Schwank P40U Fenwal - Manual (Page 35)

35
P40U-F / P40U-IF I&O Manual
IM101220
RD: MAY 2014
RL: 5A
24. TROUBLESHOOTING GUIDE — HEATER OPERATION — FENWAL DSI
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
APPLY 120 VOLTS - GREEN LIGHT
 CHECK 120V TO DSI AT “L1”
 CHECK 120V OUT AT “IND” FROM DSI TO
COMBUSTION AIR BLOWER
AIR PROVING SWITCH HAS
CLOSED 24 VOLTS IS PRESENT
AT “PSW” AT DSI CONTROL.
 CHECK TUBING TO SWITCH IS CON-
NECTED AND NOT BLOCKED OR KINKED
 CHECK AIR PRESSURE WITH MANOME-
TER
 CHECK FOR OBSTRUCTION IN THE AIR
INTAKE
 CHECK DSI CONTROL FUSE FOR CONTI-
NUITY
 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 OVERHEAT-
ING
 IF “YES” ... TAKE PROTECTIVE ACTION TO
SHIELD CABLE AND BOOT FROM EXCES-
SIVE TEMPERATURE; REPLACE ANY DE-
FECTIVE COMPONENT
SPARK IGNITER / SENSOR
24V TO GAS VALVE - RED LIGHT
CONTINUED
SEQUENCE OF EVENTS (also see DSI Troubleshooting previous page)
NO
YES
YES
YES
NO
NO
 REMEDY 120 VOLTS SUPPLY FAULT NO
NO
 FAULTY RELAY SWITCH IN DSI — RE-
PLACE DSI
BLOCKED FLUE SWITCH IS
CLOSED
24 VOLTS IS PRESENT AT “TH” AT
YES
NO
 CHECK TUBING TO SWITCH IS CON-
NECTED AND NOT BLOCKED OR KINKED
 CHECK AIR PRESSURE WITH MANOME-
TER
 CHECK INTEGRITY OF SWITCH
 REPLACE DEFECTIVE SWITCH
WARNING