Honeywell 7800 Series Product Data page 12

7800 SERIESS7800A2142 4-Line LCD Keyboard Display Module
Sequence
The KDM indicates the burner status and that the Low Fire Switch is jumpered.
PURGE HOLD:
The Low Fire Switch is bypassed, welded or otherwise prematurely closed. The
T18 (Low Fire
system automatically adds 30 seconds to allow the firing rate motor addition-
Switch Jum-
al drive time to reach or near the closed damper position before starting the
pered)
ignition sequence.
The KDM indicates the burner status and that a flame is detected. The burner
PURGE HOLD:
sequence does not advance through PREPURGE because a flame is detected
F/G(Flame De-
as being present. The sequence holds waiting for the flame signal to clear. If the
tected)
time exceeds 30 seconds, the relay module locks out.
The KDM indicates the burner status and that the Low Fire Switch is not closed.
PURGE HOLD:
The firing rate motor is driving to its Low Fire position in preparation for Ignition
T18 (Low Fire
Trials. If this time exceeds four minutes and fifteen seconds, the relay module
Switch)
locks out.
PURGE HOLD: The KDM indicates the burner status and that the Running Interlock is not
T7 (Running closed. The sequence does not advance to ignition until the Running Interlock
Interlock) proves closed. If this time exceeds 30 seconds, the relay module locks out.
The KDM indicates the burner status, PILOT IGN, and the timing of the PILOT
PILOT IGN
IGN trial begins, in seconds. During this period, the relay module permits the
mm:ss
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: The KDM indicates the burner status, PILOT IGN, and that the Run/Test Switch
TEST (Run/Test is in the TEST position. The sequence does not continue until the Run/Test
Switch) Switch is placed in the RUN position.
The KDM indicates the burner status, MAIN IGN, and the timing of the MAIN
MAIN IGN mm:ss IGN trial begins, in seconds. During this period, the relay module permits the
main valve to open and the main flame to establish.
The KDM indicates the burner status, RUN, which is the period of time after the
RUN 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: The KDM indicates the burner status and that the Run/Test Switch is in the
TEST (Run/Test TEST position. Normal modulation or operation does not continue until the
Switch) Run/Test Switch is placed in the RUN position.
The KDM indicates the burner status, POSTPURGE, which is the period of time
POSTPURGE
after the RUN period when the blower motor continues to run. The timing of the
mm:ss
POSTPURGE period is fifteen seconds.
Waiting for con- The KDM has power but is waiting to receive a signal from the relay module to
nection... continue operation.
The KDM indicates the burner status, RESET/ALARM TEST. This condition in-
RESET/ALARM dicates that the reset button is pressed. If it is held for more than four seconds,
TEST the alarm output is energized. The alarm output is de-energized when the reset
button is released.
Additional Sequence Status Information When An Expanded Annunciator is Connected to the
Relay Module:
BURNER OFF: T6 The KDM indicates the Burner Switch is not closed. The burner sequence does
(Burner Switch) not advance to PREPURGE until the Burner Switch closes.
The KDM indicates the burner status, STANDBY, and that the Operating Control
STANDBY is not closed. The burner sequence does not advance to PREPURGE until the
Operating Control closes.
STANDBY HOLD: The KDM indicates the burner status, STANDBY, and that a limit is not closed.
T6 (EA Hold The burner sequence does not advance to PREPURGE until one or all limits
Message) close downstream from the Operating Control.
The KDM indicates the burner status, STANDBY, and that the control input is not
STANDBY HOLD:
closed. The burner sequence does not advance to PREPURGE until the control
T6 (Circuit Fault)
input closes.
Table 3. Keyboard Display Module Sequence and Status Hold Messages .
32-00110-07
Status
12