Cold snap causes boilers to stop working

4th November 2019

The first proper cold snap this winter has seen a large number of calls coming in from tenants who have lost their heating and hot water as a result of the condensate pipe from their boiler freezing up.

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 and/or
  • 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 the first kettle 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.


  • Never attempt to thaw a condensate pipe above waist level, 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

Contact Us

Connect With Us