User Guide

174 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 70°F/21.1°C ambient
Water
temp
(ºF)
Surface temperature (°F)
No insulation
½" insulation
1" insulation
1½" insulation
2" insulation
30 34.2 58.8 64.0 66.1 67.2
40 43.1 61.6 65.5 67.1 67.9
50 52.1 64.4 67.0 68.1 68.6
60 61.0 67.2 68.5 69.0 69.3
70 70.0 70.0 70.0 70.0 70.0
80 79.0 72.8 71.5 71.0 70.7
90 87.9 75.6 73.0 71.9 71.4
100 96.9 78.4 74.5 72.9 72.1
110 105.8 81.2 76.0 73.9 72.8
120 114.8 84.0 77.5 74.9 73.5
130 123.7 86.8 79.0 75.8 74.2
140 132.7 89.5 80.5 76.8 74.9
150 141.7 92.3 81.9 77.8 75.6
160 150.6 95.1 83.4 78.7 76.3
170 159.6 97.9 84.9 79.7 77.0
180 168.5 100.7 86.4 80.7 77.7
190 177.5 103.5 87.9 81.6 78.4
200 186.4 106.3 89.4 82.6 79.1
2" Uponor PEX heat loss
at 70°F/21.1°C ambient
Water
temp
(ºF)
Heat loss (btu/hr·ft)
No insulation
½" insulation
1" insulation
1½" insulation
2" insulation
30 -19.9 -9.1 -6.4 -5.2 -4.5
40 -14.9 -6.9 -4.8 -3.9 -3.4
50 -10.0 -4.6 -3.2 -2.6 -2.2
60 -5.0 -2.3 -1.6 -1.3 -1.1
70 0.0 0.0 0.0 0.0 0.0
80 5.0 2.3 1.6 1.3 1.1
90 10.0 4.6 3.2 2.6 2.2
100 14.9 6.9 4.8 3.9 3.4
110 19.9 9.1 6.4 5.2 4.5
120 24.9 11.4 8.1 6.5 5.6
130 29.9 13.7 9.7 7.8 6.7
140 34.9 16.0 11.3 9.1 7.8
150 39.9 18.3 12.9 10.4 9.0
160 44.8 20.6 14.5 11.7 10.1
170 49.8 22.8 16.1 13.0 11.2
180 54.8 25.1 17.7 14.3 12.3
190 59.8 27.4 19.3 15.6 13.5
200 64.8 29.7 21.0 16.9 14.6