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Direct-Fired Make-up Air •
MUA-SVX01A-EN
Trouble Shooting
Ignition Trials
The pilot flame establishing period (PFEP) begins when:
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The pilot valve and ignition transformer, terminals 8 and 10, are energized.
The RM7895A/B, EC7895A, and RM7896A/B modules have an intermittent
pilot valve, (terminal 8). The RM7895C/D, EC7895C, and RM7896C/D modules
have an interrupted pilot valve (terminal 8).
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Flame must be proven by the end of the 10-second PFEP (4-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 shut down occurs.
With flame proven, the ignition, terminal 10, is energized. This main flame
establishing period (MFEP) begins when:
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After ignition trials, 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.
•
The RM7895C/D, EC7895C, and RM7896C/D modules have a 10-second MFEP.
After ignition trials and with the presence of flame, the main fuel valve,
terminal 9, is powered. If the flameout occurs, the relay module locks out
within 0.8 or 3-seconds, depending on the amplifier FFRT.
Run
The RM7895C/D, EC7895C, RM7896C/D has a delayed main valve that is
energized once the "run" period is entered.
The relay module is now in "run" and remains in "run" until the controller input,
terminal 6, opens, indicating that the demand is satisfied or a limit has opened.
Post Purge (RM7896 A/B/C/D only). After the demand is satisfied or a limit
opens, de-energizing (terminal 6), the ignition/pilot valve, main valve, and
delayed main valve (terminal 8, 9 and 21). The blower motor (terminal 4) remains
powered for 15-seconds.
Run/Test Switch (RM7895C/D, EC7895C, RM7896C/D only). The "run/test switch"
is located on the top side of the relay module. This switch allows the burner
sequence to be altered as follows:
•
In the measured "prepurge" sequence, the "run/test switch", placed in the
"test" position, causes the prepurge timing to stop.
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In the "pilot flame establishing period" sequence, the "run/test switch", placed
in the "test" position, stops the timer during the first 8-seconds of a 10-second
PFEP selection, or during the first 3-seconds of a 4-second PFEP.
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It also allows for pilot turn-down test and other burner adjustments. This
activates a 15-second flameout timer that permits pilot flame adjustment
without nuisance safety shutdowns. The run/test/switch is ignored during
