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Belt Drive Supply Air Inverter Start-Up
A-Design Specifications
Use table 22 to fill in field-provided, design specified
blower CFM.
B-Set Maximum CFM
Use table 22 to determine highest blower CFM for
appropriate unit. Adjust the blower pulley to deliver that
amount of CFM with only the blower operating. See
Determining Unit CFM
in the Blower Operation and
Adjustment section.
TABLE 22
Blower CFM Design Specifications
Blower Speed
Design
Specified CFM
Heating
Cooling High
Cooling Low
Ventilation
C-Enter Design Specifications Into Controller
Use the following menu to enter the blower design
specified CFM into the Unit Controller. Make sure blower
CFM is within limitations shown in table 23 or 24. Refer to
the Unit Controller manual provided with unit.
SETUP > TEST & BALANCE > BLOWER >
Enter the Heating, Cooling High, Cooling Low and Ventilation
speed per table 22. Adjust the blower RPM to deliver the
target CFM based on the measured static pressure using the
blower table.
After adjusting the RPM, read the static pressure again and
apply the RPM/static to blower tables to determine adjusted
CFM. Repeat adjustments until design CFM is reached.
D-Set Damper Minimum Position
To maintain required minimum ventilation air volumes
when the unit is in the occupied mode, two minimum
damper positions must be set. The Unit Controller will open
the dampers to “Min OCP Blwr Low” when blower CFM is
BELOW a “midpoint” CFM. The Unit Controller will open
the damper to “Min OCP Blwr High” when blower CFM is at
or ABOVE the “midpoint” CFM.
The Unit Controller will calculate the “midpoint” CFM.
Set Minimum Position 1
Use the following menu in the Unit Controller to set “Min
OCP Blwr Low” for the blower CFM below the “midpoint”
CFM. When navigating into this menu, the Unit Controller
will bring on the corresponding blower speed and allow
damper position adjustment.
SETTINGS > RTU Options > EDIT PARAMETER >
ENTER DATA ID - 9 > MIN DAMPER LOW BLOWER =
X.X %
Measure the intake air CFM. If the CFM is lower than the
design specified CFM for ventilation air, use the Unit
Controller to increase the damper percent open. If the
CFM is higher than specified, decrease the damper
percent open.
Note - Intake air CFM can also be determined using the
outdoor air temperature, return air temperature and
mixed air temperature. Refer to the economizer or
outdoor air damper installation instructions.
Set Minimum Position 2
Use the same menu in the Unit Controller to set “Min OCP
Blwr High” for the blower CFM above the “midpoint” CFM.
When navigating into this menu, the Unit Controller will
bring on the corresponding blower speed and allow
damper position adjustment.
SETTINGS > RTU OPTIONS > DAMPER > MIN
DAMPER POSITION BLOWER ON HIGH = X.X %
Measure the intake air CFM. If the CFM is lower than the
design specified CFM for ventilation air, use the Unit
Controller to increase the damper percent open. If the
CFM is higher than specified, decrease the damper
percent open.
Note - Intake air CFM can also be determined using the
outdoor air temperature, return air temperature and
mixed air temperature. Refer to the economizer or
outdoor air damper installation instructions.
E-Inverter Bypass Option
Units equipped with a supply air inverter are factory-set to
by-pass the inverter manually. To by-pass the inverter and
operate the blower in the constant air volume mode, use
the following Unit Controller menu and set to “YES”:
SETTINGS>RTU OPTIONS>BLOWER>VFD BYPASS
To configure the unit to by-pass the VFD automatically,
use the following Unit Controller menu and set to
“automatic”:
SETUP > INSTALL > PRESS SAVE UNTIL THE
MENU READS CONFIGURATION ID 1 >
CHANGE CHARACTER POSITION 6
TH
TO “A”
FOR AUTOMATIC BYPASS OPTION AND
SAVE
Caution - Units not equipped with an inverter will be set to
SETUP > INSTALL > CONFIGURATION ID 1
(CHARACTER POSITION 6
TH
) TO “N” NOT
APPLICABLE. The blower motor could be damaged
and/or result in product or property damage if the setting
is changed to automatic or manual.
