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Don’t be cold! Learn how thawing your boiler’s condensate pipe could rescue you this Winter.

Posted on September 20th 2018

The condensate pipe is the exhaust for your combi-boiler which runs outside the house expelling waste water and can become frozen in cold weather. If this happens it will prevent your heating from working effectively and is likely to cause boiler breakdown.

There are a few warning signs you can look out for, which will tell you whether your condensate pipe is frozen.

  1. Error codes EA appearing on the boiler.
  2. A gurgling noise coming from the boiler, indicating that the condensate isn’t escaping.
  3. Heating working inefficiently.

If you notice any of these warning signs go outside and check the pipe. If nothing is being expelled from it but the boiler is active, then you can be fairly sure it’s frozen.

Thawing a condensate pipe can be very simple, depending on where it is located. If it’s easily accessible then, according to Worcester Bosch, the most effective way to thaw the pipe is with warm water. Simply pour the water in a stream until the pipe has thawed.

Note – Never use boiling water as this can cause a frozen pipe to crack.

You can now reset your boiler and it should be working.

If your condensate pipe is not easily accessible then thawing it will be trickier and you should call one of Diamond Gas and Heating’s engineers. It may be that we are able to talk you through a solution in a face to face consultation over the phone using the Facetime app.


Although fixing a frozen condensate can be straightforward, prevention is better than cure and since it’s still September there is time to take precautions in the event of a winter like that of 2017.

There are a couple of great solutions from Worcester Bosch which are really cost-effective and will offer you peace of mind.

The first of these is insulation – special insulation sleeves can be wrapped around the pipe to prevent it from freezing. In addition, Worcester Bosch recommends having the route of the pipe running vertically so the water can run through as quickly as possible, giving it less chance to freeze. If your combi boiler has been fitted by a Worcester Bosch accredited installer then it likely is vertical.

Worcester Bosch also offers another very innovative solution – the CondenseSure Syphon.

This clever bit of kit, which comes built in to some boilers (see below), can be easily fitted by an engineer and stores half a litre of water which runs through the pipe all at once making freezing less likely. It can also be fitted to the central heating flow pipe so the condensate water is warmer when it is expelled from the boiler.

Worcester Bosch’s Greenstar i and Greenstar CDi classic boilers both come with CondenseSure siphon built in.

According to the brand, this has been proven to be effective at preventing frozen condensate up to -15°C over a sustained period of 48 hours.

So, if you think your boiler pipes could do with insulating, or if you would like to enquire about a new boiler or CondenseSure siphon, then contact Diamond Gas & Heating today.