VCB-X Operator Interface SD
VCB-X CONFIGURATION
49
Air Temperature is the full Proportional Window amount from setpoint.
So, with a 5
˚
Proportional Window, if the Supply Air Temperature is 5
˚
or more from setpoint, the signal change will be 10% per time period.
At 4
˚
difference, the signal change will be 8% per time period. By the
time the difference is 1
˚
, the signal change will be 2% per time period.
With a Proportional Window of 2
˚
, if you are 2
˚
or more from setpoint,
the amount of signal change will be 10% per time period, and at 1
˚
from setpoint the change would be 5% per time period. So, a larger
proportional window allows for
fi
ner tuning of the control signal to
prevent overshooting.
The Time Period is the length of time between Modulating Signal adjust-
ments. Short Time Periods may cause hunting of the Modulating Signal.
Description
Minimum
Default
Maximum
Mod Heat Proportional
Window
.1ºF
(.1
º
C)
10ºF
(5.5
º
C)
30ºF
(16.6
º
C)
Mod Heat Time Period
5 sec
10 sec
240 sec
Setpoint Screen #26 - Mod Cool Proportional
Window and Time Period
VCBX Spts ID 101
Mod Cool
Prop Window: 10.0
º
F
Time Period: 30.0s
The Modulating Cooling Proportional Window is the control range of the
Modulating Signal above and below the Active Supply Air Temperature
Setpoint. The size of the Proportional Window will determine how much
of a signal change the controller will make per Time Period for every
˚
F the Supply Air Temperature is from setpoint. The maximum signal
change per time period is 10% when the Supply Air Temperature is the
full Proportional Window amount from setpoint. So, with a 5
˚
Propor-
tional Window, if the Supply Air Temperature is 5
˚
or more from setpoint,
the signal change will be 10% per time period. At 4
˚
difference, the
signal change will be 8% per time period. By the time the difference is
1
˚
, the signal change will be 2% per time period. With a Proportional
Window of 2
˚
, if you are 2
˚
or more from setpoint, the amount of signal
change will be 10% per time period, and at 1
˚
from setpoint the change
would be 5% per time period. So, a larger proportional window allows
for
fi
ner tuning of the control signal to prevent overshooting.
The Time Period is the length of time between Modulating Signal adjust-
ments. Short Time Periods may cause hunting of the Modulating Signal.
Description
Minimum
Default
Maximum
Mod Cool Proportional
Window
.1ºF
(.1
º
C)
10ºF
(5.5
º
C)
30ºF
(16.6
º
C)
Mod Cool Time Period
5 sec
30 sec
240 sec
Setpoint Screen #27 - Head Pressure
Setpoints - Cooling and Reheat
VCBX Spts ID 101
Head Pressure Spts
Cooling: 315PSI
Reheat: 400PSI
If a Head Pressure Transducer is connected to the VCB-X EM1 Module
you can control a Condenser Fan or a Condenser Water Valve to maintain
these Head Pressure Setpoints in the Cooling and Dehumidi
fi
cation
Reheat Modes.
Description
Minimum
Default
Maximum
Cooling Head Pressure
Setpoint
240 PSI
315 PSI
420 PSI
Reheat Head Pressure
Setpoint
240 PSI
400 PSI
420 PSI
Setpoint Screen #28 - Economizer Enable
Setpoint
VCBX Spts ID 101
Economizer Enable
Setpt: 55.0
º
F
If this unit has been con
fi
gured for Economizer control and an Outdoor
Humidity Sensor is not connected to the VCB-X Controller, if the
Outdoor Temperature falls below this setpoint, the Economizer can
be used for free cooling. If a combination Outdoor Air Temperature/
Humidity Sensor is connected to the VCB-X Controller and the Wetbulb
or Dewpoint Temperature falls below this setpoint, the Economizer can
be used for free cooling.
Description
Minimum
Default
Maximum
Economizer Enable
-30ºF
(-34.4
º
C)
55ºF
(12.8
º
C)
80ºF
(26.6
º
C)
Setpoint Screen #29 - Economizer Minimum
Damper Position
VCBX Spts ID 101
Economizer Min
Damper Pos: 10%
The Economizer (OA Damper) Minimum Position Setpoint is maintained
during the Occupied Mode even if the Economizer is disabled due to the
OA Temperature being above the Economizer Enable Setpoint.
Description
Minimum
Default
Maximum
Economizer Min Position
0%
10%
100%
VCB-X Setpoint Screens
