User Guide

176 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
3" 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 35.8 58.6 63.7 65.8 67.0
40 44.4 61.5 65.3 66.9 67.7
50 52.9 64.3 66.9 67.9 68.5
60 61.5 67.2 68.4 69.0 69.2
70 70.0 70.0 70.0 70.0 70.0
80 78.5 72.8 71.6 71.0 70.8
90 87.1 75.7 73.1 72.1 71.5
100 95.6 78.5 74.7 73.1 72.3
110 104.2 81.4 76.3 74.2 73.0
120 112.7 84.2 77.9 75.2 73.8
130 121.3 87.1 79.4 76.3 74.6
140 129.8 89.9 81.0 77.3 75.3
150 138.3 92.8 82.6 78.4 76.1
160 146.9 95.6 84.2 79.4 76.9
170 155.4 98.4 85.7 80.4 77.6
180 164.0 101.3 87.3 81.5 78.4
190 172.5 104.1 88.9 82.5 79.1
200 181.0 107.0 90.5 83.6 79.9
3" 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 -28.0 -12.3 -8.5 -6.7 -5.7
40 -21.0 -9.2 -6.3 -5.0 -4.3
50 -14.0 -6.1 -4.2 -3.3 -2.8
60 -7.0 -3.1 -2.1 -1.7 -1.4
70 0.0 0.0 0.0 0.0 0.0
80 7.0 3.1 2.1 1.7 1.4
90 14.0 6.1 4.2 3.3 2.8
100 21.0 9.2 6.3 5.0 4.3
110 28.0 12.3 8.5 6.7 5.7
120 34.9 15.4 10.6 8.4 7.1
130 41.9 18.4 12.7 10.0 8.5
140 48.9 21.5 14.8 11.7 9.9
150 55.9 24.6 16.9 13.4 11.4
160 62.9 27.6 19.0 15.1 12.8
170 69.9 30.7 21.1 16.7 14.2
180 76.9 33.8 23.2 18.4 15.6
190 83.9 36.9 25.4 20.1 17.0
200 90.8 39.9 27.5 21.8 18.5