Orion System VCC-X Controller - Manual (Page 6)

OVERVIEW
6 VCC-X Controller Technical Guide
Applications
Applications
Variable Air Volume Unit
The VCC-X can be confi gured to control a VFD Supply Fan for Duct
Static Pressure control. If the unit is not equipped with a VFD, but
Duct Static Pressure control is needed, a modulating Zoning Bypass
Damper can be controlled by the VCC-X.
VAV units are typically designed for occupied Cooling with Morning
Warm-up Heating. This option is available with the VCC-X. The
VCC-X can also be used for a Zoning System that needs Duct Static
Pressure control and Occupied Cooling and Heating.
The VCC-X also has the ability to be confi gured for Duct Static
Pressure Control by controlling the Supply Fan VFD for the purpose
of maintaining proper Duct Static Pressure in response to varying
fi lter loading conditions.
When an indoor humidity sensor is connected to the system, the
VCC-X allows Dehumidifi cation Priority on a VAV unit. This could
be useful on a building with a very low internal sensible load, but
which has a high internal and/or external latent load. During VAV
Dehumidification, the VCC-X activates Cooling based on the
Evaporator Coil Temperature and activates AAON
® Modulating
Hot Gas Reheat to warm the Supply Air Temperature to the Active
Supply Air Temperature Setpoint.
Constant Air Volume Unit
The VCC-X can be confi gured to activate a Constant Volume Supply
Fan. In most cases, this is a very basic unit with Space Temperature or
Return Air Temperature control. The VCC-X can be used for kitchen,
restaurant, or lab environments that are 100% Outdoor Air part of
the time and Return Air part of the time. The Hood On input allows
the VCC-X to know when to switch to 100% Outdoor Air control
based on an exhaust hood activating. The VCC-X requires Outdoor
and Indoor Air Temperature 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 confi gured for VAV Cooling and either VAV or
CAV Heating. VAV operation requires the use of modulating Heating
or Cooling sources.
Make-Up Air Unit
The VCC-X can be confi gured for 100% Outdoor Air control for
Make-Up Air. All HVAC Modes are determined from the Outdoor
Air Sensors. The Outdoor Air Volume must always be at least 50%
or higher to be confi gured 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 a Space Temperature Sensor as the Controlling Sensor.
AAON ® Return Air Bypass Control provides improved moisture
removal capabilities while utilizing internal space loads for reheat
by redirecting the Return Air path from the upstream side of the DX
Evaporator Coil to the downstream side of the coil.
For AAON ® Return Air Bypass confi gured units, the Return Air
Bypass Damper is only used during the Dehumidifi cation Mode.
When the VCC-X Controller is in Dehumidifi cation Mode, the Return
Air Bypass Damper will modulate open as the Space Temperature
falls below the Cooling Setpoint. Modulation of the Return Air
Bypass Damper is controlled using a proportional range from 0%
(when the Space Temperature is equal to the Cooling Setpoint) up
to 100% (when the Space Temperature falls to the halfway point
between the Cooling and Heating Setpoints). A separate Return Air
Damper Actuator will modulate the Return Air Damper slightly
further towards its closed position as the Return Air Bypass Damper
opens. This is to ensure that enough Return Air is bypassed around
the Evaporator Coil through the Return Air Bypass Damper to raise
its temperature. The rate which the Return Air Damper closes while
the Return Air Bypass Damper is open is user-adjustable.