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Water heater element?

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Posted by stu on July 19, 2008, 4:42 am
 
I want to use the element in a hot water heater as a dump load. If the
element is 240VAC 2400W and I am dumping 30V 3 phase DC,  am I limited to
the current of the element at 240V? 2400/240A?
Thanks

*by 3 phase DC I of course me rectified 3 phase



Posted by M Q on July 19, 2008, 5:03 am
 
stu wrote:


240 V / 10 A = 24 ohms.
At 30 V and 24 ohms you get 30/24 = 1.25 Amps

30 V * 1.25 A = 37.5 watts

Probably not what you had in mind.


Posted by Charles Foot on July 19, 2008, 11:42 am
 M Q wrote:

On the right track though... you just need more of them, i.e. 2 in
parallel = 75 watts, 4 in parallel = 150 watts, etc...

Posted by Jim Wilkins on July 19, 2008, 4:43 pm
 
How much power do you have to put into the water? A string of power
resistors around the tank under the insulation might do it.

Posted by stu on July 20, 2008, 1:23 am
 

No it isn't. But thanks. (still shaking my head as to why I didn't use ohms
law myself... must be getting old)


If the elements on the new water heaters are like the one on my old water
heater, it would be pretty easy to tap into it in 6+ places. I'll look into
it.


How much power do you have to put into the water? A string of power
resistors around the tank under the insulation might do it.

Well I have tested it to 200W, around 500W should be possible.

Thanks again guys, I'll look into modifying the element.



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