54
Installation and Servicing
Section 4 - Fault Finding
FAUL
T FINDING
4.13 NO DHW OPERATION
4.12 NO DISPLAY
Is there 230Vac to the boiler at L and N?
YES
NO
Supply power to the boiler
Is the wiring from the terminal block to the PCB
connected securely?
YES
NO
Connect the wiring from the terminal block to the
PCB securely.
Replace the PCB?
Is the cylinder stat calling for heat?
YES
NO
Adjust cylinder stat
Is DHW timer on?
NO
Switch timer on
Is OFF shown under Tap symbol?
YES
Press mode button until OFF is not shown under the
Tap symbol
Is there 230V at SL2 IN?
NO
Check system controls and wiring
Is an Outside Sensor connected?
YES
YES
YES
4.14 FLOW/RETURN DIFFERENTIAL GREATER THAN 50°C
Are isolation valves open?
YES
NO
Open isolation valves
Is pump operating?
YES
NO
Check pump wiring, if Ok replace pump
Are radiator valves open?
Open radiators valves
YES
Check for system blockages
NO
YES
Press mode button until OFF is not shown under the
Tap symbol
Check wiring from terminal strip to PCB.
YES