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REFRIGERANT PIPING DESIGN
Selecting Field-Supplied Copper Tubing
Figure 16: Coiled Expansion Loops and Offsets.
L
R
Large Tubing U-bend (>3/4 in.)
Table 23: Radii of Coiled Expansion Loops and Developed Lengths of Expansion Offsets.
Anticipated Linear
Expansion (LE) (inches)
1/2
1
1-1/2
2
2-1/2
3
3-1/2
4
R = Centerline Length of Pipe.
1
Definitions
Physical Pipe Length: Actual length of straight segment(s) of pipe.
Equivalent Pipe Length: Actual length of pipe plus equivalent lengths of long radius elbows, Y-branches, and valves.
Layout Procedure
1. Draft a one-line diagram of the proposed piping system connecting outdoor unit to indoor units. Follow the pipe limitations listed on page
43.
2. Calculate the physical length of each pipe segment and note it on the drawing.
3. Calculate the equivalent pipe length of each pipe segment.
Using Elbows
Field-supplied elbows are allowed as long as they are long radius and designed
for use with R410A refrigerant. The designer should be cautious with the quantity
and size of fittings used, and must account for the additional pressure losses in
equivalent pipe length calculation. The equivalent pipe length of each elbow must
be added to each pipe segment. See Table 24 for equivalent lengths.
Field-Provided Isolation Ball Valves
It is acceptable to install field-supplied ball valves with Schrader ports at the indoor unit. Full-port isolation ball valves with Schrader ports
(positioned between valve and indoor unit) rated for use with R410A refrigerant should be used on both the liquid and vapor lines.
If valves are not installed and the indoor unit needs to be removed or repaired, the entire system must be shut down and evacuated. Position
valves with a minimum distance of three (3) to six (6) inches of pipe on either side of the valve. Valves must be easily accessible for service.
If necessary, install drywall access doors or removable ceiling panels, and position the valves to face the access door or ceiling panel open-
ing. Mount valves with adequate space between them to allow for placement of adequate pipe insulation around the valves. Recommended
best practice is to clearly label and document locations of all service valves. The equivalent pipe length of each ball valve must be added to
each pipe segment.
46 | REFRIGERANT DESIGN
L
1/4
R
6
1
L
2
38
R
1
9
L
2
54
R
1
11
L
2
66
R
12
1
L
2
77
R
1
14
L
86
2
R
1
15
L
2
94
R
1
16
L
2
102
R
17
1
L
2
109
L = Centerline Minimum Radius (inches).
2
©
R
Loop
Nominal Tube Size (OD) inches
3/8
7
44
10
63
12
77
14
89
16
99
17
109
19
117
20
126
Table 24: Equivalent Piping Length for Piping Components.
Component
Long Radius Elbow (ft.)
L
Small Tubing U-bend (<3/4 in.)
1/2
3/4
8
9
50
59
11
13
70
83
14
16
86
101
16
19
99
117
18
21
111
131
19
23
122
143
21
25
131
155
22
26
140
166
Size (Inches)
1/4
3/8
1/2
5/8
3/4
0.5
0.6
0.7
0.8
1.2
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