Weil-McLain 550-110-260/02002 manual 9a Operation — sequence, Boiler Manual

Boiler Manual

9a Operation — sequence

1.Read Lighting instructions on page 34. This information is also located on a label on the inside of the boiler jacket door panel.

2.Raise room thermostat to call for heat.

3.Inducer and circulator energize. After pressure switch proves proper airflow, control module initiates 30-second prepurge.

4.Control module sparks the pilot and opens pilot valve in main gas valve.

a.If pilot does not light within 15 seconds, pilot valve is closed and spark generator is turned off. Control module initiates a 15-second postpurge, then starts a new cycle.

b.If pilot does light and control module senses flame current, spark generator is turned off and main valve opens.

5.During main burner operation:

a.Control module monitors pilot flame current. If signal is lost, main valve closes, spark generator activates and sequence returns to step 4.

b.If power is interrupted, control system shuts off pilot and main gas valves and restarts at step 1 when power is restored.

6.In the event the limit control shuts down the boiler — The control module closes the pilot and main gas valves, but keeps the inducer operating for 15-second postpurge.

— The circulator continues to operate.

7.Lower room thermostat setting to stop call for heat. Thermostat is satisfied — Pilot and main gas valves are closed — Inducer operates for 15-second postpurge — Circulator is shut off.

8.Boiler is now in the off cycle.

9.Repeat steps 1 through 6 several times to verify operation.

10.Return the thermostat to normal setting.

11.Set thermostat heat anticipator setting to 0.4 amps, adjusted for gas valve and control current.

Figure 18 Control module sequence of operation — status light indications

Steps		Call for	POWER	TSTAT	LIMIT	PRESS	FLAME Timing
		heat?		CIRC		SWITCH
(Fol low ing s tep 8, cycle goes bac k to step 1 .)
1.	Standby	NO					—
	· Waiting for call for heat
2.	Call for heat	YES					—
	· Circulator on

·Blower on

3. Limit circuit	YES	—
· Limit controls closed

·Block switch contacts closed

4. Pressure circuit

· Pressure switch contacts closed YES 35 sec

· Prepurge for 30 seconds

5.Pilot flame proven *

·	Gas valve open	YES	15 sec
·	Pilot remains on

·Boiler producing heat

6. Limit cycle	YES	—
· Limit circuit open

·Gas valve closed

7. Flame outage *	YES	—
· Flame out

·Boiler recycles

8. Thermostat satisfied

· Circulator off NO 15 sec

·Blower postpurge

9. Circulator exercise routine	NO				30 sec
· Circulator turns on for 30 seconds
if boiler not operated for 30 days
		or	= "ON"	= "OFF"

*If pilot flame is not proven in 15 seconds, control module will flash the FLAME light, but will continue indefinitely with attempts to light the pilot burner. The control module will not lockout on a failure to establish flame. It will lockout if line voltage polarity is reversed, stray voltage is sensed on thermostat line, pressure switch sticks closed or fails to make within 5 minutes or if flame is sensed when it shouldn’t be there. The boiler will reset after these lockouts if any of the following occurs:

• 1 hour waiting period • Opening and closing of thermostat circuit • Removal of 120 VAC power for at least 45 seconds. 26030

Part number 550-110-260/0200 31