User Guide

178 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 90°F/32.2°C ambient
Water
temp
(ºF)
Surface temperature (°F)
No insulation
½" insulation
1" insulation
1½" insulation
2" insulation
30 32.7 74.9 82.5 85.3 86.7
40 42.3 77.4 83.7 86.1 87.2
50 51.8 79.9 85.0 86.9 87.8
60 61.4 82.4 86.2 87.6 88.3
70 70.9 85.0 87.5 88.4 88.9
80 80.5 87.5 88.7 89.2 89.4
90 90.0 90.0 90.0 90.0 90.0
100 99.5 92.5 91.3 90.8 90.6
110 109.1 95.0 92.5 91.6 91.1
120 118.6 97.6 93.8 92.4 91.7
130 128.2 100.1 95.0 93.1 92.2
140 137.7 102.6 96.3 93.9 92.8
150 147.3 105.1 97.5 94.7 93.3
160 156.8 107.7 98.8 95.5 93.9
170 166.3 110.2 100.0 96.3 94.4
180 175.9 112.7 101.3 97.1 95.0
190 185.4 115.2 102.5 97.8 95.6
200 195.0 117.8 103.8 98.6 96.1
¾" 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 -13.1 -7.4 -5.6 -4.8 -4.3
40 -10.9 -6.2 -4.7 -4.0 -3.5
50 -8.7 -5.0 -3.8 -3.2 -2.8
60 -6.6 -3.7 -2.8 -2.4 -2.1
70 -4.4 -2.5 -1.9 -1.6 -1.4
80 -2.2 -1.2 -0.9 -0.8 -0.7
90 0.0 0.0 0.0 0.0 0.0
100 2.2 1.2 0.9 0.8 0.7
110 4.4 2.5 1.9 1.6 1.4
120 6.6 3.7 2.8 2.4 2.1
130 8.7 5.0 3.8 3.2 2.8
140 10.9 6.2 4.7 4.0 3.5
150 13.1 7.4 5.6 4.8 4.3
160 15.3 8.7 6.6 5.6 5.0
170 17.5 9.9 7.5 6.4 5.7
180 19.7 11.2 8.5 7.2 6.4
190 21.9 12.4 9.4 8.0 7.1
200 24.0 13.6 10.4 8.8 7.8