Ix-Staged Supply Air Operation - Lennox LGT Series Unit Information

IX-Staged Supply Air Operation

This is a summary of cooling operation for both belt and
direct drive blowers.
Note - During a dehumidification demand the blower op-
erates at the highest speed. Free cooling is locked-out
during reheat operation. Refer to Hot Gas Reheat start-up
and operation section for details.
A-Two-Stage Thermostat
1-Economizer With Outdoor Air Suitable
Y1 Demand -
Compressors Off
Blower Cooling Low
Dampers modulate to maintain 55° supply air
Y2 Demand -
Compressors Off
Blower Cooling High
Dampers Modulate to maintain 55° supply air
Note - If dampers are at maximum open for three minutes,
compressor 1 is energized and blower stays on cooling
high.
2-No Economizer or Outdoor Air Not Suitable
Y1 Demand -
Compressor 1 On
Blower Cooling Low
Y2 Demand -
Compressor 1 and 2 On
Blower Cooling High
B-Three-Stage Thermostat OR Zone Sensor
1-Economizer With Outdoor Air Suitable
Y1 Demand -
Compressors Off
Blower Cooling Low
Dampers modulate to maintain 55° supply air
Y2 Demand -
Compressors Off
Blower Cooling High
Dampers Modulate to maintain 55° supply air
Note - If dampers are at maximum open for three minutes,
compressor 1 is energized and blower stays on cooling
igh. Economizer stays at maximum position after com-
pressors are energized.
Y3 Demand -
Compressors 1 and 2 On
Blower Cooling High
Dampers Maximum Open
2-No Economizer or Outdoor Air Not Suitable
Y1 Demand -
Compressor 1 On Part Load
Blower Cooling Low
Y2 Demand -
Compressor 1 On Part Load Compressor 2 On.
Blower Cooling Medium
Y3 Demand -
Compressors 1 and 2 On
Blower Cooling High
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