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Common Reasons For Boiler Breakdown


Common Reasons For Boiler Breakdown

Why Does My Boiler Keep Shutting Off?

There are many reasons why a boiler will shut off automatically. In this article, we discuss the most common problems for boiler shutdowns and briefly explain how you can fix them.

While we recommend calling a gas-safe registered engineer to handle repairs for you, there are some checks and quick-fixes that you can perform yourself.

No Fuel

When gas-fired heaters are in operation you will be able to see a blue flame. If no fuel is coming through the most likely cause is that the gas feed is closed and is restricting the flow of gas to the boiler.

For mechanical problems such as this, it is advisable to call a qualified engineer.

No Heat or Water

If water is not coming through to your taps, the most likely cause is either a broken airlock or failure of a motorised valve. The other reason is because the water in the pipe is frozen.

Check the valve on the pipe to see if you have any water flow. If you can hear water, and the weather is not freezing cold, call out a gas-safe engineer to have the parts changed.

Frozen Condensate Pipe

The other reason that you may not be getting any water through is that the pipe is frozen. This can easily occur in cold weather when the temperature drops below freezing.

When this happens, boilers automatically shut down because they cannot vent air. To overcome this problem, pour warm (not boiling) water into the pipe and wrap rag or old towels around the pipe to help thaw them out.

Air in the System

Boilers automatically shut down when there is too much air in the system. You can easily rectify this problem by bleeding your radiators.

You will know if there is too much air in the system if the heat is not evenly spread across the radiator. The classic sign of too much air in the system is when the top of the radiator is cold and the bottom is warm.

Low Water Pressure

Low water pressure is usually caused by a leak in the system or after bleeding your radiators. You can assess water pressure by checking the gauge on your boiler. It should ideally be floating around 1 bar.

You should be able to find instructions on how to re-pressurise your boiler in the manufacturer’s manual, but if you are unsure, call a gas-safe engineer to do it for you.


If the thermostat is broken, your boiler will not be able to measure the water temperature and subsequently shut down to avoid the system overheating. This is a common problem in older boilers and will require the assistance of a qualified technician to install a new thermostat.

Broken Pump

The pump is needed to circulate water around the system but the boiler will automatically shut down if it is unable to move enough water through the pipes.

To check for a broken pump, open a tap and listen to the boiler to see if you can hear the pump mechanism working. If you can’t hear anything the pump is broken and will need replacing by a qualified service technician.

If your boiler is not working after carrying out the checks above, or mechanical repairs are required, make sure you seek the assistance of a certified gas safe engineer.

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