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Part Number 550-142-300/0520
35
CGa Series 3 Gas-Fired Water Boiler — Boiler Manual
Figure 24 Ignition control module sequence of operation — status light indications
4.
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.
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.
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.
Operation — spark-ignited pilot boilers
9a
STEPS
(following step 7, cycle goes back to step 1.)
Call for
Heat?
POWER TSTAT
CIRC
LIMIT DAMPER FLAME LWCO
Timing
1. Standby
• Waiting for call for heat
NO
—
2. Call for heat
• Circulator on
YES —
3. Limit circuit
• Limit controls closed
YES —
4. Damper circuit
• Damper proven open
YES —
5. Flame proven *
• Gas valve open
• Ignitor remains on
• Boiler producing heat
YES 15 sec
6. Limit cycle
• Limit circuit open
• Gas valve closed
YES —
7. Flame outage *
• Flame out
• Boiler recycles
YES
—
8. Thermostat satisfied
• Circulator off
NO
—
9. Circulator exercise routine
• Circulator turns on for 30 seconds if
boiler not operated for 30 days
NO
30 sec
10. LWCO circuit
• LWCO circuit open
YES/NO —
= ON
= OFF
* 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
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
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