IM 1287-4 • REBEL APPLIED ROOFTOP 58 www.DaikinApplied.com
Unit Operation
Unit Operation
Preparing Unit for Operation
Power-up
There is a 115 VAC control circuit transformer and several
24VAC circuit transformers within the unit to control the various
loads and sensors within the unit. See as-built schematics that
are sent with the unit to familiarize yourself with the various
features and control circuits.
NOTE:
Unit ships with factory installed jumpers in the
emergency override circuit on TB2 between terminals
202 and 203.
Start Up Operating State
When a unit is commanded to start it will always enter the
Startup operating state from the OFF operating state. The unit
remains in the Startup operating state for an adjustable time
period (default 180 seconds) before entering the recirculating
operating state.
Recirculating Operating State
During the Start up operating state the fans remain off,
the outdoor air dampers are driven closed, and variable
speed supply air fan’s remain at 0%. Cooling and heating
are disabled, except for 100% OA heating start sequences.
Recirculating Operating State Units with return air always
enter the Recirculating operating state after the completion
of the Startup operating state. In the Recirculating operating
state fans are started and operate while the outdoor air
dampers remain closed. This allows temperature conditions
throughout the unit and space to equalize before temperature
control begins. Cooling and heating remain disabled. The
unit remains in the Recirculating operating state until the
Recirculate State Timer (default 180 seconds) expires.
NOTE:
100% outdoor air units do not transition through the
Recirculating operating state.
Fan Only
The unit enters the Fan Only operating state after the
recirculation timer expires. Units configured for 100% outside
air operation will transition directly from the Start up operating
state into the Fan Only operating state. Once entering the Fan
Only state of operation the unit will then, based on sensor
inputs transition into any of the 4 remaining states of operation
- heating, cooling, economizer, or minimum discharge air
heating. Min DA
Fan Operation
Within 120 seconds after the fans start, the controller expects
to get feedback from the fans (via modbus) that they are
operating properly. If MCB-the controller does receive that
feedback, the controller assumes the fans did not start. It then
shuts down the unit and generates an alarm. Units configured
for VAV control, the supply fan(s) is modulated to maintain
the duct static pressure setpoint. On VAV units or CAV
units equipped with return fan capacity control, the fan(s) is
modulated to maintain an acceptable building static pressure.
Economizer Operation
If the unit is equipped with a 0-100% modulating economizer
and the conditions are suitable for free cooling, the unit
attempts to satisfy the cooling load by using the outdoor air
economizer before using mechanical cooling.
If the unit is configured for Zone Temperature Control the
transition to economizer operation will occur if all the following
are true:
• The control temperature rises above the occupied cooling
set point by more that ½ the occupied cooling high
deadband
• The discharge air temperature is greater than the Min
DAT limit by more than ½ the DAT heating deadband.
This will prevent more cold air from being brought in when
the DAT is already cold
• The economizer operation is not disabled
If the unit is configured for Discharge Air Temperature Control
the transition to Mechanical cooling will occur if all the following
are true:
• The control temperature rises above the occupied cooling
set point by more that ½ the occupied cooling deadband
• The discharge air temperature is greater than the DAT
cooling set point by more than ½ the DAT cooling
deadband
• Post heat operation is complete
• Economizer operation is not disabled
Summary of Contents for Rebel Applied DPSA
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