74
NO CH OPERATION
Is the mode knob in the ON position?
YES
YES
YES
YES NO
NO
Move the mode knob to the ON position
Are the Timer and the Room Thermostat or cylinder
thermostat switched on?
NO
NO
Switch the Timer, Room Stat and Cylinder Stat On
Are the Radiator Valves Open?
Is there 230Vac at (A)?
Check wiring from
terminal strip to
PCB.
Open the Radiator Valves
There is no Voltage from the
Timer/Room Stat. This is not
boiler fault. Ensure Voltage is
supplied to boiler by rectifying
external wiring.
A
75
NO DISPLAY
Is there 230Vac to the boiler at L and N (see Frame 79?
NO
Supply power to the boiler
Is the wiring from the terminal block to the Main PCB
connected securely?
NO
Connect the wiring from the terminal block to the
Main PCB securely.
Is the ribbon cable from the main PCB to the User
Interface PCB connected securely?
NO
Connect the ribbon from the main PCB to the User
Interface PCB securely
Replace the
User Interface
PCB
L
N
Is ribbon cable damaged?
Replace ribbon cable
NO
YES
YES
YES
YES
76
NO HW
Is the cylinder stat calling for heat?
YES
NO
Adjust cylinder stat
Is DHW timer on?
NO
Switch timer on
Is boiler mode knob in the ON position?
NO
Move the mode knob to the ON position
Is there 230V at (A) Refer to Frame 79?
NO
Check system controls and wiring
Check wiring from terminal strip to PCB.
YES
YES
YES
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