JOHNSON CONTROLS
130
FORM 145.05-NOM7
ISSUE DATE: 10/31/2019
SECTION 5 – SEQUENCE OF OPERATION
Air Economizer Operation
Do not confuse AIR ECONOMIZER with VENTILA-
TION. These operations use the same damper, but they
have different operational purpose. The AIR ECONO-
MIZER is for cooling only, and it overrides the damper
if the unit is in VENTILATION mode on a call for
cooling. In turn, the VENTILATION mode is an act
of adding fresh outside air to a building, and this func-
tion overrides the AIR ECONOMIZER if DEMAND
VENTILATION is ENABLED and used in the unit’s
configuration based on CO2 levels.
If the AIR ECONOMIZER is inactive, the outside air
damper either closes completely or it goes to a fixed
minimum position that has been setup under VENTI-
LATION.
Once the “ECONO SYS STATUS” is “NORMAL -
ACTIVE,” the Unit Controller uses the “ECONOMIZ-
ER CONTROL OUTPUT” to control the return and
outdoor damper to maintain the “SUPPLY AIR TEMP
ACTIVE SP.”
Economizer is used in COOLING mode only. When
the UNIT MODE switches to OCCUPIED COOLING
or UNOCCUPIED COOLING and the conditions are
met within the programmed guidelines for economizer,
operation becomes active. The Unit Controller attempts
to use outdoor air to lower the Supply Air Temperature
to the “ACTIVE SAT SETPOINT.” The following pa-
rameters must be programmed into the Unit Controller
through the User Interface to enable economizer opera-
tion:
• OPTIONS key, ECONOMIZER subsection:
“ECONO INSTALLED” should be set with these
choices: DRY BULB, SINGLE ENTHALPY,
DUAL ENTHALPY, BEST AVAILABLE
• PROGRAM key, ECONOMIZER subsection:
• “ECONOMIZER” should be set to EN-
ABLED
• “ECONO METHOD TO USE” should be set
with these choices: DRY BULB, SINGLE
ENTHALPY, DUAL ENTHALPY, BEST
AVAILABLE
• SETPOINTS key, ECONOMIZER subsection:
set depending on the control method type selected
for AIR ECONOMIZER
• SETPOINTS key either using SINGLE EN-
THALPY, DUAL ENTHALPY, BEST AVAIL-
ABLE. This setpoint possibly needs to be set to
“OUTSIDE AIR ENTHALPY SETPOINT” (de
-
fault is 28 BTU#)
Normally the LSWU units do not come
with an outdoor temperature sensor or
enthalpy controls. This is a separate sec-
tion of the unit with its own part numbers
and factory recommended controls.
Dry Bulb
When the “ECONO METHOD TO USE” is set to DRY
BULB, the Unit Controller references the OUTSIDE
AIR TEMP only to determine the “ECONO SYS STA-
TUS.”
The “ECONO SYS STATUS” is NORMAL - ACTIVE
if all of the following conditions are met:
• The OUTSIDE AIR TEMP is less than or equal
to the “SUPPLY AIR TEMP ACTIVE SP” or up
to 8.0°F over the “SUPPLY AIR TEMP ACTIVE
SP”
• The current UNIT MODE is OCC COOLING or
UNOCC COOLING
Once the “ECONO SYS STATUS” is NORMAL - AC-
TIVE, the “ECONO SYS STATUS” is set to NOR-
MAL - INACTIVE if any of the following are met:
• The OUTSIDE AIR TEMP is 10.0°F or higher
than the “SUPPLY AIR TEMP ACTIVE SP”
• The current UNIT MODE is not OCC COOLING
or UNOCC COOLING
Single Enthalpy
When the “ECONO METHOD TO USE” is set to SIN-
GLE ENTHALPY, the Unit Controller references the
OUTSIDE AIR TEMP and OUTSIDE AIR ENTHAL-
PY (derived from the OUTSIDE AIR TEMP and OUT
-
SIDE AIR HUMIDITY) to determine the “ECONO
SYS STATUS.”
The “ECONO SYS STATUS” is NORMAL - ACTIVE
if all of the following conditions are met:
• The OUTSIDE AIR TEMP is less than or equal
to the “SUPPLY AIR TEMP ACTIVE SP” or up
to 8.0°F over the “SUPPLY AIR TEMP ACTIVE
SP”
• The OUTSIDE AIR ENTHALPY is less than
or equal to the “OUTSIDE AIR ENTHALPY
SETPOINT”
• The current UNIT MODE is OCCUPIED COOL-
ING or UNOCCUPIED COOLING
