User Guide

170 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
¾" 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 31.8 59.9 65.0 66.9 67.8
40 41.4 62.4 66.2 67.6 68.3
50 50.9 65.0 67.5 68.4 68.9
60 60.5 67.5 68.7 69.2 69.4
70 70.0 70.0 70.0 70.0 70.0
80 79.5 72.5 71.3 70.8 70.6
90 89.1 75.0 72.5 71.6 71.1
100 98.6 77.6 73.8 72.4 71.7
110 108.2 80.1 75.0 73.1 72.2
120 117.7 82.6 76.3 73.9 72.8
130 127.3 85.1 77.5 74.7 73.3
140 136.8 87.7 78.8 75.5 73.9
150 146.3 90.2 80.0 76.3 74.4
160 155.9 92.7 81.3 77.1 75.0
170 165.4 95.2 82.5 77.8 75.6
180 175.0 97.8 83.8 78.6 76.1
190 184.5 100.3 85.0 79.4 76.7
200 194.1 102.8 86.3 80.2 77.2
¾" 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 -8.7 -5.0 -3.8 -3.2 -2.8
40 -6.6 -3.7 -2.8 -2.4 -2.1
50 -4.4 -2.5 -1.9 -1.6 -1.4
60 -2.2 -1.2 -0.9 -0.8 -0.7
70 0.0 0.0 0.0 0.0 0.0
80 2.2 1.2 0.9 0.8 0.7
90 4.4 2.5 1.9 1.6 1.4
100 6.6 3.7 2.8 2.4 2.1
110 8.7 5.0 3.8 3.2 2.8
120 10.9 6.2 4.7 4.0 3.5
130 13.1 7.4 5.6 4.8 4.3
140 15.3 8.7 6.6 5.6 5.0
150 17.5 9.9 7.5 6.4 5.7
160 19.7 11.2 8.5 7.2 6.4
170 21.9 12.4 9.4 8.0 7.1
180 24.0 13.6 10.4 8.8 7.8
190 26.2 14.9 11.3 9.6 8.5
200 28.4 16.1 12.2 10.3 9.2