My Condensate Pipe has frozen

"How to... thaw a frozen condensate pipe”

Our heateam "How to..." video guide for "How to thaw a frozen condensate pipe” is applicable to Baxi, Potterton, Main and Remeha condensing, high efficiency or gas adaptive boilers. The video will show you how to thaw a frozen condensate pipe.


Can I prevent my condensate pipe from freezing?

"How to prevent your condensate pipe from freezing”

Our heateam "How to...” video guide for "How to prevent your condensate pipe from freezing" is applicable to Baxi, Potterton, Main and Remeha condensing, high efficiency or gas adaptive boilers. The video will show you how to prevent your condensate pipe from freezing.

PDF Download

Printable instructions on how to identify and thaw a frozen condensate pipe can be downloaded by clicking the link below

Identifying and thawing a frozen condensate pipe


Why does my condensate pipe freeze?

In recent years, the UK has experienced some extreme winter weather with temperatures dropping as low as minus 20 degrees Celsius for long periods of time. This has had a dramatic effect on condensing, high efficiency boilers.

As a bi product, condensing, high efficiency boilers produce condensation or water vapour via the combustion process, and require a condensate pipe to drain the collected condensate away from the boiler.  The condensate pipe can very often run outside the heating envelope of the property,  through enclosed but unheated areas of the home like the garage, loft or outside wall.

Exposed areas of condensate pipe can quickly freeze if subjected to long periods of low temperatures or extreme freezing temperatures, creating blockages and forcing water back up the condensate pipe and into the boiler, causing the boiler to stop working.

If left unchecked, the first symptom you may experience is no heating and/or no hot water, in addition to digital error codes or indicator lights that will appear on the boiler control panel.  In the case of Baxi products, error code E133 is most commonly displayed. 

Other ways your boiler will signify the condensate pipe is frozen include a solid, flashing red indicator light next to the flame failure symbol, the boiler locking out or the boiler making gurgling sounds.

What can I do to unfreeze a frozen condensate pipe?

Health and Safety advice:

  • Only attempt the process provided you feel competent to take the actions described.
  • Do not attempt to unfreeze your condensate pipe if it is not accessible from standing at ground level.
  • Apply salt or grit to the standing areas before and after you thaw the frozen condensate pipe.

Step One

Locate the frozen, blocked part of the condensate pipe.

Step Two

Warm the condensate pipe across the whole of the exposed length in order to thaw and unblock it. heateam recommend customers use one of the following methods.

  •  A hot water bottle.
  • A microwaveable heat pack
  • Warm water poured from a container such as a watering can.

Step Three

Once the condensate pipe has been unblocked, reset your boiler.

What can I do to prevent my condensate pipe from freezing?

As winter approaches, you may want to take precautionary measures to ensure you don't encounter a freezing condensate pipe issue. The simplest solution is to insulate the condensate pipe with a water-proof, weather-proof insulation around the outside of the pipe. Available from DIY outlets and plumbing/heating suppliers.

Changing the way in which we use the boiler during extreme winter weather will help reduce the risk of your condensate pipe freezing. Temporarily run the heating system with the boiler thermostat (as distinct from the room thermostat) set to maximum. Turn back to the normal setting used once the cold spell is over.

Also temporarily set the central heating timer/programmer to "continuous” (24hr) mode, setting the room thermostat overnight to around 15oC.   Again, return to the normal settings once the cold spell is over.

heateam recommend all customers ask a Gas Safe registered engineer to carry out any remedial work, but longer term options you should consider are:

  • Increasing the diameter of the condensate pipe system. The pipe should be a minimum of 32mm diameter and should also be insulated.
  • Reinstall the condensate pipe for the shortest route possible, with few bends and a sloping fall across its whole length.
  • Reinstall the condensate pipe and have it routed internally to discharge into the household plumbing system, like your washing machine would do.
  • If you live in a flat, install a condensate pump to move the condensate to where it needs to be discharged.
  • Installing a trace heat system onto the condensate pipe. A temperature sensor fitted outside will switch on an electrical current that will pass down the trace heating wire keeping the condensate pipe warm.

Make sure that you are prepared for the winter and ask your Gas Safe registered engineer to review the installation of the condensate discharge during your annual boiler service.

back to top

Approved Spares Stockists

Approved Spares Stockists

If you would like more information on products to prevent condensate pipe freeze, please follow the link to Interpart to find an approved spares stockist.