Weil-McLain 550-141-850/0599 IXb Operation — sequence, Steps, Standby, Call for heat, Limit cycle

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IXb Operation — sequence

Figure 22 Ignition control module sequence of operation — status light indications

Steps			POWER TSTAT	LIMIT	PRESS FLAME
		Call for	CIRC		SWITCH	Timing
		heat?
(Following step 8, cycle goes back to step 1.)
1.	Standby	NO				—
	· Waiting for call for heat
2.	Call for heat
	· Circulator on	YES				—

· Blower on

3.Limit circuit

·	Limit controls closed	YES	—
· Block switch contacts closed
4. Pressure circuit
·	Pressure switch contacts closed	YES	35 sec

·Igniter heating

5.Flame proven

·Gas valve open

·	Ignitor remains on	YES	6 sec
·	Boiler producing heat
6. Limit cycle
·	Limit circuit open	YES	—

· Gas valve closed

7.Flame outage *

· Flame out YES —

· Boiler recycles

8.Thermostat satisfied

· Circulator off NO 30 sec

·Blower postpurge

or = "ON" = "OFF"

*If flame is not proven in 4 seconds, boiler recycles 2 times to retry for ignition before going into lockout. Recycle igniter timing is 30 seconds. Postpurge and prepurge are performed on every cycle. In event of lockout, ignition control will automatically restore sequence of operation after either:

1 hour waiting period.

Opening and closing of thermostat circuit.

Removal of 120 VAC power for at least 45 seconds. 85050

Part number 550-141-850/0699 51