If you want to diagnose the problem, the first port of call should be your boiler manual. It is a knowledge resource that explains error codes and lets you know if you can fix the problem yourself.
If you can’t find your manual, most manufacturers offer an online copy for download on their websites.
Read on to find out the most common faults on your boiler and how much you should expect for common repairs.
If your boiler is beyond repair and you need a new one, use ours Boiler ratings find a reliable replacement
Frequent boiler faults
Most serious boiler faults are difficult for a layperson to diagnose, and unless you are an experienced heating professional, you should never do repairs that involve removing the boiler casing. This is dangerous and will void any warranty you may have on the boiler.
However, two of the three most common boiler failures can be fixed by a skilled home improvement and do not always require the attention of an expensive heating professional.
Frozen boiler condensate pipe
During a cold snap, it is remarkably common for a frozen condensate pipe (a condensate pipe is a feature of condensing boilers) to shut down your boiler. Technically it is not a fault in the boiler, but if the condensate line freezes, the boiler switches itself off for safety reasons.
Before billing for a costly call from a technician, always make sure that the condensate line is not the problem. Always make sure that your condensate is properly insulated with foam as shown in the picture above, as this is to prevent it from freezing in the first place.
Find out in our instructions on how to defrost the pipe safely How to thaw a frozen boiler condensate tube
The boiler loses pressure
If your boiler loses pressure it could be one of several things. Most often, however, it’s either a leak, you’ve recently vented your radiators and the system has lost pressure, or your heater has been off for a long time and has lost pressure.
You can re-pressurize your system yourself by opening the filling circuit taps on your boiler until you have reached the desired pressure (usually around 1 bar). When this is done, be sure to close both taps and your boiler should start operating again.
If your boiler is constantly losing pressure, you should have it checked by a trained technician to permanently fix the problem.
If your radiators heat unevenly, they may need to be evened out. Read our How to balance your radiators Instructions to find out how to reduce your heating bills
Water leaks from the boiler
This is usually the result of old and corroded washers. You need a trained heating specialist to open the boiler and replace it for you.
When it’s time for a new kettle, check out ours best brands for gas and oil boilers Guide to Finding the Most Reliable Brand
Boiler repairs cost parts
Although the three errors mentioned above are relatively common, there are many specific and technical errors that a heating professional can help you with your boiler.
In 2021 we asked 153 Which? Trusted trader heating installer how much they would charge for parts and labor to fix the 10 most common boiler failures. Make sure you compare all the quotes you get for repairing your boiler against the prices above and make sure you don’t get ripped off.
The table below tells you more about the most common boiler parts that fail. Just logged in Which? Members can unlock the table and reveal what these parts are affecting and how much it usually costs to replace them. If you are not a member, Sign up now.
If you need a new boiler, you will find our expert guide at buy the best boiler helps you get the best installation
What does a boiler service cost?
To avoid future problems with your boiler, it is important to emphasize the importance of annual maintenance of your system. Annual boiler service is the best way to keep it in good condition, diagnose problems early, and limit costly repairs.
If your boiler is not serviced annually, the guarantee will in most cases be void.
In our 2021 survey among 153 which? Trusted dealers, average price for a service was £ 86 and definitely worth it to keep you safe and warm during the colder months.
Have your kettle a. wait Which? Trustworthy dealer. All which? Trusted traders have been screened by a trade standards officer and go through our own rigorous screening processes.
Make sure you are getting the best boiler service by reading our guide get the best boiler service
Dangerous boiler faults
According to the NHS, around 60 people die of carbon monoxide each year in England and Wales.
CO is a colorless, odorless gas that is produced by the incomplete combustion of carbon-based fuels, including gas. CO prevents the blood from carrying oxygen around the body and can kill quickly.
Symptoms include headache, shortness of breath, nausea, dizziness, loss of consciousness, light-headedness, vomiting, chest pain, stomach pain, or blurred vision.
The best way to protest the dangers of carbon monoxide is to buy one Best buy carbon monoxide detector which warns you when a dangerous leak occurs.
Annual service is also essential to ensure that your boiler remains safe.
Owners of old-fashioned, non-ventilated boilers and systems with hidden smoke outlets are particularly at risk from the dangers of carbon monoxide.
What to do if a carbon monoxide alarm goes off – Follow our six point plan to protect yourself
Do you need a heating specialist to repair your boiler?
If after reading this guide you decide that you need a heating professional to diagnose and fix your boiler problem, make sure that you: a Which? Trustworthy dealer. You can also use our Trusted Trader search tool below to find a local trader near you. You don’t have to be what Member to use Which one? Trustworthy traders.
