Data Aire gForce Ultra - 9.3 Safeties and Alarms

110 ● gForce Ultra User Manual 10-2014
 If Energy saver chilled water is available (inlet water temperature is below
energy saver water thermostat set in menu B-setpoint), the chilled water will be
used as a primary cooling, and DX will be a supplemental cooling.
 The Energy Saver/Auxiliary Chilled Water Cooling logic will be the same as the
chilled water cooling logic of the discharge air temperature control, this means
dap4™ uses a preset PID loop to control the CW valve to maintain a discharge
air temperature setpoint,
 Low discharge temperature alarm limit must be set in menu K-Alarms & Limits. If
Discharge temperature drops below this limit, compressors will be inhibited for at
least 15 minutes and discharge temperature rises above this limit.
 If discharge temperature drops below the limit while the variable speed
compressor finishing its minimum runtime the CW should close until discharge
temperature rises above the limit.
 The following is the compressor staging sequence.
Compressors on cycle with energy saver
 Variable speed compressor C1 comes on at Temperature Setpoint +
Temperature Deadband + STS Band. Once variable speed compressor comes on
it will use PID logic to maintain temperature setpoint + 1⁰F (to make sure CW is
fully utilized).
 Fixed speed compressor C2 (*) comes on at Temperature Setpoint +
Temperature Deadband + 1⁰F + STS DB and variable speed compressor C1 has
operated at 95% for at least the C2 on delay.
Compressors off cycle during energy saver mode
 Fixed speed compressor c2 (*) cycles off at Temperature Setpoint + STS DB for
a C2 off delay duration and variable speed compressor C1 runs at 100% .
 Variable speed compressor C1 cycles off at Temperature Setpoint Compressor
will not violate its minimum runtime and short cycle regulation.
* This applies on dual compressor system.
9.3 Safeties and Alarms
NOTE: All suction safeties are only applied to the variable speed
compressor, not the fixed speed compressor.