Halstead Platinum, DHW ok, No CH

[Vera]

My boiler is 1 year old and tripped out with excessive heat as the fault cold.
I ran it in DHW mode for12 hours with no problems. I am now trying to get the CH working and now it doesn't trip but does not respond to CH demand.
Room stat is max and timer is on.

 

[ChrisR]

Does it do anything - click, whirr..? Worth checking external controls if not.

 

[Vera]

Hi Chris
The boiler did nothing, I checked externals and found a faulty room stat, I relaced this with a shorting link and the boiler now does it's start up checks but still no CH.
Halstead suggested I turn the control to the spanner setting, this should fire the boiler up in low heat/service mode, this had no effect.
The knob was found to have a broken spindle and the ch now works.