27
SST Extreme X & SST Extreme S MODULATING I&O Manual
RD: JAN 2021
RL: 1A
SEQUENCE OF EVENTS
(also see DSI Troubleshooting previous page)
11. TROUBLESHOOTING GUIDE
-
HEATER OPERATION
WARNING
Improper adjustment, alteration, service or maintenance can
cause property damage, injury or death. This heater must be
installed and serviced only by a trained gas service technician
SET THERMOSTAT TO CALL FOR HEAT
APPLY 120 VOLTS
•
CHECK 120V TO DSI AT
“
L1
”
•
Check 24VDC Power Unit for 24vdc at the output
COMBUSTION AIR BLOWER STARTS
AIR PROVING SWITCH HAS CLOSED 24
VOLTS IS PRESENT AT
“
PSW
”
AT DSI
CONTROL.
•
CHECK TUBING TO SWITCH IS CONNECTED AND
NOT BLOCKED OR KINKED
•
CHECK AIR PRESSURE WITH MANOMETER
•
CHECK FOR OBSTRUCTION IN THE AIR INTAKE
•
REPLACE DEFECTIVE BLOWER
•
VISIBLY CHECK IF IGNITER IS SHORTING OUT
•
CHECK GROUND WIRING
•
REMOVE AND INSPECT IGNITER AND LEAD
•
CHECK BOOT OF THE IGNITION CABLE FOR SIGNS
OF MELTING OR OVERHEATING
•
IF
“
YES
” ...
TAKE PROTECTIVE ACTION TO SHIELD
CABLE AND BOOT FROM EXCESSIVE TEMPERA-
TURE; REPLACE ANY DEFECTIVE COMPONENT
•
CHECK CERAMIC INSULATOR AND CAP
•
CHECK SPARK GAP SETTING IS
3/16”
(ADJUST BY
MOVING THE GROUND PRONG ONLY)
SPARK IGNITER / SENSOR
24V TO GAS VALVE
CONTINUED
NO
YES
YES
YES
NO
NO
•
REMEDY 120 VOLTS SUPPLY FAULT
NO
NO
•
FAULTY RELAY SWITCH IN DSI —
REPLACE DSI
BLOCKED FLUE SWITCH IS CLOSED
24 VOLTS IS PRESENT AT
“
TH
”
AT DSI
CONTROL.
YES
NO
•
CHECK TUBING TO SWITCH IS CONNECTED AND
NOT BLOCKED OR KINKED
•
CHECK AIR PRESSURE WITH MANOMETER
•
CHECK INTEGRITY OF SWITCH
•
REPLACE DEFECTIVE SWITCH
