Potterton Boiler Not Firing Up

Why is My Potterton Boiler Not Firing Up? Troubleshooting

Last updated on June 8th, 2024

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

I have been fitting and fixing boilers full-time for over a decade and have brought many Potterton boilers back to life.

Common Reasons for a Potterton Boiler Not Firing Up

There are some very easy fixes for a boiler not firing up.

Potterton boiler fault

Here is some boiler troubleshooting you can check yourself:

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

No Power Supply

When your boiler is not working and 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 a Potterton 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. This will cause the Potterton E133 fault code on some boilers.

Here are some possibilities:

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

Low Boiler Pressure

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

Low pressure on a combi boiler
Low boiler pressure

Having your boiler pressure low is an easy fix but if your pressure is dropping too low constantly, 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.

Here are some things you can check:

  1. The thermostat temperature is turned up
  2. The batteries are good (on wireless thermostats)
  3. Faulty thermostat

Frozen Boiler Condensate Pipe

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

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

Which Parts Cause a Boiler to Stop Working?

Heating But No Hot Water

Having no hot water from the boiler but the heating is working could be caused by many things.

Potterton boiler fault

Combi Boiler

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

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

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

Hot Water But No 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

Pilot Light Not Firing Up

A boiler 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

Potterton Boiler Guides


When your Potterton 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 fixed or replaced you should call a gas engineer to get it checked out properly and fixed.

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.

    View all posts
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2 thoughts on “Why is My Potterton Boiler Not Firing Up? Troubleshooting”

  1. Hi,

    I have a potterton that fires and heats. But once temp is reach the boiler shuts off as normal. Then when thermostat clicks to turn heat back on it doesn’t fire. The only way to get it to fire is to turn off the fuse switch next to the boiler 2 or 3 times quickly for it to fire up… any ideas what could be the cause? Happens almost every time and it only fires again when I turn the fuse switch on and off quickly 2 or 3 times. If I do it slowly it doesn’t fire.

    1. Steven Reid

      Hi Ben, sounds like you’ve got an electric supply problem if you have to keep doing that, or possibly a thermostat problem.

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