A cold snap can cause boilers to stop working

13th December 2022

Every year the first period of cold weather can cause large numbers of tenants to lose their heating and hot water as they have forgotten to check their condensate pipe from their boiler.

Please remember to follow the advice below:

If caught early enough, this issue is often quick and simple for someone to solve for themselves without having to wait for a heating engineer to attend.

If you get your heating and hot water from a gas or oil combi boiler, it will most likely have a condensate pipe – this will usually be white plastic and will run away from the boiler to a drain – often going to an outside wall and looking like an overflow pipe.

In cold weather the small amount of water that runs from this pipe can freeze up, eventually causing the boiler to shut down and stop working. By defrosting the pipe and removing the frozen blockage, you can get your boiler working again.

How to defrost a frozen condensate boiler pipe

  • Use hot water – not boiling – heated by a kettle or a microwave and pour over the end of the pipe where it is frozen using a suitable container like a watering can or jug
  • Hold a hot water bottle or heat wrap around the condensate pipe.
  • Give the pipe a gentle tap with a wooden spoon or similar to dislodge the frozen water.
  • If your first try has no effect, repeat the process a number of times until things start to move.
  • Once the pipe has thawed you should re-set your boiler by holding in the re-set button for 10 seconds and wait for the boiler to re-fire.


  • Do not use boiling water
  • Never attempt to thaw a condensate pipe above waist level with hot water, or disconnect the condensate pipe in order to do so.
  • Never attempt to access the condensate pipe or any other pipe work within the boiler.
  • Beware of ice on the ground that will form from the water you have poured.

If in any doubt, phone our Customer Service team on 01768 861400/0800 358 1401

The following short video from Worcester Bosch demonstrates how to safely thaw the pipe https://www.youtube.com/watch?v=3iFyHf4in8k&noredirect=1

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