Carrier 42QFD048D8S Service Manual page 14

2. Pipe Length and Drop Height
The length and elevation of connection pipe are shown in the table below. if the pipe length exceeds max pipe length,
additional refrigerant should be charged to ensure nominal cooling/heating capacity.
Capacity(Btu/h) Standard Length
48k
If oil flows back into the outdoor unit's compressor, this might cause liquid compression or deterioration of oil return. Oil
traps in the rising gas pipe can prevent this.
-An oil trap should be installed every 6m(20ft) of vertical suction line riser (<36000Btu/h unit).
-An oil trap should be installed every 10m(32.8ft) of vertical suction line riser (≥36000Btu/h unit).
Max Pipe Length
5m (16.4ft) 65m(213.25ft)
Indoor unit/
Outdoor unit

Max Elevation
30m(98.4ft)
Indoor unit/
Outdoor unit
6m/20ft (＜36000Btu/h unit)
10m/32.8ft (≥36000Btu/h unit)
6m/20ft (＜36000Btu/h unit)
10m/32.8ft (≥36000Btu/h unit)
Specifications 3 
Additional Refrigerant
24g/m (0.26oz/ft)