Sequence Of Operation - Honeywell RM7895A1014 Installation Instructions Manual

RM7895A,B,C,D/EC7895A,C; RM7896A,C,D 7800 SERIES RELAY MODULES
g. Internal system fault occurred.
h. Purge card is removed.
i. Purge card is bad.
6. RUN PERIOD
a. No flame present.
b. Airflow lockout feature is enabled and the airflow
switch opens.
c. Interrupted pilot valve terminal is energized
(RM7895C, RM7896C,D; EC7895C).
d. Main valve terminal is not energized.
e. Delayed main valve terminal is not energized
(RM7895C, RM7896C,D; EC7895C).
f. Internal system fault occurred.
g. Purge card is removed.
h. Purge card is bad.
i. Ignition terminal is energized.
OPERATION

Sequence of Operation

The RM7895A,B,C,D/EC7895A,C; RM7896A,B,C,D has the
operating sequences listed below; see Fig. 2 and 3. The
RM7895A,B,C,D/EC7895A,C; RM7896A,B,C,D LED
provide positive visual indication of the program
sequence: POWER, PILOT, FLAME, MAIN and ALARM.
Initiate
The EC7895A,C/RM7895A,B,C,D;RM7896A,B,C,D Relay
Module enters the INITIATE sequence when the relay
module is powered. The EC7895A,C/RM7895A,B,C,D;
RM7896A,B,C,D can also enter the INITIATE sequence if
the relay module verifies voltage fluctuations of +10/-
15% or frequency fluctuations of ±10% during any part of
the operating sequence. The INITIATE sequence lasts for
ten seconds unless the voltage or frequency tolerances
are not met. When not met, a hold condition is initiated
and displayed on the optional KDM for at least five
seconds; when met, the INITIATE sequence restarts. If the
condition is not corrected and the hold condition exists for
four minutes, the EC7895A,C/RM7895A,B,C,D;
RM7896A,B,C,D locks out. Causes for hold conditions in
the INITIATE sequence:
1. AC line dropout detection.
2. AC line noise that can prevent a sufficient reading of
the line voltage inputs.
3. Low line voltage brownouts.
The INITIATE sequence also delays the burner motor
starter from being energized and de-energized from an
intermittent AC line input or control input.
Standby
The EC7895A,C/RM7895A,B,C,D;RM7896A,B,C,D is ready
to start an operating sequence when the operating control
input determines a call for heat is present. The burner
switch, limits, operating limit control and all
microcomputer-monitored circuits must be in the correct
state for the relay module to continue into the PREPURGE
sequence.
Normal Start-Up Prepurge
The EC7895A,C/RM7895A,B,C,D/RM7896A,B,C,D Relay
Module provides PREPURGE timing selectable from two
32-00156—01
seconds to thirty minutes with power applied and the
operating control indicating a call for heat.
1. The Airflow Interlock, burner switch, Run/Test switch
and all microcomputer-monitored circuits must also
be in the correct operating state.
2. The motor output, terminal 4, is powered to start the
PREPURGE sequence.
3. The Airflow Interlock input closes ten seconds into
PREPURGE or within the specified purge card tim-
ing; otherwise, a recycle to the beginning of PRE-
PURGE or lockout occurs, depending on how the
Airflow Switch selectable jumper (JR3) is configured.
Ignition Trials
1. Pilot Flame Establishing Period (PFEP):
a. When the PFEP begins:
(1) The pilot valve and ignition transformer,
terminals 8 and 10, are energized. The
EC7895A, RM7895A,B, and RM7896A,B have
an intermittent pilot valve, terminal 8. The
EC7895C, RM7895C,D, and RM7896C,D
have an interrupted pilot valve, terminal 8.
(2) Flame must be proven by the end of the ten
second PFEP (four seconds if Configuration
Jumper JR1 is clipped) to allow the sequence
to continue. If a flame is not proven by the
end of PFEP, a safety shutdown occurs.
b. With flame proven, the ignition, terminal 10, is
de-energized.
NOTE: For the RM7895C1020 and RM7896C1036, during
the first 8 seconds of PFEP, when a flame signal is
detected, terminal 10 is de-energized. If the flame
signal is lost, terminal 10 will re-energize.
2. Main Flame Establishing Period (MFEP):
a. After PFEP, and with the presence of flame, the
main fuel valve, terminal 9, is powered. If a
flameout occurs, the relay module locks out or
recycles (depending on status of jumper JR2)
within 0.8 or 3 seconds, depending on the Flame
Failure Response Time (FFRT) of the amplifier.
b. The EC7895C, RM7895C,D and RM7896C,D
have a ten second MFEP. After the Ignition Trials,
the pilot valve, terminal 8, is de-energized. If a
flameout occurs, the relay module locks out or
recycles (depending on status of jumper JR2)
within 0.8 or 3 seconds, depending on the Flame
Failure Response Time (FFRT) of the amplifier.
Run
1. The EC7895C, RM7895C,D, RM7896C,D has a
delayed main valve that is energized once the RUN
period is entered.
2. The relay module is now in RUN and remains in RUN
until the controller input, terminal 6, opens, indicat-
ing that the demand is satisfied or a limit has
opened.
Post Purge (RM7896A,B,C,D Only)
After demand is satisfied or a limit opens, de-energizing
terminal 6, the Ignition/Pilot valve, main valve and
delayed main valve, terminals 8, 9 and 21, are de-
energized. The blower motor, terminal 4, remains powered
for 15 seconds.
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