16
®
Link
Heat
Fixed Point F1
(
1
⁄
2
∆L)
L1
L2
Fixed Point F2
(L)
(
1
⁄
2
∆L)
L1
Quick Reference Table - "U" Offset
Length of L1 & L2 for 50ft of PEX
PEX Size
∆T (°F)
1⁄2"
3⁄4"
1"
11⁄4"
11⁄2"
2"
20
L1
4.0"
4.7"
5.3"
5.9"
6.4"
7.3"
L2
2.0"
2.4"
2.7"
3.0"
3.2"
3.7"
40
L1
5.6"
6.7"
7.6"
8.3"
9.1"
10.4"
L2
2.8"
3.3"
3.8"
4.2"
4.5"
5.2"
60
L1
6.9"
8.2"
9.2"
10.2"
11.1"
12.7"
L2
3.4"
4.1"
4.6"
5.1"
5.6"
6.4"
80
L1
8.0"
9.4"
10.7"
11.8"
12.8"
14.7"
L2
4.0"
4.7"
5.3"
5.9"
6.4"
7.3"
100
L1
8.9"
10.5"
11.9"
13.2"
14.3"
16.4"
L2
4.4"
5.3"
6.0"
6.6"
7.2"
8.2"
120
L1
9.7"
11.5"
13.1"
14.5"
15.7"
18.0"
L2
4.9"
5.8"
6.5"
7.2"
7.9"
9.0"
140
L1
10.5"
12.5"
14.1"
15.6"
17.0"
19.4"
L2
5.3"
6.2"
7.1"
7.8"
8.5"
9.7"
160
L1
11.3"
13.3"
15.1"
16.7"
18.2"
20.8"
L2
5.6"
6.7"
7.6"
8.3"
9.1"
10.4"
180
L1
11.9"
14.1"
16.0"
17.7"
19.3"
22.0"
L2
6.0"
7.1"
8.0"
8.9"
9.6"
11.0"
200
L1
12.6"
14.9"
16.9"
18.7"
20.3"
23.2"
L2
6.3"
7.4"
8.4"
9.3"
10.1"
11.6"
Expansion U Offset
Example 2:
There is a 100ft straight run of 2" PEX tubing on a tray in a ceiling space for
DHW. Again we need to allow for 100°F of temperature difference. In this case a U offset
will work best.
The equation on the previous page also applies to an expansion “U", but the arm length (D)
is divided into three sections.
Common ∆T Range
D = C × √(Ø + 0.125) × ∆L
D = 12 × √(2 + 0.125) × 100ft × 1.1"⁄10°F⁄100ft × (160 − 60)
D = 58"
L1 = 2⁄5 × D
L2 = 1⁄5 × D
L1 = 23.2"
L2 = 11.6"
"U" offset should be square when
tubing is cold.
