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Jan 8, 2022
2
0
1
Portsmouth
Member Type
DIY or Homeowner
Woke this morning to no hot water but heating was working fine. Checked the forums and checked all the common problems:

Water and boiler pressure both ok
Timer ok (hot water set to all day)
No leaks and condenser pipe not frozen
No error codes
Tried running hot water with heating turned off

When I ran the hot water I didn’t get either the pilot light or hot water demand symbol on the boiler display. Only S code was S.7 which manual says is a heating code.

I did get a couple of bursts of hot water - once after setting the warm start function (for the first time ever) and again after resetting the boiler. during this I got the S codes S.20 (warmstart demand) and S.24 (burner ignited) But the temperature was lukewarm not hot. After turning the tap off I got S.25 (fan and water pump running) and S.27 (pump overrun). Stopped running the tap, tried again 10 minutes later and back to square one - freezing cold water, no pilot light coming on and no whirring noises from the boiler.

Any idea what this could be?
 
I’m a little confused, some of what you’re posting suggests combi boiler, but timer set to all day? If you have a motorised valve, then this is likely your issue.
 
Sorry the sunvic heating/hot water programmer (not the boiler itself) is set to have hot water all day and not just between certain times
Sounds like your motorised valve is stuck. At a guess I’m saying you have a 3 Port valve, and you get hot water when the heating is on.

Post a photo of the boiler and the cylinder cupboard.
 

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