www.johnsonandstarley.co.uk
38
FLUE TEMPERATURE SENOR LOCKOUT
NO DISPLAY
NO DHW BUT CH ON
NO CH OPERATION BUT DHW WORKS OK
YES
YES
YES
Is the wiring secure to 9 way connector X5 on Interface PCB
Replace the PCB
NO
NO
Connect the wiring.
Secure connection.
Is the wiring securely connected to sensor?
See graph Figure 51.
YES
YES
Replace the PCB
NO
NO
Supply power to boiler.
Connect the wiring from the terminal block to the
Main PCB securely.
Is there 230VAC to the boiler at L & N?
Is the wiring from the terminal block to the main PCB connected securely?
YES
YES
YES
YES
Are the radiator valves open?
Replace the diverter valve
NO
NO
NO
NO
Toggle to the Winter position.
Switch the timer and room
thermostat on.
There is no voltage from the
timer/room thermostat. This
is not a boiler fault. Ensure
voltage is supplied to the
boiler by rectifying external
wiring.
Open the radiator valves.
Is the mode knob in the Winter position?
Are the timer and room thermostat switched on?
Is there 24V at ‘A’? (see diagram)
YES
NO
YES
NO
NO
YES
YES
YES
YES
YES
Is the hot & cold pipework crossed?
Replace the PCB.
Is the wiring connected between PCB &
DHW sensor?
Re-connect wiring
Replace turbine
sensor.
Remove the turbine,
check for debris in
the turbine & filter.
Replace turbine if
necessary. IS DHW
working?
NO
NO
NO
NO
NO
NO
NO
YES
Is the turbine working?
Adjust flow rates to achieve 35° temperature
rise and check filter fitted in turbine is not
blocked with debris.
Reconnect the wiring or replace wiring
harness if no continuity.
Re-engage diverter head and secure clip to
group set.
Change diverter Valve cartridge - rear
section.
Change diverter Valve cartridge - rear
section.
Replace the PCB.
Does the display show the hot water symbol?
Are the flow rates correct?
Is the wiring between the PCB and the
diverter valve motor connected?
Check diverter head is fully engaged and clip
is secured onto group set?
Check and replace diverter valve motor head.
Is boiler DHW working?
Check and replace diverter valve motor head.
Is boiler DHW working?
Is diverter stuck in the CH position
NO