Blog, Boilers

How to thaw a frozen condensate pipe

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How to thaw a frozen condensate pipe

Boiler not working in freezing temperatures?

If your boiler has stopped working in freezing temperatures, then there is a good chance that your condensate pipe has frozen. Luckily, this isn’t a big problem and it can be easily resolved yourself without the need for an engineer. This page will provide you with all the information needed to help you defrost your condensate pipe.

How do I know if the condensate pipe is frozen?

If part of your condensate pipework is outside and does freeze during a prolonged period of very cold weather, you might hear a gurgling noise coming from the boiler and if your boiler has a digital display, you may see an ‘EA’ error code too. There’s no need to worry if your condensate pipe freezes. You can usually thaw it safely without the need to call an installer or engineer.

How to safely thaw a frozen condensate pipe

  1. 1. Look for an outdoor pipe connected to your boiler (it’s usually white plastic connecting to an external drain.)
  2. 2. If safe to do so, pour WARM water along the pipe (not boiling water)
  3. 3. Reset your boiler. All should be working normally (if the pipe is defrosted)

This video from Worcester Bosch provides step by step guidance on safely defrosting a condensate pipe:

What is a condensate pipe?

Condensing boilers require an additional pipe to be fitted to carry away waste water that forms as a result of the normal condensing process. This is called the condensate pipe, it is normally plastic and runs from the boiler to a household drainage system or soakaway outside.

Evidence of condensed water running through the condensate pipe is an indication that your boiler is working normally.

Where is the condensate pipe?

The condensate pipe runs from the boiler to a suitable existing waste pipe system, or external drain pipe. If it is connected to an external drain pipe, it will be found outside your property leading out from your boiler. Prolonged periods of freezing weather can cause this pipe to freeze, affecting the operation of the boiler.

Minimising the risk of frozen condensate

  • – Turn the heating control on the boiler to maximum (only for as long as needed)
  • – Install a drain cover to protect the pipe end
  • – Insulate the external pipe work


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