Zone
Zone
VCB-X CONFIGURATION
VCB-X Operator Interface SD
52
VCB-X Setpoint Screens
Setpoint Screen #38 - Supply Air Cutoffs -
Cooling/Heating
VCBX Spts ID 101
Supply Air Cutoffs
Cooling: 40.0
º
F
Heating: 150.0
º
F
The VCB-X controller will temporarily disable Heating or Cooling if
while in Heating or Cooling Mode the Supply Air Temperature rises
above the Hi SAT Cutoff Heating Setpoint or falls below the Lo SAT
Cutoff Cooling Setpoint. See the
VCB-X Controller Technical Guide
for
detailed information on the Lo and Hi Supply Air Temperature Cutoff
sequence of operation.
Description
Minimum
Default
Maximum
Cooling SAT Cutoff
0ºF
(-17.7
º
C)
40ºF
(4.5
º
C)
100ºF
(37.7
º
C)
Heating SAT Cutoff
0ºF
(-17.7
º
C)
150ºF
(65.5
º
C)
250ºF
(121.1
º
C)
Setpoint Screen #39 - Hot Water Valve
Protection Position
VCBX Spts ID 101
Hot Water Valve
Protection POS: 0%
If the Supply Fan is on and the Supply Air Temperature (SAT) falls below
the Low SAT Cutoff Setpoint for 1 minute, the Hot Water Valve will
move to this position. If the SAT rises 5°F above the Low SAT Cutoff,
the valve will return to normal operation. If the SAT remains below the
Low SAT Cutoff Setpoint for 10 minutes, the unit will shut down and a
Low SAT Cutoff Alarm will be generated.
If the Supply Fan is off or during Emergency Shutdown and the Outdoor
Air Temperature (OAT) falls below the Low Ambient Setpoint, the Hot
Water Valve will move to this position. If the OAT rises back above
the Low Ambient Setpoint, the valve will return to its normal position.
If this setpoint is left at the default value of 0%, then the controller
will not initiate this protection sequence.
For SCR heat this should
be left at 0%.
Description
Minimum
Default
Maximum
Hot Water Valve
Protection Position
0%
0%
100%
Setpoint Screen #40 - Preheat Relay Setpoint
VCBX Spts ID 101
Preheat Relay
Setpt: 30.0
º
F
For cold climates where freezing temperatures may be experienced, a
Pre-Heater relay output can be activated to control a preheat coil based
on the Outdoor Air Temperature to prevent freezing of Water Coils. One
of the VCB-X Relay Outputs must be con
fi
gured for the Pre-Heater
control. When con
fi
gured, any time the Outdoor Air Temperature falls
below the Preheat Setpoint during Occupied Mode and the HVAC unit’s
fan is running, the Pre-Heater relay will activate. This setpoint will also
be used to enable the Preheater if the PREHEAT-X Controller is being
used in conjunction with the VCB-X Controller. IF the PREHEAT-X
Controller is being used with the VCB-X Controller, a relay on the VCB-
X cannot also be con
fi
gured as Preheat and energize for Preheat function.
Description
Minimum
Default
Maximum
Preheat Setpoint
-30ºF
(-34.4
º
C)
30ºF
(-1.1
º
C)
70ºF
(21.1
º
C)
Setpoint Screen #41 - Low Ambient Setpoint
VCBX Spts ID 101
Low Ambient
Setpt: 30.0
º
F
Similar to the Pre-Heat Relay, a Low Ambient Relay can be con
fi
gured
to energize anytime (during Occupied or Unoccupied Mode) the Outdoor
Air Temperature falls below this setpoint. The Low Ambient Relay,
though, can energize whether the fan is running or not. This could be
used to energize a boiler, for instance.
Description
Minimum
Default
Maximum
Low Ambient Setpoint
-30ºF
(-34.4
º
C)
30ºF
(-1.1
º
C)
70ºF
(21.1
º
C)
Setpoint Screen #42 - Heat Pump Defrost
Interval
VCBX Spts ID 102
Heat Pump Defrost
Interval: 30 Min
If this is a heat pump unit with a Defrost Coil Temperature Switch
installed and con
fi
gured, a Heat Pump Defrost Mode is available. If
the Defrost Coil Temperature Switch closes during Heat Pump Heating
operation, the unit will enter the Defrost Mode for 10 minutes or until
the Defrost Coil Temperature Switch opens. The Heat Pump Defrost
Interval is the length of time that must be met between Defrost Modes.
The length of this Defrost Interval can be automatically adjusted by the
Adaptive Defrost Interval Adjustment described in Setpoint Screen #43.
Description
Minimum
Default
Maximum
Heat Pump Defrost Interval
10 Min
30 Min
120 Min
