Lennox LHT180 Installation Instructions Manual page 25

HEATING, VENTILATION & SMOKE MINIMUM AND MAXIMUM CFM
Unit
Model Speed
Low
Std
LDT180H
Med
High
HP W/O EH
LHT180H
15, 30, 45, 60, 90 KW
Low, Std, Med
LDT240H
High
HP W/O EH
LHT240H
15, 30, 45, 60, 90 KW
*Use highest value between Heating and Cooling High CFM Max.
TABLE 10
COOLING MINIMUM AND MAXIMUM CFM
LHT/
Cooling Low CFM
LDT
Default Min Max
Unit
180H 3900 2000 7200
240H 5200 3000 9600
*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.
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 9
Heating CFM
Default
Heat Code
L
S
M
6000
H
N
E, J, K, L, P
L, S, M
H
8000
N
E, J, K, L, P
Cooling High CFM
Default Min Max
5400 5000 7200
7200 6250 9600
Vent CFM
Min
Max Default
2725
4325
4500
7200 6000
5125
4500
6000
4500
5125
9600 8000
6000
6000
E-Inverter Bypass Option
The supply air inverter is factory-set to by-pass the
inverter manually. To by-pass the inverter and operate the
blower in the constant air volume mode, use the following
Unit Controller menu and set to "engaged":
SETTINGS > RTU OPTIONS > BLOWER > VFD
To configure the unit to by-pass the inverter automatically,
use the following Unit Controller menu.
Press SAVE until the menu reads:
CONFIGURATION ID 1
th
Change the 6 character position to A for automatic
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 25
Smoke CFM
Min Default
Max
2250 7200 6000
3000 9600 8000
BYPASS
SETUP > INSTALL
508336-01
Min
Max
2250 7200
3000 9600
1/2023