York LL8V*DH, PV8*DH This Diagram Shows Two Ignition Attempts, Timing Lengths Are Not To Scale

271015-UUM-A-0407

ON

W2 SIGNAL

	OFF
HIGH INDUCER	ON
HIGH STAGE PRESSURE	OFF
	ON
SWITCH AND 2ND STAGE
MAIN VALVE	OFF
CIRCULATOR HIGH	ON
HEAT SPEED	OFF
	CALL HIGH HEAT AFTER LOW
2ND STAGE	HEAT IS ESTABLISHED

HIGH

HEAT

OFF DELAY 30 SEC.

	CLOSED
HIGH LIMIT
	OPEN
W1 SIGNAL	ON
	OFF
LOW	ON
INDUCER
	OFF
LOW STAGE	CLOSED
PRESSURE
SWITCH	OPEN
HSI	ON
	OFF
1ST STAGE	ON
MAIN VALVE
	OFF
FLAME	PRESENT
SENSE	ABSENT
LOW CIRCULATOR	ON
HEAT SPEED	OFF
		HSI		INTER-	HSI	HEAT FAN	BURN
		WARM		PURGE	WARM	DELAY ON	TIME
		UP		60 SEC.	UP	30 SEC.
	LOW PRESSURE	17 SEC.			27 SEC.
1ST STAGE
	SWITCH CLOSE							POST
	RECOGNITION			IGNITION				PURGE
								15 SEC.
				DEACTIVATION
	IGNITION			PERIOD
				3 SEC.				HEAT FAN DELAY OFF
	ACTIVATION
			TRIAL FOR

PERIOD	IGNITION	SELECTABLE
		60,90,120,180 SEC.
4 SEC.
	7 SEC.

NOTE:

1.THIS DIAGRAM SHOWS TWO IGNITION ATTEMPTS

2.TIMING LENGTHS ARE NOT TO SCALE

FIGURE 7: Furnace Control Event Schedule

Unitary Products Group 9