Heat Loss Calculations and System Design
Contact Urecon for more info and help with custom design/calculations.
It is recommended that a safety factor of 10 to 25% be added to allow for such field conditions as voltage drop, under voltage condition, etc.
Heat Flow Chart Watts/ft/hr/100°F T(2)
Dia.(1) | Urethane Insulation Thickness | ||||
25 mm (1 in) | 40 m (1½ in) | 50 mm (2 in) | 63 mm (2½ in) | 75 mm (3 in) | |
1 | 1.8 | 1.4 | 1.2 | 1.1 | 1.0 |
2 | 2.9 | 2.2 | 1.8 | 1.6 | 1.4 |
4 | 4.9 | 3.6 | 2.9 | 2.5 | 2.2 |
6 | 6.9 | 4.9 | 3.9 | 3.3 | 2.9 |
8 | 8.9 | 6.3 | 4.9 | 4.1 | 3.6 |
10 | n/a | 7.6 | 5.9 | 4.9 | 4.2 |
12 | n/a | 9.0 | 6.9 | 5.8 | 4.9 |
14 | n/a | 10.4 | 7.9 | 6.5 | 5.6 |
16 | n/a | n/a | 8.9 | 7.4 | 6.2 |
18 | n/a | n/a | 9.9 | 8.3 | 6.9 |
20 | n/a | n/a | 10.8 | 9.0 | 7.6 |
22 | n/a | n/a | 11.8 | 9.9 | 8.3 |
24 | n/a | n/a | 12.7 | 10.8 | 9.0 |
Heat flow in watts per lineal foot
The table is based upon the application
of the following formula: Where: |
|
Formula
The heat loss for an externally traced pipe may be calculated by the following formula:
Where:
W = Watts per foot of pipe
Tm = maintained temperature°F
Ta = ambient temperature°F
Ln = natural log
Di = outside diameter of insulation (in)
Dp = outside diameter of pipe (in)
Ki = K value of insulation (BTU • in / hr • ft² •°F)
Dj = outside diameter of jacket (in)
Kj = K value of jacket
(BTU • in / hr • ft² •°F)
Sf = Safety Factor
For more information on time to freeze and raw data requirements: