How to prevent a frozen condense pipe

Boiler fault call outs are on the rise, the cold weather is really setting in and causing lots of boiler problems. 

A common fault in very cold weather is a frozen condense pipe. Since 2005 the government brought in a new regulation that only condensing boilers can be installed.

The way that condensing boilers work is by returning water at a cool temperature, the cool water meets with the hot exhaust flue in the heat exchanger and this is the heat that causes condensation to form, when the temperature drops, the condensation is taken away and can freeze, this is where problems can occur.

You can try to gently unfreeze the condense pipe with something like a hot water bottle, heat pads or a warm jug of water (not boiling). Once it is unfrozen hold down the reset button on the boiler and it should start to work again. (Please only attempt to do this if your pipe is easily accessible at ground level, under no circumstances should you attempt to thaw a condense pipe which is at height, without the assistance of a professionally trained engineer).


Now is the time to start thinking about measures to prevent this from happening as a frozen condensate can back up into the boiler creating a very expensive repair bill.

How to prevent your condensate from freezing:

Replace the pipe with a larger diameter which is less likely to freeze, or even routed inside the house or a more sheltered spot then insulate.

Some other great tips to prevent cold weather plumbing problems:

  • Keep your eye on your water pressure or water flow because the first sign of a frozen pipe is restricted water flow. Consider leaving your tap open slightly in order to allow water to flow. This water movement can prevent freezing, although it will affect your water bill over extended periods of time.
  • Disconnect garden hoses and drain outdoor pipes as they can cause major damage if left connected and freeze.
  • Cover outside faucets using a faucet insulation kit.
  • Keep garage doors closed if you have any pipes in there to keep temperature higher.
  • Get your boiler serviced to ensure it is working correctly and there are no leaks and drips which can freeze.
  • Know where your property’s internal stop tap is, and make sure it will turn off if you ever need to. Most stop taps are fitted under the kitchen sink and close by turning clockwise.
  • Open kitchen and bathroom cabinet doors to allow warmer air to circulate around the plumbing.
  • If it gets very cold consider raising the temperature on your thermostat. If you normally lower the temperature at night, leave it at the daytime setting.

For help and assistance with boiler faults please call us on 01204 396669.