Heating not firing, hot water ok

22 Apr 2012
Reaction score
United Kingdom

I have a Worcester Bosch 40cdi conventional boiler. Controlled via Hive.

During the recent big freeze the boiler has been working fine with both heating and hot water working fine.

Now that the big thaw is occurring I find that my boiler won't fire for heating! The boilers core temperature with the water off is 17 deg C. Not the 50 deg c it normally sits at.

The boiler pressure is correct at 1 bar. When Hive requests hot water the boiler fires ok. However when Hive requests heating nothing happens.

I have checked that the A->B valve is opening when heating is requested and the condensate pipe seems to be unfrozen (but hey it did not get below freezing last night).

I have just turned the boiler off for two minutes and i have turned it back on with heating and hot water demanded and i am now waiting for it to complete it's calibration cycle. But I doubt this will sort it.

Anything else I should be looking at?

Any advice greatfully recieved!

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Nope turning here on and off did not help. Still working fine for water, but no heat.
We did have a 20 mins power cut yesterday and the Mrs thinks that the heating was working after that but never managed to reach its 18 deg c desired temperature.

Possibly relevant.

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