Frozen Condensate Pipe

Even the most looked after boiler will struggle to function if its condensate pipe freezes. Luckily, it’s not a difficult job to put things right if it does happen. This handy guide will help you get your boiler up and running quickly and easily.

What is a condensate pipe?

A condensate pipe carries condensation from your boiler to your outside drain. It’s usually a white or grey plastic pipe that travels from your boiler through the wall directly outside where your boiler is located. During cold weather, the condensation in this pipe may freeze and cause a blockage causing the condensation to back up into the boiler and cause it to shut down.

Step-by-step guide

If you suspect that your boiler condensate pipe has frozen, the following steps should help you get things back to normal quickly.
Remember, if you don’t feel confident when following this guide then you should contact an expert boiler engineer for help.

1. Confirm the condensate pipe is frozenDepending on the make and model of your boiler, a frozen condensate pipe may be indicated by a ‘fault code’ or warning light on the boiler’s display. Gurgling or bubbling sounds coming from the boiler or the condensate pipe are another sign that the condensate pipe has frozen.
2. Locate the blockageThe pipe is probably frozen at its most exposed point. This may be the open end of the pipe, or at a bend or elbow. Running your hands over the pipe until you find a section that feels colder than the rest should help you identify the blockage quickly.
3. Use hot water to thaw the pipeUsing a jug or watering can, pour hot water along the length of the pipe, repeating the process until the pipe has thawed (do not use boiling water as this can crack or damage the pipe). If you’re using a kettle, make sure to cool the kettle for at least 15 minutes once it’s boiled. Alternatively, you can use a hot water bottle or a heat pack to slowly defrost the pipe.
4. Restart your boilerOnce the frozen section has been melted and cleared, check your boiler manual for instructions on how to reset the boiler correctly. Your boiler should now restart.
5. Not fixed? Keep tryingIt may take several attempts before your boiler restarts, but if it doesn’t, you may need to call out a qualified boiler engineer.