The Ultimate Boiler Fault Finding Resource [40 Detailed Guides Included]

Over the past few years, we’ve posted hundreds of heating articles, many of which relate to boiler fault finding and central heating problems. I’ve spent a while trying to organise 40 of them into a straightforward boiler fault finder resource.

We’ll be using this page as our central heating and boiler fault finder guide and adding to it over time. So, feel free to bookmark it and come back to it when you’re stuck.

Before You Use Our Boiler Fault Finder

To begin, we’ve created a generic guide to common boiler problems here. It’s a good starting point whenever your boiler is acting up, especially if you have no idea what’s causing the problem.

Once you’ve used that boiler problem guide to figure out what could be causing the issue, come back to this page and you’ll find the specific guide listed below.

Not all boiler fault-finding missions are going to end positively. When they don’t, we’d suggest checking out Heatable. They’re a reputable online boiler installation company with great connections with boiler manufacturers, who always put customers first. This means Worcester boilers with Heatable are about as cheap as you’ll find them in the United Kingdom. You can fill in their anonymous, 90-second questionnaire to get a range of fixed price boiler quotes.

Boiler Fault Finding Guide

Below, we’ve grouped our resources based on the various boiler problems you may find yourself running into. These apply whether you’re fault-finding system, regular, or combi boilers.

Boiler Parts

If you suspect your boiler fault finding relates to a specific part, click on the relevant links below:

• Heat Exchanger
• Boiler Timer
• Heating Pump
• Diverter Valve
• PCB
• Air Pressure Switch

We’d always suggest getting repair quotes. But if your boiler is out of warranty and repairs are likely to cost £500+, it might be time to consider a replacement. You can get on-screen prices (no personal details needed) within 2 minutes using this clickable form from Heatable.

Noisy Boilers & Central Heating

Below, we’ve listed boiler fault finding guides that relate to noisy central heating systems:

• Noisy Heating Pumps
• Noisy Boilers
• Noisy Radiators
• Noisy Heating Pipes

Boiler Fault Finder Posts for Pressure & Leaks

Here are some fault finding resources for leaks and pressure:

• What Pressure Should A Boiler Be?
• Boiler Is Losing Pressure
• Boiler Leaking (From The Bottom Of The Casing)
• Boiler Is Leaking (General)

Boiler Lockouts

Causes, fixes, and boiler fault-finder guides for boiler lockouts:

• Causes Of Boiler Lockouts
• How To Reset A Boiler
• Central Heating Sludge Build Up [Causes & Fixes]
• No Power To A Boiler
• Boiler Is Overheating
• No Hot Water
• Boiler Return Pipe Cold
• Boiler Won’t Ignite

Brand & Model-Specific Boiler Fault Finder Guides

Not sure what part is causing the issue, but know the boiler brand or model?

Click on the relevant link below to start fault-finding your boiler brand:

• Ariston
• Biasi
• Alpha
• Viessmann
• Potterton
• Worcester (click here for Worcester Bosch RI)
• Glow-Worm
• Ideal
• Vokera (and specifically, red lights)
• Halstead
• Ferroli
• Baxi
• Ravenheat
• Vaillant (And, A Specific Article On The F75 Fault)

Boiler Fault Finder FAQs

Below, we’ll answer some of the most common fault finding questions.

How do you fault-find on a boiler?

As a user, you have 3 basic ways to find faults on a boiler — check the fault codes, assess visible defects, or contact a Gas Safe heating engineer for help.

Looking up what your fault codes mean is a great way to start; although some error codes may be too technical or inconclusive, at least you’ll get a general idea of what’s malfunctioning. This way, you can corroborate an observable fault (such as a low pressure reading or boiler noise), or at least tell the Gas Safe engineer what you think the problem is before they show up at your home.

Visually inspecting the boiler and the central heating system can also help you identify boiler faults. That said, you should never attempt taking the boiler apart, or assessing the internal components for damage. If you boiler is mafunctioning, the best thing to do is call a Gas Safe engineer for assistance.

What causes a boiler to stop working?

You boiler can stop working for various reasons, including faulty internal components, unsafe operating conditions, a loss of power, or problems with the gas supply.

The boiler may lock out as a precaution if it cannot operate safely; this may happen if there’s a fault with the boiler’s fan, if the condensate pipe is frozen, or if there are circulation issues that are causing the boiler to overheat. Likewise, it can stop working due to damaged boiler components, such as the pilot light, PCB, heat exchanger, or electrodes. Finally, there may simply be no power to the boiler due to a power cut or a blown fuse; or, you may experience trouble with the gas supply.

In either scenario, the best way to get your boiler working again is to consult with a Gas Safe registered engineer. Heating engineers can diagnose the problem quickly, and perform the necessary safety checks to make sure the boiler can operate safely.

Why is my boiler not heating the house?

If your combi boiler is not heating the house, it may be because the boiler has locked out, it’s lacking power or gas supply, or the heat isn’t being channeled to the central heating system.

In the event that your boiler is producing no heat at all, you should try to establish if it’s locked out due to a safety concern or a malfunctioning internal part. You should also make sure that the boiler is getting its power and gas supply.

However, if you’ve got hot water in your taps but the radiators won’t warm up, the boiler is probably working fine and the diverter valve is the culprit. To find and fix the root cause quickly, consult with a Gas Safe engineer.

Why does my boiler fire up randomly?

If your boiler is firing up when you don’t expect it too, the boiler and thermostat are probably not communicating with each other properly. Typically, a boiler will fire up when the temperature setting on the thermostat is higher than the actual temperature. If the thermostat is faulty, or there’s some problem with the boiler’s PCB, the boiler may be getting incorrect signals and firing up when it shouldn’t be.

What’s Next?

Thanks for reading our fault finding guide. If you’re struggling to fix a problem with your gas boiler, you can get a qualified engineer to come and give you a hand.

Is there anything we missed? If you couldn’t find your boiler problem listed above, leave us a comment below and we’ll get back to you as soon as possible.

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