How to prevent a frozen boiler condensate pipe this winter

It’s that time of year again when the clocks go back, the evenings get darker and temperatures begin to fall. It is also the time of year when people can begin experiencing problems with their heating due to a frozen condensate pipe. Here’s how to avoid having a problem, and what to do before you call an engineer.

What is a boiler condensate pipe?

A boiler condensate pipe is a small but crucial part of your condensing boiler - but also one of the most vulnerable components as far as the weather is concerned. Since 2005, UK energy-saving standards have meant that all new boilers - both gas and oil - must use condensing technology. This allows the boiler to capture excess heat that exists in the flue gasses and recycle it into the boiler, instead of simply allowing the 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, usually with your household wastewater.

In many cases, the condensate will leave the boiler through an external wall to join the outside drainage network. Because of this, there is a risk of encountering a frozen condensate pipe if the weather is particularly cold.

How to prevent a frozen boiler condensate pipe

Just like with anything else, prevention is better than cure when it comes to looking after your boiler and central heating system. It only takes a moment of your time to reduce the risk of a frozen condensate pipe with a simple, low-cost solution - pipe insulation.

All you need to do is locate the condensate pipe and insulate it with high quality, waterproof cladding. It’s easy to do and will cost next to nothing.

If you regularly experience a frozen condensate pipe in winter and insulation has not solved the problem, it may be worth speaking to a heating engineer about other options such as relocating the pipe or changing the angle.

Where is my boiler condensate pipe?

No idea how to find your boiler condensate pipe? Don’t stress, there is an easy way to find - it will be the only plastic pipe connected to your boiler. The pipe is usually just over 2cm in diameter if connected to the drainage system or about an inch if it is connected externally, as it is in most older properties. The bigger diameter pipe helps to reduce the risk of freezing.

You will usually find an external boiler condensate pipe near the bottom of the boiler, typically about the same height as a ground floor window sill. It will either come down vertically or at a steep angle. This helps to make sure wastewater from your sink and other appliances can’t travel back up the pipe and cause problems.

How can I tell if my condensate pipe is frozen?

Although you may notice your boiler making an unusual gurgling sound, the first sign of a frozen boiler condensate pipe is usually when you unexpectedly wake up to a freezing cold house! This is because in the UK, the lowest temperatures are usually experienced at night.

Modern boilers are fitted with many sensors to protect you and your household. This means it will probably shut down if the condensate pipe is blocked. If you have a digital control panel, you may also 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, the following steps will help you to diagnose and solve the problem yourself before calling an engineer and risking an unnecessary expense.

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

Never use boiling water
This is dangerous for you and can also damage the pipe. Use hot but not boiling water in a container that is easy to carry and pour.

Never 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.

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