Smith Cast Iron Boilers GT Series manual Operational Flow Chart

GT INSTALLATION AND OPERATION INSTRUCTIONS Page 31

Figure 43 - Operational Flow Chart

	120v Power		Displays version			Boiler in
	Applied		t2.0 or t4.0			standby Mode
				Indirect thermostat or flow			Thermostat End switch
				switch closes A-C			or relay closes T-C
Energizes 3 way	Combi model	Combi or		(Call for Domestic)		Awaiting	(Call for Heat)
diverter valve		indirect				Input
	Indirect						Energizes Primary
Energizes Primary	Water		Energizes Indirect Pump
	Heater		(Ap) turns off C1				Pump (C1)
Pump (C1)
				Air
Error			Closed	Switches		Sentry 2100	(Call for Ignition)
ASC
				Open			Sentry 2100
						Sentry 2100
24 Volt signal
to blower							24 V
						Sentry 2100	Manifold & Stack Limit
					Fan to SFS (75)
				Open			(GT 150 & GT 200)
	Open		Closed				Manifold Limit & Flow
	NC			NO			Switch
	Hi pressure	Closed					(GT 400)
Error	N. C. switch on
	GT 400 only
ASO							24 V
		Power to ignitor		Prepurge		IGNITION MODULE
		120v from S1				S1 L1 L2 S2 W MV GND
	Igniter warm-up
	5 seconds						Three retries
							for flame

Power to Gas valve

Flame Probe

Sentry 2100

Modulates fan based

upon setpoint and

programming

Signal <1 microA

Less than 1.0 microA

Greater than 1.0 microA

Call for flame ends