How To Thaw A Frozen Boiler Condensate Pipe

One of the most common causes of a boiler breaking down is due to a frozen condensate pipe. A condensate pipe is an important part of a condensing boiler system, as it removes wastewater and dispenses of it into the sewer. When temperatures drop, the condensate pipe is prone to freezing, which then results in the boiler shutting down.

 listen to your boiler

To identify whether the problem is definitely caused by a frozen condensate pipe listen to your boiler, as it may be making a gurgling noise. If this is the case, there is a very good chance that you have correctly diagnosed the issue as being a frozen condensate pipe.

The reason this is such a common issue is that the condensate pipe is usually located on the outside of the property, therefore the water inside often freezes when the external temperature drops low enough. Fortunately, there is a simple method of thawing a frozen boiler condensate pipe:

 Locate the condensate pipe

1 - Locate the condensate pipe

The first step is to locate the pipe. You are looking for a white pipe that runs from your boiler and through your external wall, down into a drain. If you bought the house from a previous owner, they may have insulated the pipe, so if you cannot find a white pipe, look for a pipe that looks like it has insulation wrapped around it. Whilst insulation usually prevents the pipe from freezing, extremely cold snaps or badly fitted insulation might mean that the pipe still freezes occasionally.

Pour warm water on the pipe

2 - Pour warm water on the pipe

As your boiler is not working, you will need to get your hot water from boiling the kettle. You are going to use warm water to thaw the frozen pipe and it is important that you do not use boiling water as this can crack the pipe. Instead, wait for the water to cool to a warm temperature.

If your pipe has insulation around it, you should remove it so that you can pour warm water directly onto the pipe. It is better to work from the top of the pipe downwards, so that your warm water runs down the pipe, helping to thaw quicker.

 Reset your boiler

3 - Reset your boiler

Once you have poured the warm water all over the pipe, you can then reset your boiler to start it up again. If it has worked, the gurgling noise should have disappeared and your boiler is back working as normal. If not, try repeating the process of pouring warm water on the pipes until you are successful.
Preventing frozen condensate pipes

Whilst it is usually quite simple to rectify a frozen condensate pipe, it can be quite inconvenient – especially for the person who has to go outside in the cold to pour water onto the pipe! To prevent this problem from reoccurring, you should try insulating the pipe. You can buy insulating kits from DIY stores, or you can ask your plumber to do it for you, particularly if it is difficult to access.

If you are at the stage of installing a new boiler then you can make a decision on where you want the condensate pipe to go and you can choose for the majority of the pipe to stay inside your home, meaning the cold temperature is only affecting a part of the pipe. You can also ensure that the pipe is as steep as possible, as any horizontal points collect water and are therefore more inclined to freeze. The size of the pipe is also something that affects the situation. If you have a larger pipe (32mm to 40mm) then there is a much lower chance of it becoming frozen in the cold weather.

As far as boiler issues go, thawing a frozen condensate is one of the easiest repairs you will ever make when you know what you are looking for. If your pipe is not insulated, it is a good idea to get it insulated before winter arrives, even if it is one of the larger pipes and it is fairly steeply angled. Now you should be able to easily identify whether your condensate pipe is frozen and know how to fix it yourself without requiring a qualified plumber to do the job.

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