Orion System VCM-X Modular E-BUS - Manual (Page 6)

OVERVIEW
VCM-X Modular E-BUS Controller Technical Guide 6
E-BUS Module Applications
VCM-X Modular E-BUS Controller
The AAON ® Tulsa VCM-X Modular E-BUS Controller (OE332-23E-
VCMX-MOD-A) will interface with the One Condenser Head Pressure
Module (OE370-23-HP1C), the Two Condenser Head Pressure Module
(OE370-23-HP2C), and the Full Digital Module (OE370-23-FD-A).
The AAON ® Coil VCM-X Modular E-BUS Controller (OE332-23E-
VCMX-MOD-C) will interface with the Two Condenser Head Pressure
Module (OE370-23-HP2C) and the Dual Digital Module (OE370-
23-DD-C).
In both cases, these E-BUS Modules allow independent control of
multiple digital scroll compressors and control of the condenser fan(s)
or valve(s). See pages 38-47 of this manual and the individual manu-
als for each of these modules (referenced on those pages) for detailed
wiring and application details.
VCM-X WSHP E-BUS Controller
The AAON ® Tulsa VCM-X WSHP E-BUS Controller (OE332-23E-
VCMX-WSHP-A) will interface with the One Condenser Head Pressure
Module (OE370-23-HP1C), the Two Condenser Head Pressure Module
(OE370-23-HP2C), and the Water Source Heat Pump Modules (OE334-
23-WPM-A and OE334-23-WPM-22-A).
The AAON ® Coil VCM-X WSHP E-BUS Controller (OE332-23E-
VCMX-WSHP-C) will interface with the Two Condenser Head Pressure
Module (OE370-23-HP2C) and the Water Source Heat Pump Module
(OE334-23-WPM-C).
In both cases, these E-BUS Modules allow independent control of
multiple digital scroll compressors and control of the condenser fan(s)
or valve(s). See pages 38-47 of this manual and the individual manu-
als for each of these modules (referenced on those pages) for detailed
wiring and application details.
VCM-X E-BUS Controller Applications
Variable Air Volume Unit
The VCM-X E-BUS 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 VCM-X E-BUS .
VAV units are typically designed for occupied Cooling with Morning
Warm-up Heating. This option is available with the VCM-X E-BUS.
The VCM-X E-BUS can also be used for a Zoning System that needs
Duct Static Pressure control and Occupied Cooling and Heating. The
VCM-X E-BUS 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.
The VCM-X E-BUS 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 Dehumidifi cation, the VCM-X E-BUS 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 VCM-X E-BUS can be confi gured to activate a Constant Volume
Supply Fan. In most cases, this is a very basic unit with Space Tempera-
ture control. The VCM-X E-BUS 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 VCM-X E-BUS to
know when to switch to 100% Outdoor Air control based on an exhaust
hood activating. The VCM-X E-BUS requires Outdoor and Indoor Air
Temperature Sensors to accomplish this application.
Make-Up Air Unit
The VCM-X E-BUS 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 ® PAC (Precision Air 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 ® PAC 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 down-
stream side of the coil.
For AAON ® PAC confi gured units, the Return Air Bypass Damper is only
used during the Dehumidifi cation Mode. When the VCM-X Controller is
in Dehumidifi cation Mode, the Return Air Bypass Damper will modulate
open as the Space Temperature falls below the Cooling Setpoint. Modula-
tion 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.
AAON ® DPAC (Digital Precision Air Control)
This control scheme can only be used on Constant Volume HVAC units
that are equipped with a Return Air Bypass Damper and a Copeland Digi-
tal Scroll™ Compressor.
AAON ® DPAC also uses a Space Temperature
Sensor as the Controlling Sensor.
The AAON ® DPAC control scheme provides improved moisture removal
capabilities over the AAON ® PAC control scheme and provides for tighter
temperature control by combining a Copeland Digital Scroll™ Compres-
sor with the Return Air Bypass Damper. See the Cooling Mode section
on page 56 for detailed Copeland Digital Scroll™ Compressor operation.
Refer to AAON
® PAC Control previously described for detailed Return
Air Bypass Damper operation.
The Copeland Digital Scroll™ Compressor is used during both Cooling
and Dehumidifi cation Modes. The Return Air Bypass Damper is used
only during the Dehumidifi cation Mode.
Features and Applications