Ignition Trials; Run/Test Switch - Honeywell 7800 Series Installation Instructions Manual

RM7898A 7800 SERIES VALVE PROVING PRIMARY RELAY MODULES
Pre-Purge
The RM7898 Relay Module provides PREPURGE timing,
selectable with ST7800 Purge Timer cards, from two
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.
4. Valve Proving test occurs concurrent with Purge if
feature Before, Both, or Split are selected.

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
RM7898 has an interrupted pilot valve,
terminal 8; intermittent if terminal 19 is
powered. (RM7898A1018 shuts the ignition
off when flame is sensed.)
(2) Flame must be proven by the end of the ten
second PFEP (four seconds if Configuration
Jumper JR1 is clipped). If a flame is not
proven by the end of PFEP, a safety shutdown
occurs.
(3) the Pre-Ignition Interlock is ignored through-
out the Trial for Ignition State.
2. Main Flame Establishing Period (MFEP):
a. After PFEP, and with the presence of flame,
the main fuel valve, terminal 9 (and 21 for Valve
Proving operation) is powered.
b. The RM7898 has a ten second MFEP. The
interrupted pilot valve, terminal 8, is de-
energized (with terminal 19 powered, terminal 8
will remain on [intermittent pilot] throughout the
run period).
(1) If flameout occurs, the RM7898 recycles to
the beginning of Purge. In VP mode, valve
proving testing will not repeat.
(2) If Configuration Resistor (JR2) is clipped, the
RM7898 will lockout and Postpurge if pro-
grammed. Valve Proving testing will be con-
ducted if Both, Split, or After option is
selected.
3. Direct Spark Ignition with Valve Proving feature:
Demand Input is terminal 17 and Enable (120V
power) connected to terminal 18.
32-00209-03
a. When this main flame establishing period
begins:
(1) Ignition, Main Valve 1, and Main Valve 2 ter-
minals, 9, 10, and 21, are turned on simulta-
neously.
(2) Flame must be proven at the end of the 4-sec-
ond main flame establishing time. Ignition
terminal 10 is shut off and system is in Run.
The RM7898A1018 will shut off the ignition
when flame is sensed, but the establishing
period continues.
(3) If flame is not proven by the end of this main
flame establishing period, safety shutdown
occurs.
(4) The Pre-Ignition Interlock is ignored through-
out the trial for ignition period.
Run
The relay module is now in RUN and remains in RUN until
the controller input, terminal 6 (terminal 17 if in VPS
mode), opens, indicating that the demand is satisfied or a
limit has opened.
Post-Purge
After demand is satisfied or a limit opens, de-energizing
terminal 6 (terminal 17 if in VPS mode), Pilot valve, main
valve 1, main valve 2, terminals 8, 9 and 21, are de-
energized. The blower motor, terminal 4, remains powered
during the specified programmed time. The Pre-Ignition
Interlock closes within the first five seconds of Post Purge.
The Valve Proving test is conducted concurrent with the
Post- Purge if options Split, Both or After are enabled.

Run/Test Switch

The Run/Test Switch is located on the top side of the relay
module, see Fig. 25. The Run/Test Switch allows the
burner sequence to be altered as follows:
1. In the measured PREPURGE sequence, the
Run/Test Switch, placed in the TEST position,
causes the PREPURGE timing to stop.
2. In the Pilot Flame Establishing Period, the Run/Test
Switch, placed in the TEST position, stops the timer
during the first eight seconds of a ten-second PFEP
selection or during the first three seconds of a
four-second PFEP selection. It also allows for pilot
turn-down test and other burner adjustments. This
activates a fifteen-second flameout timer that
permits pilot flame adjustment without nuisance
safety shutdowns. The Run/Test Switch is ignored
during PFEP if terminals
8 and 9 are jumpered.
IMPORTANT
When the relay module is switched to the TEST
mode, it stops and holds at the next Run/Test
Switch point in the operating sequence. Make sure
that the Run/Test Switch is in the RUN position
before leaving the installation.
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