reFrIGerant deSIGn | 45
Refrigerant Piping Design & Layout Best Practices
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refrigerAnT PiPing DeSign
Figure 19: Coiled Expansion Loops and offsets.
Large Tubing U-bend (>3/4 in.)
Loop
Small Tubing U-bend (<3/4 in.)
R
L
R
L
L
Anticipated Linear
Expansion (LE) (inches)
nominal Tube Size (oD) inches
1/4
3/8
1/2
3/4
1/2
R
1
6
7
8
9
L
2
38
44
50
59
1
R
1
9
10
11
13
L
2
54
63
70
83
1-1/2
R
1
11
12
14
16
L
2
66
77
86
101
2
R
1
12
14
16
19
L
2
77
89
99
117
2-1/2
R
1
14
16
18
21
L
2
86
99
111
131
3
R
1
15
17
19
23
L
2
94
109
122
143
3-1/2
R
1
16
19
21
25
L
2
102
117
131
155
4
R
1
17
20
22
26
L
2
109
126
140
166
1
R = Centerline Length of Pipe.
2
L = Centerline Minimum Radius (inches).
Table 19: Radii of Coiled Expansion Loops and Developed Lengths of Expansion offsets.
Selecting Field-Supplied copper tubing
Physical Pipe Length:
Actual length of straight segment(s) of pipe.
Equivalent Pipe Length:
Actual length of pipe plus equivalent lengths of elbows, Y-branches, and valves.
1. Draft a one-line diagram of the proposed piping system connecting outdoor unit to heat recovery and indoor units. Follow the pipe
limitations listed on page 44.
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 designed for use with
R410A refrigerant. The designer, however, 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 20 for equivalent lengths.
Table 20: Equivalent Piping Length for Piping Components.
Definitions
layout Procedure
Component
Size (Inches)
1/4 3/8 1/2 5/8 3/4
Elbow (ft.)
0.5 0.6 0.7 0.8 1.2
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 opening. 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.
