Lennox LCH036 Installation Instructions Manual page 89

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