IOM 1322 • WATER-COOLED SCROLL COMPRESSOR 60 www.DaikinApplied.com
The Active Leaving Water set point is adjusted by the 4 to 20
mA reset analog input.
Cooling Mode
The Active Leaving Water set point is adjusted by the 4 to 20
mA reset analog input.
Parameters used:
1. Evaporator Leaving Water Temperature set point (Evap
LWT)
2. Cooling Maximum Reset set point (Clg MaxRes)
3. LWT Reset signal 4-20mA
Reset is 0ºF and the active leaving water set point is equal to
the Evap LWT set point if the reset signal is less than or equal
to 4 mA. Reset is equal to the Max Reset set point and the
active leaving water set point is equal to the Evap LWT plus
Max Reset set points if the reset signal equals or exceeds
20 mA. The amount of reset will vary linearly between these
extremes if the reset signal is between 4 mA and 20 mA. An
example of the operation of 4-20 reset in Cool mode is shown
below.
The Active Leaving Water set point is adjusted by the 4 to 20
mA reset analog input.
Parameters used:
1. Heating Leaving Water Temperature set point (Heat
LWT)
2. Heating Maximum Reset set point (Htg MaxRes)
3. LWT Reset signal 4-20mA
Reset is 0ºF and the active leaving water set point is equal to
the Heat LWT set point if the reset signal is less than or equal
to 4 mA. Reset is equal to the Max Reset set point and the
active leaving water set point is equal to the Heat LWT minus
Max Reset set points if the reset signal equals or exceeds
20 mA. The amount of reset will vary linearly between these
extremes if the reset signal is between 4 mA and 20 mA. An
example of the operation of 4-20 mA reset in Heat mode is
shown below.
Cooling Mode
The Active Cooling Leaving Water set point is adjusted based
upon the dierence between the chiller’s entering and leaving
evaporator water temperatures.
The active cooling leaving water set point is reset using the
following parameters:
1. Evaporator Leaving Water Temperature set point (Evap
LWT)
2. Cooling Maximum Reset set point (Clg MaxRes)
3. Cooling Start Reset Delta Temperature (Clg StrtResDT)
4. Evaporator Delta Temperature (evaporator entering
water temperature minus leaving temperature)
Reset is accomplished by changing the Active Cooling Leaving
Water set point from the Evap LWT set point to the sum of
Evap LWT (+) Cooling Maximum Reset set points as the
evaporator delta temperature (entering minus leaving) varies
from the Cooling Start Reset Delta T set point towards 0º F
delta temperatures.
Heating Mode
The Active Heating Leaving Water set point is adjusted based
upon the dierence between the chiller’sentering and leaving
condenser water temperatures.
The active heating leaving water set point is reset using the
following parameters:
1. Heating Leaving Water Temperature set point (Heat
LWT)
2. Heating Maximum Reset set point (Htg MaxRes)
3. Heating Start Reset Delta Temperature (Htg StrtResDT)
4. Condenser Delta Temperature (condenser leaving water
temperature minus entering temperature)
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