How to Fix a Frozen Condensate Pipe

How to Fix a Frozen Condensate Pipe

Posted on March 4, 2019

As the temperature is set to plummet again, the chance is higher that your boiler’s condensate pipe will freeze. This results in your boiler switching itself off to prevent damage from flooding as water cannot get through, leaving you without heating. However, you can fix this problem yourself easily, or even prevent it from happening in the first place, with our handy guide.

You might be asking “What is a Condensate Pipe, where is it located and how do I know if it’s frozen?”

All condensing boilers have a condensate pipe. This pipe sends the acidic wastewater which is produced when your boiler extracts energy from flue gases, outside and down a drain. It is easy to find the condensate pipe as it is the only pipe coming from your boiler that is made from plastic rather than metal. The condensate pipe then leads through a wall fairly low down, and right above a drain. If your boiler has stopped working, to be sure that the frozen pipe is the cause, boilers will often display an error code, or if not you may hear a gurgling sound coming from your heating system.

Here is a list of boiler manufacturers and their corresponding error code meaning it has a frozen condensate pipe. If your boiler is not listed then check the manual or you might need to call an engineer:


ATAG                       133

Baxi                         E133 or E28

Glow-worm              F1, F4, F28 or F29

Main                        E133

Potterton                 E133

Vaillant                    F28 or F29

Viessmann              F4EE

Worcester Bosch    EA229 D5


“Ok I’ve identified the issue, now how do I fix it?”

First things first, you need to find the part of the pipe that has the blockage so you know you’re thawing out the right area. To help you, there will often be a bend or dip there in the pipe. There are several different methods you can use to thaw it out:

* applying a hot water bottle to the area

* applying a microwaveable heating pack

* applying a warm cloth

* pouring hot water over it using a watering can. (Caution – do not use boiling water as this could melt the plastic pipe!)


Once you have unfrozen the pipe, your boiler should restart automatically, however you might need to reset it. Check the manual to be sure.

“Can I prevent this from happening again?”

Yes, there are a few things you can do:

* covering the condensate pipe with foam insulation

* leaving your heating on overnight

* turning your thermostat up however your radiators may then be too hot

“I need help!”

If you would like help unfreezing or insulating your boiler’s condensate pipe, contact Aura Heating now and we will send out an engineer in no time at all.

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