Zone
Zone
VCB-X CONFIGURATION
VCB-X Operator Interface SD
48
Setpoint Screen #23 - Heat Reset Source
Setpoints - Low Space/High Reset/VFD
VCBX Spts ID 101
Heat Rst Source Spts
If Low Spc: 70.0
º
F
Then Hi Rst: 55
º
F
If no SAT Reset Source has been con
fi
gured in Con
fi
guration Screen #9
and the unit has not been con
fi
gured for Single Zone VAV, then this screen
will read, “No Heat Rst Con
fi
g” and will not be used. If the unit has been
con
fi
gured for Single Zone VAV, see the last paragraph for this screen.
If a Reset Source has been con
fi
gured in Con
fi
guration Screen #9, the
third line will display “If Low Spc”, “If Low OAT”, “If Low RAT”, or “If
Low VFD” – depending on the Reset option that has been chosen. This
screen will then allow you to input the lower limit for the Reset Source
on Line 3. Line 4 (Then SAT) will show the corresponding Supply Air
Cooling Hi Rst Setpoint that was entered on Setpoint Screen #18. The
exception is for “If Low VFD”. When using VFD Reset in the Heating
Mode, the “Low VFD” value will correspond to the Supply Air Heating
“Setpt” value entered on Setpoint Screen #18.
Please note that the Low Rst (or SAT) value cannot be changed on this
screen; it is simply displayed from what was entered on the Setpoint
Screen #21. The value on Line 3 corresponds to the value on Line 4. So,
if the Space Temperature Sensor has been con
fi
gured as the Reset Source,
then when the Space Temperature is at or below the Low Spc Setpoint,
the Supply Air Heating Setpoint will be reset to its highest value, the
Heating Hi Rst Value. Then, as the Space Temperature moves from this
low value (Low Spc) to its high value (Hi Spc) con
fi
gured on Setpoint
Screen #22, the Supply Air Cooling Setpoint will be proportionally reset
from the Hi Rst Limit Setpoint to its SAT Setpoint.
Heating Supply Air Reset Examples:
Space Temperature Heating Reset of SAT Setpoint:
Space Temp (Hi Spc) = 71
˚
F SAT Stpt (SAT) = 90
˚
F
Space Temp (Low Spc) = 68
˚
F SAT Stpt (Hi Rst) = 120
˚
F
VFD Percentage Heating Reset of SAT Setpoint:
VFD Percentage (Hi VFD) = 100% SAT Stpt (SAT) = 120
˚
F
VFD Percentage (Low VFD) = 30% SAT Stpt (Hi Rst) = 90
˚
F
VCBX Spts ID 101
SZ VAV Fan Heat Rst
If Low Spc: 70.0
º
F
Then VFD: 90%
If this unit was con
fi
gured for Single Zone VAV application on Con
fi
gura-
tion Screen #7, this screen will appear. In the Heating Mode, the Supply
Fan VFD speed will proportionally modulate as the Space Temperature
falls within the range set on this screen and the previous screen. Upon
entering the Heating Mode, the fan will start at the Min Heating VFD
Speed (entered on Setpoint Screen #17) and modulate the Max Heat
VFD Speed (entered on Setpoint Screen #17) as the Space Temperature
falls from the Hi Spc Setpoint (entered on the previous screen) to the
Low Spc Setpoint entered on this screen. So, on this screen the Low
Spc Setpoint should correspond to the VFD Max Heat Setpoint from
Setpoint Screen #17. Please note that the VFD Speed Displayed on this
screen cannot be changed on this screen; it is simply displayed from
what was entered as the Max Heat VFD Speed on Setpoint Screen #17.
Single Zone VFD Heating Reset Example:
Space Temp (Hi Spc) = 71
˚
F VFD Speed (Then VFD) = 50%
Space Temp (Low Spc) = 68
˚
F VFD Speed (Then VFD) = 90%
Description
Minimum
Default
Maximum
If Low Space
-30ºF
(-34.4
º
C)
70ºF
(21
º
C)
150ºF
(65.5
º
C)
Setpoint Screen #24 - Stage Off Window -
Cooling/Heating
VCBX Spts ID 101
Stage Off Window
Cooling: 5.0
º
F
Heating: 5.0
º
F
When the VCB-X Controller is in Cooling Mode, if the Supply Air Tem-
perature drops below the Active Supply Air Cooling Setpoint minus the
Cooling Stage Off Window value, a Cooling Stage will be deactivated
after its Minimum Run Time. In the Heating Mode, if the Supply Air
Temperature rises above the Active Supply Air Heating Setpoint plus the
Heating Stage Off Window value, a Heating stage will be deactivated
after its Minimum Run Time.
Description
Minimum
Default
Maximum
Stage Off Window Cooling
1ºF
(.6
º
C)
5ºF
(2.8
º
C)
30ºF
(16.6
º
C)
Stage Off Window Heating
1ºF
(.6
º
C)
5ºF
(2.8
º
C)
50ºF
(27.7
º
C)
Setpoint Screen #25 - Mod Heat Proportional
Window and Time Period
VCBX Spts ID 101
Mod Heat
Prop Window: 10.0
º
F
Time Period: 10.0s
The Modulating Heating Proportional Window is the control range of
the Modulating Signal above and below the Active Supply Air Tempera-
ture Setpoint. The size of the Proportional Window will determine how
much of a signal change the controller will make per Time Period for
every 1
˚
F the Supply Air Temperature is from setpoint. The maximum
signal change per time period is 10% which occurs when the Supply
VCB-X Setpoint Screens
