CAUTION
•  Oil traps
If the indoor unit is installed higher than 
the outdoor unit:
-If oil ows back into the outdoor unit’s 
compressor, this might cause liquid 
compression or deterioration of oil 
return. Oil traps in the rising gas piping 
can prevent this.
An oil trap should be installed every 
10m (32.8ft) of vertical suction line riser.
 
Oil trap
Gas piping
Indoor unit
Outdoor unit
Liquid piping
10m/32.8ft
10m/32.8ft
The indoor unit is installed higher than the 
outdoor unit
CAUTION
If the outdoor unit is installed higher 
than the indoor unit:
-It is recommended that vertical suction 
risers not be upsized. Proper oil return 
to the compressor should be maintained 
with suction gas velocity. If velocities 
drop below7.62m/s (1500fpm (feet per 
minute)), oil return will be decreased. 
An oil trap should be installed every 
6m(20ft) of vertical suction line riser.
Oil trap
Gas piping
Indoor unit
Outdoor unit
Liquid piping
6m/20ft
6m/20ft
The outdoor unit is installed higher than the 
indoor unit
Refrigerant piping 
Connection
 Page 18-GB