User Guide

166 l uponorengineering.com
1. All calculations based on cylindrical thermal resistance methodology (ASHRAE).
2. Based on uid velocity of 8 ft./sec. at 160°F/71.1°C (maximizing heat transfer from 100% water).
3. Pipe convection set to be 1.761 Btu/hr•ft²•°F (based on standard value for free convection of air).
4. This heat loss comparison uses 0.24 Btu•in/(hr•ft2•°F) as the insulation thermal conductivity.
This is a standard value for berglass pipe insulation at a 100°F/37.8°C mean temperature.
Pipe heat loss and surface temperature
2" Uponor PEX surface
temperature at 50°F/10°C ambient
Water
temp
(ºF)
Surface temperature (°F)
No insulation
½" insulation
1" insulation
1½" insulation
2" insulation
30 32.1 44.4 47.0 48.1 48.6
40 41.0 47.2 48.5 49.0 49.3
50 50.0 50.0 50.0 50.0 50.0
60 59.0 52.8 51.5 51.0 50.7
70 67.9 55.6 53.0 51.9 51.4
80 76.9 58.4 54.5 52.9 52.1
90 85.8 61.2 56.0 53.9 52.8
100 94.8 64.0 57.5 54.9 53.5
110 103.7 66.8 59.0 55.8 54.2
120 112.7 69.5 60.5 56.8 54.9
130 121.7 72.3 61.9 57.8 55.6
140 130.6 75.1 63.4 58.7 56.3
150 139.6 77.9 64.9 59.7 57.0
160 148.5 80.7 66.4 60.7 57.7
170 157.5 83.5 67.9 61.6 58.4
180 166.4 86.3 69.4 62.6 59.1
190 175.4 89.1 70.9 63.6 59.8
200 184.3 91.9 72.4 64.6 60.5
2" Uponor PEX heat loss
at 50°F/10°C ambient
Water
temp
(ºF)
Heat loss (btu/hr·ft)
No insulation
½" insulation
1" insulation
1½" insulation
2" insulation
30 -10.0 -4.6 -3.2 -2.6 -2.2
40 -5.0 -2.3 -1.6 -1.3 -1.1
50 0.0 0.0 0.0 0.0 0.0
60 5.0 2.3 1.6 1.3 1.1
70 10.0 4.6 3.2 2.6 2.2
80 14.9 6.9 4.8 3.9 3.4
90 19.9 9.1 6.4 5.2 4.5
100 24.9 11.4 8.1 6.5 5.6
110 29.9 13.7 9.7 7.8 6.7
120 34.9 16.0 11.3 9.1 7.8
130 39.9 18.3 12.9 10.4 9.0
140 44.8 20.6 14.5 11.7 10.1
150 49.8 22.8 16.1 13.0 11.2
160 54.8 25.1 17.7 14.3 12.3
170 59.8 27.4 19.3 15.6 13.5
180 64.8 29.7 21.0 16.9 14.6
190 69.8 32.0 22.6 18.2 15.7
200 74.7 34.3 24.2 19.5 16.8