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Thaw a condensate pipe

If your boiler has stopped working overnight and it was a particularly cold night, don't panic - your condensate pipe might just be frozen. If that's the case it's a quick and easy fix that you should be able to do yourself.


What is a condensate pipe?

A condensate pipe carries condensation from your boiler outside to drain. It's usually a white or grey plastic pipe that travels from your boiler through the wall directly outside where your boiler is located. 

During cold weather, the condensation in this pipe may freeze and cause a blockage causing the boiler to shut down. 

How do I defrost or thaw a condensate pipe?

Even if you take the best care of your boiler, it will struggle to function if the condensate pipe freezes. 

  1. Confirm the pipe is frozen
    Depending on the model of our boiler, a frozen condensate pipe may cause a fault code to show as a warning light on your boiler's display. You may also hear gurgling sounds coming from your boiler or the condensate pipe. 

  2. Locate the blockage
    The pipe is most often frozen at its most exposed point. This may be the open end of the pipe, at the bend, or at the elbow of the pipe. Run your hands along the pipe and find the section that feels colder than the rest. This is your blockage. 

  3. Use hot water to thaw the pipe
    Boil your kettle and let it cool for 15 minutes. DO NOT use boiling water as this can crack and damage the pipe. Instead, using a jug pour the hot water along the length of the pipe until you feel the blockage has thawed. 

  4. Restart your boiler
    Once you've cleared the blockage, check your boiler's manual for the instructions and reset it. This should make your boiler restart, but it may take several reset attempts before coming back on. 

  5. Not fixed? Report a repair
    If you've tried the above steps and troubleshooted issues using our boiler help page, report the issue as a repair and we'll resolve the issue for you. 

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