VCC-X SETPOINTS
VCC-X Operator Interface SD
50
Setpoint Screen #36 - Building Pressure
Setpoint & Deadband
VCC-X Spts ID:#
Building Pressure
Setpoint: 0.02”
Deadband: 0.01”
The VCC-X can maintain Building Static Pressure anytime the
Supply Fan is operating. A Building Pressure Transducer must be
connected to the VCC-X. The following are the available control
options.
Direct Acting Building Pressure Control
•
On/Off Exhaust Fan
—If an On/Off Exhaust Fan is
being used, a relay output must be con
fi
gured for
“Exhaust Fan”. This relay will energize whenever the
Building Pressure rises above the Building Pressure
Setpoint by the Deadband amount. The relay will de-
energize when the Building Pressure falls below the
Building Pressure Setpoint by the Deadband amount.
•
Exhaust Fan VFD or Modulating Exhaust
Damper
—If con
fi
gured for Modulating Exhaust, a user-
adjustable voltage output (AOUT4 – Building Pressure
Output on the VCC-X) will be used to control this fan or
damper. An Exhaust Relay can be con
fi
gured if
necessary to enable the fan or damper. Whenever the
Building Pressure rises above the Building Pressure
Setpoint by the Deadband amount, the Exhaust Fan
Relay will energize and the Modulating Signal will
activate to control to the Building Pressure Setpoint. If
the Building Pressure falls below the Building Pressure
Setpoint by the Deadband amount, the Modulating
Signal will modulate towards 0% as it attempts to
maintain the Building Pressure Setpoint. The Exhaust
Fan Relay remains energized as long as the Modulating
Signal is above 0%.
Reverse Acting Building Pressure Control
•
Outdoor Air Damper—
If this option is con
fi
gured,
the VCC-X will use the user-adjustable Economizer/
Outdoor Air Damper output signal (AOUT2 –
Economizer Control Signal) to maintain the Building
Pressure Setpoint. Whenever the Building Pressure
falls below the Building Pressure Setpoint by the
Deadband amount, the modulating Economizer Output
Signal will modulate the damper open to control to
the Building Pressure Setpoint. If the Building Pressure
rises above the Building Pressure Setpoint by the
Deadband amount, the damper will modulate towards
closed as it attempts to maintain the Building Pressure
Setpoint. When this option is selected, no Economizer
free cooling or CO
2
IAQ operation will be available.
•
Supply Fan VFD
– Contact WattMaster regarding this
Reverse Acting Building Pressure Control option. It
should not be used in most applications. If this option
is selected, the user-adjustable Supply Fan VFD Output
(AOUT1 on the VCC-X) will be used to control the
Supply Fan VFD to maintain the Building Pressure
Setpoint in similar fashion to the Outdoor Air Damper
control described above.
Description
Min.
Default
Max.
Building Pressure Spt
-0.20
″
WG
0.02
″
WG
0.20
″
WG
Building Pressure
Deadband
0.01
″
WG
0.01
″
WG
0.10
″
WG
Setpoint Screen #37 - OAT Lockouts -
Comp Cool/Comp Heat
VCC-X Spts ID:#
OAT Lockouts
Comp Cool: 50.0
º
F
Comp Heat: 35.0
º
F
The VCC-X will Lockout Compressor (Mechanical) Cooling and
Heat Pump Compressor Heating when the Outdoor Air Temperature
is below these Compressor Cool and Heat Lockout Setpoints.
Description
Minimum
Default
Maximum
OAT Lockout
Compressor Cooling
-30ºF
(-34.4
º
C)
50ºF
(10
º
C)
100ºF
(37.7
º
C)
OAT Lockout
Compressor Heating
-30ºF
(-34.4
º
C)
35ºF
(1.6
º
C)
100ºF
(37.7
º
C)
Setpoint Screen #38 - OAT Lockouts - Heat
VCC-X Spts ID:#
OAT Lockouts
Heat: 90.0
º
F
The VCC-X will Lockout Mechanical Heating when the Outdoor
Air Temperature is above this Setpoint.
Description
Minimum
Default
Maximum
OAT Lockouts Heating
-30ºF
(34.4
º
C)
90ºF
(32.2
º
C)
150ºF
(65.5
º
C)
VCC-X Setpoint Screens
