Page 47
SGH/SCH036, 060, 120, 240
Compressors Off
Blower Cooling Low
Dampers modulate
Y2 Demand -
Compressors Off
Blower Cooling High
Dampers Modulate
Note - If dampers are at maximum open for three minutes,
compressor 1 is energized and blower stays on cooling
high.
Y3 Demand -
Compressors 1 and 2 On
Blower Cooling High
Dampers Maximum Open
Y4 Demand -
All Compressors On
Blower Cooling High
Dampers Maximum Open
2-No Economizer or Outdoor Air Not Suitable
Y1 Demand -
Compressor 1 On
Blower Cooling Low
Y2 Demand -
Compressors 1 and 2 On
Blower Cooling Medium Low
Y3 Demand -
Compressors 1, 2 and 3 On
Blower Cooling Medium High
Y4 Demand -
All Compressors On
Blower Cooling High
Direct Drive Blower Start-Up
A-Set Blower Speed
1- Use table 26 to fill in field-provided, design specified
blower CFM.
TABLE 26
Blower CFM Design Specifications
Blower Speed
Design
Specified CFM
Heating
Cooling High
Cooling Low
Ventilation
2- Use the following menu to enter the blower design
specified CFM into the Unit Controller.
Don't press
“SAVE” until all CFM are entered
.
Make sure blower
CFM is within limitations shown in table 27. Refer to the
Unit Controller manual provided with unit.
SETUP > TEST & BALANCE > BLOWER
3- Once all four speeds are entered, the target (highest of
the heating and cooling settings) CFM and default RPM
will be displayed.
Note - When units are not equipped with heat, the Blower
Heat speed will not be displayed. Blower Cooling High will
be the first blower speed to appear.
4- Measure the static pressure as shown in the Blower
Start-Up section. Use the static pressure, target CFM
and blower tables to determine the RPM needed.
Values in the blower table reflect the static pressures
taken in locations shown in figure 24.
5- Enter the RPM and repeat the previous step until the
design CFM is reached.
6- Press SAVE followed by MAIN MENU.
Note - Once the CFM settings are saved, the Unit Controller
will set all other blower CFM.
B-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.
