Tutorial

Freezing weather and the boiler goes kaput - flue condensate frozen: guide

  • 15 February 2021
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Freezing weather and the boiler goes kaput - flue condensate frozen: guide
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Most of us across the country felt bone-chilling freeze over the last fortnight. Due to sustained heavy snow and the subzero temperature plunged the thermometer further causing my boiler to go kaput last night. 

I found myself without heating and hot water as my 10+ years old Worcester Bosch Combi boiler decided to give up ghost. After a cold night, I received some technical support which might come in handy if you face a similar situation. This might save a trip from the gas engineer, especially in covid restrictions.

The (frozen) condensate in the flue is the main culprit for the boiler to pack in this weather. Due to the fail-safe mechanism, the boiler shuts down till the emission can be detected again. A hot water bottle and/or reasonably hot water (not boiling) is a good rescue trick to melt the frozen condensate. Once the water has thawed your boiler will start working again.

Secondly, you would have to reset the boiler so follow the instruction manual for your respective boiler. In my case, it was holding the reset button for three seconds after complete power off. Additionally, adjustment of pressure might be required - again follow the instructional manual for your boiler. 

Lastly, I learnt in my frantic research to arrange a replacement boiler that the flue replacement is now a legal requirement when changing to a new boiler. Do check this with your installer if you are planning to get a replacement sometime soon.

I hope this helps!


3 replies

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Thanks for the tips @sylm_2000 ! :hugging:

Tim’s gone ahead and upgraded your post to a Tutorial thread, which also comes with a boost to help it stand out. If you’ve got any more tutorials or guides you’d like to share, feel free to post them anytime.

Userlevel 7
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When my Worcester Bosch gas boiler was installed  over 10 years ago it was common practice to route the condensate to the outside using 21mm PVC overflow pipe. The small diameter pipe would inevitably freeze in winter.

I rerouted this through an internal wall to join a 32mm waste pipe from the kitchen sink. That still ends up going to a gulley outside, but the larger diameter and frequent flushing of warm washing-up water means that there’s no risk of blockage due to ice.

Userlevel 5
Badge +1

When my Worcester Bosch gas boiler was installed  over 10 years ago it was common practice to route the condensate to the outside using 21mm PVC overflow pipe. The small diameter pipe would inevitably freeze in winter.

I rerouted this through an internal wall to join a 32mm waste pipe from the kitchen sink. That still ends up going to a gulley outside, but the larger diameter and frequent flushing of warm washing-up water means that there’s no risk of blockage due to ice.

 

Good call @Transparent! One night without heating and water made me realise how essential and dependent these services are. A small solution like you proposed can be incorporated as part of the design to avoid novice like me frantically searching for a cure on Google. 

 

I was on phone with my work colleagues in Houston (used to travel frequently for work) and their stories have a catastrophic end, including many loss of life. People have died because of carbon monoxide poisoning or fire in a desperate attempt to escape from cold weather. I feel blessed with hot water and heating working!

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