Buying Guide

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In the majority of low-pressure heating systems employing copper
tube and installed in small houses or private dwellings, provision
for expansion and contraction is relatively simple. Mains, risers,
and branches to radiators should be free or floating at one end of
the line. Holes should be large enough to permit free movement of
the tube, and care should be exercised so that pipe hangers and
supports permit unrestricted movement and do not anchor the tube.
Wrought copper tube hangers that are both practicable and neat in
appearance are available.
Unusually long runs of copper tubing should be provided with an
expansion bend or loop. By bending soft temper copper tube, a
simple form of expansion loop can be made. With the addition of
combination flared-tube to solder joint fittings, as illustrated in
Figure 1, these types of loops can be used when space or other
limitations exist. The correct proportions of such expansion loop to
meet various conditions are shown in the accompanying table.
FIGURE 1
EXPANSION AND CONTRACTION
U.S. customary units in this document are the standard; the metric units are provided for
reference only. The values stated in each system are not exact equivalents.
RADII OF COILED EXPANSION LOOPS AND DEVELOPED LENGTHS OF EXPANSION OFFSETS
Expected Expansion
Nominal 1/2 1 1 1/2 2 2 1/2 3 3 1/2 4
Tube R L R L R L R L R L R L R L R L
Size Inch (mm) Inch (mm) Inch (mm) Inch (mm) Inch (mm) Inch (mm) Inch (mm) Inch (mm) Inch (mm)
1/4 6 (152.4) 38 (965.2) 9 (228.6) 54 (1371.6) 11 (279.4) 66 (1676.4) 12 (304.8) 77 (1955.8) 14 (355.6)
3/8 7 (177.8) 44 (1117.6) 10 (254.0) 63 (1600.2) 12 (304.8) 77 (1955.8) 14 (355.6) 89 (2260.6) 16 (406.4)
1/2 8 (203.2) 50 (1270.0) 11 (279.4) 70 (1778.0) 14 (355.6) 89 (2260.6) 16 (406.4) 99 (2514.6) 18 (457.2)
3/4 9 (228.6) 59 (1498.6) 13 (330.2) 83 (2108.2) 16 (406.4) 101 (2565.4) 19 (482.6) 117 (2971.8) 21 (533.4)
1 11 (279.4) 67 (1701.8) 15 (381.0) 94 (2387.6) 18 (457.2) 115 (2921.0) 21 (533.4) 133 (3378.2) 24 (609.6)
1 1/2 13 (330.2) 80 (2032.0) 18 (457.2) 113 (2870.2) 22 (558.8) 138 (3505.2) 25 (635.0) 160 (4064.0) 29 (736.6)
2 15 (381.0) 91 (2311.4) 21 (533.4) 129 (3276.6) 25 (635.0) 158 (4013.2) 29 (736.6) 183 (4648.2) 33 (838.2)
2 1/2 16 (406.4) 102 (2590.8) 23 (584.2) 144 (3657.6) 28 (711.2) 176 (4470.4) 32 (812.8) 203 (5156.2) 36 (914.4)
3 18 (457.2) 111 (2819.4) 25 (635.0) 157 (3987.8) 30 (762.0) 191 (4851.4) 35 (889.0) 222 (5638.8) 40 (1016.0)
3 1/2 19 (482.6) 120 (3048.0) 27 (685.8) 169 (4292.6) 33 (838.2) 206 (5232.4) 38 (965.2) 239 (6070.6) 43 (1092.2)
4 20 (508.0) 128 (3251.2) 29 (736.6) 180 (4572.0) 35 (889.0) 220 (5588.0) 41 (1041.4) 255 (6477.0) 45 (1143.0)
5 23 (584.2) 142 (3606.8) 32 (812.8) 201 (5105.4) 39 (990.6) 245 (6223.0) 45 (1143.0) 284 (7213.6) 51 (1295.4)
Inch (mm) Inch (mm) Inch (mm) Inch (mm) Inch (mm) Inch (mm) Inch (mm)
86 (2184.4) 15 (381.0) 94 (2387.6) 16 (406.4) 102 (2590.8) 17 (431.8) 109 (2768.6)
99 (2514.6) 17 (431.8) 109 (2768.6) 19 (482.6) 117 (2971.8) 20 (508.0) 126 (3200.4)
111 (2819.4) 19 (482.6) 122 (3098.8) 21 (533.4) 131 (3327.4) 22 (558.8) 140 (3556.0)
131 (3327.4) 23 (584.2) 143 (3632.2) 25 (635.0) 155 (3937.0) 26 (660.4) 166 (4216.4)
149 (3784.6) 26 (660.4) 163 (4140.2) 28 (711.2) 176 (4470.4) 30 (762.0) 188 (4775.2)
179 (4546.6) 31 (787.4) 196 (4978.4) 34 (863.6) 212 (5384.8) 36 (914.4) 226 (5740.4)
205 (5207.0) 36 (914.4) 224 (5689.6) 39 (990.6) 242 (6146.8) 41 (1041.4) 259 (6578.6)
227 (5765.8) 40 (1016.0) 249 (6324.6) 43 (1092.2) 269 (6832.6) 46 (1168.4) 288 (7315.2)
248 (6299.2) 43 (1092.2) 272 (6908.8) 47 (1193.8) 293 (7442.2) 50 (1270.0) 314 (7975.6)
267 (6781.8) 47 (1193.8) 293 (7442.2) 50 (1270.0) 316 (8026.4) 54 (1371.6) 338 (8585.2)
285 (7239.0) 50 (1270.0) 312 (7924.8) 54 (1371.6) 337 (8559.8) 57 (1447.8) 361 (9169.4)
318 (8077.2) 55 (1397.0) 348 (8839.2) 60 (1524.0) 376 (9550.4) 64 (1625.6) 402 (10210.8)
The above chart is calculated using 10ft (3.05m) of copper tubing
as the reference point. You may use it as follows: 100ft (30.5m) of
copper tube, with a 200°F (93.3°C) temperature change. Reference
point .2256 inches for 10ft, (5.73mm for 3.05m), multipy by 10 for
100ft (30.5m), resulting in an answer of 2.256 inches (57.3mm) of
expansion or contraction.
NOTE: Calculations for expansion and contraction should be
based on the average coefficient of expansion of copper which is
0.0000094 per °F (0.00001692 per °C) between 77°F and 212°F
(25°C and 100°C). For example, the expansion for each 10ft (3.05m)
of any size of tube heated from room temperature of 70°F (21.1°C) to
170°F (76.7°C), that is, 100°F (55.6°C) rise, is:
Rise Coefficient
100°F 10ft 12 inches 0.000094 0.1128 in.
x x x =
(55.6°C) (3.05m) (1000mm) (0.00001692) (2.87mm)
a. U-Bend
c. Offset and
Return
b. Coiled Loop