Filter
Top Products
51Part number 550-141-850/0699
• Installation • Start-Up • Parts • Maintenance
Operation — sequenceIXb
1. Standby
Waiting for call for heat
·
2. Call for heat
·
·
Circulator on
Blower on
3. Limit circuit
·
·
Limit controls closed
Block switch contacts closed
4. Pressure circuit
·
·
Pressure switch contacts closed
Igniter heating
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
Blower postpurge
* If flame is not proven in 4 seconds, boiler recycles 2 times to retry for ignition before going into lockout. Recycle igniter timing is 30 seconds.
Postpurge and prepurge are performed on every cycle. In event of lockout, ignition control will automatically restore sequence of operation
after either:
1 hour waiting period.
Opening and closing of thermostat circuit.
Removal of 120 VAC power for at least 45 seconds.
POWER TSTAT
CIRC
LIMIT
PRESS
SWITCH
FLAME
Call for
heat?
Timing
or
= "ON" = "OFF"
NO
NO
YES
YES
YES
YES
YES
YES
—
—
—
35 sec
6 sec
—
—
30 sec
Steps
(Following step 8, cycle goes back to step 1.)
85050
Figure 22 Ignition control module sequence of operation — status light indications