Winter 2018 – Prevent a common winter boiler problem

We’ve grown used to relatively mild winters in the UK but the cold snap in late winter 2018 (and also this century in 2009, and 2010) has shown that large numbers of modern condensing boiler installations can succumb to the cold and stop running just when they are almost essential.

The common reason is frozen condensate pipes. Modern gas and oil boilers are by statute condensing to make them more energy efficient. They achieve the increased efficiency by condensing the water vapour in the exhaust gas thus recovering its latent heat of vaporisation. The condensate is mildly acidic water.

In large numbers of boiler installations the condensate pipe is run to an outside drain or just an open ended outside pipe. If there is a sustained period of freezing or below freezing temperatures, particularly when wind chill further reduces the temperature felt by the pipe, an exposed condensate outlet can freeze. Once the condensate in the pipe backs up the boiler will detect the problem and shut down.

This is a preventable problem. In most cases it is caused by the exposed nature of the condensate pipe. Occasionally poor installation is a factor, such as not enough fall or the pipe being run into a gutter or another drain which freeze up. If this is the case in your home ask you installer to correct it. Possible solutions to simply over exposed condensate pipes include:

  • Running the condensate pipe to an internal drain or soil stack
  • Replacing the existing pipe with an insulated condense pipe
  • Running the pipe on a wall which is not northerly and gains sunlight during daylight hours
  • Protecting the condensate pipe from the elements through covering and insulating.

If you have a frozen condensate pipe view The 50plus what to in an emergency page for information on what to do.

For more information on home and business maintenance, please contact us on 0845 22 50 495 or email