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How do I fix a frozen condensate pipe?

Everything you need to know so you can find, fix, thaw and prevent a frozen condensate pipe

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What is a condensate pipe?

The condensate pipe’s purpose is to transport wastewater left over from the condensing process to the outside of the property, this water is slightly acidic and is the resulting by-product from recycling the heat from flue gases. 

Condensate pipes should be prevalent on every boiler that was installed after April 2005, as this was when condensing boiler regulations were introduced in hopes of reducing carbon emissions and boosting efficiency.

If your condensate pipe is installed so that part of the pipe is on the exterior of the property, then it will be prone to freezing over when the temperature drops below 0°C.

How to know if a condensate pipe is frozen

When the condensate pipe becomes frozen it can cause the acidic water to revert back into the system leading to a breakdown, the boiler will normally shut down before this happens and display a relevant fault code. Some of the most common fault codes to identify frozen condensate pipes are: EA299 D5 (Worcester Bosch), F28 or F29 (Vaillant) and E133 or E28 (Baxi). These are just a few of many fault codes that may be applicable, if the code shown on your boiler interface isn’t one of these refer to your user manual to find out what the fault code displayed means. 

Another sign you may have a frozen condensate pipe is a loud gurgling noise coming from your boiler system, for more information on unexpected noises coming from your boiler system check out this article.

How to find and thaw a frozen condensate pipe

Once you have diagnosed the issue as a frozen condensate pipe you then have to thaw out the frozen section. First you will have to locate the condensate pipe, it will be located underneath your boiler and is easily identifiable as it should be the only plastic pipe coming from your boiler if the system was installed correctly. 

After the condensate pipe has been located you will then need to find the frozen section of the pipe. To do this follow the pipe until you find the section that feels the coldest in comparison to the rest of the pipe, the blockage will often occur where there is a dip or bend in the pipe. The frozen part of the condensate pipe is normally located outside but it can happen internally also if the boiler is in a loft space or basement which gets cold. When the frozen part of the pipe has been identified you then have to warm it up to melt the frozen water. 

Condensate pipes are just like us, they like to be kept warm and cosy. To the point that they are even heated in a similar manner such as by a hot water bottle or insulating the pipe as you would yourself with a jumper. Alternatively, you can pour hot water onto the pipe, although make sure the water hasn’t reached its boiling point as it could melt or warp the pipe.

How to stop a condensate pipe from freezing

Sometimes a frozen condensate pipe can become a recurring issue, if this is the case then there are some preventative measures you can take to stop this from happening. The easiest and most recommended would be to install lagging to your pipework, also known as pipe insulation. Installing lagging to your pipe should help keep the inside of the pipe at an ambient temperature which will stop the water from freezing, this is normally seen as the most cost effective and least invasive solution. 

A condensate pipe that continues to freeze even after lagging has been applied may need to be relocated by an engineer to an internal location, in the circumstances of especially cold weather. In the circumstance a pipe can’t be relocated, then trace heating may be a more viable option. This will provide a continuous heat source to the pipes in question and keep them at an ambient temperature.

The Heating & Hot water Industry Council (HHIC) recommends running your boiler at a higher temperature than normal as this will reduce the amount of condensate left over. With less water present inside the condensate pipe it will be less likely to freeze over and cause a blockage, although this can lead to higher energy bills which is why it isn’t our preferred method of prevention.

How to find and thaw a frozen condensate pipe

Once you have diagnosed the issue as a frozen condensate pipe you then have to thaw out the frozen section. First you will have to locate the condensate pipe, it will be located underneath your boiler and is easily identifiable as it should be the only plastic pipe coming from your boiler if the system was installed correctly. 

After the condensate pipe has been located you will then need to find the frozen section of the pipe. To do this follow the pipe until you find the section that feels the coldest in comparison to the rest of the pipe, the blockage will often occur where there is a dip or bend in the pipe. The frozen part of the condensate pipe is normally located outside but it can happen internally also if the boiler is in a loft space or basement which gets cold. When the frozen part of the pipe has been identified you then have to warm it up to melt the frozen water. 

Condensate pipes are just like us, they like to be kept warm and cosy. To the point that they are even heated in a similar manner such as by a hot water bottle or insulating the pipe as you would yourself with a jumper. Alternatively, you can pour hot water onto the pipe, although make sure the water hasn’t reached its boiling point as it could melt or warp the pipe.

How to stop a condensate pipe from freezing

Sometimes a frozen condensate pipe can become a recurring issue, if this is the case then there are some preventative measures you can take to stop this from happening. The easiest and most recommended would be to install lagging to your pipework, also known as pipe insulation. Installing lagging to your pipe should help keep the inside of the pipe at an ambient temperature which will stop the water from freezing, this is normally seen as the most cost effective and least invasive solution. 

A condensate pipe that continues to freeze even after lagging has been applied may need to be relocated by an engineer to an internal location, in the circumstances of especially cold weather. In the circumstance a pipe can’t be relocated, then trace heating may be a more viable option. This will provide a continuous heat source to the pipes in question and keep them at an ambient temperature.

The Heating & Hot water Industry Council (HHIC) recommends running your boiler at a higher temperature than normal as this will reduce the amount of condensate left over. With less water present inside the condensate pipe it will be less likely to freeze over and cause a blockage, although this can lead to higher energy bills which is why it isn’t our preferred method of prevention.

What next?

After the frozen condensate pipe has been thawed out and the correct preventative measures have been taken you will need to reset your boiler to get rid of the fault code and get it started again. If you are ever unsure about what is causing an issue with your boiler feel free to contact us on our 24/7 customer service helpline and we will organise for a qualified engineer to visit your property to diagnose and solve the problem.