Advertisement
74 NO CH OPERATION
Is the mode knob in the ON position?
Are the Timer and the Room Thermostat or cylinder
thermostat switched on?
Are the Radiator Valves Open?
Is there 230Vac at (A)?
YES
Check wiring from
terminal strip to
PCB.
75 NO DISPLAY
Is there 230Vac to the boiler at L and N (see Frame 74?
Is the wiring from the terminal block to the Main PCB
connected securely?
Is the ribbon cable from the main PCB to the User
Interface PCB connected securely?
YES
Is ribbon cable damaged?
YES
Replace ribbon cable
76 NO HW
Is the cylinder stat calling for heat?
Is DHW timer on?
Is boiler mode knob in the ON position?
Is there 230V at (A) Refer to Frame 74?
Check wiring from terminal strip to PCB.
54
FAULT FINDING
YES
YES
YES
NO
There is no Voltage from the
Timer/Room Stat. This is not
boiler fault. Ensure Voltage is
supplied to boiler by rectifying
external wiring.
YES
YES
Replace the
NO
User Interface
PCB
YES
YES
YES
YES
NO
Move the mode knob to the ON position
NO
Switch the Timer, Room Stat and Cylinder Stat On
NO
Open the Radiator Valves
L
N
NO
Supply power to the boiler
NO
Connect the wiring from the terminal block to the
Main PCB securely.
NO
Connect the ribbon from the main PCB to the User
Interface PCB securely
NO
Adjust cylinder stat
NO
Switch timer on
NO
Move the mode knob to the ON position
NO
Check system controls and wiring
A
Installation and Servicing
Advertisement
