JOHNSON CONTROLS
81
SECTION 5 – SEQUENCE OF OPERATION
FORM 100.50-NOM6
ISSUE DATE: 8/07/2017
5
•
“ECONOMIZER SECOND STAGE SETPOINT”
– must be programmed using Parameter 34 un-
der the PROGRAM key on the Simplicity control
board or under the ECONOMIZER/EXHAUST
tab in the Simplicity PC software package.
The Simplicity Control will try to modulate the out-
door air damper and the compressors to maintain the
supply air temperature to plus or minus 1.0° F of the
following setpoints based on the method of control:
•
With a Y1 input from a thermostat the Simplic-
ity Control will use the
“ECONOMIZER FIRST
STAGE SETPOINT”
.
•
With a Y2, Y3, or Y4 input from a thermostat the
Simplicity Control will use the
“ECONOMIZER
SECOND STAGE SETPOINT”
.
•
When the space temperature is 1.5° F to 1.9°
F above the “
CV OCCUPIED COOLING
SETPOINT”
or “
CV UNOCCUPIED COOLING
SETPOINT”
the Simplicity Control will use the
“ECONOMIZER FIRST STAGE SETPOINT”
.
•
When the space temperature is 2.0° F above the
“CV OCCUPIED COOLING SETPOINT”
or
“CV UNOCCUPIED COOLING SETPOINT”
the
Simplicity Control will use the “
ECONOMIZER
SECOND STAGE SETPOINT”
.
Variable Air Volume Economizer Setpoint
The Simplicity Control will try to modulate the out-
door air damper and the compressors to maintain the
supply air temperature to plus or minus 1.0° F of the
following setpoints based on the method of control:
•
With a Y1 input from a thermostat the Simplic-
ity Control will use the
“VAV COOLING SUPPLY
AIR TEMP UPPER SETPOINT”
.
•
With a Y2, Y3, or Y4 input from a thermostat the
Simplicity Control will use the
“VAV COOLING
SUPPLY AIR TEMP LOWER SETPOINT”
.
•
When the space temperature is less than 2.0° F
above the
“VAV SUPPLY AIR TEMP RESET
SETPOINT”
the Simplicity Control will use the
“VAV COOLING SUPPLY AIR TEMP UPPER
SETPOINT”
.
•
When the space temperature is equal to or greater
than 2.0° F above the
“VAV SUPPLY AIR TEMP
RESET SETPOINT”
the Simplicity Control will
use the
“VAV COOLING SUPPLY AIR TEMP
LOWER SETPOINT”
.
Economizer / Compressor Operation
The Simplicity Control will use outdoor air without
compressor operation when the following is true:
•
Economizer is active.
•
The outdoor air temperature is equal to or less
than the economizer setpoint.
The Simplicity Control will use outdoor air with com-
pressor operation when the following is true:
•
Economizer is active.
•
The outdoor air temperature is above the econo-
mizer setpoint.
When outdoor air and compressor operation is avail-
able the compressors operation will be controlled as
follows:
•
If the supply air temperature is 5.1° F or more
above the economizer setpoint and the Econo-
mizer PI output is saturated (100%) the Simplic-
ity Control will turn on a compressor and start a 3
minute timer.
•
If after 3-minutes the temperature is still 5.1° F
above the economizer setpoint and the Econo-
mizer PI output is saturated (100%) the Simplic-
ity Control will bring on a second compressor and
start a three minute timer.
•
This sequence would continue until all the com-
pressors ON.
•
If after the 3-minute timing the supply air tem-
perature is within plus or minus 5.0° F of the
economizer setpoint no change will be made to
the number of compressors operating.
•
If after the 3-minute timing the supply air tem-
perature is 5.1° F or more below the economiz-
er setpoint and the Economizer PI output is low
(dampers at the minimum position setting) the
Simplicity Control will turn off a compressor.
•
As long as the supply air temperature is 5.1° F be-
low the economizer setpoint and the Economizer
PI output is low (damper at minimum position set-
ting) the Simplicity Control will turn off compres-
sors every 3-minutes until all the compressor have
been turned off.
