DC Inverter Multi VRF System User Manual
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4.3 Oil Loop
4.3.1 Objective of setting oil loop
When large drop height exists in the system, oil loop is required to be set on the vertical pipeline
so as to guarantee effective oil return to compressor.
4.3.2 Priciple of setting oil loop
When large drop height exists between indoor and outdoor units, oil loop is required to be set on
the vertical gas pipe for every 10m from down to the top. Oil loop can be made by 2 U-type bends or
an O-type bend. Its height should be 3~5 times of the pipe size.
4.3.3 Precautions for oil loop installation
1) Oil loop can be set as U-type or O-type.
2) If the drop height between indoor and outdoor units is above 10m, then oil loop is required to
be set on the vertical gas pipe for every 10m from down to the top, as well as at the lowest
and highest positions of the vertical pipe.
4.3.4 Making of the Oil Loop
A
R
C
Fig.10 Oil Loop
To prevent pipeline damage during pipe bending, please check the following table for the size of
oil return bend.
A
R
C
mm
inch
mm
mm
Φ19.05
3/4
≥
34
≤
105
4.4 Installation of the Connection Pipe
4.4.1 Precautions for the Installation of Connection Pipe
1) Conform to the following principles during pipe connection: Connection pipe should be as
short as possible, so is the height difference between indoor and outdoor units. Keep the
number of bends as little as possible. Radius of curvature should be as large as possible.
2) Weld the connection pipe between indoor and outdoor units. Please strictly follow the
requirements for welding process. Rosin joint or pin hole is not allowed.
3) When laying the pipe, be careful not to distort it. Radius of bending parts should be over
200mm. Note that pipes cannot be repeatedly bent or stretched; otherwise the material will
get harder. Do not bend or stretch the pipe for more than 3 times at the same position.
