Schwank 2-Stage Series - Manual (Page 37)

37
SET(U)-F / ITT(U)-F Manual
IM091221
RD: FEB 2014
RL: 8B
Improper adjustment, alteration, service or maintenance can
cause property damage, injury or death. This heater must be
SEQUENCE OF EVENTS (also see DSI Troubleshooting previous page)
22. TROUBLESHOOTING GUIDE - HEATER OPERATION
WARNING
SET THERMOSTAT TO CALL FOR HEAT
APPLY 120 VOLTS
 CHECK 120V TO DSI AT “L1”
 CHECK 120V OUT AT “IND” FROM DSI TO BLOWER 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
 CHECK INTEGRITY OF SWITCH
 REPLACE DEFECTIVE SWITCH
 CHECK DSI CONTROL FUSE FOR CONTINUITY
 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)
 PERFORM IGNITION LEAD TEST (See SPARK IGNI-
TION CIRCUIT INSTRUCTIONS—Section 22)
 GOOD SPARK.....REPLACE IGNITER
 NO SPARK/OR WEAK.....REPLACE CONTROL
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
 CHECK FOR AND REMEDY ANY OBSTRUCTION IN
THE VENT / TUBE