Worcester CDI37 - heating wont start

[antdaz68]

Hot water is fine, have reset system and bled radiators, also changed room thermostat (has illumination light when not at temperature).
Next step is heating engineer unless somebody can help

 

[twgas]

How's the pressure?

 

[antdaz68]

pressure is fine ..... circa 1.3 bar.

Have currently got heating working for only 15 minutes at a time by holding the boost button in for 10 seconds, all radiators are heated okay (this I think is a servicing function)

 

[ianmcd]

sounds like a controls fault , what controls do you use it it a plug in timer or external or external thermostat ?

 

[antdaz68]

I have an analogue timer but always have heating permanently at ON and control the need for heating by altering the thermostat.
The thermostat is also a WIRED basic one (Honeywell T6360B) which I've already replaced

 

[ianmcd]

if you are confident with electrics then "link out" your external controls to rule them out, if everything is heating when you run it in Control override mode or test mode as you call it then that suggests the problem is with the external controls