Midco F400-33 - Manual (Page 9)

■ After the ignition trials, and with the presence of flame,
the main valve is energized. ("MAIN" LED will be lit.) If a
flame-out occurs, the RM7895 will lockout or recycle
within 3-seconds, depending on "jumper" configuration.
Refer to Honeywell literature for proper configuration.
RUN
■ The RM7895 is now in RUN mode and will remain in
run mode until the controller input opens, indicating that
the call for heat has been satisfied or a limit has opened.
Once this occurs the RM7895 will sequence back to the
STANDBY mode.
Notes:
1. During STANDBY and during RM7895
sequencing the "POWER" LED will blink
every four seconds. This is normal.
2. The "ALARM" LED will be lit in the event of
any flame failure.
3. To maintain proper operation of this device
in MUST be electrically grounded. Refer to
Honeywell RM7895 literature for criteria.
XV SPECIAL EQUIPMENT (OEM VERSIONS)
Special equipment, either factory or field installed,
can cause variations in the procedures and descriptions
given in this manual. Generally, any burner ordered with
special factory installed equipment will be supplied with
the appropriate wiring diagram and related instruction
manuals from the special equipment manufacturer
Consult these manuals to identify any differences in
construction, operation, and testing. Field installed
special equipment is the responsibility of the installing
contractor.
-9-
FIGURE 7 General Assembly
INITIATE ("POWER" LED is lit).
■ The RM7895 enters the INITIATE sequence when it is
powered. The INITIATE sequence lasts for ten seconds
unless the voltage or frequency tolerances are not met
(refer to Honeywell RM7895 literature for criteria). When
tolerances are met, the INITIATE sequence will restart. If
the conditions not corrected and the hold condition exists
for four minutes, the RM7895 will lock-out. Causes for
hold conditions in the INITIATE sequence are in the
Honeywell RM7895 literature.
STANDBY ("POWER" LED is lit).
■ The RM7895 is idle in this state of sequencing. When
the burner switch, limits, operating limit controls, and all
microprocessor monitored circuits are in the correct state
for the RM7895 to continue, sequencing will advance to
PREPURGE.
PREPURGE ("POWER" LED is lit).
■ The RM7895 in this application features a prepurge
time of 30-seconds for ON-OFF, 90-seconds for 2-Step
or Modulating burners.
■ Once the STANDBY sequence has a "CALL FOR
HEAT" input, normal start-up prepurge will be initiated.
A. The blower motor is powered to start the prepurge
sequence.
B. The airflow interlock switch must close in
ten seconds of prepurge or within the specified
purge card timing. Otherwise a recycle to the
beginning of prepurge or lockout will occur,
depending on how the airflow switch selectable
jumper is configured. Refer to Honeywell
RM7895 literature for configuration requirements.
IGNITION TRIAL
1. PILOT FLAME ESTABLISHING PERIOD (PFEP)
A. The pilot valve and spark generator are
energized.
B. Flame must be proven by the end of the 4 or
10-second PFEP to allow the sequence to
continue. If flame is not proven by the end of
PFEP, a safety shutdown occurs.
2. MAIN FLAME ESTABLISHING PERIOD (MFEP)