Johnson Controls 40 25 TON, Installation Operation & Maintenance

Page: 139 / 251

139
JOHNSON CONTROLS
5276178-JIM-C-0118
5
•
The
“OUTSIDE AIR ENTHALPY”
is less than
or equal to the “OUTSIDE AIR ENTHALPY
SETPOINT”.
•
The current “UNIT MODE” is OCCUPIED
COOLING or UNOCCUPIED COOLING.
Once the
““ECONO SYS STATUS”
is NORMAL
–
ACTIVE, the
“ECONO SYS STATUS”
is set to
NORMAL – INACTIVE if any of the following are
met:
•
The “OUTSIDE AIR TEMP” is greater than or
equal to the “SUPPLY AIR TEMP ACTIVE SP”
plus10°F.
•
The “OUTSIDE AIR ENTHALPY” is greater
than or equal to the
“OUTSIDE AIR ENTHALPY
SETPOINT”
plus 1 BTU/LB.
•
The current
“UNIT MODE”
is not OCC COOL-
ING or UNOCCUPIED COOLING.
Dual Enthalpy
When the “ECONO METHOD TO USE” is set
to “DUAL ENTHALPY” , the Unit Controller will
reference the
“OUTSIDE AIR TEMP”
,
“OUTSIDE AIR
ENTHALPY” (derived from “OUTSIDE AIR TEMP”
and “OUTSIDE AIR HUMIDITY”) , and “RETURN AIR
ENTHALPY” (derived from “RETURN AIR TEMP”
and “RETURN AIR HUMIDITY”) to determine the
“ECONO SYS STATUS”.
The “ECONO SYS STATUS” will be 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” plus
8°F.
•
The
“OUTSIDE AIR ENTHALPY”
is less than
or equal to the “RETURN AIR ENTHALPY” – 1
BTU/LB.
•
The current “UNIT MODE” is OCCUPIED
COOLING or UNOCCUPIED COOLING.
Once the “ECONO SYS STATUS” is NORMAL –
ACTIVE, the “ECONO SYS STATUS” is set to
NORMAL INACTIVE if any of the following
are met:
•
The
“OUTSIDE AIR TEMP”
is greater than or
equal to the
“SUPPLY AIR TEMP ACTIVE SP”
plus 10°F.
•
The “OUTSIDE AIR ENTHALPY” is greater than
or equal to the “RETURN AIR ENTHALPY” .
•
The current “UNIT MODE” is not OCCUPIED
COOLING or UNOCCUPIED COOLING.
Best Method
When the
“ECONO METHOD TO USE”
is set
to “BEST AVAILABLE” , the Unit Controller will
determine the “ECONO METHOD TO USE” based
on the sensor that installed and reliable. The “DRY
BULB” method will be used if only the “OAT SENSOR
RELIABLE”
is true. The Single Enthalpy method will
be used if both the “OAT SENSOR RELIABLE” and
the “OA HUMIDITY SENSOR RELIABLE” are true.
The Dual Enthalpy method shall be used if the “OAT
SENSOR RELIABLE”, “RET SENSOR RELIABLE”,
“OA HUMIDITY SENSOR RELIABLE”
and the
“RA
HUMIDITY SENSOR RELIABLE” are all true.
With this setting, all of the above logic for Dry Bulb,
Single enthalpy, and Dual Enthalpy apply.