Set Blower Speeds; Set Damper Minimum Position; Blower Cfm Design Specifications - Lennox LGH180H Installation Instructions Manual

TABLE 22

Blower CFM Design Specifications

T'Stat or
Unit
Zone Con­
trol Stages
156,
180, 2
210
156,
3 or 4
180,
210
180U,
1
240U
180U,
240, 2
300
180U,
3
240,
300
180U,
4
240,
300
*Available blower speeds vary by unit and thermostat stages.
C-Set Blower Speeds
1- Use the following menu to enter the blower design
specified CFM into the Unit Controller. Make sure
blower CFM is within limitations shown in table 23.
Refer to the Unit Controller manual provided with unit.
SETUP > TEST & BALANCE > BLOWER >
2- Enter the following design specifications as shown in
table 22.
Design
Blower Speed
Specified
CFM
Htg.
Clg. High
Clg. Low
Ventilation
Htg.
Clg. High
Clg. Med.
Clg. Low
Ventilation
Htg.
Clg. High
Clg. Low
Ventilation
Htg.
Clg. High
Clg. Low
Ventilation
Htg.
Clg. High
Clg. Med.
Clg. Low
Ventilation
Htg.
Clg. High
Clg. Med. High
Clg. Med. Low
Clg. Low
Ventilation
Blower / Heat CFM
Cooling High CFM
Cooling Low CFM
Vent CFM
3- Adjust the blower RPM to deliver the target CFM
based on the measured static pressure using the
blower table.
4- Measure the static pressure again and apply the
static pressure and RPM to the blower tables to
determine adjusted CFM.
5- Repeat adjustments until design CFM is reached.
1
The Unit Controller will prompt when more cooling
stages are available depending on the number of
compressors and the control mode.
D-Set Damper Minimum Position
To maintain required minimum ventilation air volumes
when the unit is in the occupied mode, two minimum
damper positions must be set. The Unit Controller will open
the dampers to "Min OCP Blwr Low" when blower CFM is
BELOW a "midpoint" CFM. The Unit Controller will open
the damper to "Min OCP Blwr High" when blower CFM is at
or ABOVE the "midpoint" CFM.
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.
Page 43
1
1
X.X%
507124-04 3/2016