• 1. Even the most well looked-after boiler will struggle to function if its condensate pipe freezes or becomes blocked with some foreign material. When having a new boiler installed it is also good practise to run the condensate pipe internally. Luckily, itʼs not a difficult job to put things right if it does happen. This handy guide will help you get your boiler up and running quickly and easily.

    If the outside weather is extremely cold/wintery and your boiler is showing an error code, then your condensate pipe may be frozen.

    What is a condensate pipe?

    • A condensate pipe carries condensation from your boiler to your outside drain. Itʼs 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 condensation to back up into the boiler and cause it to shutdown.
    How to defrost the pipe
    If you suspect that your boiler condensate pipe has frozen, the following steps should help you get things back to normal quickly. Remember, if you donʼt feel confident when following this guidance then you should contact an expert boiler engineer for help.
  • 2. Confirm the condensate pipe is frozen
    Depending on the make and model of your boiler, a frozen condensate pipe may be indicated by a ‘fault code’ or warning light on the boilerʼs display. Gurgling or bubbling sounds coming from the boiler or the condensate pipe are another sign that the condensate pipe has frozen.
  • 3. Locate the blockage
    The pipe is probably frozen at its most exposed point. This may be the open end of the pipe, or at a bend or elbow. Running your hands over the pipe until you find a section that feels colder than the rest should help you identify the blockage quickly.
  • 4. Thaw the pipe
    Using a jug or watering can, pour warm water along the length of the pipe, repeating the process until the pipe has thawed (donʼt use boiling water as this can crack or damage the pipe). Alternatively, you can use a hot water bottle or a heat pack to slowly defrost the pipe.
  • 5. Prevent pipes freezing
    It's best practice to cover your outside pipes, particularly the condensate pipe, in pipe insulation.
  • We update the maintenance tips and troubleshooting guidance from time to time and aim to make it as helpful as possible. The purpose of the maintenance and troubleshooting section of this website is to provide you with general guidance. Please ensure you read and follow our instructions carefully and do not undertake the maintenance or troubleshooting unless you are aged 18 or over, are competent to do so and are confident that you can complete the maintenance. If in doubt do not attempt any actions and where an appliance is gas fuelled refer to a Gas Safe engineer for assistance.

    This website is not intended to be a substitute for professional advice and does not:
    - cover every reason that your product could fail;
    - cover all of the maintenance that can be undertaken for your product;
    - supersede any advice in your instruction manual or from your product manufacturer.

    Do not carry out any maintenance or use the troubleshooting guide if it puts you or anyone else in danger or if you believe it may cause damage to your, or another person’s property.