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The pipe should be sized to ensure optimum performance and proper oil return. The
sizing must also consider the full capacity range through which this particular unit will
need to operate.
Pipe runs should be kept as short as possible, using the minimum number of
directional changes. Use large radius bends and avoid trapping of oil and refrigerant.
This is particularly important for the suction line. The suction line should ideally slope
gently towards the unit. Recommendation slope is 1/200~1/250. P traps, double
risers and reduced pipe diameters may be required for suction lines where long
vertical risers cannot be avoided. All pipes should be adequately supported to prevent
sagging which can create oil traps.
The recommended pipe clamp support distance is shown in the table.
1/2 inch
5/8 inch
7/8 inch
11/8 inch
1.2 M
1.5 M
1.85 M
1.2 M
Tube Size
Max distance between 2 clamp support
d. Refrigerant line insulation
-
Insulate suction lines from the evaporators to the condensing unit with
minimum 1” thickness closed-cell type insulation on low temperature circuits.
-
Long liquid lines run in areas exposed to high temperatures should be fully
insulated with minimum 1/2” insulation.
-
Suction and liquid lines should never be taped or soldered together.
e. Electrical
a. All electrical work must be done in accordance with the National Electrical
Code and existing local codes.
b.
Power supply must be the same as specified on the unit name plate.
c.
Voltage fluctuations in excess of 10 percent must be corrected.
d.
Before starting the unit, ensure that all protective devices are in place and
that all wiring is secure.
f. Brazing Recommendation
Maintain a flow of oxygen-free nitrogen through the system at a very low pressure
during brazing. Nitrogen displaces the air and prevents the formation of copper oxides
in the system. If copper oxidization is allowed to form, the copper oxide material can
later be swept through the system and block screens such as those protecting
capillary tubes, thermal expansion valves, and accumulator oil return holes. This
minimizes any entry of contaminants and moisture.
