Data Aire gForce Ultra User Manual page 106

 If Chilled water temperature drops below Energy saver setpoint or return air
temperature drops below setpoint plus deadband then system will switch back to
Energy saver cooling after the energy saver lock out time delay.
9.2.1.4 Energy saver/ Auxiliary cooling with DX cooling assist.
 Energy Saver/Auxiliary Chilled Water Cooling can operate simultaneously with
compressor cooling if Energy saver assist mode is set to 1 Comp or 2 Comp and
the optional Discharge Air Sensor is required.
 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 and
compressor rules for short-cycle time will not be violated.
 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.
 When DX cooling requires, the compressors will stage on as follows:
Compressors on cycle
 Variable speed compressor C1 comes on at Temperature Setpoint +
Temperature Deadband + 1+ STS DB. For instance: SP=72⁰F, DB=2⁰F and
STS=0.3⁰F, the C1 compressor will on at 75.3⁰F.
 Once variable speed compressor comes on it will ramp up its speed maximum
speed for delay modulation then uses PI logic to maintain setpoint +1⁰F.
 Fixed speed compressor C2 comes on at Temperature Setpoint + Temperature
Deadband + 2ºF + STS DB and variable speed compressor has run at 95%
speed for a C2on delay. This step only applies to dual compressor system. For
instance: SP=72⁰F, DB=2⁰F and STS=0.3⁰F, the C2 compressor will on at 76.3⁰F.
Compressors off cycle
 Fixed speed compressor C2 cycles off at Temperature Setpoint + 2ºF, variable
speed compressor C1 continues to run at 100%. For instance: SP=72⁰F, the C2
compressor goes off at 74⁰F.
106 ● gForce Ultra User Manual 10-2014