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VCCX2 Controller Technical Guide
VCCX2 Controller Inputs
AI1 - Space Temperature Sensor Input
The Space Temperature Sensor will initiate Occupied Heating and
Cooling modes if the unit is configured for Space Temperature
control. It is always the sensor used to initiate Unoccupied
Heating and Cooling modes. If the Space Temperature Sensor
used is equipped with the optional Push-Button Override feature,
this input will detect user overrides and switch the unit from the
Unoccupied Mode back to the Occupied Mode operation for a
user-adjustable amount of time. The Space Temperature can
also be configured to reset the Supply Air Temperature Setpoint.
AI2 - Space Temperature Sensor Slide Adjust
If the Space Temperature Sensor being used has the optional
Slide Adjust feature, its AUX output is connected to this input.
The Slide Adjust control is used to vary the HVAC Mode Heating
and Cooling Setpoints by a user-configured maximum amount.
If the Space Temperature is configured as the SAT Reset Source,
the Slide Adjustment adjusts both the HVAC Mode Enable
Heating and Cooling Setpoints and the SAT Reset Source Heating
and Cooling Setpoints simultaneously by a user-configurable
maximum amount.
AI3 - Supply Air Temperature (SAT) Sensor
Input
Once the unit is in the Heating or Cooling Mode (based on the
temperature at the mode enable sensor), the unit will control
the staging or modulation of the heating or cooling sources to
maintain a Heating or Cooling SAT Setpoint. The HVAC unit
must always have a SAT Sensor installed.
AI4 - Return Air Temperature Sensor Input
If you want to generate occupied Heating and Cooling demands
based on Return Air Temperature, select this sensor as the HVAC
Mode Enable Sensor. The Return Air Temperature Sensor is also
used to initiate or cancel the Morning Warm-up / Cool-down
Period on VAV-configured units. If the Return Air Temperature
Sensor is connected, the Outdoor Air Temperature must be at
least 5°F below the Return Air Temperature to allow Economizer
Cooling operation.
AI5 - Building Static Pressure Sensor Input
This Sensor is only required if you wish to configure the VCCX2
Controller for Building Pressure Control. Building Pressure
Control can be accomplished by using one of two main control
methods. One control method uses the 0-10 VDC signal to control
an Exhaust Fan VFD or an Exhaust Damper Actuator for Direct
Acting Pressure Control applications. In addition, for Reverse
Acting Pressure Control applications, it can control an Outdoor
Air Damper Actuator (or in certain cases, the VFD Supply
Fan). The other available control method is to configure one of
the output relays as an exhaust fan output that will activate the
exhaust fan any time the building pressure is above the Building
Pressure Setpoint.
AI6 - Remote Supply Air Temperature Reset
Signal
If a Remote SAT Reset Signal is configured as the Reset Source,
this input can be used to accept a configurable voltage input
between 0-10 VDC (Direct or Reverse Acting) to reset the
SAT Setpoint. See the SAT Reset section in the Sequence of
Operations for more details.
AI7 - Outdoor Air Temperature Sensor Input
The Outdoor Air Temperature is used to lock out Heating or
Cooling to conserve energy at whatever temperature you deem
appropriate for each Mode of Operation. This sensor is also
used to initiate Heating and Cooling modes on a Make Up Air
unit. The Outdoor Air Temperature Sensor can also be used for
Preheater operation and for Low Ambient Protection operation.
NOTE:
For AI1, AI3, AI4 and AI7, all Temperature Sensors
must be Thermistor Type III which provide 77.0°F
@ 10K ohms resistance.
AI8 - Supply Duct Static Pressure Sensor
Input
This jack-style input connection accepts a Duct Static Pressure
Sensor modular cable input. The Duct Static Pressure Sensor
reading is used to determine current Duct Static Pressure. This
Static Pressure reading is used to control the output signal
supplied to the Supply Fan VFD or Zoning Bypass Damper
Actuator. If you have configured the HVAC unit for Constant
Volume operation, this sensor is optional. If it is installed on
a Constant Volume unit, it can be used for filter loading VFD
control or used for a status-only reading.
BIN1 - Proof of Flow Input
A Proof of Flow Switch (by others) that provides a wet contact
closure whenever the HVAC unit Supply Fan is operating can
be connected to this input. If the Proof of Flow Switch contact
opens while the Supply Fan is operating, all Heating and Cooling
is suspended or disabled.
BIN2 - Dirty Filter Contact Closure Input
This wet contact input is required for Filter Status Indication
and requires a Differential Pressure Switch to initiate a Dirty
Filter alarm.
INPUTS AND OUTPUTS
VCCX2 Controller Inputs