Frozen Boiler Condensate Discharge Pipe – Advice and Guidance

Your boiler condensate discharge pipe may be at risk of freezing in prolonged cold weather conditions. Recent years have seen temperatures as low as -20°c in some parts of the UK. If your pipe runs externally, or in an unheated space for at least some of its length, it is liable to freeze. It’s essential to ensure that your current pipes have been installed with the latest guidance to help guard against freezing. Here at Bluewater Plumbing, we understand the inconvenience of being without your boiler during the winter. We have compiled a list of tips and advice to help our customers across Barnet and the surrounding North London areas. 

How to Fix Frozen Boiler Condensate Pipe

If your pipe freezes, it will cause your boiler to go into “shut off” at a time when you need your heating and hot water the most. Your heating engineer will advise you on the solutions available to reduce the risk of your pipe freezing. Running the discharge pipe to an internal drainage point is the preferred method. Installing one of the available products designed to give you added protection against freezing conditions, may also be effective. They will also clearly identify the external condensate discharge pipe for your future reference and may apply an identification label or tape. 

If appropriate, it may be advised to operate the boiler temperature at a higher flow temperature. This will help to decrease the amount of condensate generated and reduce freezing potential. You can achieve this by turning the boiler thermostats to a high setting. During this situation, the radiator surfaces will be hotter than normal and the boiler efficiency will be slightly reduced. Return the boiler thermostat back to its normal position after the extreme cold spell has ended.

Thawing Frozen Condensate Pipes 

  1. Locating the blockage, the condensate discharge pipe usually freezes at the most exposed points outside. This could be the open end of the pipe, at a bend or elbow, or where there is a dip in the pipe where condensate can collect. Once the blockage in your pipes has been located, you’ll know where to target. 


  1. The condensate pipe can be thawed in a number of ways. By applying a hot water bottle, microwaveable heat packs around the blockage, or by pouring warm water onto the pipe. It is important that you do not use boiling water. Please take care if your condensate discharge pipe is not easily reached from ground level, and do not put yourself at any undue risk without seeking assistance or engaging a professional heating engineer.


  1. Reset/restart the boiler. Once the frozen blockage has been cleared, the boiler will usually need to be reset. Advice on how to do this can be found in the user instructions manual for your boiler. Normally, this will involve simply pressing a reset button on the front of the boiler, or in some cases by isolating the electrical supply to the boiler and switching it back on. As always, if you’re unsure, it’s best to contact a reputable engineer. 


For any further advice on how to deal with Frozen Condensate pipes, do not hesitate to contact Bluewater. We have emergency plumbers on hand to help solve your problems quickly and efficiently with expert advice. 

Frozen Boiler Condensate Discharge Pipe

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