Constant Fan Speed (Const Speed); Compressor; Return Air Temperature Control Mode - Data Aire gForce Ultra User Manual

9.1.6 Constant Fan Speed (Const Speed):

In this mode, the fan speed can be set at the required speed and remains fixed at that
speed. Field adjustment is available via the front display panel and can be manually
adjusted via the "Constant Fan Speed" menu. This value is adjustable from 70% to
100%, which results in an analog output of 7 VDC to 10 VDC. In this mode, the fans
will start and operate at this constant design fan speed all the time.

Compressor

9.2

9.2.1 Return Air Temperature Control Mode

9.2.1.1 Single DX circuit- one variable speed compressor system
 Compressor settings type in dap4™ Factory Settings menu is programmed to
"Single Variable" and Control mode is set to "Return Temp".
 There is a five (5) minute delay between start-to-start of the compressor. 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.
 Once variable speed compressor C1 comes on, it must remain on for a minimum
runtime even setpoint satisfies.
 If variable speed compressor C1 runs at the minimum speed for a period of time,
it will automatically ramp up to the maximum speed for one minute to maintain
the minimum compressor oil level. The temperature may drop slightly during this
override period.
 Compressor C1 cycles on and modulate as follows to maintain setpoint:
Return air temperature is rising (On cycle):
 When return air temperature = Temperature Setpoint + Temperature Deadband
variable speed compressor starts and ramp up to maximum speed. For instance:
SP = 72⁰F, DB = 2⁰F. Compressor will be on at 74⁰F.
 Variable speed compressor will then use PI (Proportional and Integral) control
algorithm to main the setpoint. Proportional band is the same as deadband.
The Integral band is programmed in Factory settings menu. In most cases there
is no need to change the P and I value as the result of temperature control
fluctuation.
102 ● gForce Ultra User Manual 10-2014