User Guide

172 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
1¼" 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 32.8 59.3 64.5 66.5 67.5
40 42.1 61.9 65.9 67.4 68.1
50 51.4 64.6 67.2 68.2 68.7
60 60.7 67.3 68.6 69.1 69.4
70 70.0 70.0 70.0 70.0 70.0
80 79.3 72.7 71.4 70.9 70.6
90 88.6 75.4 72.8 71.8 71.3
100 97.9 78.1 74.1 72.6 71.9
110 107.2 80.7 75.5 73.5 72.5
120 116.5 83.4 76.9 74.4 73.1
130 125.8 86.1 78.3 75.3 73.8
140 135.1 88.8 79.7 76.2 74.4
150 144.4 91.5 81.0 77.0 75.0
160 153.7 94.2 82.4 77.9 75.6
170 163.0 96.8 83.8 78.8 76.3
180 172.3 99.5 85.2 79.7 76.9
190 181.6 102.2 86.6 80.6 77.5
200 190.9 104.9 87.9 81.4 78.2
1¼" 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 -13.4 -6.7 -4.9 -4.0 -3.5
40 -10.0 -5.0 -3.7 -3.0 -2.6
50 -6.7 -3.3 -2.4 -2.0 -1.8
60 -3.3 -1.7 -1.2 -1.0 -0.9
70 0.0 0.0 0.0 0.0 0.0
80 3.3 1.7 1.2 1.0 0.9
90 6.7 3.3 2.4 2.0 1.8
100 10.0 5.0 3.7 3.0 2.6
110 13.4 6.7 4.9 4.0 3.5
120 16.7 8.3 6.1 5.0 4.4
130 20.1 10.0 7.3 6.0 5.3
140 23.4 11.7 8.5 7.1 6.2
150 26.8 13.3 9.8 8.1 7.1
160 30.1 15.0 11.0 9.1 7.9
170 33.5 16.7 12.2 10.1 8.8
180 36.8 18.4 13.4 11.1 9.7
190 40.2 20.0 14.6 12.1 10.6
200 43.5 21.7 15.9 13.1 11.5