Pipe Length And The Drop Height - COMFORT-AIRE Century VMH-SV Series Service Manual

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
6k~12k
18k
7.5m (24.6ft)
24k~30k
36k
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.
1. Indoor unit is installed higher than outdoor unit
If indoor unit is installed higher than outdoor unit, oil trap should be set every 10m(32.8ft) of vertical distance.
If the outdoor unit is installed higher than the indoor unit, proper oil should return to the compressor along with the
suction of refrigerant to keep lubrication of compressor. If the suction flow velocity drops below 7.62m/s(1500fpm (feet
per minute)), oil won't return to the compressor. An oil trap should be installed every 6m(20ft) of vertical distance.
Max Pipe Length Max Elevation
25m (82.0ft) 10m (32.8ft)
30m (98.4ft) 20m (65.6ft)
50m (164.04ft) 25m (82.02ft)
65m (213.2ft) 30m (82.02ft)
2. Outdoor unit is installed higher than indoor unit
Specifications 3
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Specifications 3
Additional Refrigerant
15g/m (0.16oz/ft)
30g/m (0.32oZ/ft)
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