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General boiler info, Troubleshooting

What's wrong with my boiler?

Try our basic boiler checks

Having trouble with your boiler? If you’re wondering ‘why has my boiler stopped working?’, then we’re here to help you identify and repair basic boiler faults, problems, issues and error codes.

Performing basic boiler maintenance doesn’t always require expert help –though it will save you time and money to get your boiler regularly serviced by a Gas Safe registered heating engineer.

However, if you don’t know ‘what’s wrong with my boiler?’, there could be a simple fix needed. Let’s help you identify and troubleshoot common queries, like low boiler pressure, frozen condensate pipes, and if the pilot light keeps switching off, among others.

Why has my boiler stopped working?

It's showing an error code

Boilers are complex machines. As the heart of your home, it’s responsible for keeping your rooms warm and your water hot. From time to time, they can play up and stop working. When this happens, you’ll see an error code telling you what the issue is. If you have a BAXI boiler, you can take a look at our entire list of error codes.

Even if you don’t have a BAXI boiler, your boiler should still show an error code, so long as it has a digital display. Your manual will help you find out what this is. Or you can check the manufacturer’s website.

It's not switching on

If there’s no power to your boiler, or it just doesn’t turn on, it seems like there might be an issue with your electrics. Check your other appliances in the same room or area of your home. If these are also not working, your power supply might have failed. Check your fuse box for any tripped switches.

If you’ve tried this, and your boiler’s still completely unresponsive, it’s time to contact your heating engineer for maintenance, servicing, or a replacement.

Why is my heating working but no hot water?

If your radiators are working just fine, but your hot water’s not running or running cold, there’s a few things you can check.

First, check you have water running from your cold tap, then check the hot water control on the boiler or cylinder to make sure it’s set to at least 60°C (the minimum temperature required to kill harmful bacteria in the water). If your boiler has a timer, check that the clock is correct. Next, try a hard reset of your boiler: most have a reset switch. You may have to check your manual to find it. If it’s winter time, ensure you don’t have a frozen condensate pipe (see below).

If after all this you’re still wondering ‘why is my heating working but no hot water?’, it might be a problem inside the boiler itself. Combi boilers seamlessly divert hot water from heating to taps and showers as and when needed. To do this, they use a diverter valve. If you have a combi boiler and you’ve tried all of the above to no avail, there’s a good chance the valve might be stuck.

If this is the case, this requires a heating engineer to fix what’s wrong with your boiler. Your heating engineer should be able to locate the issue and fix it.

Why does the pilot light keep switching off?

This is more common with older boilers – particularly those with a pilot light (a small naked flame) that needs to stay lit permanently. Modern boilers tend to ignite electronically and automatically, so they don’t need a permanent flame. If this light keeps going out, it could be due to several factors:

  • Is the flame fully protected from draughts?
  • Is there a build-up of residue stopping the light from staying lit?
  • Is the gas supply to the boiler constant? An interrupted supply, caused by a faulty thermocouple (the safety device that detects whether pilot light is on).

Reigniting a pilot light is a simple procedure if you know exactly what you are doing! Get help from a heating engineer if you’re not 100% confident. If the pilot light keeps switching off persistently, it might be worth upgrading to a newer boiler (they are much more efficient nowadays, so you’ll be saving money in the long run).

Do I have a frozen condensate pipe?

If you have a condensing boiler, it should have a condensate pipe attached to it. This pipe is generally made of hard white PVC, and leads from your boiler to a drain outside your home. It carries condensed water vapour (a few litres an hour) through it.

In sub-zero temperatures, there’s a chance the condensate might freeze and block the pipe. A frozen condensate pipe results in the boiler not even turning on (as it will damage it). You should see an error code telling you this, but if you don’t, you might hear the boiler gurgling as it struggles to pump out condensate from the boiler.

The way to solve this is to thaw out the pipe. Locate where the blockage is (usually outside, where it’s exposed) and run warm (not hot!) water along the pipe. Keep going until the ice falls out, or the boiler starts working normally again. This may be some time after clearing the blockage. Head here more information on how to thaw a frozen condensate pipe.

Afterwards, make sure you insulate the exposed pipe to stop it from happening again.

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