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JOHNSON CONTROLS
FORM 100.50-NOM6 (1207)
Sequence of Operation
VAV Supply Fan Speed Control
The following values need to be programmed:
“DUCT PRESSURE SETPOINT” – Using parameter
30 under the PROGRAM key on the Simplicity control
board or under the FAN tab in the Simplicity PC
software package.
“DUCT PRESSURE SHUTDOWN SETPOINT”
– By using the FAN tab in the Simplicity PC software
package.
The Simplicity Control uses a proportional-integral
control algorithm to maintain the “DUCT PRESSURE
SETPOINT” by varying the speed of the supply fan. As
the duct static pressure goes up the speed goes down.
On a call for supply fan operation the Simplicity Control
sends a 24 VAC signal from the FAN terminal of the
P13 connector to the supply fan relay.
The Duct Static Pressure Transducer has a range of 0.0
to 5.0” WC. The transducer sends a 0.0 to 5.0 volt DC
signal to the Simplicity Control through the DP+ and
DP- connections at the P21 connector. The Simplicity
Control then sends a 2.0 to 10.0 volt DC signal to the
supply fan VFD through the VFD+, VFD- terminals at
connector P14 to vary the speed of the VFD.
If the duct static pressure is equal to or greater than the
“DUCT PRESSURE SHUTDOWN SETPOINT” the
Unit Controller will turn off all outputs and lockout
until the control is reset.
ECONOMIZER
Economizer is used in the cooling mode only. As soon
as the unit switches into Occupied or Unoccupied
Cooling and the conditions are within the programmed
guidelines for economizer operation the Simplicity
Control will attempt to use outdoor air to lower the
supply air temperature to the active economizer set
point. The Simplicity Control can be confi gured to use
the following economizer control methods:
• Dry Bulb
• Single Enthalpy
• Dual Enthalpy
The following parameter must be programmed to allow
economizer operation:
“ECONOMIZER INSTALLED” – must be enabled using
Parameter 32 under the PROGRAM key on the Simplicity
control board or under the ECONOMIZER/EXHAUST
tab in the Simplicity PC software package.
Dry Bulb
The following parameter must be programmed to allow
economizer operation:
“ECONOMIZER OUTSIDE AIR TEMP ENABLE
SETPOINT” – must be programmed using Parameter
39 under the PROGRAM key on the Simplicity control
board or under the ECONOMIZER/EXHAUST tab in
the Simplicity PC software package.
The economizer will become active and use outdoor air
for cooling when:
• The outside air temperature is less then or equal
to the “ECONOMIZER OUTSIDE AIR TEMP
ENABLE SETPOINT”.
• The Simplicity Control has a demand for cooling
operation.
• If the outdoor air temperature was above the
“ECONOMIZER OUTSIDE AIR TEMP ENABLE
SETPOINT” when the cooling cycle was initi-
ated, the Simplicity Control will activate econo-
mizer operation when the outdoor air temperature
is 1.0° F below the “ECONOMIZER OUTSIDE
AIR TEMP ENABLE SETPOINT”.
The economizer will become inactive and eliminate the
use of outdoor air for cooling when:
• The outside air temperature is 1.0° F greater than
the “ECONOMIZER OUTSIDE AIR TEMP EN-
ABLE SETPOINT”.
• The Simplicity Control does not have an Occu-
pied or Unoccupied cooling demand.