Electronic Hot Water heater eddy currents

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So, with my IoT plant growing thing, I was thinking about an energy efficient pre-heating of the irrigation water. Vegetables love warm-ish water (15-20C).

An obvious idea is to use eddy current. So, the metal sleeve arrangement would be something like 304 stainless (internal resistance) coupled with, say, a 50kHz oscillator/driver.

You need about 4.2 joules to heat 1g of water 1C. If I’m supplying 10l/min of water coming in to the IoT thingy at 10C, that means I need to get 10000g x 10C x 4.2J over a minute to get it up to 20C.

That’s 420kJ over a period of a minute. Doable, I reckon, but I need to go back to my fluid mechanics textbook to read up as there’s a lot of potential losses in there mechanically.

It also seems an obvious idea for replacing gas HWS with efficient electrickery. What do you guys think?

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Hi Gerard,

Could you elaborate a little more on why you chose eddy currents? (maybe a corrosion thing)?

My understanding is that compressors always win for efficiency compared to pure resistive heating.

Keen to hear more about your project!

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Hi James,

The germ of the idea came from talking to my better half about replacing the gas cooktop with an induction top. It kind of went from there.

I know, for example, that you can get a HWS based on microwave principles using, I’m sure, a magnetron as the driving source.

I like the idea of using induction principles. Lightweight, probably compact and not outrageously expensive.

I did OK with AC theory at Uni…enough to get me into trouble but probably not enough to get me out of trouble!! :grin:

Hence my posing it up here where experts reside!!

Gerard