Manifold controller not calling for heat?

[pacemaker1000]

I have two manifolds on two floors. Second floor is working perfectly, room stat calls for heat, actuators open, pump comes on and demand light comes on and calls for heat from the boiler.

ground floor has suddenly stoped demanding heat?

stats on, actuators open and pump comes on but demand light doesn’t come on and boiler won’t start?

 

thanks

 

 

 

[pacemaker1000]

Had two red herrings.🙄

bulb gone in 'heat demand' tested with metre and ok.

temperature sensor in wrong place. Was on 2nd manifold tee meaning only way it got heat was conductive and not flow.

 

adjusted and boiler now comes on at 40 and off at 45