Honeywell 7800 Series Product Data page 11

Sequence
The Keyboard Display Module (KDM) indicates the burner status, INITIATE, a
stabilization period for the relay module to check for any fluctuations in ac line
INITIATE mm:ss voltage inputs or control inputs on power up or during normal operation. The
timing of the INITIATE period is either two seconds or ten seconds, depending
on the model, before entering STANDBY.
If the relay module is in an INITIATE HOLD status, the following conditions could exist:
The KDM indicates the burner status and that it is waiting for excess line noise
to clear up, which prevents sufficient reading of the line voltage inputs. The
INITIATE HOLD:
burner sequence does not advance into STANDBY until the excess line noise
(AC Frequency/
ceases or a line frequency error occurs; this is caused by using a 60 Hz device
Noise)
on a 50 Hz line, or vice versa on devices with a date code earlier than 9804, is
corrected.
INITIATE HOLD: The KDM indicates the burner status and that ac line power has momentarily
(AC Line Drop- dropped out. The burner sequence does not advance into STANDBY until the ac
out) line voltage has stabilized throughout the INITIATE sequence.
The KDM indicates the burner status and that line frequency is faster than the
INITIATE HOLD: expected value. The burner sequence does not advance into STANDBY until the
(AC Frequency) line frequency returns to the proper value; this is perhaps caused by using a 60
Hz device on a 50 Hz line for devices with a date code earlier than 9804.
The KDM indicates the burner status and that low line voltage (10% lower
INITIATE HOLD:
than rated voltage) has occurred. The burner sequence does not advance
(Low Line Volt-
into STANDBY until the line voltage is at a sufficient level for proper operating
age)
parameters.
The KDM indicates the burner status, STANDBY. The burner can be placed in
STANDBY by opening the burner switch or if the operating controller indicates
its setpoint is satisfied. If a demand is present for burner operation, the burner
STANDBY
sequence does not advance from STANDBY to PURGE until the recycle limits
close. If an Expanded Annunciator is connected, the display messages are
enhanced.
If the relay module is in a STANDBY HOLD status, the following conditions could exist:
The KDM indicates the burner status and that a flame is detected. A demand
STANDBY HOLD:
is present for burner operation. The sequence does not advance to PREPURGE
F/G (Flame
until the flame signal clears. If the flame signal does not clear within 40 sec-
Detected)
onds, the relay module locks out.
The KDM indicates the burner status and that the Pre-Ignition Interlock is not
STANDBY HOLD:
closed. A demand is present for burner operation, but the burner sequence does
T20(Pre-Ignition
not advance to PREPURGE until the Pre-Ignition Interlock proves closed. If this
Interlock)
time exceeds a 30 second hold, the relay module locks out.
The KDM indicates the burner status and that the Lockout Interlock is closed.
STANDBY HOLD:
A demand is present for burner operation, but the burner sequence does not
T7(Lockout
advance to PREPURGE until the Lockout Interlock proves open. If this time
Interlock)
exceeds the 120 second hold, the relay module locks out.
STANDBY HOLD: The KDM indicates the burner status and that the Running Interlock is closed.
T7 (Running A demand is present for burner operation, but the burner sequence does not
Interlock) EC/ advance to PREPURGE until the Running Interlock proves open. If this time
RM7850 exceeds the 120 second hold, the relay module locks out.
The KDM indicates the burner status, PURGE, which is the period of time the
PURGE 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: The KDM indicates the burner status and that the High Fire Switch is not closed.
T19 (High Fire The firing rate motor is driving to its PURGE rate position. If this time exceeds
Switch) four minutes and fifteen seconds, the relay module locks out.
The KDM indicates the burner status and that the High Fire Switch is jumpered.
PURGE DELAY:
The High Fire Switch is bypassed, welded or otherwise prematurely closed. The
T19 (High Fire
system automatically adds 30 seconds to allow the firing rate motor additional
Switch Jum-
drive time to reach or near the open damper position before starting the PURGE
pered)
sequence.
PURGE HOLD: The KDM indicates the burner status and that the Run/Test Switch is in the
TEST (Run/Test TEST position. The sequence does not continue until the Run/Test Switch is
Switch) placed in the RUN position.
7800 SERIESS7800A2142 4-Line LCD Keyboard Display Module
Status
11 32-00110-07