User Guide

162 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 50°F/10°C ambient
Water
temp
(ºF)
Surface temperature (°F)
No insulation
½" insulation
1" insulation
1½" insulation
2" insulation
30 30.9 45.0 47.5 48.4 48.9
40 40.5 47.5 48.7 49.2 49.4
50 50.0 50.0 50.0 50.0 50.0
60 59.5 52.5 51.3 50.8 50.6
70 69.1 55.0 52.5 51.6 51.1
80 78.6 57.6 53.8 52.4 51.7
90 88.2 60.1 55.0 53.1 52.2
100 97.7 62.6 56.3 53.9 52.8
110 107.3 65.1 57.5 54.7 53.3
120 116.8 67.7 58.8 55.5 53.9
130 126.3 70.2 60.0 56.3 54.4
140 135.9 72.7 61.3 57.1 55.0
150 145.4 75.2 62.5 57.8 55.6
160 155.0 77.8 63.8 58.6 56.1
170 164.5 80.3 65.0 59.4 56.7
180 174.1 82.8 66.3 60.2 57.2
190 183.6 85.3 67.5 61.0 57.8
200 193.1 87.9 68.8 61.8 58.3
¾" 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 -4.4 -2.5 -1.9 -1.6 -1.4
40 -2.2 -1.2 -0.9 -0.8 -0.7
50 0.0 0.0 0.0 0.0 0.0
60 2.2 1.2 0.9 0.8 0.7
70 4.4 2.5 1.9 1.6 1.4
80 6.6 3.7 2.8 2.4 2.1
90 8.7 5.0 3.8 3.2 2.8
100 10.9 6.2 4.7 4.0 3.5
110 13.1 7.4 5.6 4.8 4.3
120 15.3 8.7 6.6 5.6 5.0
130 17.5 9.9 7.5 6.4 5.7
140 19.7 11.2 8.5 7.2 6.4
150 21.9 12.4 9.4 8.0 7.1
160 24.0 13.6 10.4 8.8 7.8
170 26.2 14.9 11.3 9.6 8.5
180 28.4 16.1 12.2 10.3 9.2
190 30.6 17.4 13.2 11.1 9.9
200 32.8 18.6 14.1 11.9 10.6