how many kilo watt needed for the heating elements for an electric water heater tank capacity 80 gallon?

Answer 1

Most are "dual power" now.

Typical mfgr (A.O. Smith) runs as follows:

ProMax+ : 4500W standard, 6000W max
Conservationist : 4500W standard, 5500W max

Sears brand:

PowerMiser : 3800W, 5500W

That should put you in the ball park.

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Answer 2

Standard 40 gallon tanks use 4000 or 4500 Watt elements (dual 2000 Watt). You wouldn't necessarily double it for a double-sized tank. I've seen 5000 and 5500 Watt elements (dual 2500 Watt, etc.), but that might be a bit underpowered.

Dual 3000 Watt elements would probably work, OK.

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Answer 3

The equation goes like : to heat water from 57 degree F to 110 degree F, it takes 0.2 kWh/ gallon. Hence its comes to 0/2*80 = 16KW.

Here is a very good article for energy effecient homes . May be you are intrested in peeking once into it.

http://www.energyefficienthomearticles.com/Article/energy-efficient-home-improvement--materials---Return-on-Investment--ROI--on-Tankless-Water-Heaters-/3151

Answer 4

80 US gallons of water = 302,833 grams
1000 watts heat input is 239 calories/second.

For every kilowatt of heat input you will raise the average temperature of 80 gallons of water 2.8 degrees C/hour. How much volume/hour do you need after initial startup?