Supplied By www.heating spares.co Tel. 0161 620 6677
36
221474C
3 Fault Finding
5665
If mains potential room thermostat is connected, ensure that the switch live is connected to
Pin 1 in the 5 pole connector.
Check continuity of clock/timer harness, ensure an electrical supply is available,
ensure that remote controls are calling for heat.
Isolate the boiler from electrical supply,
remove outer case.
Switch on electrical supply, is there a
display on clock/timer?
Faulty clock/timer. Replace.
Disconnect and insulate the yellow cables from
heating common and heating on
Advance clock/timer until a demand is indicated
Is there now continuity between heating
common and heating on?
Clock/timer in order if no central heating,
refer to main fault finding.
NO
NO
YES
YES
Faulty clock/timer. Replace.
5666
Diagram 3.6
DIGITAL CLOCK/TIMER
Does clock keep time
Set clock to off period. Is there continuity
across common and heating on
Clock in order if no
central heating refer to
main fault finding
Isolate electrical supply set clock to on period
Is there continuity across
common and heating on
Faulty clock
replace
No
No
No
If a mains potential room thermostat is connected, make sure that the switch line is connected to pin 1
the 5 pole connector.
Check continuity of clock harness, make sure an electrical supply is available make sure that remote
controls are calling for heat.
Yes
Yes
Yes
ELECTRO/MECHANICAL CLOCK/TIMER FAULT FINDING
Diagram 3.7
If mains potential room thermostat is connected, make sure that the switch live is connected
to Pin 1 in the 5 pole connector.
Check continuity of clock/timer harness, make sure an electrical supply is available,
make sure that remote controls are calling for heat.