Lennox LGT156H Installation Instructions Manual page 61

HEATING, VENTILATION & SMOKE MINIMUM AND MAXIMUM CFM
Tons Model
LGT156H Low
13
Std
Med
LGT156H All
15 LGT180H Low
Std
Med
High
LCT180H 15,30,45,60kW
17.5 LGT210H Low, Std, Med
High
LCT210H 15,30,45,60kW
90kW
20 LGT240H Low, Std, Med
High
LCT240H 15,30,45,60kW
90kW
25 LGT300S Low, Std, Med
High
LCT300S 15,30,45,60kW
90kW
*Use highest value between Heating and Cooling High CFM Max.
TABLE 19
COOLING MINIMUM AND MAXIMUM CFM
Cool 1 CFM
LGT/
Cooling Low CFM
LCT
De­
Unit
Min Max
fault
156H 3380 1500 6250
180H 3900 2000 7200
210H 4550 2500 8400
240H 5200 3000 9600
300S 6500 3500 12000
*Use Cooling High CFM Max.
Set Minimum Position 2
Use the following mobile service app 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 run damper calibration and
allow damper position adjustment.
RTU MENU > SETTINGS > RTU OPTIONS > DAMPER
Tap "Next" to skip tabs and complete damper position
calibration until "Damper Calibration Blower Speed High"
tab appears.
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.
Unit
Speed Heat Code
L
S
M
N, E, J, K, L
L
S
M
H
N, E, J, K, L
L, S, M
H
N, E, J, K, L
P
L, S, M
H
N, E, J, K, L
P
L, S, M
H
N, E, J, K, L
P
Cool 4 CFM
Cooling High CFM
Default Min
5200 4000
5400 5000
6300 6000
7200 6250
9000 7000
TABLE 18
Heating CFM
De­
Min
Max
fault
5200 2725 6250
4325
4500
5200
6000 2725 7200
4325
4500
5125
5200
7000 4500 8400
5125
5200
6000
8000 4500 9600
5125
5200
6000
10000 4500
5125
5200
6000
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.
E-Inverter Bypass Option
Max
The supply air inverter is factory-set to by-pass the
6250
inverter manually. To by-pass the inverter and operate the
7200
blower in the constant air volume mode, use the following
8400
Unit Controller menu and set to "engaged":
9600
SETTINGS > RTU OPTIONS > BLOWER > VFD
12000
To configure the unit to by-pass the inverter automatically,
use the following Unit Controller menu.
Press SAVE until the menu reads:
Change the 6
bypass option.
Press SAVE
Caution - Units not equipped with an inverter will have the
th
6 character set to N, indicating the inverter is not
bypassed. The blower motor could be damaged and/or
result in product or property damage if the setting is
changed to automatic or manual.
Page 61
Vent CFM
De­ De­
Min Max
fault fault
5200 1950 5200
6000 2250 6000
7000 2625 7000
8000 3000 8000
10000 3750 10000 3750 12000
BYPASS
SETUP > INSTALL
CONFIGURATION ID 1
th
character position to A for automatic
508288-01
Smoke CFM
Min Max
1950 6250
2250 7200
2625 8400
3000 9600
9/2022