Settings And Adjustments; Selectable Site-Configurable Jumpers - Honeywell 7800 Series Installation Instructions Manual

RM7845A 7800 SERIES RELAY MODULES
b. Flame must be proven by the end of the ten-second
PFEP (four if JR1 is clipped) 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):
a. Terminal 9 is energized when the presence of flame
is verified at the end of a 10-second Pilot Flame
Establishing Period (PFEP) (four seconds if JR1 is
clipped).
b. Terminal 8 is turned off 10 seconds after Terminal 9
is energized.
Run
1. A ten-second stabilization period occurs at the
beginning of the RUN period.
2. The firing rate motor releases to modulation. Damper
motor is energized.
Device Initiate Standby Purge
RM7845 10 sec.. *
* STANDBY and RUN can be an infinite time period.
**PURGE determined by which ST7800A purge card is selected.
Run/Test Switch
The Run/Test Switch is located on the top side of the
RM7845A, see Fig. 6. The Run/Test Switch allows the burner
sequence to be altered as follows:
1. In Prepurge Drive To High Fire Position, the Run/Test
Switch, when placed in the TEST position, holds in
PREPURGE with the firing rate motor in the High Fire
position.
2. In the measured PREPURGE sequence, the Run/Test
Switch, when placed in the TEST position, causes the
PREPURGE timing to stop. The firing rate motor is in
the High Fire position.
3. In Prepurge Drive to Low Fire position, the Run/Test
Switch, when placed in the TEST position, holds the
burner sequence in PREPURGE with the firing rate
motor in the Low Fire position.
4. In PFEP, the Run/Test Switch, when placed in the TEST
position, stops the timer during the first eight seconds
when a ten second PFEP is selected or during the first
three seconds when a four second PFEP is selected,
allowing pilot-turn-down test and other burner
adjustments to be made. This activates a fifteen second
661147—1
Table 6. Sequence Timing for Normal Operation.
Flame Establishing
Period
Pilot Main
** 4 or 10 10 sec.
sec.
3. The RM7845A is now in RUN and remains in RUN until
the controller input, terminal 6, opens, indicating that the
demand is satisfied or a limit opened.
Postpurge
The RM7845A provides a fifteen-second
POSTPURGE following the completion of the RUN period.
The blower motor output is powered to drive all products of
combustion and any unburned fuel from the combustion
chamber. It also supplies combustion air to burn fuel being
purged from the fuel line downstream of the fuel shutoff valve.
1. The main fuel valve, Terminal 9, is de-energized and the
firing rate motor is commanded to the low fire position to
begin the POSTPURGE period.
2. After the fifteen-second POSTPURGE period is
completed, the RM7845A reenters Standby.
Post-
Purge Interlock
Run Timing Circuits
* 15 sec. Preignition,
Lockout,
High and
Low Fire
flameout timer that permits pilot flame adjustment
without nuisance safety shutdowns. The Run/Test
Switch is ignored during PFEP for the RM7845A if
Terminals 8 and 9 are jumpered.
5. During Run, the Run/Test Switch, when placed in the
TEST position, drives the firing rate motor to the Low
Fire position.
NOTE: When RM7845A 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.

SETTINGS AND ADJUSTMENTS

Selectable Site-Configurable Jumpers

The RM7845A has two site-configurable jumper options, see
Fig. 4 and Table 7. If necessary, clip the
site-configurable jumpers with side cutters and remove the
resistors from the Relay Module.
10
Firing Energy Approval
Rate Saving
Circuit Prepurge Bodies
4-wire Yes FM/IRI/UL
modulating Modulating
Code