Fulton Pulse DWH (PDWH) Domestic Water Heater - Manual (Page 32)

IGNITION TRIALS
(Without Flame Rod Option)
a. Combustion Pressure Establishing
Period (CPEP):
1. The ignition transformer, terminal 10,
is energized two seconds prior to
opening of the main fuel valve.
2. The main fuel valve, terminal 8. is
energized for four seconds. Com-
bustion pressure must be proven by
the end of the six seconds of CPEP
to allow the sequence to continue to
the Combustion Pressure Stabilization.
Period (CPSP). If combustion pressure
is not proven by the end of CPEP, the
RM7865 will recycle to PREPURGE.
b. Combustion Pressure Stabilization
Period (CPSP):
1. If the combustion pressure switch is
energized at the end of CPEP, the
RM7865 enters an eight second
Combustion Pressure Stabilization
Period. If the combustion pressure
switch ILK opens, the RM7865 will
recycle to PREPURGE only if the
selected number of retry attempts is not
exceeded. After the eight seconds, the
RM7865 will enter the RUN period.
Ignition Trials (RM7865B)
with Flame Rod Option
(Natural Gas Only)
a. Main Flame Establishing period (MFEP)
1. The ignition transformer, terminal
10, is energized for two seconds prior
to opening of the main fuel valve.
2. 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.
b. 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,
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.
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-ener-
gized 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.
Operation
29-PDWH