Why does my boiler keep turning off?

Updated on 5th November 2026:

Kieran Haig

Technical Repair Engineer, British Gas

A boiler that keeps turning itself off can leave you frustrated as well as cold. Boilers will normally cycle on and off to stop your home from overheating, but if it keeps happening unexpectedly then it’s likely to be because of a fault. 

Learn the causes, fixes, and your next steps for a boiler that keeps turning on and off.

Is it normal for a boiler to keep turning off?

Even on the coldest days, boilers don’t usually run continuously. Boilers usually turn off when your home reaches the target temperature you set, and should then only switch back on to top up the heat if the room falls below it again. This is because boilers have a maximum and minimum output. 

Some times, depending on the boilers, even on the minimum output, your boiler can overheat your home. To prevent stop this happening, your boiler will automatically cycle, turning itself off at regular intervals to let the your home cool down and maintain a low but regular steady temperature.

However, this is very different to a boiler that shuts down unexpectedly, displays an error code or fails to provide leaves you without heating or hot water. While short cycles may be necessary, they can also be a sign that something isn’t right, and frequent cycles or repeated lockouts can suggest that there may be a problem that needs attention.

Why does my boiler keep turning off?

There are a handful of reasons why your boiler might keep turning off, and sometimes it’s a combination of more than one.

Low boiler pressure

Insufficient pressure in a sealed heating system can stop your boiler from working properly. If your boiler needs pressure to work, you should be able to check the reading on the pressure gauge. If you can’t top it up yourself, or if the pressure carries on falling, you may need an engineer to investigate.

Thermostat problems

Miscommunication between your thermostat and your heating system may be another reason your boiler is turning off. This could be due to:

• Low batteries if thermostat is battery powered 
• Being placed too far apart or not being able to send signals if it’s wireless 
• A faulty thermostat

Overheating

If your boiler is overheating, it may shut down to prevent damage to the system. Overheating may be a symptom of a separate issue, such as blockages, pump problems or restrictions in the system that prevent water circulation.

A frozen condensate pipe

Condensate can freeze in an external pipe when the weather is particularly cold, which can trigger a boiler shutdown. If this happens, you may hear a gurgling or bubbling noise coming from your boiler and the external pipe may be coated in frost. If you suspect your condensate pipe has frozen, consult the manufacturer-approved guidance for your boiler.

A faulty component

Your boiler could be shutting down because of problems with parts inside it like:

• Sensors 
• Fans
• Pumps
• Valves

If you’re concerned internal components may be broken, you’ll need a qualified engineer to inspect your boiler.

Poor water circulation or a blockage

Having these in your heating system can cause your boiler to keep turning off. This may be the result of sludge or restrictive pipework slowing down the water. Issues with radiators or circulation can affect system performance and can even lead to overheating. 

Why does my boiler keep turning off when heating the radiators?

If your boiler is turning off when heating your radiators, it may be simply because your home’s reached the temperature set on your thermostat. If this isn’t the case, then it may be shutting down due to a fault in your boiler.

If your radiators are still cold or heating unevenly, it’s worth getting things checked out by a qualified engineer.

Why does my boiler keep turning off when using hot water?

The cause of your boiler is shutting off when you’re using hot water may be a different what causes it to shuts off during central heating. You may have an issue with:

• Demand if too many people need hot water at the same time
• Faulty temperature sensors so your boiler doesn’t know when water is too cold
• The Heat exchanger issues can prevent the water from being heated
• Flow detection if there are issues with water circulation 
• Overheating 

The exact cause of your hot water turning off will depend on the type of boiler you own and whether it's a combi boiler or a system boiler with a hot water cylinder. 

What should I check if my boiler keeps turning off?

To help you understand why your boiler might be turning off, check:

• Your thermostat is switched on and set to the temperature you want
• For an error code or warning light on the boiler display 
• The pressure gauge or display if your boiler has one, and compare it with the manufacturer's recommended range
• Your heating timer or programmer is set correctly
• If your boiler stops during central heating, hot water use or both
• How often it switches off and whether it restarts by itself

It’s important that you don’t remove the boiler casing or adjust internal components. You can also cause damage by repeatedly resetting a boiler that keeps locking out, so if it keeps happening, get a qualified engineer to look at it.

Is it safe to keep using a boiler that keeps turning off?

Don’t ignore repeated shutdowns - they can be a sign of a serious problem in your boiler.

Resetting your boiler repeatedly is, at best, a temporary fix. To keep yourself safe, you should have your system checked by a Gas Safe registered engineer.

Call 0800 111 999 immediately if:

• You smell gas
• Your carbon monoxide alarm goes off

If you’re concerned about the general safety of your boiler, then call an expert engineer immediately.

Other than not working properly, signs of a faulty boiler are:

• A flickering yellow flame instead of a consistent blue one
• Sooty marks on your boiler
• The pilot light in your boiler keeps going out

An increase in condensation on the inside of nearby windows.

How much does it cost to fix a boiler that keeps turning off?

The cost of repairing a boiler that keeps turning off will depend on the underlying fault, the boiler make and model, parts and labour.. 

The cost will largely depend on the severity of the issue, whether it’s a minor control problem or a serious fault with a component that needs replacing. With British Gas, a standard one-off boiler repair costs £295. 

We also offer boiler cover, which gives you unlimited call-outs and repairs and can be useful if you have an older boiler. If your boiler is particularly old, it may be safer or more convenient to replace your current boiler with a new one. 

If this is the case, your engineer will let you know.

How can I prevent my boiler from repeatedly switching off?

While faults and breakdowns do affect boilers, one of the best ways to prevent your boiler from repeatedly switching off is to have an annual boiler service so an engineer can check that everything is working as it should be and spot any issues in before they become major problems. 

You can also stay on top of your boiler’s health by following the user manual when you see error codes or pressure loss, and getting any issues checked out as soon as they arise. Keeping the thermostat and heating controls correctly configured can help too.  

Need help?

If your boiler keeps turning itself off, or if you’re concerned about any other issues, get in touch and book an engineer visit.