VCC-X SETPOINTS
VCC-X Operator Interface SD
46
Setpoint Screen #21 - Heat Reset Source
Setpoints - High Reset/Low Reset
VCC-X Spts ID:#
Heat 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, 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 between the limits that were
con
fi
gured in
Setpoint Screen #20
. At the High Reset Source Tem-
perature, the Supply Air Setpoint will be reset to the Supply Air
Heating Setpoint con
fi
gured in
Setpoint Screen #20
. At the Low
Reset Source Temperature and below, the Supply Air Setpoint will be
reset to the Heating Supply Air Hi Reset Limit con
fi
gured in
Setpoint
Screen #20
. 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 High Reset Limit values set
in
Setpoint Screen #20
.
If this unit is con
fi
gured for SZ VAV operation in the Heating Mode,
the setpoints (Space Temperature only) on this screen will reset the
VFD fan speed in order to maintain the Space Temperature Heat-
ing Setpoint. So, if the Space Temperature is at or below the Low
Reset Source value on this screen, the VFD Fan Speed will set at
the Max Heat VFD Speed set in
Setpoint Screen #17
. If the Space
Temperature is at or above the High Reset Source value on this
screen, the VFD Fan Speed will be at the Min Heat VFD Speed from
Setpoint Screen #17
. As the Space Temperature moves between the
High and Low values set on this screen, the VFD Fan speed will be
proportionally reset between the Min and Max Heat VFD Speeds
on
Setpoint Screen #17
.
If the Reset Source is the Fan VFD Signal or a Remote Voltage
Reset Signal, then the Heat High Reset value will be the VFD
Signal Percentage or the Voltage Signal that will reset the Supply
Air Setpoint to the Supply Air Heating Setpoint in
Setpoint Screen
#20
. The Heat Low Reset value will be the VFD Signal Percentage
or the Voltage Signal that will reset the Supply Air Setpoint to the
Supply Air Heating High Reset Limit Setpoint in
Setpoint Screen
#20
. Note that for a Voltage Reset, for example, either 0 or 10 volts
can be used for the Heating Low Reset value based on which volt-
age you want to correspond to the Supply Air Heating High Reset
Limit Setpoint. The opposite voltage would then be used for the
Supply Air Heating High Reset value corresponding to the Supply
Air Heating Setpoint.
Description
Minimum
Default
Maximum
High Reset Limit
1ºF
(-17.7
º
C)
75ºF
(24
º
C)
150ºF
(65.5
º
C)
Low Reset Limit
-30ºF
(-34.4
º
C)
70ºF
(21
º
C)
150ºF
(65.5
º
C)
VCC-X Setpoint Screens
Setpoint. So, if the Space Temperature is at or below the Low Reset
Source value on this screen, the VFD Fan Speed will set at the Min
Cool VFD Speed set in
Setpoint Screen #16
. If the Space Tempera-
ture is at or above the High Reset Source value on this screen, the
VFD Fan Speed will be at 100%. As the Space Temperature moves
between the values set on this screen, the VFD Fan speed will be
proportionally reset between the Min Cool VFD Speed (
Setpoint
Screen #16
) and 100%. The max fan speed in Cooling is
fi
xed at
100% and cannot be changed.
If the Reset Source is the Fan VFD Signal or a Remote Voltage
Reset Signal, then the Cool High Reset value will be the VFD
Signal Percentage or the Voltage Signal that will reset the Supply
Air Setpoint to the Supply Air Cooling Setpoint in
Setpoint Screen
#18
. The Cool Low Reset value will be the VFD Signal Percentage
or the Voltage Signal that will reset the Supply Air Setpoint to the
Supply Air Cool High Reset Limit Setpoint in
Setpoint Screen #18
.
Note that for a Voltage Reset, for example, either 0 or 10 volts can
be used for the Cooling Low Reset value based on which voltage
you want to correspond to the Supply Air Cooling High Reset Limit
Setpoint. The opposite voltage would then be used for the Cooling
High Reset value corresponding to the Supply Air Cooling Setpoint.
Description
Minimum
Default
Maximum
High Reset Limit
1ºF
(-17.2
º
C)
75ºF
(24
º
C)
150ºF
(65.5
º
C)
Low Reset Limit
-10ºF
(-23.3
º
C)
70ºF
(21
º
C)
150ºF
(65.5
º
C)
Setpoint Screen #20 - Supply Air Heating
Setpoint and High Reset Limit
VCC-X Spts ID:#
Supply Air Heating
Setpoint: 120.0
º
F
Hi Rst Lmt: 120.0
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
Heating Setpoint. Line 4 will 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 Hi Reset
Limit setpoint. So, the SAT will be the lowest temperature the Sup-
ply Air Setpoint can be reset to and Reset Limit will be the highest
temperature the Supply Air Setpoint can be reset to. The Heating
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).
NOTE:
For a Supply Air Tempering application, the Heating Supply Air
Setpoint should be set at least 2°F below the Cooling Supply Air Setpoint.
Description
Minimum
Default
Maximum
SAT Heating Spt
40ºF
(4.5
º
C)
120ºF
(48
º
C)
240ºF
(115.5
º
C)
Reset High Limit
0ºF
(-17.7
º
C)
120ºF
(48
º
C)
250ºF
(121.1
º
C)
