User Guide

182 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 90°F/32.2°C ambient
Water
temp
(ºF)
Surface temperature (°F)
No insulation
½" insulation
1" insulation
1½" insulation
2" insulation
30 36.3 73.2 81.0 84.2 85.8
40 45.2 76.0 82.5 85.1 86.5
50 54.2 78.8 84.0 86.1 87.2
60 63.1 81.6 85.5 87.1 87.9
70 72.1 84.4 87.0 88.1 88.6
80 81.0 87.2 88.5 89.0 89.3
90 90.0 90.0 90.0 90.0 90.0
100 99.0 92.8 91.5 91.0 90.7
110 107.9 95.6 93.0 91.9 91.4
120 116.9 98.4 94.5 92.9 92.1
130 125.8 101.2 96.0 93.9 92.8
140 134.8 104.0 97.5 94.9 93.5
150 143.7 106.8 99.0 95.8 94.2
160 152.7 109.5 100.5 96.8 94.9
170 161.7 112.3 101.9 97.8 95.6
180 170.6 115.1 103.4 98.7 96.3
190 179.6 117.9 104.9 99.7 97.0
200 188.5 120.7 106.4 100.7 97.7
2" Uponor PEX heat loss
at 90°F/32.2°C ambient
Water
temp
(ºF)
Heat loss (btu/hr·ft)
No insulation
½" insulation
1" insulation
1½" insulation
2" insulation
30 -29.9 -13.7 -9.7 -7.8 -6.7
40 -24.9 -11.4 -8.1 -6.5 -5.6
50 -19.9 -9.1 -6.4 -5.2 -4.5
60 -14.9 -6.9 -4.8 -3.9 -3.4
70 -10.0 -4.6 -3.2 -2.6 -2.2
80 -5.0 -2.3 -1.6 -1.3 -1.1
90 0.0 0.0 0.0 0.0 0.0
100 5.0 2.3 1.6 1.3 1.1
110 10.0 4.6 3.2 2.6 2.2
120 14.9 6.9 4.8 3.9 3.4
130 19.9 9.1 6.4 5.2 4.5
140 24.9 11.4 8.1 6.5 5.6
150 29.9 13.7 9.7 7.8 6.7
160 34.9 16.0 11.3 9.1 7.8
170 39.9 18.3 12.9 10.4 9.0
180 44.8 20.6 14.5 11.7 10.1
190 49.8 22.8 16.1 13.0 11.2
200 54.8 25.1 17.7 14.3 12.3