Why Does My Boiler Keep Turning Off?

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Last updated: October 26, 2023

If your boiler keeps turning off, you are undoubtedly feeling rather frustrated. When boilers start malfunctioning, we truly realise how much we rely on them, especially during those colder winter months when we need hot water on demand and an effective central heating system that can effectively heat all of our radiators with ease.

There are several reasons why your boiler might be switching off, and it is essential to get to the route of the problem. However, this doesn’t mean that you should not consult professionals if there is a fault. Whenever you are dealing with boiler problems, it is best to consult gas safe registered engineers. Legally, those working with gas appliances have to be registered as gas safe for security purposes. As such, it is always a good idea to opt for professional support in light of a fault.

These professionals will ensure that your boiler system is safe and fix the problem in no time. While the call out cost might feel expensive, it’s much cheaper than a boiler replacement if the problem persists and much more preferable than an at-home repair job that might become a safety hazard and cause even more significant issues down the line.

Added to this, fixing a broken boiler can often save you money in the long run. When a boiler keeps igniting and shutting off and random intervals, more energy is used, and this can add up at the end of each month. Sometimes fixing the problem at hand is the most innovative energy solution.

Reasons Why Your Boiler Keeps Turning Itself Off

There are several reasons why your boiler might be switching off, and while you will need to consult a registered engineer, it’s worth understanding the various components and possibilities for such an occurance. These may include:


Short-cycling is often a problem with larger boilers. When this happens, the system shuts down once it has satisfied the heating demands of the building. Having an oversized boiler means that your unit is too big for the basic demands of your home. The boiler will thus keep firing up and switching off so as not to overheat. These boilers are often older models since engineers in the past would usually install larger devices into homes. However, in modern times, smaller and more compact units can do the job just fine.

If your boiler is much larger than you need, you’ll end up spending a great deal on energy bills. It might be worth chatting to a technician about the price of changing your system to a more energy-efficient solution.

Valve issue

Valve issues, such as trapped air in the system, can also cause problems to your boiler, and this might result in it switching off. The pressure release valves, known as the PRV, is a safety feature that is specifically installed to prevent the build-up of excess pressure. When the pressure is too high and reaches dangerous levels, it automatically opens and releases enough pressure until the pressure levels are safe again. If this function is broken and unable to regulate the pressure, your boiler might switch off as a safety mechanism.

These valves might also leak, and this too can cause problems with the heating system. If you notice a problem with the PRV, a gas safe technician will have to install a new one for you.

The boiler could also be switching off because of trapped air in the system. If this is the case, you might be able to bleed your radiators. A clue here will be that parts of your radiators are cold, even when the central heating is turned up. To bleed them, turn off the heating and open the top valve to release air. Once the air has escaped, the hissing sound will stop, and you can close it and turn the boiler on again. If the radiators feel hotter and your boiler remains on, it’s worked!

Low water pressure

Low water pressure can cause many problems within a boiler system and might cause it to switch off at random moments or malfunction entirely. Low water pressure is reflected on the pressure gauge and can be caused by a few factors, including a central heating leak or a leak in the pressure relief valve. However, it can also be caused by a few other issues such as airlocks, corroded pipes, or a faulty expansion vessel. Since so many things can cause this to occur, getting a technician to find the problem and fix it fast is best.

Heat exchanger

The heat exchanger consists of a specialised coil pipe. As its name suggests, it exchanges heat between different substances (such as water and gas) without the two ever mixing together. If your heat exchanger is broken, however, this can cause many problems and could, in fact, be dangerous. If the heat exchanger is broken, it could cause your boiler to randomly switch off, and it will need to be replaced by a professional technician as soon as possible.

Thermostat problems

When the thermostat in your boiler is broken, it becomes impossible for the boiler to detect the temperature of the water. In response, it will turn off the system. This is actually to protect the system because, without the temperature reading, it assumes that the water has already heated up. It then switches off to prevent any overheating, which could ultimately cause bigger problems.

In this instance, you will probably need to replace the thermostat completely. Happily, in many cases, this might save you in terms of energy costs.

Lack of water flow

A lack of water flow in your boiler can be caused by numerous issues, such as trapped air, low water pressure, or broken components. If the water is not flowing effectively or at all, it’s time to get an engineer in to determine the cause of the problem. This is often due to a faulty pump that cannot effectively circulate the hot water or a closed valve. The technician will identify the issue and replace any faulty parts if needed.

Frozen Condensate Pipes

Condensate pipes are necessary to drain any excess water; however, since they are often located outside of the home, there is the possibility that they might freeze. While you can thaw it with some warm water, it might be a good idea to consult an engineer about insulating the pipes to stop this from occurring in future. This ultimately keeps the pipes warm and prevents any freezing. This is particularly useful if you live in very cold conditions.

Faulty pump

Faulty pumps can cause several problems and might occur for a few reasons; this might include incorrect installation, low pressure, or a blown seal. Sometimes the pump, over time, can also work itself loose. Signs that your pump is faulty include your boiler making a strange knocking noise, no sound, and an inability for the boiler to start.


If your boiler has been switching off, it is certainly time to get a gas safe engineer in. They will quickly identify the problem and get your central heating system up and running in no time. While most of these issues can be picked up during your annual boiler service, problems can sometimes arise. It is also worth double-checking that there is not an issue with the fuel delivery to your boiler. To check this out, simply contact your gas supplier.

By getting it fixed by a certified professional, you can once again enjoy the reliability and the perfect temperature all year long.

If you have any questions or concerns, always consult a gas safe professional!

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