Condensing boiler tips

Why the condensate pipe can freeze

Condensing or 'condensate' boilers work in a similar way to conventional gas boilers, but use energy more efficiently by reusing heat from the flue gases to heat additional water.

During this process the boiler produces left over water vapour that cools to leave 'condensate'. This condensate is disposed of through your home's waste water system.

The outlet pipe for the condensate may be outside your home if there wasn't room for it inside. If so, cold temperatures can freeze the condensate in the pipe and this can cause a blockage that will shut your boiler down.

Usually, there will be a fault code on the boiler's display or an alarm will sound. Your boiler's operating manual will explain the fault code. However, the most obvious sign may be that you have no hot water or heating.

What you can do if it's frozen

If you feel confident and safe enough, try to thaw your pipe:

1. Locate the blockage – it's likely to be at the most exposed external point, or at a bend or dip in the pipe
2. Thaw the frozen pipe – use a hot water bottle close to the blockage (don't pour boiling water directly on to the pipe)
3. Restart your boiler – follow the instructions in your boiler's manual to do this

How to stop it from freezing

There are a few steps you can take to help prevent your condensate pipe from freezing up in cold weather:

• Insulate your condensate pipe with weather-proof insulation to help protect it from the cold
• Leave your heating on overnight at a lower temperature to keep the condensate warm. Although this uses energy, your boiler will take less time to heat up your home in the morning
• Set your boiler thermostat to a higher temperature. This will use more energy and so reduce the amount of condensate created. Only do this if you have radiators rather than underfloor heating. And be careful as your radiators will get very hot

If you do change any heating settings, remember to return them to normal once the cold spell is over.

These steps may not prevent freezing in extreme weather conditions. If you want to take further action, detailed guidance will be available from your installer or service engineer.