Honeywell 7800 Series Manual page 29

Fig. 22—DSI High/Low Stepfire sequence timing diagram.
IGNITION- T10
PILOT- T8
MAIN- T9
AIR VALVE-T5
FLAME PROVEN- T21
ALARM- T3
MOTOR POSITION- T12-T15
@ LOW FIRE INPUT- T18
LIMITS COMPLETE- T7
SF1 SPECIAL FUNCTION- T6
SF2 SPECIAL FUNCTION- T17
SF3 SPECIAL FUNCTION- T19
SF4 SPECIAL FUNCTION- T20
FLAME SENSED
STANDBY HIGH/LOW
STEPFIRE-
INPUT &
PART 1
OUTPUT
SIGNALS
STANDBY-
PURGE
4 SECONDS
POWER
POWER POWER
PILOT
PILOT
FLAME
FLAME
MAIN
ALARM
L/H/MOD L
29
HIGH/LOW HIGH RETURN TO
STEPFIRE- HIGH/LOW
PART 2 STEPFIRE-
PART 2
2 TO 2 TO
INFINITE INFINITE
SECONDS SECONDS
POWER POWER
POWER
PILOT PILOT PILOT
FLAME FLAME FLAME
MAIN
(SEE
PREVIOUS
COLUMN
FOR PART 2)
L MOD
RM7888A
OPERATION
M9499
65-0175