My Boiler is Overheating

If your boiler overheats it is a serious problem that can, in the worst cases, put your appliance in danger of exploding. Most modern boilers have a variety of safety features fitted to prevent such a catastrophe, but overheating can still cause you an array of problems, especially if you don’t have boiler cover.

But how do you even know that your boiler is overheating and what can you do to fix it? Well, to help you out we’ve compiled this handy list of common overheating problems as well as anything you can do to alleviate them.


Why is my boiler overheating?

Faulty safety feature

One of the most common reasons for a boiler to overheat is a failure in a safety feature on the appliance that is allowing the device to reach temperatures that it shouldn’t.

Most modern boilers are designed to cut out when they detect a temperature that is dangerous or damaging to the appliance. If this fails, you may find your boiler reaching temperatures higher than it is designed to operate at. More often than not, a failure to the safety features will see the boiler shut down altogether and you may see an error code in its display.

Limescale build-up within the boiler’s heat exchanger

The heat exchanger within a boiler burns gas to heat cold water that is then circulated around your radiators via a pump. Because water from your mains supply is constantly passing over the heat exchanger, limescale can build up over time and begin to restrict the flow of water. As the water moves slower it gets hotter than it would do if it flowed freely. Another side effect of this problem is that your boiler will become more expensive to run.

If you think that limescale build up is the reason your boiler is overheating, you will need to call an engineer who will flush the system with a limescale remover. This will clean the heat exchanger and bring your boiler back up to maximum efficiency.


Blockage in the boiler or pipes

As well as limescale, you can also get a build-up of sludge and other debris within your central heating system. Again, these blockages will prevent the flow of hot water around your system and lead to it becoming too hot. A sure-fire sign of blockages is a strange sound or knocking from your boiler or pipework and your radiators may fail to become warm.

If a blockage is the reason that your boiler is overheating, you will need an engineer who will perform something called a poweflush. This will cleanse your entire central heating system of rust, limescale, and other debris.

Faulty pump

The pump in your boiler is responsible for circulating hot water around your central heating system. If the pump begins to fail, the water will be stuck in the boiler and will keep heating up until either the safety cut-out kicks in or your boiler completely fails. Pumps are incredibly robust considering how much work they perform and generally last for about 15 years. Unfortunately, the only fix for a faulty pump is to get a qualified gas engineer to take apart your boiler and replace it.

An issue with the thermistor

The thermistor within your boiler monitors how hot the water is so that it can be increased or decreased depending on your needs. If the thermistor develops a fault, then the temperature of the water could become too cold, failing to heat the radiators, or too hot, leading to the boiler overheating.

A thermistor is an integral part of the boiler and the only way to fix it is to get a qualified engineer out to repair the boiler.

What are the risks of an overheating boiler?

Due to the safety features and technology within modern boilers, the risks of serious damage are slim and most boilers can function fine even when pressure and water temperatures are above-recommended levels.

Prolonged overheating or temperatures that are incredibly high can cause a vast array of problems, including:

  • Overheating of components that begin to function poorly or not at all (there are some examples above).
  • Some components may begin to melt, especially if they are made from plastic. This can in turn release smoke and toxic fumes into your home.
  • In the worst-case scenario, the build-up of pressure caused by the superheated water can lead to an explosion.

What about Boiler Cover?

If you have a boiler insurance policy from Prominence Support, then you already know you are covered for any boiler issues. Our comprehensive and cost-effective policies are there for you when you need them. Give us a call today on 03300885768.

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