A.O. Smith 3400 - Manual (Page 46)

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5. PILOT FLAME ESTABLISHING PERIOD (PFEP):
a. Lockout Interlock opens (if enabled).
b. Pilot Valve terminal is not energized.
c. No flame is present at the end of the PFEP, or after
programmed number of retry attempts.
d. Main valve terminal is energized.
e. Internal system fault occurred.
6. MAIN FLAME ESTABLISHING PERIOD (MFEP):
a. Lockout Interlock opens (if enabled).
b. Pilot valve terminal is not energized.
c. Main valve terminal is not energized.
d. No flame present at the end of MFEP.
e. Internal system fault occurred.
7. RUN PERIOD:
a. No flame is present, or flame is lost (if enabled-lockout).
b. Lockout Interlock opens) if enabled).
c. IAS Purge and Ignition enabled and the Interlock opens.
d. Pilot terminal energized (if programmed as Interrupted
Pilot).
e. Main valve terminal is not energized.
f. Internal system fault occurred.
8. POSTPURGE PERIOD:
a. Preignition Interlock does not close in five seconds.
b. Pilot Valve terminal is energized.
c. Main Valve terminal is energized.
d. Internal system fault occurred.
e. Flame sensed 240 seconds accumulated time after the
RUN period.
SAFETY SHUTDOWN:
1. If the lockout interlocks open or a sensor designated as a
safety limit are read as defective, Control System will lockout
and the blower motor will be de-energized.
If these open during the firing period, all fuel valves will be de-
energized, the system will complete postpurge, and will lockout
indicated by an alarm.
2. If the main flame is not detected at the end of the last recycle
attempt of the main flame establishing period, all fuel valves
will be de-energized, the device will complete postpurge,
and will lockout indicated by an alarm.
3. If the flame sensing signal is lost during the run period (if
lockout is selected), all fuel valves will be de-energized within
4 seconds after the loss of the flame signal, the device will
complete postpurge, and will lockout indicate by an alarm.
4. Manual reset is required following any safety shutdown.
Manual reset may be accomplished by pressing the push
button on the device, pressing the remote reset wired into
connector J10, or through an attached display.
Interrupting power to Control System will cause electrical resets,
but does not reset a lockout condition.
8. Approvals:
Underwriters Laboratories, Inc. (UL): Component Recognized:
File No. MP268 (MCCZ)
• R7910 is certified as UL372 Primary Safety Controls.
• The R7910 is certified as UL353 Limit Rated device when
using part number 50001464 dual element limit rated NTC
sensors.
CSD-1 Acceptable.
Meets CSD-1 section CF-300 requirements as a Primary Safety
Control.
Meets CSD-1 section CW-400 requirements as a Temperature
Operation control.
Meets CSD-1 section CW-400 requirements as a Temperature
High Limit Control when configured for use with 10 kohm NTC
sensors.
Federal Communications Commission, Part 15,
Class B. Emissions.
BURNER CONTROL OPERATION
SAFETY SHUTDOWN OF BURNER CONTROL FUNCTIONS
Safety Shutdown (Lockout) occurs if any of the following occur
during the indicated period:
1. INITIATE PERIOD:
a. A/C line power errors occurred.
b. Four minute INITIATE period has been exceeded.
2. STANDBY PERIOD:
a. Flame signal is present after 240 seconds.
b. Main Valve Terminal is energized.
c. Internal system fault occurred.
3. PREPURGE PERIOD:
a. Flame signal is detected for 10 seconds accumulated time
during PREPURGE.
b. Purge Rate Fan RPM or High Fire Switch fails to close
within four minutes and fifteen seconds after the firing rate
motor is commanded to drive to the high fire position at the
start of PREPURGE.
c. Light off Rate Fan RPM or Low Fire Switch fails to close
within four minutes and fifteen seconds after the firing rate
motor is commanded to drive to the low fire position at the
end of PREPURGE.
d. Lockout Interlock (if programmed) does not close within
10 seconds.
e. Lockout Interlock opens during PREPURGE.
f. Main Valve terminal is energized.
g. Internal system fault occurred.
4. PRE-IGNITION TIME
a. Lockout Interlock opens.
b. IAS Purge and Ignition enabled and the Interlock opens.
c. Preignition Interlock opens.
d. Pilot Valve terminal is energized.
e. Main Valve terminal is energized.