Worcester boiler not firing up

Why is My Worcester Boiler Not Firing Up? Common Causes

Last updated on June 8th, 2024

Everyone will experience their boiler not firing up at some point, which will probably ruin your day, especially on a cold winter’s night.

I have been fixing and servicing boilers full-time for over a decade.

In this post, I’ll show you some of the many Worcester boiler problems I come across based on my good and bad experiences when I get called to a boiler that won’t fire up.

Common Reasons for Not Firing Up

There are some very easy fixes for a Worcester boiler not working.

Worcester boiler problems

Here are some things you can troubleshoot and check yourself:

  • No power supply
  • No gas supply
  • Low boiler pressure
  • Thermostat problems
  • Frozen boiler condensate pipe

No Power Supply

When you have no lights on the boiler, there is a good chance you don’t have any electricity to the boiler.

Here are some things to check:

  1. The fuse in the switched spur next to the boiler (should be 3 amp)
  2. The circuit hasn’t tripped at the consumer unit (main fuse board for the house)
  3. The fuse in the boiler (usually 2 amp)
  4. You have money on a pre-payment electric meter

No Gas Supply

Having your boiler go to lockout when it tries to fire up could mean you don’t have any gas getting to the boiler.

Gas meter ecv turned off
Gas meter ECV turned off

Here are some possibilities:

  • Gas is turned off at the gas meter emergency control valve (ECV)
  • Gas credit has run out on a pre-payment gas meter

Low Pressure

Low Worcester boiler pressure is a very common reason for a boiler not firing up. You will need to repressurise the boiler to fix this problem.

Worcester boiler pressure low

Having low pressure is an easy fix but if your boiler pressure keeps dropping too low, that means you have a problem that needs to be found and fixed.

Thermostat Problems

A thermostat problem could be the reason your boiler is not working.

Thermostat Problem
Room thermostat

Here are some things you can check:

  • The thermostat temperature is turned up
  • The batteries are good (on wireless thermostats)
  • Faulty thermostat

Frozen Boiler Condensate Pipe

A frozen condensate pipe will probably be the reason for your boiler not working if it’s below freezing outside.

When a boiler condensate pipe freezes, the boiler will go to lockout until it has been defrosted.

frozen condensate pipe

A Worcester boiler frozen condensate pipe needs hot water poured over it to defrost it before the boiler will start working again.

Faulty Parts?

No Hot Water

Having no hot water could be caused by many things:

Combi Boiler

A combi boiler not firing up for hot water could be for one of these reasons:

  • The diverter valve is stuck or damaged
  • The temperature sensor is broken
  • The flow/micro switch is broken
  • The plate heat exchanger is blocked
Worcester plate heat exchanger
Worcester plate heat exchanger

Heat Only or System Boiler

  • A 2 or 3-port valve is stuck or broken
  • The hot water cylinder thermostat is turned down or faulty
  • The programmer is not working properly

No Central Heating

When the central heating is not working but the hot water is, there could be many different reasons for this.

Here are some of those reasons:

Combi Boiler

  • The diverter valve is stuck or damaged
  • The room thermostat is turned down, broken, or needs the batteries replaced
  • The temperature sensor is faulty

Heat Only or System Boiler

  • 2 or 3-port valve is stuck or broken
  • The room thermostat is turned down, broken, or needs the batteries replaced
  • The programmer is not working properly
Programmer problem

Pilot Light Not Firing Up

A pilot light is a constant small flame that is used to light the burner when the heating or hot water is called for.

Modern boilers don’t use pilot lights anymore, they use spark electrodes which fire the boiler up using electric sparks every time it’s needed.

If you have an old boiler with a pilot light and it’s not firing up, here are some potential reasons:

  1. Gas supply problem (blockage or no gas for example)
  2. Gas valve problem

If the pilot light is on but not firing up the boiler, this will usually indicate a faulty gas valve problem.

Boiler Clicking But Not Igniting

A boiler clicking but not igniting means you are getting electricity, and your external controls are working, so it has to be something further on in the firing-up process that’s causing the problem.

Here are some potential reasons why it’s clicking but not igniting:

  1. A gas supply problem
  2. The spark electrode is faulty
boiler service electrodes
Worcester spark electrodes

Worcester Boiler Problems

Here are some other common Worcester boiler problems you can learn about:


When your boiler is not working there are quite a few simple things you can check yourself and rule out without having to open the boiler up.

When it comes to needing boiler parts to be repaired or replaced, you should call a registered gas engineer.

Regular boiler servicing includes checking boiler parts and should be done every year to help prevent boiler breakdowns.

Feel free to ask me any questions in the comment section below and I’ll try my best to help.

Please share this post if you find it helpful.


  • Steven Reid

    I am a full-time plumber and Gas Safe registered engineer. I incorporated Housewarm Ltd. in 2011 to provide heating and plumbing services to homes in Newcastle upon Tyne, England. I now blog about what I've learned over the years to help DIYers and plumbers.

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1 thought on “Why is My Worcester Boiler Not Firing Up? Common Causes”

  1. Keith Desmond Hancock

    Hi I recently had my gas meter moved the property is empty so combi was switched off now it won’t fire up have changed pcb board pump and fan run any ideas

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