Prepare for a cold snap: How to thaw a condensate pipe

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10th February 2021

Prepare for a cold snap: How to thaw a condensate pipe

If your gas boiler stops working during a cold snap, one easy fix could be a frozen condensate pipe. It's a good idea to check this before you call for an engineer. 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. Knowing how to unfreeze it could save you from going without heating when you need it the most.

Your boiler's condensate pipe will run directly into a drain, in most cases externally to your property. If this pipe gets blocked with ice, or anything else, then your boiler will automatically shut down as a safety measure. If you suspect that your boiler condensate pipe has frozen, the following steps should help you get things back to normal quickly.

Step-by-step guide

Remember, if you don’t feel confident when following this guide then you should contact us on 0818 81 81 70 and request a visit from one of our registered gas installers.

1. Confirm the condensate pipe is frozen

Depending 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 blockage

The 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 pipe

Using 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 boiler

Once 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 trying

It may take several attempts before your boiler restarts, but if it doesn’t, you may need one of our Registered Gas Installers to visit to repair the boiler.

We’re here to help! Call our Service Team on 0818 81 81 70*. Monday to Friday 8.30am - 5.30pm (excluding Bank Holidays). Alternatively, you can email to log a request for your boiler repair. We will respond to your email within one working day.