Page 14
LGH/LCH036, 048, 060, 072, 074
A-Blower Operation
Refer to the Unit Controller Installation and Setup Guide
to energize blower. Use the menu navigation arrows and
select button; see SERVICE > TEST.
B-Determining Unit CFM
1- The following measurements must be made with air
filters in place.
IMPORTANT - High Efficiency Units -
On units equipped with direct drive blowers, a low speed
adjustment less than 2/3 of high speed will improve
humidity removal; refer to product data for more
information.
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 19.
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 4 or 5 for minimum airflow when
electric heat is installed.
TABLE 4
MINIMUM AIRFLOW-LCH UNITS WITH ELECTRIC
HEAT (DIRECT DRIVE)
kW
CFM
Downflow & Horizontal Airflow
LCH036H, U
1080
LCH048H, U
1280
LCH060H, U
LCH074U
1600
TABLE 5
MINIMUM AIRFLOW-LCH UNITS WITH ELECTRIC
HEAT (BELT DRIVE)
kW
CFM
Downflow Horizontal
30 1900 2000
22.5 1500 1600
15 1200 1300
7.5 1050 1200
C-Adjusting Unit CFM - High Efficiency Direct Drive
Blowers
Note - To adjust CFM on units configured for optional
“Advanced Air Flow Control”, refer to Advanced Air Flow
Control Start-Up section.
The supply CFM can be adjusted by changing Unit
Controller settings. Refer to table 6 for menu paths and
default settings. Adjustments can also be made by using
optional software. Record any CFM changes on the
parameter settings label located on the inside of the
compressor access panel.
FIGURE 19
LOCATION OF STATIC PRESSURE READINGS
SUPPLY AIR
READING
LOCATION
SUPPLY
RE
TURN
INSTALLATIONS WITH DUCTWORK
SUPPLY
RE
TURN
INSTALLATIONS WITH CEILING DIFFUSERS
MAIN
DUCT RUN
FIRST BRANCH
OFF OF MAIN RUN
DIFFUSER
ROOFTOP UNIT
ROOFTOP UNIT
SUPPLY AIR
READING
LOCATION
RETURN AIR
READING LOCATION
RETURN AIR
READING
LOCATION
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