Common boiler faults

Common Boiler Faults

Discover the most common boiler faults

Modern boilers are very reliable. However they are not indestructible and things do go wrong, with most boilers breaking down during the colder months of the year, adding to the misery and inconvenience of boiler repairs.

The heating industry generally see a big spike in boiler repair services in September and October when most boilers are switched back on after being off over the warmer summer months. However, we also see a big demand whenever the weather hits freezing temperatures, and boilers are used to their maximum performance.

Gas Boiler

Common boiler faults

It’s not always possible to determine exactly what is causing the problem without physically examining the boiler. However, knowing what the symptoms are would help identify possible causes. Also, if you have a modern boiler then it’s likely that you’ll see an error message or error code on the boiler’s display. Make a note of this because it will help a boiler repair engineer with the diagnosis.

The most common boiler faults cause the following :

  • No hot water or heating
  • Pressure issues
  • Boiler switching off
  • Strange or loud noises
  • Leaky boilers
  • Pilot lights gone out
  • Freezing
  • Faulty thermostat
  • Radiators not getting hot


What maybe causing these common boiler faults?

Here are some brief explanations of what could be causing the boiler to breakdown.

No heat/hot water: Having no heat or hot water could be caused by a number of reasons such as;  low pressure, airlocks, faulty thermostat, valves, a broken diaphragm or another component.

Pressure issues: We recommend you check the pressure first as a boiler may switch off if the pressure becomes too low (below 1bar). To top up the pressure the valves can be opened either by tap handles, or by using a flat headed screwdriver. Open both valves to allow the cold water into the system (you should be able to hear it). Keep an eye on the pressure gauge until it reaches 1.5bar, then close both valves, one after the other.

Noises: Boilers that are making loud noises could have a build up of limescale, especially if the boiler is exposed to hard water. Limescale causes a boiler to work harder as sludge builds up in the heat exchanger, the water then overheats causing it to boil or steam, known as the kettling effect. A product which helps to prevent the build up of limescale is a Magnacleanclick here for more info (or contact us on 01628 533 550). If the noise coming from the boiler is a banging noise then this is most likely to be an issue with the pump.

Leaks: A leak from the boiler can be another issue and the source of the leak will help determine the cause of the breakdown. The most common cause of a leak are faulty components such as the pressure valve, pump seal, pipes or the tank.

Pilot light: When the pilot light goes out, causes could be a draught, broken thermocouple or possibly a deposit build up. It’s worth checking the issue isn’t with the main gas supply; test another gas appliance to see if it works.

Freezing: We mentioned that most boiler repairs happen in the colder months when most people are using their boilers more frequently. A fault can arise with a condensing boiler if the condensate pipe freezes. The condensate pipe runs from the boiler to outside the house so inevitably is more exposed to freezing conditions. If you have identified the pipe then you can take precautionary measures to ensure it doesn’t freeze, however it’s advisable to seek professional advice before doing anything yourself. We also recommend that if you are considering having a condense boiler installed, then the installation is undertaken by an experienced company (like us) who factor these things in before installing.

Thermostat controls: The thermostat can sometimes be the cause too, but not because it is faulty but merely because it has been incorrectly set up. We always try to diagnose over the phone before sending out an engineer, as in many cases the thermostat hasn’t been set up correctly or simply needs resetting. Doing some checks first may save you having to pay unnecessary repair bills.

Radiators: If you discover that your radiators are not getting hot or parts of the radiators are not heating up, it could be caused by a build up of sludge or air. Try bleeding and/or balancing the radiators and then see if that has fixed the problem. If your central heating system is quite old then it may require a power flush, or even a new boiler system. We recommend a magnaclean to help prevent the build up of sludge in the central heating system.

common boiler faults

Preventing boiler problems

Boiler manufacturers and the Gas Safety authority highly recommended that you have an annual boiler service for safety reasons and to help prevent nasty boiler repair bills. If you still have a boiler warranty, then make sure you check the small print, as it may be a requirement to have an annual service to validate the warranty.

It is also recommended that a boiler isn’t switched off for long periods of time (weeks/months). Having a smart thermostat will help provide the ultimate control over the heating and will also allow users to control the boiler remotely.

How much does a boiler repair cost?

For a gas boiler repair we charge £90+VAT for one hour and generous discounts for more work in excess of one hour. Within this time we aim to diagnose the issue and repair it. If parts are required, or the work is going to take longer than one hour, then our engineers will explain what is wrong and provide a quotation, always seeking approval before proceeding.

Our costs for commercial boiler repairs, biomass boiler repairs or oil boiler repairs, vary due to the requirement of specialist engineers. Check out our pricing and price promise here.

