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Does anyone have experience with inline water heaters?

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Mar 27, 2018
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I was thinking about upgrading our water heater to a solar-charged DC induction heating system, so I started in on the math. The numbers I get sugest on-demand water heaters are a joke, so I gotta know if someone out there has had success with them.

The water comes out of the ground at just under 9°C (48°F) and to get it to get it to 42°C (108°F), it needs to go up by 33.3°C. Our shower head has a flow rate of 5.3L/min (1.4gpm). 5300g h20 * 4.1813J/g * 33.3°C = 738000J/min or 12.3kW! So, if I want to take cold water and make it shower hot at a rate of 1.4gpm, I need to burn over 100A at 120v or 1000A using a 12v system (assuuming perfect efficiency). I don't understand how there is even a product that claims to be for home use on typical home wiring. You would burn the house down before you could make a cup of tea. The keurig in the kitchen puls 1800w and takes a whole minute to burp out a cup of hot water. So, who here has a practical inline heater that actually works, and how big is your transformer outside?

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