28
Compact
7.12.4 FAULT FINDING TEST ‘B’: CHECK CONTROL IN DHW MODE
NO
NO
NO
NO
NO
YES
YES
YES
IS
VOLTAGE
ACROSS TERMINALS
OF MODULATOR
COIL >
10 VDC
REPLACE WIRE
AND
CONNECTIONS
REPLACE
CONTROL BOARD
REPLACE
MODULATOR COIL
IS THE
RESISTENCE OF
MODULATOR COIL
ABOUT 70/80
OHM
IS
THERE A
VOLTAGE >10 VDC
BETWEEN TERMINALS
CN9.7 & CN9.8
ON PCB
DOES
BURNER LIGHT
CHECK BOILER
STARTUP:
TEST A
TURN ON TAP
SWITCH ON BOILER AND
SELECT MODE TO
SUMMER. DHW
THERMOSTAT AT MAX.
START
YES
SWITCH DHW
THERMOSTAT AT MIN.
DO
BURNER AND FAN
SWITCH OFF
IS
TEMPERATURE
>40 ˚C
WAIT D.H.W.
TEMPERATURE
>40 ˚C
REPLACE
CONTROL BOARD
YES
NO
YES
NO
IS
THERE 24 Vdc
BETWEEN TERMINALS
CN9.7 & CN9.8
ON PCB
REPLACE
CONTROL
BOARD
YES
CHECK WIRING AND
CONNECTIONS OR
DHW SWITCH
YES
NO
IS
THERE 0 Vdc
BETWEEN TERMINALS
CN9.7 & CN9.8
ON PCB
NO
WAIT TILL THE
VOLTAGE BETWEEN
TERMINAL CN9.3 & CN9.4
ON PCB IS < 1.2 Vdc
IS THE
VOLTAGE BETWEEN
TERMINAL CN9.3 &
CN9.4 ON PCB IS
< 1.2 Vdc
IS
TEMPERATURE
>60 ˚C
WAIT D.H.W.
TEMPERATURE
>60 ˚C
YES
YES
NO
IS
D.H.W. NTC
OK
REPLACE D.H.W. NTC
REPLACE
CONTROL BOARD
YES
B
NO
D.H.W.
D.H.W.
