JOHNSON CONTROLS
79
SECTION 5 – SEQUENCE OF OPERATION
FORM 100.50-NOM6
ISSUE DATE: 8/07/2017
5
On a call for supply fan operation the Simplicity Con-
trol sends a 24VAC 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 5.0VDC
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 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 sup-
ply air temperature to the active economizer setpoint.
The Simplicity Control can be configured to use the
following economizer control methods:
•
Dry Bulb
•
Single Enthalpy
•
Dual Enthalpy
“ECONOMIZER INSTALLED”
must be programmed
to allow economizer operation by 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
“ECONOMIZER OUTSIDE AIR TEMP ENABLE
SETPOINT”
must be programmed to allow econo-
mizer operation by using Parameter 39 under the PRO-
GRAM 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 than or equal to
the
“ECONOMIZER OUTSIDE AIR TEMP EN-
ABLE 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.
Single Enthalpy
The following parameters must be programmed to al-
low economizer operation:
•
“ECONOMIZER OUTSIDE AIR ENTHALPY
SETPOINT”
– must be programmed using Pa-
rameter 37 under the PROGRAM key on the Sim-
plicity control board or under the ECONOMIZ-
ER/EXHAUST tab in the Simplicity PC software
package.
•
“OUTSIDE AIR HUMIDITY SENSOR IN-
STALLED”
– must be enabled using Parameter 36
under the PROGRAM key on the Simplicity con-
trol board or under the EQUIPMENT INSTAL-
LATION tab in the Simplicity PC software pack-
age.
The economizer will become active and use outdoor air
for cooling when:
•
The outside air enthalpy is less than or equal to
the
“ECONOMIZER OUTSIDE AIR ENTHALPY
SETPOINT”.
•
The Simplicity Control has a demand for cooling
operation.
•
If the outdoor air enthalpy was above the
“ECONOMIZER OUTSIDE AIR ENTHALPY
SETPOINT”
when the cooling cycle was initiated
the Simplicity Control will activate economizer
operation when the outdoor air enthalpy is 1.0
BTU/LB below the
“ECONOMIZER OUTSIDE
AIR ENTHALPY SETPOINT”
.
