Combi Boiler Fires Up Then Cuts Out…What Should I Do?

A failing boiler is easily one of the most frustrating experiences you have to put up within your home. It’s even more frustrating when you have to take a cold bath in the morning because the engineer has not arrived yet.

One of the most common combi boilers failures is when the boiler starts out fine but cuts out immediately after. It’s a confusing problem because the boiler will show different fault codes which can be difficult to interpret.

Wondering what to do if your combi boiler is having the same issue? This blog could help you with some great tips and possibly even save you some money.

Find out what the problem is

Your first challenge is identifying what the problem is. Some problems are easy to diagnose and others not so much. It’s best to start with the easiest and work your way up to the harder one. Some of the problems that could be causing your boiler to start then fail to include:

Low Water Pressure

This happens more often than you would expect. To protect the boiler from damage, the system will shut off if the pressure is too low.

For the boiler to function, the water pressure needs to be about 1.5bar. If it falls below 0.5bar, the boiler will not fire. Low water pressure can be caused by a leak in the system or bleeding your radiators too much. To check for boiler pressure, all you have to do is check the pressure gauge.

If the boiler pressure is low and you don’t have a leak, the fix is quite simple. Just find the filling loop and top up the water which tops up the water pressure. You can then restart the boiler and it will work just fine.

Frozen Condensate Pipes

Most combi boilers have most of the pipework inside the house. But, if you have a unique set up and you have a source pipe that’s outdoors or goes through the loft, you might want to check if it’s frozen.

This is more so the source of the problem if the boiler is not only shutting down but has some gurgling noises. The fix, in this case, is simple. Just boiler some water and pour on the pipe to thaw it out. Once the flow is restored, the boiler should work perfectly.

Water Feed Issues

Water feed issues can arise from frozen main pipes or blockages. No matter what the cause is, not having enough water flowing into the boiler for heating will cause the boiler to cut off after starting.

Try and find out what could be causing the problem with water feeds. If the pipes are frozen, you can thaw them, but, if it’s a blocked pipe its best left for a qualified engineer to handle it.

Air in the System

If for some reason air has found its way into your central heating system, it could cause your combi boiler to cut off when it starts.

It can be difficult to diagnose if trapped air is the problem. A trick that often works is to check for cold spots on the radiators as soon as the heating is turned on.

Once you’re certain that is what is causing the boiler to cut out, you can iron out the problem by bleeding the radiators. This is a simple task that you can safely do by yourself. You just need to carefully follow the instructions laid out in the user manual.

Why not also read our latest blog: How To Repressurise a Boiler without the Filling Loop.

Fuel Feed Issues

This sounds more like the water feed issue. However, if the water is flowing fine, it could be that the boiler is running out of fuel which is causing it to shut down.

Fuel feed issues are serious and best handled by a professional. If you suspect your boiler is not having enough fuel to function, call your installer or a Gas Safe registered engineer to help you find the fault and fix it.

Faulty Thermostat

If these simple fixes don’t yield any results, it’s time to consider other serious problems that could be plaguing the boiler. One such problem is a faulty thermostat.

You’re more likely to have this problem if the thermostat is old. If the thermostat is the problem, the only solution is to replace it and the boiler should resume normal functions once the thermostat is replaced.

Faulty Pump

A faulty pump will cause the boiler to switch off. The pump is an essential component in the central heating system. It helps to move water around the central heating system. If it fails, the hot water just stays in the boiler and this causes the boiler to cut out.

There’s no alternative remedy to a faulty pump other than replacing the pump. Because you have to take some components of the combi boiler apart, it’s best to have a professional do the replacement to prevent additional damage.

These are some of the leading problems that could be causing your combi boiler to cut shortly after starting up. If the problem is persistent, have an engineer to a check-up to see what other problems your boiler could be facing.

Remember, it’s easy to avoid such problems happen to your boiler by having it serviced regularly and checked often. If the problems are noticed early, you can save money on repairs and the inconvenience of a cold shower in the morning.

If you are looking for a Boiler Installer, we can help! Get in touch with our friendly team today.

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