10
VCCX2 Controller Technical Guide
Variable Air Volume Unit
The VCCX2 Controller can control VAV units that are typically
designed for occupied Cooling Mode only, where VAV boxes
equipped with reheat satisfy heating demands in individual
spaces. In this application, unit heat is typically used for Morning
Warm-Up. Morning Cool-Down is also available. The controller
can be configured to control the supply fan VFD to maintain a
Duct Static Pressure Setpoint.
The VCCX2 can also control VAV units that may require
Occupied Heating operation to “temper” the outdoor air if it is
too cold outside for the mixed air to maintain the Cooling Supply
Air Setpoint.
Constant Air Volume Unit
The VCCX2 Controller can be configured for Constant Volume
applications that are typically Space Temperature or Return Air
Temperature controlled.
The VCCX2 can also be used for restaurant kitchen or lab
applications that are 100% outdoor air part of the time and
Recirculating Air part of the time. A Hood On binary input
forces the VCCX2 to switch to 100% outdoor air control based
on an Exhaust Hood Switch activation. The VCCX2 requires
Outdoor and Indoor Air Temperature (and Humidity) Sensors
to accomplish this application.
Single Zone VAV
This is a hybrid CAV/VAV application for a unit serving a single
space and using Space Temperature Setpoints to enable Heating
and Cooling Modes. Heating and cooling are controlled to their
respective Supply Air Setpoints while the supply fan modulates
to maintain the Space Temperature Setpoints. Single Zone VAV
applications can be configured for VAV Cooling and either VAV
or CAV Heating. Single Zone VAV operation requires the use of
modulating heating or cooling sources.
Space Temperature Control of High
Percentage Outdoor Air Units
This application allows the unit to be configured to use the space
temperature to initiate Cooling and Heating Modes on units that
are high percentage outdoor air or 100% outdoor air units. Before
entering the Space Vent Mode, the VCCX2 will first determine if
the Outdoor Air Temperature is above or below special Outdoor
Air Cooling and Heating Setpoints. If so, the unit will leave
stages of cooling or heating on as necessary to achieve a neutral
Supply Air Temperature – thus avoiding dumping very hot or
cold air into the space.
Make-Up Air Unit
The VCCX2 can be configured for 100% Outdoor Air control
for Make-Up Air units. All HVAC Modes are determined from
the Outdoor Temperature and Humidity Sensors. The Outdoor
Air Volume should be at least 50% or higher to be configured
for Outdoor Air control.
AAON
®
Return Air Bypass Control
This control scheme can only be used on Constant Volume
HVAC units that are equipped with a Return Air Bypass Damper
and that use Space Temperature and Humidity Sensors as the
controlling sensors.
AAON
®
Return Air Bypass Control provides improved moisture
removal capabilities while utilizing internal space loads for
reheat by redirecting Return Air from the upstream side of the
DX Evaporator Coil to the downstream side of the coil during
Dehumidification.
Zone Voting
The VCCX2 can be configured to be the unit controller in a
zone voting system where the individual zones vote to put the
unit into occupied Cooling or Heating Mode. To be used in this
application, Orion zone controllers must also be used in order to
allow communication between the zones and the VCCX2. Duct
Static Pressure Control can be accomplished with a supply fan
VFD or a bypass damper.
OVERVIEW
Applications
