Daikin DPS Installation And Maintenance Manual page 112

Duct Static Pressure Control
The control parameter for the fan speed is the duct static
pressure setpoint . If the duct static pressure is below the duct
static pressure setpoint by more than ½ the deadband, the
fan speed will increase . Likewise if the duct static pressure
is above the duct static pressure setpoint by more than ½
the deadband the fan speed will decrease . Example - if the
duct static pressure setpoint is 1 .2" and the deadband is 0 .1",
the duct static pressure must reach 1 .14 before the fan will
increase in speed . The Duct Static Pressure setpoint may be
set through the keypad or via a network signal . The active
setpoint is changed whenever either of these values changes
so it equals whichever value was changed most recently .
Speed/Network Control
When speed/network control is selected, the fan operates
at the larger of its minimum speed or a value provided via a
connected network or the keypad/display .
Single Zone VAV Control
When single zone VAV control is selected, the supply fan is
controlled with a PI_Loop to maintain the Control Temperature
input at the Occupied Cooling Setpoint or Occupied Heating
Setpoint . This control choice is designed for DAC control
type and will be used in applications where the unit will act
as a single VAV box to control space temperature . Cooling
and heating discharge air temperature control and outside air
damper control will function in the normal manner as with VAV
units .
OM 1141-3 • MICROTECH UNIT CONTROLLER
Exhaust Fan Capacity Control
A DPS unit can be equipped with either a CAV or VAV exhaust
fan . This fan is shipped from the factory set up for VAV
operation controlled based on building static pressure . Units
equipped with the 0-100% modulating economizer operation
should always remain set up for VAV control on building
pressure . Unit's equipped with 0-30% OA or 100% OA hoods
can be set up for either CAV or VAV operation .
VAV Exhaust Fan
A VAV exhaust fan can be set for one of three different
methods of control with the RF/EF Ctrl= parameter . These are
building static pressure, manual/network speed, or outdoor air
damper position based control .
Building Static Pressure Control
Once the fan is running the capacity of the fan is controlled
with a PI Loop to maintain the building static pressure at the
building static pressure setpoint .
Speed/Network Control
Once the fan is running the capacity of the fan is controlled
to the RemExhFCap= setting which is changed via the unit
keypad or a network signal .
Outdoor Damper Position Control
Once the fan is running the capacity of the fan is controlled
between the minimum value (Default=5%) and 100% as the
outdoor damper position varies between the ExhOnOAPos=
setting (Default=40%) and the ExhMxOAPos= setting
(Defaut=100%) .
CAV Exhaust Fan
A DPS unit can be configured for CAV exhaust fan operation
via the Unit Configuration menu. When configure this way
the exhaust fan is turned on 4 seconds after the supply fan
is started and runs at full speed as long as the supply fan is
running . The exhaust fan is stopped whenever the supply fan
stops .
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