Preventing and Thawing Frozen Condensate Pipes

It's important to know how to thaw frozen condensate pipes.

With the UK experiencing bitterly cold winter temperatures, it’s important your heating system is working efficiently. Here’s some simple advice on how to thaw out a frozen condensate pipe.

You boiler condensate discharge pipe may be at risk of freezing in prolonged, and extreme cold weather conditions.

If your condensate pipe runs externally, it could be at risk of freezing. If it does freeze, it will cause your boiler to stop working, which wouldn’t be ideal.


During extremely cold conditions it may be wise to increase your flow temperature on your boiler (the temperature that flows out of the boiler). This should decrease the condensate and reduce the risk of freezing during a very cold spell.

Just remember to return the flow temperature back to its normal position once the cold patch is over.

1. Locate the blockage

The condensate discharge pipe usually freezes at its most exposed points, such as the open end of the pipe, at a bend or elbow, or where there is a dip in the pipe where condensate can collect.

2. Thaw the frozen pipe

The condensate can be thawed in a number of ways. Either apply a hot water bottle or microwaveable heat pack around the blockage, or pour warm water onto the pipe. It is important that you do not use boiling hot water.

Please take care if your condensate discharge pipe is not easily reached from ground level, and do not put yourself at any undue risk. Remember that if you’re pouring warm water onto the pipe, it can quickly freeze, causing a slip hazard.

3. Restart the boiler

Once the frozen blockage has been cleared, the boiler will usually need to be reset. Advice on how to do this can be found in the user manual. Normally, this will involve simply pressing a reset button on the front of the boiler, or in some cases by isolating the electrical supply to the boiler and switching it back on.

4. Book your annual service

Give your boiler some TLC by getting it serviced annually. This will help to maintain its efficiency and prevent breakdown. Call us today on 0800 111 40 40 to arrange.

Stay safe and stay warm!

Guidance provided by The Heating and Hotwater Industry Council (HHIC). Please get in touch with us today if you need assistance.

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