Frozen Condensate Pipe

Does your boiler have a frozen condensate pipe? Here’s a quick guide to help you.


Frozen Condensate Pipe

Frozen Condensate Pipe

A frozen condensate pipe is quite a common issue during cold months. A condensate pipe safely vents moisture from the boiler to the outside drain. The pipe is usually grey or white, and it travels from  the boiler through the external wall that is directly outside the boiler. During the winter months, the condensate pipe can freeze – even if it is insulated. Freezing can cause blockage, resulting in the condensate to backing up into the boiler and then causing a shutdown.

You would know that the condensate pipe is frozen if  you hear a bubbling sound from the boiler or the pipe. You may also see a warning light on the boiler to indicate that the pipe is frozen.

Thawing a frozen condensate pipe should really be done by a gas safe registered engineer. However, if you feel that you can do it yourself, these guidelines should help you.

  • Check to make sure that the condensate pipe is indeed frozen. Depending on your boiler’s model, there may be a ‘fault code’ or warning light on the boiler’s display to indicate that the pipe is frozen. You might also hear gurgling or bubbling sounds coming from the boiler or the condensate pipe.
  • Find the blockage. It is most likely that the blockage is located where the pipe is most exposed, such as the end of the pipe or a bend or elbow. Run your hands over the pipe. The frozen section should feel colder than the rest of the pipe.
  • Thaw the pipe. Do not disconnect the pipe at any point. Warm some water and place it in a watering can or jug. Make sure the water is warm, and not boiling. Boiling water can cause the pipe to crack (or scald you). Pour the warm water along the pipe, and repeat as needed until the pipe is thawed. You can also use a heat pack to defrost slowly.
  • Restart your boiler. Read the manual to get the right steps in properly restarting your boiler.

If your boiler still does not restart, call your local engineer to get it checked.

Avoid getting a frozen condensate pipe in the future. Provide insulation for the pipe. If you do not have insulation, use towels to wrap the pipe in. Go to your local DIY store and buy foam pipe insulation. The insulation comes in different sizes. Make sure you measure the pipe’s diameter before buying.

During very cold months, your may still experience getting a frozen condensate pipe even if the pipe is insulated. If you continue to experience problems, it is best to get help from a local engineer.


Call RJ Gas today and we’ll help your with your frozen condensate pipe and other boiler problems.