Vav System - Lennox LGM Series Manual

X-VAV System
Units contain a supply air blower equipped with a variable
frequency drive A96 (VFD) which varies supply air CFM.
The supply air VFD (A96) is located in the control area.
See figure 37.
A-Start-Up
1 - A pressure transducer (A30) is shipped in a box
in the blower compartment. Install the transducer
according to manufacturer's instructions.
Note - Make sure the transducer is installed in the
main duct at least 2/3 of the distance away from the
unit.
2 - Two twisted pairs of shielded cable must be used to
connect the pressure transducer. See figure 36. J/
P378 connector is hanging in the control box.
3 - Open all zone dampers and/or boxes.
4 - Locate the A55 Unit Controller. Refer to figure 37.
5 - Use the mobile service app to calibrate the blower
CFM. Select this menu to start the blower:
SETUP > TEST & BALANCE > BLOWER
The mobile app will display the percent of blower speed.
Adjust blower speed percentage to meet design airflow
specifications. Allow blower speed to stabilize.
6 - Press NEXT and follow the instructions to calibrate
static pressure. If the static pressure meets the
design specification, press NEXT again to set the
setpoint. If the static pressure does not meet the
design specification, adjust the pressure and press
NEXT to set the setpoint.
7 - Record new setpoints in table 26.
8 - If the desired CFM cannot be met with current
pulley setup, refer to the Blower Operation and
Adjustments section to adjust CFM.
Parameter
386
387
388
389
A30
_
+S
CONNECTED
CONNECTED
+
Note - The Unit Controller will lock-out the unit for 5 min-
utes if static pressure exceeds 2.0"w.c. for 20 seconds.
The Unit Controller will permanently shut down the unit af-
ter three occurrences. See mobile service app parameters
110, 42, and 43 to adjust default values.
CONTROL AREA
A96
SUPPLY AIR VFD
Figure 37
Page 50
TABLE 26
RECORD ADJUSTED SETPOINTS
Setpoint Setpoint
Description
Smoke
Ventilation
Heating
Cooling
PRESSURE TRANSDUCER WIRING
TWISTED
PAIR
DRAIN
NOT
TWISTED
NOT
PAIR
UNUSED WIRE
FIGURE 36
Display
"w.c. Setting
P378
1
2
3