Orion System VCC-X Controller - Manual (Page 60)

Zone
Zone
SEQUENCE OF OPERATIONS
VCC-X Controller Technical Guide 60
Remote Contact Control, Space Sensor, Morning Warm-Up/Cool-Down
VCC-X Remote Contact Control
A Remote Contact Control option can be confi gured on the VCC-X
Controller to initiate the HVAC Modes of operation. If this option is
confi gured, all Heating, Cooling, and Dehumidifi cation modes will
only be initiated based on 24 VAC wet contact closures on the Forced
Heating, Forced Cooling, and Forced Dehumidifi cation inputs on
the EM2 Expansion Module. This is a single confi guration option
that applies to all three modes.
If both the Forced Heating and Forced Cooling inputs are inactive
or if both are simultaneously active, then the unit is in a Vent mode
(neutral) state. In this condition in the Occupied Mode, only the
fan would be on for ventilation. In this condition in the Unoccupied
Mode, the unit would just be Off.
If Forced Dehumidifi cation is also being used, it will operate in
conjunction with the Forced Heating and Forced Cooling inputs
according to which Dehumidifi cation option you have confi gured.
The four confi guration options are described in the Dehumidifi cation
Mode section on page 57.
Space Sensor Operation
Space Sensors are available as a Plain Sensor, Sensor with Override,
Sensor with Setpoint Slide Adjust, and Sensor with Override and
Setpoint Slide Adjust (this is the version that is factory supplied).
An E-BUS Digital Space Sensor is also available with override and
setpoint adjustment capability.
Sensors with Setpoint Slide Adjust can be programmed to allow
Space Setpoint adjustment of up to ± 10° F.
If the Space Temperature is the SAT/Reset Source, then the Slide
Adjust will adjust the HVAC Mode Enable Setpoints and the SAT/
Reset Source Setpoints simultaneously.
During Unoccupied hours, the Override Button can be used to force
the unit back into the Occupied Mode (by pressing the button for
less than 3 seconds) for a user-defi ned override duration of up to
8.0 hours. Pressing the button between 3 to 10 seconds cancels the
override.
IAQ (CO
2
) Control Operation
If you have confi gured the VCC-X Controller to monitor and control
CO
2
levels, the Economizer operation will be modifi ed as follows:
1. If the CO
2
levels remain below the Low CO
2
Level
Setpoint, the Economizer Minimum Position will remain
at its confi gured value.
2. As the level of CO
2
increases above the Minimum CO
2
Level Setpoint, the Economizer Minimum Position will be-
gin to be reset higher. The Economizer Minimum Position
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 will be reset to the Maximum Reset Position.
3. The Maximum Reset Position Setpoint is the highest
the Economizer Minimum Position 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.
4. CO
2
Economizer control cannot be used in conjunction
with Outdoor Airfl ow control of the Outdoor Air Damper
in this version.
Morning Warm-Up Mode Operation
NOTE: Morning Warm-Up can be confi gured for any appli-
cation but should not be used on 100% Outdoor Air
Units, since the Outdoor Air Damper remains closed
during Warm-Up.
When the VCC-X Controller is confi 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 effect 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 confi 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 VCC-X Controller is confi 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 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.