VCB-X Operator Interface SD
VCB-X CONFIGURATION
47
Speed (entered on Setpoint Screen #16) and modulate up to 100% as
the Space Temperature rises from the Low Spc Setpoint (entered on this
screen) to the Hi Spc Setpoint entered on the previous screen. So, on
this screen the Low Spc Setpoint should correspond to the VFD Min
Cool Setpoint from Setpoint Screen #16. Please note that the VFD speed
cannot be changed on this screen; it is simply displayed from what was
entered as the Min Cool VFD Speed entered on Setpoint Screen #16.
Single Zone VFD Cooling Reset Examples:
Space Temp (Hi Spc) = 75
˚
F VFD Speed (Then VFD) = 100%
Space Temp (Low Spc) = 72
˚
F VFD Speed (Then VFD) = 30%
Description
Minimum
Default
Maximum
If Low Space
-30ºF
(-23.3
º
C)
70ºF
(21
º
C)
150ºF
(65.5
º
C)
Setpoint Screen #21 - Supply Air Heating
Setpoint and High Reset Limit
VCBX Spts ID 101
Supply Air Heating
Setpt.........: 120.0
Hi Rst Limit.: 120.0
If no Reset Source has been con
fi
gured in Con
fi
guration Screen #9, then
this Setpoint 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
gura-
tion Screen #9, 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 Supply 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 two screens).
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 Limit Spt
0ºF
(-17.7
º
C)
120ºF
(48
º
C)
250ºF
(121.1
º
C)
Setpoint Screen #22 - Heat Reset Source
Setpoints - High Space/SAT/VFD
VCBX Spts ID 101
Heat Rst Source Spts
If Hi Spc: 75.0
º
F
Then SAT: 55
VCB-X Setpoint Screens
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 Hi Spc”, “If Hi OAT”, “If Hi RAT”, or If Hi
VFD” – depending on the Reset option that has been chosen. This screen
will then allow you to input the upper limit for the Reset Source on Line
3. Line 4 (Then SAT) will show the corresponding Supply Air Cooling
Setpoint that was entered on Setpoint Screen #18. The exception is for
“If Hi VFD”. When using VFD Reset in the Heating Mode, the “Hi
VFD” value will correspond to the Supply Air Heating “Hi Rst” value
entered on Setpoint Screen #18.
Please note that the SAT (or HiRst) 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 above the Hi Spc Temperature
Setpoint, the Supply Air Heating Setpoint will be reset to its lowest value,
the SAT Setpoint. Then, as the Space Temperature moves from this high
value (Hi Spc) to its low value (Low Spc) con
fi
gured on Setpoint Screen
#23, the Supply Air Cooling Setpoint will be proportionally reset from
the SAT Setpoint to the Hi Rst Limit Setpoint.
See Heating Supply Air Reset examples under Setpoint Screen #23.
VCBX Spts ID 101
SZ VAV Fan Heat Rst
If Hi Spc: 75.0
º
F
Then VFD: 50%
If this unit was con
fi
gured for Single Zone VAV application on Con-
fi
guration 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 next screen.
Upon entering the Heating Mode, the fan will start at the Min Heating
VFD Speed (entered on Setpoint Screen #17) and modulate up to the
Max Heat VFD Speed (entered on Setpoint Screen #17) as the Space
Temperature falls from the Hi Spc Setpoint (entered on this screen) to
the Low Spc Setpoint entered on the next screen. So, on this screen the
Hi Spc Setpoint would correspond to the Min Heat VFD speed. 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 Min
Heat VFD Speed on Setpoint Screen #17.
See Single Zone VAV Reset example under Setpoint Screen #23.
Description
Minimum
Default
Maximum
If Hi Space
1ºF
(-17.7
º
C)
75ºF
(24
º
C)
150ºF
(65.5
º
C)
