Technical data

12.0 Fault Finding
12.1 Central Heating
NO
Switch on power,
set selectors for
CH on and DHW
off.
Set all controls to
call for heat.
Does the burner
fire?
Is lockout lamp on
burner or panel
lit?
Is high limit
thermostat lamp
lit?
Is there continuity
across the boiler
stat connections
17 and 18 on the
PCB?
Is there continuity
across the
connections 28
and 30 on the
PCB?
Check power
from clock or
switch, check
wiring fuses and
mains supply.
Refer to burner
fault finding.
Press reset
button, replace if
necessary.
Check wiring,
replace boiler
thermostat.
Check relay and
PCB, replace.
Do radiators get
hot?
Does boiler cycle
on its thermostat?
Check all valves
are open and
pump is working,
check pressure,
check all air is
vented.
Check boiler
thermostat,
replace if
necessary.
HEATING IS
WORKING
NORMALLY
YES
YES
NO
NO
NO
NO
YES
YES
YES NO
YES
YES
NO
Page 44