Service manual

SC Series Boilers – Installation and Service Manual
36
Fenwal Module Fault Conditions:
LED Indication Steady on 1 flash 2 flashes 3 flashes
Error Mode Internal control
failure
Air flow fault
(hard lockout)
Flame with no call
for heat
Ignition lockout
(1 hour lockout)
The LED will flash on for ¼ second, then off for ¼ second during a fault condition. The pause between
fault codes is 3 seconds.
Troubleshooting Guides:
Symptom Cause/Cure
1. Dead
a. Miswired
b. Transformer faulty
c. Fuse/circuit breaker bad
d. Bad control (check LED for steady on)
2. Thermostat on – no blower
a. Miswired
b. Bad thermostat no voltage @ terminal W
c. Bad control (check LED for steady on)
d. Aquastat is not close
e. Air different pressure switch is not open
3. Pressure switch input okay but no trial for ignition after purge
delay
a. Miswired (check psw terminal voltage)
b. Flame sense problem (existing flame-check LED – 2
flashes)
c. Bad control (check voltage between L1 & IND)
4. Valve on, no ignition or spark
a. Shorted electrode (spark system)
b. Open HV cable (spark system)
c. Defective hot surface ignitor (hot surface)
d. Miswired
e. Bad control
5. Igniter or spark on, valve off
a. Valve coil open
b. Open valve wire
c. Bad control (check voltage between V1 & V2)
6. Flame okay during TFI, no flame sense (after TFI)
a. Bad electrode (spark)
b. Bad S1 or HV wire (spark)
c. Defective hot surface igniter (hot surface)
d. Bad S1 wire (hot surface)
e. Poor ground at burner
f. Poor flame (check flame current)
7. Flame with no call for heat a. Stuck valve (check LED for 2 flashes)
b). Flame Sensor Current Check
Flame current is the current which passes through the flame from the sensor to ground. The minimum
flame current necessary to keep the system from lockout is 0.7 microamps (µA). To measure flame
current, connect an analog DC microammeter to the FC- FC+ test pins on the module. The meter should
read 0.7 µA or higher. If meter reads below “0”, meter leads are reversed. Disconnect power and
reconnect meter leads for proper polarity.