Fulton Heating Solutions, Inc. -- PHW Manual -- 2010-0713
Page 60
g) IGNITION TRIALS (RM7865B) (with Flame Rod Option – Natural Gas Only)
1. Main Flame Establishing period (MFEP)
a) The ignition transformer, terminal 10, is energized for two seconds prior to
opening of the main fuel valve.
b) The Main Fuel valve, terminal B, is energized for four seconds. Flame signal
must be proven and the Purge Fan switch must be proven Off (open) by the
end of the six seconds of MFEP to allow the sequence to continue to the
main Flame Stabilization Period. If the flame signal is not proven or the
Purge Fan switch is on, the RM7865 will recycle to PREPURGE, if the
selected number of retry attempts is not exceeded. If the retry attempts
exceed the limit, lockout occurs.
2. Main Flame Stabilization Period (MFSP), The RM7865 enters an eight second Main
Frame Stabilization Period. If the Flame signal is lost or the Purge Fan switch closes
during this time, the RM7865 will recycle to PREPURGE, if the selected number of
entry attempts is not exceeded. If the retry attempts exceed the limit, lockout occurs.
h) RUN: After the CPSP/MFSP, the RM7865 will enter into the RUN sequence. The
RM7865 will remain in RUN until the controller input, terminal 6, opens indicating that the
demand is satisfied or that the limit has opened. If the Combustion Pressure Switch
Interlock opens(RM7865A) or the flame signal is lost (RM7865B), the RM7865 will enter
the POSTPURGE period. The fan motor is de-energized during RUN.
i) POSTPURGE: The RM7865 provides a 35 second POSTPURGE following the
completion of the RUN period; and the fan motor output is powered to drive all products
of combustion and any unburned fuel from the combustion chamber. The RM7865 will
also enter POSTPURGE if the operating control input is de-energized during CPEP,
CPSP or RUN.
1. The main fuel valve and ignition, terminals 8 and 10, are de-energized. The purge fan
switch is energized and the POSTPURGE period begins.
2. After the 35 second POSTPURGE period is completed, the RM7865 returns to
STANDBY.
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