Submittal Sheet

7800 SERIES S7800A2142 KEYBOARD DISPLAY MODULE
32-00110—05 12
STANDBY HOLD: T7
(Lockout Interlock)
The KDM indicates the burner status and that the Lockout Interlock is closed. A demand is
present for burner operation, but the burner sequence does not advance to PREPURGE until the
Lockout Interlock proves open. If this time exceeds the 120 second hold, the relay module locks
out.
STANDBY HOLD: T7
(Running Interlock)
EC/RM7850
The KDM indicates the burner status and that the Running Interlock is closed. A demand is
present for burner operation, but the burner sequence does not advance to PREPURGE until the
Running Interlock proves open. If this time exceeds the 120 second hold, the relay module locks
out.
PURGE The KDM indicates the burner status, PURGE, which is the period of time the blower motor is
running before the Ignition period. The timing of the PURGE period is selectable.
If the relay module is in a PURGE HOLD status, the following conditions could exist:
PURGE HOLD: T19
(High Fire Switch)
The KDM indicates the burner status and that the High Fire Switch is not closed. The firing rate
motor is driving to its PURGE rate position. If this time exceeds four minutes and fifteen seconds,
the relay module locks out.
PURGE DELAY: T19
(High Fire Switch
Jumpered)
The KDM indicates the burner status and that the High Fire Switch is jumpered. The High Fire
Switch is bypassed, welded or otherwise prematurely closed. The system automatically adds 30
seconds to allow the firing rate motor additional drive time to reach or near the open damper
position before starting the PURGE sequence.
PURGE HOLD: TEST
(Run/Test Switch)
The KDM indicates the burner status and that the Run/Test Switch is in the TEST position. The
sequence does not continue until the Run/Test Switch is placed in the RUN position.
PURGE HOLD: T18
(Low Fire Switch
Jumpered)
The KDM indicates the burner status and that the Low Fire Switch is jumpered. The Low Fire
Switch is bypassed, welded or otherwise prematurely closed. The system automatically adds 30
seconds to allow the firing rate motor additional drive time to reach or near the closed damper
position before starting the ignition sequence.
PURGE HOLD: F/G
(Flame Detected)
The KDM indicates the burner status and that a flame is detected. The burner sequence does not
advance through PREPURGE because a flame is detected as being present. The sequence holds
waiting for the flame signal to clear. If the time exceeds 30 seconds, the relay module locks out.
PURGE HOLD: T18
(Low Fire Switch)
The KDM indicates the burner status and that the Low Fire Switch is not closed. The firing rate
motor is driving to its Low Fire position in preparation for Ignition Trials. If this time exceeds four
minutes and fifteen seconds, the relay module locks out.
PURGE HOLD: T7
(Running Interlock)
The KDM indicates the burner status and that the Running Interlock is not closed. The sequence
does not advance to ignition until the Running Interlock proves closed. If this time exceeds 30
seconds, the relay module locks out.
PILOT IGN mm:ss The KDM indicates the burner status, PILOT IGN, and the timing of the PILOT IGN trial begins, in
seconds. During this period, the relay module permits the pilot valve to open and the pilot flame
to establish.
If the relay module is in a PILOT HOLD status, the following conditions could exist:
PILOT HOLD: TEST
(Run/Test Switch)
The KDM indicates the burner status, PILOT IGN, and that the Run/Test Switch is in the TEST
position. The sequence does not continue until the Run/Test Switch is placed in the RUN
position.
MAIN IGN mm:ss The KDM indicates the burner status, MAIN IGN, and the timing of the MAIN IGN trial begins, in
seconds. During this period, the relay module permits the main valve to open and the main flame
to establish.
RUN The KDM indicates the burner status, RUN, which is the period of time after the Ignition Trials
and before the operating controller setpoint is reached. During this time, the burner is firing
under control of the firing rate control.
If the relay module is in a RUN HOLD status, the following condition could exist:
RUN LOWFIRE: TEST
(Run/Test Switch)
The KDM indicates the burner status and that the Run/Test Switch is in the TEST position.
Normal modulation or operation does not continue until the Run/Test Switch is placed in the
RUN position.
POSTPURGE mm:ss The KDM indicates the burner status, POSTPURGE, which is the period of time after the RUN
period when the blower motor continues to run. The timing of the POSTPURGE period is fifteen
seconds.
Waiting for
connection...
The KDM has power but is waiting to receive a signal from the relay module to continue
operation.
Table 3. Keyboard Display Module Sequence and Status Hold Messages (Continued).
Sequence Status