Fault Finding
Fault Finding Fault Finding Fault Finding Fault Finding Fault Finding
Independent + Combi - Installation and Servicing
84
NO HW BUT CH ON
85
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 Main PCB
connected securely?
YES
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
YES
Replace the
User Interface
PCB
N
Is ribbon cable damaged?
YES
Replace ribbon cable
NO
N
L
Does the display show “d” when a tap is on?
NO NO
YES
Are the ow rates correct as per Frame 2.
Is the wiring between the PCB and the diverter
valve motor connected?
YES
YES
Check diverter head fully engaged and clip
secured onto waterset.
YES
Is diverter stuck in the CH position
YES
Check and replace diverter valve actuator head.
Is Boiler DHW OK?
NO
Change diverter valve assembly
NO
Adjust ow rates to achieve 35º
temp rise and check lter tted in
turbine is not blocked with debris.
NO
Reconnect wiring or
replace wiring harness if
no continuity.
NO
Re-engage diverter
head and secure clip to
wateset
NO
Replace PCB
Is hot and cold pipework crossed?
Is the wiring connected
between PCB and DHW
sensor?
Remove the turbine, and
check for debris in the
turbine & lter. Replace
turbine if necessary. Is
DHW OK?
YES
NO
Re-connect wiring
NO
Replace turbine sensor
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