Quick Estimates of Wattage Requirements. George Ulanet Company

Electric Heaters
Quick Estimates of Wattage Requirements

For Heating Flowing Water:
kW = GPM x Temperature Rise (°F) x 0.16
OR
kW = Liters/min. x Temperature Rise (°C) x 0.076

For Heating Water in Tanks: Use equation or table.
kW = Gallons x Temperature Rise (°F)
375 x Heat-up Time (hrs.)
OR
kW = Liters x Temperature Rise (°C)
790 x Heat-up Time (hrs.)

1 Cu. Ft. = 7.49 Gallons

Kilowatt-Hours to Heat Water*

Amount of Liquid Temperature Rise °F

ft³ Gallons 20° 40° 60° 80° 100° 120° 140°

Kilowats to Heat in One Hour

0.66
1.3
2.0
2.7
3.3 5
10
13
20
25 0.3
0.5
0.8
1.1
1.3 0.5
1.1
1.6
2.2
2.7 0.8
1.6
2.4
3.2
4.0 1.1
2.1
3.2
4.3
5.3 1.3
2.7
4.0
5.3
6.7 1.6
3.2
4.8
6.4
8.0 1.9
3.7
5.6
7.5
9.3

4.0
5.3
6.7
8.0
9.4 30
40
50
60
70 1.6
2.1
2.7
3.3
3.7 3.2
4.0
5.4
6.4
7.5 4.8
6.4
8.0
9.6
11.2 6.4
8.5
10.7
12.8
15.0 8.0
11.0
13.0
16.0
19.0 9.6
13.0
16.0
19.0
22.0 12.0
15.0
19.0
22.0
26.0

10.7
12.0
13.4
16.7
20.0 80
90
100
125
150 4.3
5.0
5.5
7.0
8.0 8.5
10.0
11.0
13.0
16.0 13.0
14.5
16.0
20.0
24.0 17.0
19.0
21.0
27.0
32.0 21.0
24.0
27.0
33.0
40.0 26.0
29.0
32.0
40.0
48.0 30.0
34.0
37.0
47.0
56.0

23.4
26.7
33.7
40.0
53.4
66.8 175
200
250
300
400
500 9.0
11.0
13.0
16.0
21.0
27.0 18.0
21.0
27.0
32.0
43.0
53.0 28.0
32.0
40.0
47.0
64.0
80.0 37.0
43.0
53.0
64.0
85.0
107.0 47.0
53.0
67.0
80.0
107.0
133.0 56.0
64.0
80.0
96.0
128.0
160.0 65.0
75.0
93.0
112.0
149.0
187.0

*Read across in table from nearest amount in gallons of liquid to desired temperature rise column and note kilowatts to heat in one hour.

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Accurate Imaging, Inc. 1999