User Guide

164 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 50°F/10°C ambient
Water
temp
(ºF)
Surface temperature (°F)
No insulation
½" insulation
1" insulation
1½" insulation
2" insulation
30 31.4 44.6 47.2 48.2 48.7
40 40.7 47.3 48.6 49.1 49.4
50 50.0 50.0 50.0 50.0 50.0
60 59.3 52.7 51.4 50.9 50.6
70 68.6 55.4 52.8 51.8 51.3
80 77.9 58.1 54.1 52.6 51.9
90 87.2 60.7 55.5 53.5 52.5
100 96.5 63.4 56.9 54.4 53.1
110 105.8 66.1 58.3 55.3 53.8
120 115.1 68.8 59.7 56.2 54.4
130 124.4 71.5 61.0 57.0 55.0
140 133.7 74.2 62.4 57.9 55.6
150 143.0 76.8 63.8 58.8 56.3
160 152.3 79.5 65.2 59.7 56.9
170 161.6 82.2 66.6 60.6 57.5
180 170.9 84.9 67.9 61.4 58.2
190 180.2 87.6 69.3 62.3 58.8
200 189.5 90.3 70.7 63.2 59.4
1¼" Uponor PEX heat loss
at 50°F/10°C ambient
Water
temp
(ºF)
Heat loss (btu/hr·ft)
No insulation
½" insulation
1" insulation
1½" insulation
2" insulation
30 -6.7 -3.3 -2.4 -2.0 -1.8
40 -3.3 -1.7 -1.2 -1.0 -0.9
50 0.0 0.0 0.0 0.0 0.0
60 3.3 1.7 1.2 1.0 0.9
70 6.7 3.3 2.4 2.0 1.8
80 10.0 5.0 3.7 3.0 2.6
90 13.4 6.7 4.9 4.0 3.5
100 16.7 8.3 6.1 5.0 4.4
110 20.1 10.0 7.3 6.0 5.3
120 23.4 11.7 8.5 7.1 6.2
130 26.8 13.3 9.8 8.1 7.1
140 30.1 15.0 11.0 9.1 7.9
150 33.5 16.7 12.2 10.1 8.8
160 36.8 18.4 13.4 11.1 9.7
170 40.2 20.0 14.6 12.1 10.6
180 43.5 21.7 15.9 13.1 11.5
190 46.9 23.4 17.1 14.1 12.4
200 50.2 25.0 18.3 15.1 13.2