VCB-X Operator Interface SD
VCB-X CONFIGURATION
45
VCB-X Setpoint Screens
Setpoint Screen #16 - VFD Speed Minimums
Cool/Vent Modes
VCBX Spts ID 101
VFD Speed Limits
Min Cool: 60%
Min Vent: 60%
If this unit is con
fi
gured for Single Zone VAV operation, the Min Cool
Percentage will be the fan speed at which the VFD will start operating
at when cooling is initiated. It can then modulate up to 100% as the
space temperature rises within the range created by the Low Space (Low
Spc) and the High Space (Hi Spc) Setpoints entered in Setpoint Screens
#19 and 20. On a standard VAV unit, this will be the lowest fan speed
the VFD will operate at in the Cooling Mode as it controls to the Duct
Static Pressure Setpoint.
The Min Vent Percentage is the speed at which the fan will operate
during the Vent Mode.
Description
Minimum
Default
Maximum
Minimum Cool
0%
30%
100%
Minimum Vent
0%
20%
100%
Setpoint Screen #17 - VFD Speed Limits Min/
Max Heat
VCBX Spts ID 101
VFD Speed Limits
Min Heat: 60
%
Max Heat: 100
%
If this unit is con
fi
gured for Single Zone VAV operation, and you have a
modulating heat source that will allow VAV heating, then the Min Heat
Percentage will be the fan speed at which the VFD will start operating
at when heating is initiated. It can then modulate up to the Max Heat
Percentage as the Space Temperature falls within the range created by
the Hi Space setpoint and the Low Space Setpoint created in Setpoint
Screens #22 and 23. On a standard VAV unit, these setpoints will be the
Min and Max fan speeds the unit will operate at in the Heating Mode
as it controls to the Duct Static Pressure Setpoint.
Description
Minimum
Default
Maximum
Minimum Heat
0%
60%
100%
Maximum Heat
0%
100%
100%
Setpoint Screen #18 - Supply Air Cooling
Setpoint and High Reset Limit
VCBX Spts ID 101
Supply Air Cooling
Setpt.......: 55.0
º
F
Hi Rst Limit: 55.0
º
F
If no Reset Source has been con
fi
gured in Con
fi
guration Screen #9, then
this Setpoint will be the Supply Air Temperature Cooling Setpoint. Line 4
will be not be used. If a Reset Source has been con
fi
gured in Con
fi
gura-
tion Screen #9, then Line 4 will be used. Reset is always upward from
the SAT setpoint to the Reset Limit setpoint. So, the SAT will be the
lowest temperature the Supply Air Setpoint can be reset to and Hi Reset
Limit will be the highest temperature the Supply Air Setpoint can be
reset to. The Cooling Supply Air Temperature Setpoint will automatically
be reset warmer or colder within this range as the Reset Source moves
within its range (created in the next two screens).
Description
Minimum
Default
Maximum
SAT Cooling Setpoint
30ºF
(-1.1
º
C)
55ºF
(12.8
º
C)
80ºF
(26.6
º
C)
Cooling Reset Limit
0ºF
(-17.7
º
C)
55ºF
(12.8
º
C)
100ºF
(37.7
º
C)
