Weil-McLain CGA Series 2 Manual page 35

CGa Series 2 Gas-Fired Water Boiler — Boiler Manual
9a
Operation — spark-ignited pilot boilers
Main burner operation:
4.
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.
c. In the event the limit control shuts down the boiler — The
control module closes the main gas valve, but keeps the
circulator operating and the vent damper open.
Figure 24 Ignition control module sequence of operation — status light indications
STEPS
(following step 7, cycle goes back to step 1.)
1. Standby
• Waiting for call for heat
2. Call for heat
• Circulator on
3. Limit circuit
• Limit controls closed
4. Damper circuit
• Damper proven open
5. Flame proven *
• Gas valve open
• Ignitor remains on
• Boiler producing heat
6. Limit cycle
• Limit circuit open
• Gas valve closed
7. Flame outage *
• Flame out
• Boiler recycles
8. Thermostat satisfied
• Circulator off
9. Circulator exercise routine
• Circulator turns on for 30
boiler not operated for 30 days
10. Sensor ground
• Sensor ground circuit open
* See Section 9, Items 3b and 3c for controls response to failure to prove pilot flame.
Control will lockout under the following conditions:
• Line voltage polarity is reversed
• Stray voltage is sensed on thermostat line
• Damper end switch not proven within 5 minutes from thermostat
call for heat
• Flame is sensed when it shouldn't be there
Part Number 550-142-900/0519
Call for POWER TSTAT
Heat?
NO
YES
YES
YES
YES
YES
YES
NO
NO
seconds if
YES/NO
5. Thermostat satisfied (thermostat circuit opens) — Pilot and
main gas valves are closed — Vent damper is de-energized, and cycles
to closed position. Circulator is shut off.
6. Boiler is now in the standby mode.
7. Thermostat anticipator setting: Set thermostat heat anticipator as
instructed in Figure 25b, page 37.
LIMIT DAMPER FLAME SENSOR
CIRC
= ON
Control will reset after these lockouts :
• 1 hour waiting period
• Opening and closing of thermostat circuit for 2 to 20 seconds
• Removal of 120 VAC power for 2 to 20 seconds
Timing
GND
15
30 sec
= OFF
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sec
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