Ibc (Sequence Of Operations) - Williamson-Thermoflo GWC-070 Manual

GWC S 2
erieS gaS
Start-up
(continued)
Figure 71
Integrated boiler control (IBC) sequence of operation — status light indications
STEPS
(After Step 8, the 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
• Block switch contacts closed
• Blower on
4. Pressure circuit
• Pressure switch contacts closed
• Ignitor glows
5. Flame proven
• Gas valve open
• Ignitor remains on
6. Limit cycle
• Limit circuit open
• Gas valve closed
• Blower off after postpurge
7. Flame outage *
• Flame out
8. Thermostat satisfied
• Circulator off
• Blower postpurge
• Return to Step 1
* 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
64
-
fired water boiler
Call for POWER
Heat?
NO
YES
YES
YES
YES
YES
YES
NO
— Boiler Manual
TSTAT LIMIT
CIRC
= ON
PRESS FLAME Timing
SWITCH
30 sec
4 sec
30 sec
30 sec
= OFF
Part number 550-142-786/0712
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