34
Part Number
550-110-290/0219
CGt
GAS-FIRED WATER BOILER — Series 2 —
Boiler Manual
Operation — sequence
10a
Figure 27 Control module
sequence of operation — status light indications
1.
Read Operating instructions
in Section
10c.
This informa-
tion is also located on a label on the inside of the boiler jacket
door panel. Notice that either the room thermostat or the
tankless heater low limit control can cause a call for heat.
2.
Raise
room thermostat (or raise setting of tankless heater
low limit control) to call for heat.
3.
Circulator energizes.
If limit circuit is closed, the inducer
starts. After pressure switch proves proper airflow, control
module initiates 10-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 (or lower tankless heater low limit control
setting) to stop call for heat. Pilot and main gas valves close — Inducer oper-
ates for 15-second postpurge — Circulator shuts off.
8. Boiler is now in the
off cycle
.
9.
Repeat
steps 1 through 6 several times to verify operation.
10.
Return
the thermostat or tankless heater low limit to normal setting.
11. Set thermostat heat anticipator setting as instructed in Figure 28, page 35.
STEPS
(following step 8 cycle goes back to step 1.)
Call for
Heat?
POWER
TSTAT
CIRC
LIMIT
PRESS
SWITCH
FLAME
Timing
1. Standby
• Waiting for call for heat
NO
—
2. Call for heat
• Circulator on
YES
—
3. High limit circuit
• Limit controls closed
• Rollout TFE contacts closed
• Ambient temperature switch closed
YES
—
4. Inducer
• Inducer turns on
YES
—
5. Pressure circuit
• Pressure switch contacts closed
• Prepurge for 10 seconds
YES
10 sec
6. Flame proven *
• Gas valve open
• Ignitor remains on
• Boiler producing heat
YES
15
sec
7. Limit cycle
• Limit circuit open
• Gas valve closed
YES
—
8. Flame outage *
• Flame out
• Boiler recycles
YES
—
9. Thermostat and tankless heater
low limit satisfied
• Circulator off
• Blower postpurge
NO
15
sec
10. Circulator exercise routine
• Circulator turns on for 30
seconds if
boiler not operated for 30 days
NO
30 sec
= 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 120VAC power for at least 45 seconds. 029007
