AAON Orion VCCX2 User Manual

79
VCCX2 Controller Technical Guide
IAQ (CO
2
) Control Operation
If you have congured the VCCX2 Controller to monitor and
control CO
2
levels, the Economizer operation will be modied
as follows:
1. If the CO
2
levels remain below the Low CO
2
Level
Setpoint, the Economizer Minimum Position (or
Airow Minimum) will remain at its congured value.
2. As the level of CO
2
increases above the Minimum CO
2
Level Setpoint, the Economizer Minimum Position (or
Airow Minimum) will begin to be reset higher. The
Economizer Minimum Position (or Airow Minimum)
will be proportionally reset higher as the CO
2
rises
within the range set by the Minimum CO
2
Level
Setpoint and the Maximum CO
2
Level Setpoint. If the
CO
2
level reaches the High CO
2
Level Setpoint, the
Economizer Minimum Position (or Airow Minimum)
will be reset to the Maximum Reset Position.
3. The Maximum Reset Position Setpoint is the highest
the Economizer Minimum Position (or Airflow
Minimum) can be reset to during CO
2
Control
Operation. This setpoint is user-adjustable and does
not keep the Economizer from opening further during
Economizer operation.
Morning Warm-Up Mode Operation
NOTE: Morning Warm-Up can be congured for any
application but should not be used on 100%
Outdoor Air Units, since the Outdoor Air Damper
remains closed during Warm-Up.
When the VCCX2 Controller is congured for Morning Warm-Up
and switches to the Occupied Mode of Operation (not Override
or a Forced Mode from an Operator Interface Device), the unit
compares the Return Air Temperature to a Morning Warm-Up
Target Temperature. If the Return Air Temperature is below this
Setpoint, the Warm-Up Mode is initiated. Heating will then be
controlled to the Warm-Up Supply Air Temperature Setpoint.
This Mode remains in eect until the Return Air Temperature
rises above the Target Temperature or a user-adjustable Time
Period expires. Warm-Up Mode is not initiated by Push-Button
Overrides or Unoccupied Heating demands. The Outdoor Air
Damper remains closed during Warm-Up Mode.
Once the Warm-Up Mode has been terminated, it cannot resume
until the unit has been through a subsequent Unoccupied Mode.
Only one Warm-Up Mode is allowed per Occupied cycle.
If you have stand-alone VAV boxes that need to be forced wide
open during the Warm-Up Mode, you can congure one of the
relay outputs to be used during this Mode. If the Warm-Up Mode
is active, the relay is activated. This relay then becomes the Force
Open Command for all VAV boxes to which it is wired.
Morning Cool-Down Mode Operation
When the VCCX2 Controller is congured for Morning Cool-
Down and switches to the Occupied Mode of Operation (not
Override or a Forced Mode from an Operator Interface Device),
the unit compares the Return Air Temperature to a Morning Cool-
Down Target Temperature. If the Return Air Temperature is above
this Setpoint, the Cool-Down Mode is initiated. Cooling will then
be controlled to the Cool-Down Supply Air Temperature Setpoint.
This Mode remains in eect until the Return Air Temperature
drops below the Target Temperature or a user-adjustable Time
Period expires. Cool-Down is not initiated by Push-Button
Overrides or Unoccupied Cooling demands. The Outdoor Air
Damper remains closed during Cool-Down Mode.
Once the Cool-Down Mode has been terminated, it cannot resume
until the unit has been through a subsequent Unoccupied Mode.
Only one Cool-Down Mode is allowed per Occupied cycle.
If you have stand-alone VAV boxes that need to be forced wide
open during the Cool-Down Mode, you can congure one of
the relay outputs to be used during this Mode. If the Cool-Down
Mode is active, the relay is activated. This relay then becomes
the Force Open Command for all VAV boxes to which it is wired.
Single Zone VAV
Single Zone VAV is an application where the Supply Fan VFD
modulates to maintain the Space Temperature Setpoint while
heating or cooling is modulated to maintain the Supply Air
Setpoint. This application can be congured to use VAV Cooling
and either VAV Heating or CAV Heating. There is no Supply Air
Temperature Setpoint reset function on a Single Zone VAV Unit.
VAV Cooling and VAV Heating require modulating cooling
and heating sources in order to maintain a constant Supply Air
Temperature no matter what the fan speed is. CAV Heating must
be congured if using a staged form of heat.
The Space Temperature Sensor (cannot use Return Air
Temperature) determines the heating or cooling mode of
operation. Heating and cooling are enabled and disabled as
described previously in the Heating and Cooling sections.
SEQUENCE OF OPERATIONS
IAQ Control, Morning Warm-Up and Cool-Down, and Single Zone VAV

AAON Orion VCCX2 Specifications

General

Brand	AAON
Model	Orion VCCX2
Category	Controller
Language	English