Advice from Paul · Gas Safe #221708

Why is my boiler not working?

In short: A boiler usually stops working because of low pressure, a tripped or locked-out fault, no power or gas, a thermostat problem, or a failed part like the pump or diverter valve, and many of these show a fault code on the display.

Call Paul · 0151 440 2614 Boiler repair in Liverpool
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Boiler internals inspected and repaired by Paul
Boiler internals inspected and repaired by Paul

A boiler that suddenly stops is one of the most stressful things to go wrong in a home, especially in winter. The good news is that the causes usually fall into a handful of common categories, and some are things you can safely check yourself before calling anyone out.

Here is the honest run-through from a Gas Safe engineer with 40 years on the tools. A couple of these you can look at yourself; anything involving gas or opening the boiler up is a job for a registered engineer, not a YouTube video.

Things you can safely check yourself

Before ringing anyone, it is worth a two-minute look at the simple stuff, because sometimes that is all it is.

  1. 01

    Check the pressure gauge

    If the needle is below about 1 bar (usually in the red or near the bottom), low pressure may be stopping the boiler firing. Many boilers can be topped up via the filling loop, if you know how, but if it keeps dropping you have a leak somewhere and need it looked at.

  2. 02

    Check the power and thermostat

    Make sure the boiler has power, the fuse or switch has not tripped, and the thermostat is calling for heat and has working batteries. It sounds obvious, but a flat thermostat battery stops many boilers.

  3. 03

    Check other gas appliances

    If your gas hob will not light either, the issue may be your gas supply or a prepayment meter that has run out, not the boiler itself.

  4. 04

    Note any fault code

    If the display shows a code like F22, F28, L2 or EA, write it down. It tells the engineer a lot before he even sets off.

Common faults that need an engineer

If the simple checks do not sort it, the cause is usually one of a handful of faults: a boiler locked out on a safety fault, a failed pump, a stuck diverter valve, a faulty sensor or PCB, or an ignition problem. These need a Gas Safe registered engineer to diagnose and fix safely.

Resetting a boiler once or twice is fine, but if it keeps locking out, stop. Repeated lockouts mean a real fault the boiler is protecting you from, and hitting reset over and over will not fix it.

Rather just get it sorted?

If your boiler still will not work, ring Paul for a proper diagnosis

You get Paul on the phone, a Gas Safe engineer with 40 years behind him, not a call centre. He will give you a straight answer and a fair fixed price. See boiler repair for how he can help.

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Straight answers

Common questions

Should I keep resetting my boiler?

Once or twice is fine, but if it keeps locking out, stop and call an engineer. Repeated lockouts point to a genuine fault the boiler is protecting you from, and resetting will not fix it.

Is low boiler pressure dangerous?

Low pressure itself is not dangerous, it just stops the boiler working. But if the pressure keeps dropping after you top it up, there is a leak in the system that needs finding and fixing.

What does my boiler fault code mean?

Each make has its own codes. Note down the code and give it to Paul when you ring, after 40 years he can usually tell you roughly what it points to before he even sets off.

More helpful guides

Boiler keeps turning off? Boiler losing pressure?

Honest advice, then a proper fix

Still stuck? Give Paul a bell.

Forty years on the tools, Gas Safe registered, and the fella who quotes it is the fella who does it. No call centre, no pushy sales.

Call Paul · 0151 440 2614 Boiler repair in Liverpool
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