Installation and Maintenance Manual

Installation - Mechanical
RLC-SVX09H-EN 67
Discharge (Hot Gas) Line Sizing
The discharge lines should pitch downward, in the
direction of the hot gas flow, at the rate of 1/2 inch per each
10 feet of horizontal run.
Discharge line size is based on the velocity needed to
obtain sufficient oil return. Basic discharge line sizing is
shown in Table 52, p. 67 throughTable 63, p. 70,
depending on the unit configuration.
Discharge lines are not typically insulated. If insulation is
required, it should be approved for use at temperatures up
to 230°F (max discharge temp).
Note: The proper column for leaving evaporator water
temperature must be used to avoid catastrophic
damage to the unit. Column for 10 °F to 37°F can
only be used on units designed for low
temperature applications. Refer to the design
conditions of the unit to determine the correct
column that must be used.
Note: The discharge line should drop well below the
compressor discharge outlet before beginning its
vertical rise.This prevents possible refrigerant
drainage back to the compressor and oil separator
during the unit STOP cycle. See Figure 35, p. 59,
Figure 36, p. 59 and Figure 37, p. 60 for details.
Table 52. Discharge (hot gas) line sizing RTUD 80 ton
Leaving Water
Temperature
Leaving Water
Temperature
Ckt 1
Line
38-65
°F
10-37
°F
Ckt 2
Line
38-65
°F
10-37
°F
Total
Equiv.
Length
(ft)
25
2.125 2.125
Total
Equiv.
Length
(ft)
25
2.125 2.125
50
2.125 2.125 50 2.125 2.125
75
2.125 2.125 75 2.125 2.125
100
2.125 2.125 100 2.125 2.125
125
2.125 2.125 125 2.125 2.125
150
2.125 2.125 150 2.125 2.125
175
2.125 2.125 175 2.125 2.125
200
2.125 2.125 200 2.125 2.125
225
2.125 2.125 225 2.125 2.125
250
2.125 2.125 250 2.125 2.125
275
2.125 2.125 275 2.125 2.125
300
2.625 2.125 300 2.625 2.125
Table 53. Discharge (hot gas) line sizing RTUD 90 ton
Leaving Water
Temperature
Leaving Water
Temperature
Ckt 1
Line
38-65
°F
10-37
°F
Ckt 2
Line
38-65
°F
10-37
°F
Total
Equiv.
Length
(ft)
25
2.125 2.125
Total
Equiv.
Length
(ft)
25
2.125 2.125
50
2.125 2.125 50 2.125 2.125
75
2.125 2.125 75 2.125 2.125
100
2.125 2.125 100 2.125 2.125
125
2.125 2.125 125 2.125 2.125
150
2.125 2.125 150 2.125 2.125
175
2.125 2.125 175 2.125 2.125
200
2.125 2.125 200 2.125 2.125
225
2.625 2.125 225 2.625 2.125
250
2.625 2.125 250 2.625 2.125
275
2.625 2.125 275 2.625 2.125
300
2.625 2.125 300 2.625 2.125
Table 54. Discharge (hot gas) line sizing RTUD 100 ton
Leaving Water
Temperature
Leaving Water
Temperature
Ckt 1
Line
38-65
°F
10-37
°F
Ckt 2
Line
38-65
°F
10-37
°F
Total
Equiv.
Length
(ft)
25
2.125 2.125
Total
Equiv.
Length
(ft)
25
2.125 2.125
50
2.125 2.125 50 2.125 2.125
75
2.125 2.125 75 2.125 2.125
100
2.125 2.125 100 2.125 2.125
125
2.125 2.125 125 2.125 2.125
150
2.125 2.125 150 2.625 2.125
175
2.125 2.125 175 2.625 2.125
200
2.625 2.125 200 2.625 2.125
225
2.625 2.125 225 2.625 2.625
250
2.625 2.125 250 2.625 2.625
275
2.625 2.125 275 2.625 2.625
300
2.625 2.625 300 2.625 2.625