Can it be fixed on the day?

In most cases boiler repairs can be completed on the same day. It is certainly our objective to get your heating/hot water back to normal as quickly as possible.

If parts are required, then our engineers carry van stock of some common parts and also have access to a network of plumbing merchants. Should we have to return on another day due to parts not being available, then we have a sophisticated system in place to order the parts and return ASAP. If required we can provide electric heaters so that the customer has some form of heating.

In some cases the boiler may just need a good boiler service to sort out the problem!

Can you repair a gas boiler yourself?

No. You must never attempt to do anything that involves disturbing the gas carrying components unless you are a registered gas safe engineer.

The definition of gas ‘work’ is quite wide ranging. You can perform tasks set out in the user instructions. But if the problem is with the actual boiler then you will need a gas safe registered engineer to repair the boiler. Attempting to fix the boiler yourself is dangerous and could lead to more serious problems such as carbon monoxide poisoning or an explosion.

There are things you may be able to do if the issue is external to the boiler, such as replacing the thermostat control or topping up the pressure. However, changing or altering parts within the combustion chamber is a NO! Click here to see a fact sheet from Gas Safe boiler repairs

Beware of illegal gas fitters

It is shocking that recent studies from Gas Safe have raised concerns over the amount of illegal fitters and the amount of home owners that didn’t even check for a local Gas Safe engineer.

Gas Safe have issued a new press release around illegal gas fitters. Gas Safe recently surveyed 2,000 home owners and of those who have had gas work carried out in the last year, more than 1 in 4 (28%) didn’t even think about checking that the engineer was legal and on the Gas Safe Register. 1 in 6 even went on to admit that they would knowingly employ an illegal gas fitter if they came recommended. This is a worrying statistic as Gas Safe found from their investigations that 9 in 10 illegal gas jobs are not completed to the required standard, and one in five jobs were so dangerous their investigations officers had to switch the appliance off. Gas Safe are urging consumers to be more diligent when it comes to making sure their gas engineer is registered and qualified to do the work they need.

How to check the Gas Safe register?

Click this link and you can search – However all Gas Safe engineers will carry a Gas Safe card, make sure they produce this before doing any work. Don’t be afraid to ask because it’s your safety at risk if you use an illegal untrained gas engineer. Safety should always come first.

Is my boiler safe?

When did you last have it checked? Boilers are generally very safe and have built in safety features that will switch off the boiler should it detect malfunctions. If you are not sure or feel unsafe, then you can turn the boiler off manually. We recommend you then contact our friendly customer care team on 01628 533 550.

Boiler repair or replacement?

Sometimes boiler repairs may require a part to be replaced, and depending on a number of factors, it is possible this may lead to a further fault within the boiler. The boiler may have several intermittent issues which cannot be discovered until a part is replaced. These situations are rare but can happen. Our engineers are trained and experienced to provide honest advice on the best course of action. A new boiler may be better than trying to fix a problematic old inefficient boiler.

If the boiler is over 10 years old then replacing it could also reduce your energy bills, read more.

Check if you have a boiler warranty

It is worth checking to see if your boiler is under any warranty, as this could save you on the boiler repair costs. A boiler warranty can be anything from 1 year up to 10 years. If you are unsure then you can call the manufacturer directly and they will be able to advise. If your boiler isn’t under warranty then you will need a boiler repair engineer.

What to do if your boiler needs repairs

If you have a faulty boiler or suspect something is wrong then call 01628 533 550 for advice Alternatively you could e-mail customer or book an appointment online.

If possible have the follow information to hand, although this is not essential:

  • Boiler make and model
  • Error code if on the display
  • Description of what the issue is with the boiler

Also, as advised earlier, if the boiler is relatively new then check whether it is covered by a warranty!

Why choose Red Van Plumbers?

  • Successfully completed thousands of boiler repairs
  • Approved boiler engineers for multiple manufacturers
  • Qualified to provide gas boiler repairs, as well as oil, LPG, biomass, domestic, commercial and combi boiler repairs
  • Priority response to those with no hot water or heating
  • Our engineers are experienced, gas safe registered and fully qualified
  • It is our objective to fix the problem same day
  • Transparent pricing and always keep our customers well informed
  • Highly recommended by our customers



If you are suffering from one of these common boiler faults, these please do not hesitate in contacting Heppelthwaite the Red Van Plumbers.

Tel: 01628 533 550 



common boiler faults


Heppelthwaite the Red Van Plumbers Unit 5, Jacksons Industrial Estate Wessex Road, Bourne End Bucks, SL8 5DT
01628 533 550

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