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6/21 57-02611 / 101628 ©2021, Refrigerated Solutions Group™. All rights reserved. 16
How to figure line sizes:
1.
Determine equivalent line run = actual run + valves and fitting allowances.
2.
Use Line Sizing Tables to size lines.
3.
Note any special considerations.
Fittings in this system:
• 90° elbows in main line plus a 90° turn through a tee.
• additional 90° elbows to first evaporator.
• (4) additional 90° elbows to second evaporator.
Determine line size 1 (main line from condensing unit):
1. Main line from the condensing unit to be sized for the total capacity (balance) of the whole
system of 24,000 BTUH’s (Table 7).
2. Refer to 24,000 @100 feet at -20°F SST R404A on the chart. You will find the suction line
to be 1-3/8" and 1/2" liquid line.
3. Refer to Table 5. For every 1-3/8" 90° elbow you must add 4 equivalent feet of pipe and 2.5
equivalent feet of pipe for each 1-3/8" tee.
Therefore, total equivalent line run =
Actual line run 100 feet
+ (6) 1-3/8" elbows @ 4' 24 feet
+ (1) 1-3/8" tee @ 2.5' 2.5 feet
Total equivalent line run 126.5 feet
4. Refer to Table 7. For 126.5 total equivalent feet, the suction line size should be 1-3/8" and
the liquid line stays at 1/2" line.
Note: The gray shaded areas on Table 7. For 24,000 BTUHs, the maximum suction riser is 1-1/8" to
ensure proper oil return and pressure drop from the bottom p-trap to the top p-trap.
Determine line size 2 (evaporators):
1. Line sizing to each evaporator is based on 12,000 BTUH’s and equivalent run from condensing
unit. First evaporator has a 105 ft. run, and the second evaporator has a 120 ft. run.
2. Table 7 indicates 1-1/8" suction for the first evaporator and indicates 1-1/8" suction for the second
evaporator.
3. Refer to Table 5. Each 1-1/8" 90° elbow adds 3 equivalent feet of pipe. Each 90° turn through a 1-
1/8" tee adds 6 equivalent feet.
4. Actual line run (evap 1) 105 feet
+ (5) 1-1/8" elbows @ 3' 15 feet
+ (1) 90° turn through tee @ 6' 6 feet
Total equivalent line run 126 feet
Actual line run (evap 2) 120 feet
+ (4) 1-1/8" elbows @ 3' 12 feet
Total equivalent line run 132 feet
5. Table 7 indicates 1-1/8" suction line and 3/8" liquid line from main line to both evaporators.
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