Combination/Condensate Boilers

If you do have a combination/condensate boiler there is a quick and easy solution to get the heating back up and running without having to wait for a gas engineer to visit – just follow the advice below.

If you don’t feel confident defrosting the pipe yourself, don’t worry, ring our Technical Support Service on 0808 126 3123 or 01302 735191.

How do I know if I have a combination/condensing boiler with a condensate pipe that could freeze?

If your boiler is a Baxi/Potterton Duotec, Baxi/Potterton Solo, Vokera Mynute, Glowworm Hxi/Cxi, or a Vokera Unica, then it’s likely that you have a boiler that will have a condensate pipe fitted externally.

What does the condensate pipe do?

The boiler naturally produces a small amount of waste gas which turns to water as it cools. The condensate pipe drains this water outside.

How do I know if my boiler has a condensate pipe?

Look under the boiler to see if there is a plastic pipe - It’s usually white and around 20mm (about ¾”) wide. The pipe should run to the outside of your home and should always run into a drain.

An example of a condensate pipe is shown below. The condensate pipe is the diagonal pipe running along the side of the house.

Condensate Pipe

Why does it freeze?

The water dripping through the pipe can freeze in cold weather, preventing it from draining away. When this happens the boiler will shut down. To fix the problem the frozen water needs to be cleared.  

How do I know if my boiler has stopped working because the condensate pipe is frozen?

Check your boiler for an error code:

  • if you have a Baxi/Potterton boiler displaying ‘E1’ ‘33’ fault code; or
  • Vokera Unica or Vokera Mynute displaying the fault code ‘AL10’

then check the condensate pipe. If it is NOT frozen, ring the Technical Support Service on 0808 126 3123 or 01302 735191.

If it IS frozen and you feel able try to defrost it yourself then defrost the condensate pipe and reset your boiler following the instructions below.

How do I defrost the condensate pipe?

There are two ways to do this:

1) Pour hot water on the outside of the pipe. Don’t use boiling water to do this and only pour over the outside of the condensate pipe. Do not attempt to pour water down the pipe. Be careful to avoid any slips and trips by ensuring you do not get water on the path, as this will freeze.

2) Use either a hot water bottle or a heat wrap and place it around the pipe at the section where the water has frozen.

How do I reset the boiler?

Once defrosted, you can reset your boiler by turning the Selector switch to the Reset position and holding for at least 5 seconds. Remember, some boilers go through an electronic checking cycle after being re-set: this can take up to 15 minutes.

I’ve defrosted the condensate pipe, reset the boiler and it works fine - until it reaches a certain temperature, then it cuts out. What’s wrong?

The frozen pipe may have caused the boiler to flood causing an ignition fault. Try switching the boiler off for a few hours. If this doesn’t rectify the problem ring the Technical Support Service on 0808 126 3123 or 01302 735191.

Some things to remember …

  • Never try to thaw a condensate pipe that cannot be easily reached or disconnect the condensate pipe in the process.
  • Use extreme caution at all times when trying to find or thaw the condensate pipe.

What other issues can stop your combination boiler working in severe weather conditions?

Combination boilers work by heating hot water on demand: they take water straight from the mains supply, not from a tank. In severe weather conditions the mains water supply to your home can freeze.

Try running your taps: if there is no water from any of your taps the mains have probably frozen. If this happens you won’t be able to use your combination boiler until the mains defrost.

Regardless of whether you have a combination boiler; a condensate boiler; a gas fire back boiler; a wall mounted boiler; or a solid fuel appliance, switch your boiler off or let your fire go out until the water comes back on. Keep checking your taps. When the water comes back on you can use your appliance again.

Unfortunately there is nothing we can do to repair your boiler if your water supply has frozen.