Common Causes of Boiler Failure

Boilers need to be maintained and serviced regularly to keep them in good working order. You may find that problems occur at the change of seasons due to the boiler being somewhat inactive during the summer months.

If your boiler fails, it can be an expensive job to replace it. Below we will discuss some of the common causes of boiler failure and the symptoms to spot. Some issues are easy enough for you to fix yourself, but others will require a professional heating engineer.

If you have a particularly old boiler, over ten years old, then there may be no option but to replace it. Your boiler installation and repair company will be able to advise you on this. A well-maintained and regularly serviced boiler can last you for between 10 to 20 years.

Common Causes of Boiler Failure

Common Boiler Problems

No Hot Water or Heat

If your boiler is not producing hot water, there could be a number of factors that are the cause. Broken diaphragms, airlocks, failure of motorised valves, thermostat issues and low water levels could all be to blame. We would recommend calling out a Gas Safe registered engineer to diagnose and fix the problem.


The problem with leaking pipes is that the leak isn’t always in an obvious place as most of your pipework is hidden away. If you discover damp patches when cleaning, a drop in water pressure or your water meter appears to be running higher than it previously was, the chances are, you have a leak. You may be able to find the source and repair it yourself.

However, if the leak is coming from your boiler, you should call out a registered heating engineer as you shouldn’t try to fix this problem yourself. Broken pump valves and seals are the most common causes of leaks in boilers.

Noisy Pipes

If your pipes start making unusual noises such as banging, gurgling or even whistling; there are a few things that could be the cause, including low water pressure.

Trapped air can usually be determined if your radiators are not fully heating up. This may require a simple bleeding of the radiators, which you can do yourself. In some instances, you may need to balance your radiators, which again if you are confident, you can do yourself.

Kettling is a term given to the furring up of pipes and parts due to excessive limescale build up. This can lead to a whistling noise like a kettle boiling. It is advisable to have an engineer check this out and clean the system. If this is left untreated, it can cause pump failure.

Low Boiler Pressure

When it comes to the common causes of boiler failure, low pressure is high on the list. It is very simple to check your boiler pressure, look at the built-in pressure gauge and check that the needle is above 1. If your boiler keeps switching off, it may be due to low pressure.

Low boiler pressure can be caused by a water leak in the system, the pressure valve needs replacing, or you have recently bled radiators. If you are sure there is no leak, you could try re-pressuring the system by following the instructions given in your boiler manual. But if you are unsure, call an engineer for help.

Problems with the Thermostat

If your thermostat has become temperamental or is turning itself on and off, it may be time to invest in a new one. Before rushing out to the hardware store, there are a couple of simple checks you can make to eliminate other potential causes

It’s easy to knock a thermostat, so check that it is in the on position and set to the correct time and temperature.

You may not realise that the temperature set is lower than you require. The boiler will not allow your home to heat higher than the thermostat setting, so try increasing it until the temperature feels good for you.

As with all elements of a heating and water system, the thermostat may have just worn out over time, and it is time to invest in a new one.

Frozen Condensate Pipe

The last of our common causes of boiler failure is the condensate pipe which transports acidic water from the boiler to an outside drain. As this pipe is outside, it may freeze in winter months. Your boiler may display a fault code to alert you to this. If it does freeze, use a hot water bottle, warm water or heat pad to thaw it, do not use boiling water as this can crack the pipe.

Annual Boiler Servicing

A regularly serviced boiler will often prevent many of the common causes of boiler failure from ever occurring. As the saying goes, prevention is better than cure. It is also a lot less costly. We offer a boiler servicing package that will ensure your boiler is cleaned and maintained to a high standard and offer certificates for landlords for proof that the necessary checks have been made.

Ask The Experts

If you are unsure about any issues with your boiler or are worried that the problem is too difficult for you to repair, then get in touch with our team of experts here at First 4 Plumbing who will be happy to advise you.

As well as repairing and servicing boilers, we also carry out boiler installation and offer 0% interest finance deals. For a no-obligation assessment and quote please get in touch.