we’ve got you covered.

This simple guide explains the most common boiler issues, easy fixes you can try at home, and when to call a Gas Safe registered engineer. Stay warm and comfortable this winter!

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Why Is My Boiler Not Working?

Boiler breakdowns can happen, especially in the colder months when you need heating and hot water most. Here are the top reasons your boiler might stop working in 2025, based on the latest UK heating advice:

1. No Power: Has your boiler got power? Check if it’s switched on at the plug or fuse box.
2. Low Pressure: Boiler pressure should be around 1-1.5 bar. Too low or too high can stop it working.
3. Frozen Pipes: In winter, the condensate pipe can freeze, blocking your boiler.
4. Pilot Light Out: Older boilers need a small flame to work. If it’s out, the boiler won’t heat.
5. Thermostat Issues: A faulty or mis-set thermostat can trick your boiler into shutting off.

Be sure not to attempt to do anything with your gas boiler on the inside or mess with the gas, as this could cause some serious injury.

Only a Gas Safe registered heating engineer can do this.

What you need to check first is if your boiler is not working

Simple Boiler Fixes You Can Try at Home

Before calling an engineer, try these safe, easy steps. Never touch the gas parts inside your boiler – that’s dangerous and only a Gas Safe registered professional can handle it.

1. Check If Your Boiler Is Switched On

It sounds obvious, but many boiler call-outs in the UK are just a switched-off boiler! A power cut or someone accidentally turning it off at the mains could be the culprit.

• What to do: Check the power switch on the boiler and the fuse box. If you have no power to your boiler, look for a tripped fuse or power cut overnight. Turn it back on if needed.

2. Reset Your Boiler

A quick reset can fix glitches after a power cut or minor issue.

• How to do it: Find the reset button (check your boiler manual if unsure) and press it for a few seconds. Wait a minute. If it still doesn’t work, look for an error code on the display (e.g., E133 or F22) and search online for what it means.
• Tip: If your boiler’s over 10 years old, it might be less efficient. Rather than resetting your boiler every 5 minutes, consider a new one – price a new boiler here.

3. Check Your Gas Supply

No gas, no heat! If your gas bill isn’t paid or your pre-pay meter is out of credit, your boiler won’t work.

• What to do: Confirm your gas account is up to date. Call your supplier (e.g., British Gas, EDF, Octopus etc) to check if they’ve cut you off by mistake. If you’re on a prepayment, top up your meter if needed.

4. Fix Low Boiler Pressure

Low pressure is a top reason for boiler breakdowns in 2025. Most UK boilers need 1-1.5 bar to run properly.

How to check: Look at the pressure gauge on your boiler. It’s usually a dial with a green zone. If the needle’s below 1 bar, your boiler pressure is too low.

How to fix:

1. Find the filling loop (a silver pipe under the boiler with 1-2 black taps).
2. Turn the taps to open them (about 45 degrees) until the pressure hits 1-1.5 bar.
3. Close the taps tightly.

• Note: If pressure drops again fast, you might have a leak – call an engineer.

5. Thaw a Frozen Condensate Pipe

In cold UK winters, the condensate pipe (a white plastic pipe running outside) can freeze, stopping your boiler. A frozen condensate pipe is such an easy fix, you just need to wrap up and head outside.

• How to fix: Pour warm (not boiling) water over the frozen section until it thaws. Reset the boiler after.
• Prevention: Insulate the pipe with foam lagging – it’s cheap and easy to buy online or at DIY stores like Screwfix.

6. Check the Pilot Light (Older Boilers)

If your boiler’s old, a blown-out pilot light could be the issue.

• How to check: Look through the small window on the boiler. No flame? It’s out.
• What to do: Follow your manual to relight it safely, or call an engineer if unsure.
• Upgrade tip: Old boilers with pilot lights are inefficient. Modern ones (like the Worcester Bosch Greenstar 4000) don’t need them.

7. Test Your Thermostat

A dodgy thermostat might stop your boiler from kicking in.

Fix: Replace batteries or reset to manual mode. Still broken? Refer to the manual or get help with this. You should clear any settings and then restore them to manual operation. If all else does not work, then you need to refer to the thermostat manual. 

What to do:

Ensure it’s on and has fresh batteries.

Turn the temperature up to 21°C or higher which is above the ideal room temperature, but it will likely make your boiler work if so.

Check the Wi-Fi (for smart thermostats like Hive or Nest) and clear any holiday settings.When to Call a Gas Safe Engineer

Some problems need a professional. Here’s when to stop DIY and get help:

• Leaks: Water under your boiler or pipes? It could damage your home and boiler.
• No Hot Water but Boiler’s On: Likely a broken diverter valve.
• Strange Noises: Banging or whistling could mean a faulty pump or heat exchanger.
• Boiler Won’t Turn On: No power at all might be a dead circuit board (PCB).
• Pressure Keeps Dropping: A leak or broken part needs fixing.

Only Gas Safe registered engineers can legally work on gas boilers in the UK.

Is It Time for a New Boiler?

If your boiler’s over 10-15 years old, repairs might cost more than it’s worth. New boilers in 2025 are super efficient, saving you money on energy bills. Top picks:

• Viessmann Vitodens 050-W: Great value and energy-saving with long warranties
• Worcester Bosch Greenstar 4000: Reliable and quiet.

Get a Free Boiler Quote Today

Boiler Cover Option

Out of warranty? Our comprehensive boiler breakdown and cover plans start at £13.99/month and protect you from big repair bills.

Boiler Still Broken?

If none of these fixes work, don’t risk it. Contact us now as trusted Gas Safe engineer with experience in your boiler brand (e.g., Baxi, Vaillant, Worcester).

Stay warm this winter – act fast and get your boiler sorted.

What about if my boiler is working but you have got no hot water

This is another issue that a lot of people experience. The boiler is turned on yet there is not any hot water or the hot water is working but the central heating is not. When this happens, it indicates that there is a problem with one of the parts in your boiler. In all likelihood, it is going to be the diverter valve that is to blame for this issue.

As you may be able to tell from the name, this is the part that is responsible for diverting water to your hot water outlets, radiators, or both, depending on where you’re demanding water.

So, when this happens, the obvious solution is to get the diverter valve replaced.

There may be cases, though, whereby you need to invest in a new boiler, so it is worth keeping this in mind. 

If you have noticed that your radiators are not getting hot yet your boiler is working, the issue here probably does not lie with your boiler at all.

As time passes, heating systems, i.e. radiators and pipes, will end up being congested with dirty, congealed water and metallic debris. This causes system blockages.

If your radiators are cold at the bottom, this is a clear indicator that you have got an issue with sludge which can you to have hot water working but radiators and central heating does not work at the same time.