Blower Operation And Adjustments - Lennox LGM036 Installation Instructions Manual

Blower Operation and Adjustments

Units are equipped with variable speed, direct drive
blowers. The installer
design-specified supply air CFM into the Unit Controller
for optimal efficiency. The Unit Controller calibrates the
supply air volume which eliminates the need to manually
take duct static measurements. Refer to C-Adjusting Unit
CFM - Ultra High Efficiency Direct Drive Blowers.
IMPORTANT
Three phase scroll compressors must be phased
sequentially for correct compressor and blower
rotation. Follow "COOLING START-UP" section of
installation instructions to ensure proper compres­
sor and blower operation.
A-Blower Operation
Refer to the Unit Controller Setup Guide to energize
blower. Use the mobile service app menu; see SERVICE
> TEST.
WARNING
1-Make sure that unit is installed in accordance with the
installation instructions and applicable codes.
2-Inspect all electrical wiring, both field‐ and factory‐
installed, for loose connections. Tighten as required.
3-Check to ensure that refrigerant lines do not rub against
the cabinet or against other refrigerant lines.
4-Check voltage at disconnect switch. Voltage must be
within range listed on nameplate. If not, consult power
company and have voltage condition corrected before
starting unit.
5-Make sure filters are new and in place before start‐up.
INSTALLATIONS WITH DUCTWORK
ROOFTOP UNIT
SUPPLY
TURN
MAIN
DUCT RUN
LGM/LCM036, 048, 060, 074
is able to enter
LOCATION OF STATIC PRESSURE READINGS
RETURN AIR
READING LOCATION
RE­
FIRST BRANCH
OFF OF MAIN RUN
SUPPLY AIR
READING
LOCATION
B-Determining Unit CFM
1- The following measurements must be made with air
filters in place.
the
2- With all access panels in place, measure static
pressure external to unit (from supply to return).
Blower performance data is based on static pressure
readings taken in locations shown in figure 20.
Note - Static pressure readings can vary if not taken
where shown.
3- Measure the indoor blower wheel RPM.
4- Referring to the Blower Data tables, use static
pressure and RPM readings to determine unit CFM.
Use the Accessory Air Resistance tables when
installing units with any of the options or accessories
listed. Refer to table 3 for minimum airflow when
electric heat is installed.
MINIMUM AIRFLOW-LCM UNITS WITH ELECTRIC
kW
LCM036U
LCM048U
LCM060U
LCM074U
INSTALLATIONS WITH CEILING DIFFUSERS
ROOFTOP UNIT
SUPPLY AIR
READING
LOCATION
FIGURE 20
Page 13
TABLE 3
HEAT (DIRECT DRIVE)
CFM
Downflow & Horizontal Airflow
1350
1350
1800
RE­
SUPPLY
TURN
DIFFUSER
RETURN AIR
READING
LOCATION