Page 40
LGH/LCH036, 048, 060, 072
VCB Start-Up
Units equipped with an A184 ventilation control board
(VCB) allow the installer to enter the design-specified
supply air CFM into the Unit Controller. In addition, the
outdoor air flow (minimum damper position) can be
entered. These air volumes are typically adjusted by
taking measurements and adjusting settings.
The factory-installed VCB option is available on units
equipped with a direct drive blower and an economizer.
The VCB is located on the Unit Controller. See figure 27.
The economizer is equipped with a PT5 pressure
transducer which provides feedback for damper
minimum position. See figure 28 for PT5 location. Refer to
the economizer installation instructions and Unit
Controller manual for additional economizer set-up.
Note - Modulation of dampers for free cooling does not
change. The outdoor air flow setting determines minimum
damper position instead of adjusting a potentiometer.
ADesign Specifications
Use table 30 to fill in the field-provided,
design-specified supply air CFM and minimum required
outdoor/fresh air CFM.
TABLE 30
FIELD-PROVIDED DESIGN SPECIFICATIONS
Supply Air CFM
Heating CFM
Cooling High CFM
Cooling Low CFM
Ventilation CFM
Economizer Minimum Position
Outdoor Airflow CFM
A184 VENTILATION CONTROL BOARD
VCB BOARD
FIGURE 27
UNIT CONTROLLER
PT5 PRESSURE TRANSDUCER
PRESSURE
TRANSDUCER
FIGURE 28
ECONOMIZER
BEnter Supply Air CFM Into Unit Controller
Use the following menu path to enter each supply air CFM
into the Unit Controller. Make sure supply air CFM is
within limitations shown in table 31. Refer to the Unit
Controller manual provided with unit.
CAUTION
The BLOWER CALIBRATION process starts the in
door blower at operational speeds and moves the
economizer damper blades. Before starting this pro
cess, replace any access panels and close all unit
doors except compressor compartment door.
Settings - Control - MSAV - Blower - Heating CFM
(enter value) - Cooling High CFM (enter value) -
Cooling Low CFM (enter value) - Ventilation CFM
(enter value) - Start Blower To Calibrate (yes/no).
Select YES to start calibration. The blower calibration
status is displayed as a % complete. Upon successful
completion, the Unit Controller will display
CALIBRATE COMPLETE, save the entered values
and revert to the MSAV menu.
Select NO and the Unit Controller will display an option to
SAVE SETTINGS (YES / NO). Select YES to save
settings without performing the calibration process.
Select NO to exit the menu without saving entered values.
The display reverts to MSAV menu with either selection.
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