Have you got a frozen boiler condensate pipe? Here’s what to do

Try these tricks to get your boiler up and running again before you call the engineer

One of the most common reasons boiler engineers are called out during cold snaps is because of a frozen boiler condensate pipe. Luckily, this is a problem that is simple to fix yourself and doesn’t require you to call a GasSafe registered engineer. Read on to learn how to get your boiler working again without having to spend a penny.

What is a boiler condensate pipe?

A boiler condensate pipe is a small but crucial part of your condensing boiler. Thanks to energy efficiency regulations, all boilers fitted in the UK since 2005 are required to use condensing technology. This works by capturing excess heat that exists in the flue gasses and recycling it into the boiler, rather than simply allowing this valuable energy to go to waste. During the process, the gas in your boiler’s flue will be reduced from around 130° to 50°. This produces up to 2 litres of condensation, which needs to be drained.

The condensation created during this process is disposed of with your household waste water. While it is often possible to connect to the internal drainage pipes from your kitchen or bathroom, this is not the case in every home and sometimes it can only leave the boiler through an external wall. In such cases, there is a much higher risk of experiencing a frozen boiler condensate pipe.

Where is my boiler condensate pipe?

Unless you are familiar with the workings of a boiler, you may well have no idea what any of the pipes connected to it do. Luckily, there is an easy way to tell which pipe is the boiler condensate pipe - it will be the only plastic pipe connected to your boiler. The pipe is usually 22mm in diameter if connected to the drainage system or 32mm if it is connected externally. This is because a bigger diameter helps to reduce the risk of freezing.

If you have an external boiler condensate pipe, it will usually emerge near the bottom of the boiler, which is typically about the same height as a ground floor window sill. It will either come down vertically or at a steep angle. This is necessary to make sure waste water from your sink and other appliances can’t travel up the pipe.

How can I tell if my condensate pipe is frozen?

Like with most boiler problems, you’ll probably discover it first when the heating stops working or you have no hot water. This will often be first thing in the morning, as temperatures in the UK usually reach their lowest overnight. You may also notice your boiler making an unusual gurgling sound.

In order to protect your system form any damage, sensors will automatically cause your boiler to shut down if the condensate pipe is blocked. If you have a digital control panel, you may see an error code displayed, however this will vary across different makes and models of boiler.

If your boiler has stopped working during a particularly cold snap, a frozen condensate pipe is by far the most likely cause, so before you call an engineer and risk an unnecessary expense, Use the following steps to diagnose and solve the problem yourself.

How to fix a frozen condensate pipe yourself

1. Locate your boiler condensate pipe

2. Check to see if you can see ice blocking the exit of the pipe
If this is the case, use hot water to melt the blockage and watch to see if water begins to escape once the end of the pipe is clear. If you see a flow of water, the problem should be solved and you will be able to reset your boiler. Check the handbook if you are unsure how to do this.

>3. Tap the pipe to determine if it has become frozen inside
If the pipe does not sound hollow, then it will likely be frozen inside. This is most likely to happen at flat sections or joints where the pipe changes angle, as this reduces the flow of condensate. Pour hot water over the frozen sections until you see condensate begin to flow out of the pipe, then reset the boiler as in the previous step.

4. Use a hot water bottle
This is a handy trick to heat the pipe for a longer period of time if pouring hot water doesn’t seem to be working.

Important safety advice

Don’t use boiling water

This is dangerous for you and can also damage the pipe. Use a container that is easy to carry and pour.

Do not attempt to cut or remove the boiler condensate pipe

It is a part of your boiler system and by law only a Gas Safe engineer is legally authorised to perform physical work on the pipe itself.

How to stop your boiler condensate pipe from freezing

When it comes to looking after your boiler and central heating system, prevention is always better than cure. It is advisable to familiarise yourself with the condensate pipe arrangement for your boiler and take some simple measures to protect it from frost before the winter weather arrives.

The best way to do this is to insulate it with high quality, waterproof cladding which is easy to do and will cost next to nothing.

If you regularly experience a frozen condensate pipe in winter, it may be worth speaking to a heating engineer about other options such as relocating the pipe or changing the angle.

If you have tried the above and your boiler is still not working, call us on 01978 291 923 / 01352 620 125 to speak to a Worcester Bosch accredited heating engineer today.