750-166 2-3
TABLE 1—SEQUENCE AND STATUS HOLD MESSAGES FOR ALL CB780/CB784 CONTROLS (Continued).
Sequence Burner Control Status
STANDBY HOLD: T7
(Lockout Interlock)
The KDM indicates the burner status, STANDBY, and that the Lockout Interlock is
closed. If a demand is present for burner operation, the burner sequence will not advance
to PREPURGE until the Lockout Interlocks prove open. If this time exceeds the
120 second hold, the CB 780/CB 784 will lockout.
PURGE HOLD: T19
(High Fire Switch)
The KDM indicates the burner status, PURGE, and that the High Fire Switch is not
closed. The firing rate motor is driving to its PURGE rate position. If this time exceeds
two minutes and 15 seconds, the CB 780/CB 784 will lockout.
PURGE DELAY: T19
(High Fire Jumpered)
The KDM indicates the burner status, PURGE, and that the High Fire Switch is
jumpered. The High Fire Switch is bypassed, welded or otherwise prematurely closed.
The system will automatically add 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 mm:ss The KDM indicates the burner status, PURGE, which is the period of time before the
ignition period when the blower motor is running. The timing of the PURGE period is
selectable. PREPURGE is counted in minutes and seconds.
PURGE HOLD:TEST
(Run/Test Switch)
The KDM displays the burner status, PURGE, and that the Run/Test Switch is in the
TEST position. The sequence will not continue until the Run/Test switch is placed in the
RUN position.
PURGE HOLD:T18
(Low Fire Jumpered)
The KDM displays the burner status, PURGE, and that the Low Fire Switch is jumpered.
The Low Fire Switch is bypassed, welded or otherwise prematurely closed. The system
will automatically add 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, PURGE, and that a flame is detected. The burner
sequence will not advance through PREPURGE because a flame is detected as being
present. The sequence will hold waiting for the flame signal to clear. If the time exceeds
30 seconds, the CB 780/CB 784 will lockout.
PURGE HOLD: T18
(Low Fire Switch)
The KDM indicates the burner status, PURGE, 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 two minutes and 15 seconds, the CB 780/CB 784 will lockout.
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 of time, the CB 780/CB 784 permits the pilot
valve to be open and the pilot flame to be established.
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 will 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 of time, the CB 780/CB 784 permits the main
valve to be open and the main flame to be established.
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 the control of the firing rate controller.
RUN LOWFIRE:TEST
(Run/Test Switch)
The KDM indicates the burner status, RUN, and that the Run/Test Switch is in the TEST
position. The firing rate motor will drive to the low fire position. Normal modulation or
operation will not resume 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 during which the blower motor continues to run. The timing of the
POSTPURGE period is 15 seconds.
Waiting for connection… The display has power but is waiting to receive a signal from the CB 780/CB 784 to
continue operation.
(Continued)
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