Page 39
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.
TABLE 27
MINIMUM AND MAXIMUM CFM
DIRECT DRIVE BLOWERS
094U4E, 122U4E, 152U4E
Gas Heat Minimum CFM
Unit
Gas Heat Size
Airflow CFM*
LGH094-152
Std. , Med.
2225
LGH094-152
High
2550
Electric Heat Minimum CFM
Unit
Heat Size (kW)
Airflow CFM
LCH094
7.5
1750
LCH094
0, 15, 22.5, 30, 45
2750
LCH122, 152
15, 22.5, 30, 45
2750
LCH122, 152
0, 60
3500
Cooling Low Minimum CFM - 160 CFM/ton
Unit
Blower Speed
Airflow CFM
LGH/LCH094
Low
1200
LGH/LCH122
Low
1600
LGH/LCH152
Low
2000
Cooling High Minimum CFM - 220 CFM/ton
Unit
Blower Speed
Airflow CFM
LGH/LCH094
High
1650
LGH/LCH122
High
2200
LGH/LCH152
High
2750
Smoke and Ventilation Minimum CFM - 150 CFM/ton
Unit
Not Applicable
Airflow CFM
LGH/LCH094
NA
1125
LGH/LCH122
NA
1500
LGH/LCH152
NA
1875
Heating and Cooling Maximum CFM - 480 CFM/ton
Unit
Blower Speed
Airflow CFM
LGH/LCH094
High
3600
LGH/LCH122
High
4800
LGH/LCH152
High
6000
*Rounded to nearest 25 CFM.
