VCC-X Operator Interface SD
VCC-X SETPOINTS
45
VCC-X Setpoint Screens
Setpoint Screen #16 - VFD Speed Minimums
Cool/Vent Modes
VCC-X Spts ID:#
VFD Speed Limits
Min Cool: 30%
Min Vent: 20%
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
Cool Low Reset Source and the Cool High Reset Source Setpoints
entered in
Setpoint Screen #19
.
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
VCC-X Spts ID:#
VFD Speed Limits
Min Heat: 50
%
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 Heat High Reset Source and the Heat Low
Reset Source created in
Setpoint Screen #21
. On a standard VAV
unit, if the VFD Signal falls below the Minimum VFD Heat Setpoint
during the Heating Mode, Heating will be disabled.
Description
Minimum
Default
Maximum
Minimum Heat
0%
50%
100%
Maximum Heat
0%
100%
100%
Setpoint Screen #18 - Supply Air Cooling
Setpoint and High Reset Limit
VCC-X Spts ID:#
Supply Air Cooling
Setpoint....: 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 #11
,
then the Setpoint value will be the Supply Air Temperature Cool-
ing Setpoint. Line 4 will be not be used. If a Reset Source has been
con
fi
gured in
Con
fi
guration Screen #11
, 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 screen).
Description
Minimum
Default
Maximum
SAT Cooling Setpoint
30ºF
(-1.1
º
C)
55ºF
(12.8
º
C)
80ºF
(26.6
º
C)
Cool High Reset Limit
0ºF
(-17.7
º
C)
55ºF
(12.8
º
C)
100ºF
(37.7
º
C)
Setpoint Screen #19 - Cool Reset Source
Setpoints - High Reset/Low Reset
VCC-X Spts ID:#
Cool Rst Source Spts
High Reset: 75.0
º
F
Low Reset: 70.0
º
F
If no SAT Reset Source has been con
fi
gured in
Con
fi
guration Screen
#11
, you can disregard this screen.
If a temperature Reset Source (Space, Return Air, or Outdoor Air)
has been con
fi
gured in
Con
fi
guration Screen #11
, then this screen
will allow you to set the range of Reset Source temperatures that
will reset the Supply Air Temperature Setpoint between the limits
that were con
fi
gured in
Setpoint Screen #18.
At the Cool High Reset
Source Temperature or above, the Supply Air Setpoint will be set to
the Supply Air Cooling Setpoint con
fi
gured in
Setpoint Screen #18
.
At the Cool Low Reset Source Temperature, the Supply Air Setpoint
will be reset to the Cool Supply Air High Reset Limit con
fi
gured
in
Setpoint Screen #18
. As the Reset Source temperature moves
between the Low and High Reset Source values (set in this screen),
the Supply Air Temperature Setpoint will be proportionally reset
between the Supply Air Cooling Setpoint and the Cooling High
Reset Limit values set in
Setpoint Screen #18
.
If this unit is con
fi
gured for SZ VAV operation in the Cooling Mode,
the setpoints (Space Temperature only) on this screen will reset the
VFD fan speed in order to maintain the Space Temperature Cooling
