Gree GUD35ZD/A-T Owner's Manual page 26

DC Inverter U-match Series Floor Ceiling Type Unit
Connection pipe should adopt water-proof insulating material. Its wall thickness
should be 0.5-1.0mm and the pipe wall should be able to withstand 6.0MPa. The
longer the connection pipe is, the worse cooling and heating performance it has.
When the drop between indoor and outdoor units is larger than 10m, an oil
return bend should be added every 6 meters.
The requirement on the adding of oil return bend is as below:
(1) Outdoor unit is beneath the indoor unit.
There's no need to add non-return bend at the lowest or highest position of the
vertical pipe, as shown below:
(2) Outdoor unit is above the indoor unit.
It's necessary to add oil return bend and non-return bend at the lowest and
highest position of the vertical pipe, as shown below:
System gas pipe
Oil return bend
Outdoor unit
Non-return Non-return bend
Outdoor unit Outdoor unit
System gas System
Install Install an an oil oil return return
bend bend every every 6m 6m
22
Indoor unit
Install an oil return
bend every 6m
bend
gas pipe pipe
Oil return Oil return bend bend
Indoor unit Indoor unit