STULZ CyberRow DX Series Installation, Operation & Maintenance Manual
April, 2016)
4-12
Figure 15- Dewpoint Control
Cool Only- No
Humidifi cation
Needed
Actual
Temp/RH
(Dewpoint)
Setpoint
Psychrometric Chart
Set
Point
Cut-in
1
Cut-out
1
Start
1
Stop 1
Minimum
Run Time
Dehum
Min Temp
Figure 16- Compressor On/Off Cycle
The cooling cut-in and cut-out setpoints are set with a
minimum span of 2.0°F.
NOTE:
If the compressor cut-in/cut-out setpoints are
set too closely together when adjusting setpoints, the
compressor could run below the setpoint temperature
during periods of light heat loads because of the
minimum run time cycle.
4.4.3.2 Water-W/G
Operation
When the system is turned on the controller activates the
fl uid supply control valve with a proportional/integral (P/I),
0-10 VDC signal. The valve opens proportionally based on
head pressure. The control parameters
are adjustable in
the Factory menu. Contact STULZ Technical Support for
guidance if adjustment is needed.
The control valve changes position to adjust coolant fl ow
to keep the head pressure to the control setpoint and
maintain it. If the head pressure rises, the valve position
continues to modulate open as needed, up to 100% (fully
open), to maintain the control setpoint.
4.4.3 Operating
Confi gurations
The operating confi guration for the controller depends on
what type of air conditioner is being controlled (i.e. AR,
CW, W/G) and what features are selected. The operating
confi guration is preset by the factory according to the
application. If certain features discussed in this manual
are not factory enabled, no screens for that feature will
appear in the controller user interface display.
4.4.3.1 Compressor Operation
The controller cycles the compressor on when it is
determined that cooling is called for. The compressor is
turned on based upon the controller’s cooling response
to temperature and humidity inputs from the air sensors.
The compressor is enabled following a time delay, once
the programmed “Cooling Stage Enable” setpoint value
has been reached (see Figure 16). The compressor
runs at a constant speed and an electronic hot gas
bypass system manages capacity in accordance with
the demand for cooling. The compressor is turned off
when the control cut-out setpoint is achieved, provided
the minimum run time is expired. Operating setpoints for
the compressor are programmed by the Factory and no
adjustment should be necessary. It is recommended that
STULZ Technical Support be contacted if adjustment is
required.
Summary of Contents for CyberRow DX CRS-042-G
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