Data Aire gForce Ultra User Manual page 108

Discharge air temperature is dropping (Off cycle):
 Compressor C1 turns off when discharge air temperature drops to Temperature
Setpoint – C1 offset. C1 offset is programmed in Compressor /Factory settings
menu.
 Compressor C1 can only turn off if minimum runtime has expired.
9.2.2.2 Dual DX circuit: Combination of a variable speed compressor (C1) and a fixed
speed compressor (C2) system
 Compressor settings type in dap4™ Factory Settings menu is programmed to
"Vari+Fixed " and Control mode is set to "Supply".
 There is a five (5) minute delay between start-to-start of the same primary
stage. The delay will be increased to six (6) minutes for one (1) hour following
the detection of a short-cycle condition even if the short cycle alarm is disabled
using a short cycle alarm menu.
 There is a two (2) minute delay between stop-to-start of the same compressor.
 There is minimum two (2) minutes delay between the start of variable speed
compressor and start of fixed speed compressor.
 Once variable speed compressor C1 comes on, it must remain on for a minimum
runtime even setpoint satisfies.
 Compressor cycles on and modulate as follows:
Discharge air temperature is rising (On cycle):
 When discharge air temperature rises to temperature setpoint + 0.5 temperature
deadband (SP+1/2 DB), variable speed compressor C1will start.
 dap4™ will then use PID (proportional – Integral - derivative) logic to control the
compressor C1 speed to maintain temperature setpoint.
 Fixed speed compressor C2 will come on when discharge air temperature rises to
Temperature Setpoint + Temperature Deadband (SP+DB) and compressor C1
has operated at above 95% of its maximum speed for at least C2 on delay. C2
on delay is programmed in Compressor/Factory settings menu.
 Once fixed compressor C2 started, the variable speed compressor C1 will operate
at minimum speed for duration of Delay Modulation. Delay modulation is
programmed in Compressor/factory settings menu.
108 ● gForce Ultra User Manual 10-2014