Electronic Hot Water heater eddy currents

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!

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!!