www.DaikinApplied.com 129 IM 1287-6 • REBEL APPLIED ROOFTOP
8. The run cycle will continue until any of the following
conditions are met.
a. The call for heat is terminated
b. Any of the safety devices (high limit, air pressure,
rollout, etc.) are triggered
c. The control reaches its maximum run time of 6
hours. If this condition is reached, the control
will terminate the run cycle, continue through
the proper sequence of operations, and then
immediately enter the system check and pre-purge
cycles to prepare for reignition.
9. Once the run cycle has terminated, the redundant safety
valve will close, the modulating valve will return to its set
position, and the draft inducer will ramp up to its “light-
o” setting for a 45 second post-purge cycle.
10. After the conclusion of the post-purge, the control will
enter the “OFF” state. While safety devices are still
monitored, all system outputs are de-energized.
VB1287 BPP Staged Control - Standard
and Split Manifolds
1. A call for heat is initiated by the rooftop unit control
through a digital Modbus signal. Refrigeration Only
control packages may dier.
2. The VB1287 control will then go through a system check
to ensure that the high temperature limit and rollout
switches are closed, the air pressure switch is open, and
the modulating valve is positioned correctly.
3. The staged control will then enter the pre-purge cycle,
where the inducer will run at the programmed purge
pressure. During this cycle, the control will look for the air
pressure switch to close and open at the correct settings.
4. Once the system check and pre-purge cycles are
complete, the control will enter the ignition cycle.
a. The inducer will go to its “light o” setting (usually
high speed).
b. The DSI ignition module will be energized and the
spark ignitor will activate.
c. The control valve and any redundant safety valves
will open, allowing gas ow.
d. The burners will ignite and the VB1287 control will
receive a signal from the ame sensor.
e. The spark ignitor will remain active for the duration
of the ignition cycle, regardless of ame status.
5. If ame is not established during the ignition cycle, the
control will repeat the pre-purge and ignition cycles up to
three times. After three failed ignition attempts, the board
will enter a 1 hour lockout.
6. Once ame has been established, the control will enter a
warmup period to ensure ame stabilization and reduce
condensation in the heat exchanger.
7. After the warmup period, the control will enter the run
cycle. If equipped with a 2-stage valve, during the run
cycle the burner ring rate is determined by the heat
demand received by the control via a Modbus signal.
Two ring stages, High or Low, are available.
NOTE: If the control is paired with a split manifold, steps 1
through 6 pertain to the primary burners. Once the
control exits the warmup period and the ring rate is
dictated by the rooftop control, the control will step
the primary burners High or Low (if equipped with
a 2-stage valve) and ignite the secondary burners
based on the demand for heat.
8. The run cycle will continue until any of the following
conditions are met.
a. The call for heat is terminated.
b. Any of the safety devices (high limit, air pressure,
rollout, etc.) are triggered.
c. The control reaches its maximum run time of 6
hours. If this condition is reached, the control
will terminate the run cycle, continue through
the proper sequence of operations, and then
immediately enter the system check and pre-purge
cycles to prepare for reignition.
9. Once the run cycle has terminated, any redundant safety
valves present will close, the staged control valve will
close, and the draft inducer will ramp up to its “light-o”
setting for a 45 second post-purge cycle.
10. After the conclusion of the post-purge, the control
will enter the “OFF” state. All system outputs are
de-energized but all safety devices are still monitored.
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