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Air Bender
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Joined: 25/01/2011
Location: Australia
Posts: 206

Posted: 02:09am 28 May 2011

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I managed to score these stainless steel tanks out of the scrap skip at work. Which i plan to use as a preheating set up inline between the mains water and my existing hot water servive.

These elements from 12V car kettles i plan to fit as a dump load from my wind mill, which at the moment wont contribute a great deal to heating the water, but as the wind mill developes the out put should improve. I plan to add a home built thermo-siphon solar collector which will do the majority of the heating.

Dean.

VK4AYQ
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Joined: 02/12/2009
Location: Australia
Posts: 2539

Posted: 03:08am 28 May 2011

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Hi Dean

Nice find there mate, I tried out those little heating elements but found them to be a bit fragile as they tend to blow if the voltage climbs to much.
In the end I made a element out of a strip of stainless steel .5 mm thick by 1.5 meters long, it worked good on 12 volts as a dump load suspended in water. I got it from a sheet metal shop as a strip off cut, cost me a six pac.

I wound it on a piece of earthenware pipe as a former with holes drilled to terminate the ends.

All the best

Bob

PS:- the reason for my concern with the little elements as a dump load is if it is dumping and one goes out the other two will quickly follow and then you have a runaway mill.

Foolin Around

Air Bender
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Joined: 25/01/2011
Location: Australia
Posts: 206

Posted: 03:38am 28 May 2011

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Hi Bob

I have been wondering how durable these elements would be. i would like to get a nice big 12v element but they are not cheap. The only problem i have with making up the element is termiating through the tank and geting a good seal on them i would need to use a non conductive seal where the bolt goes through the tank. Maybe not that hard to do. The tank will be presurised to mains pressure.

All the best Dean.

VK4AYQ
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Joined: 02/12/2009
Location: Australia
Posts: 2539

Posted: 06:27am 28 May 2011

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Hi Dean

You can get away with an insulator at the positive end only, as the negative can bolt directly to the outer case / earth.

I have used two methods for insulators,
1- high temp hydraulic o rings red in color, 2 on the inside and two on the outside with one as a ring around the bolt where it goes through the outer case.
2- is to buy some teflon rod from bearing service and make a stepped insert for the inner and a washer for the outer, I have used this in boiling water with no problems.

All the best

Bob

Foolin Around

Air Bender
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Joined: 25/01/2011
Location: Australia
Posts: 206

Posted: 07:13am 28 May 2011

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Thanks Bob, insulating one terminal makes it easier. with your stainles steel strip rouhly how wide was it as we have plenty of stainless scrap at work so i should be able to get hold of something to do the job. I have enough bits at home to put together a second shunt regulator so i might add a secondry shunt as back up, which should help prevent overheating of wires and components and would be handy if the mill gets bigger down the track.

Thanks

Dean.

VK4AYQ
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Joined: 02/12/2009
Location: Australia
Posts: 2539

Posted: 11:19am 28 May 2011

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Hi Dean

It is an edge strip off a 2.4 meter sheet about 15 mm wide, in hind sight I should have left it full length but a bit was cut of before I made the shunt and I didn't have any argon for the tig to weld it back on. It absorbed over 100 amps on the 12 volt system around 1.5 kw from memory. I used a similar set up to heat oil for a solar steam project in the past and found that a flat strip heats the liquid better due to I think the larger surface area.

I got some strips of Chinese SS a while back but where no good as they developed hot spots due to allot changes in the sheet. 204 I think. The original is 316.

I used some of it as a series resistor for my old tig to get the amps down.

All the best

Bob

Foolin Around

Air Bender
Senior Member

Joined: 25/01/2011
Location: Australia
Posts: 206

Posted: 09:46am 03 Jul 2011

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Hi all

I was given a .5 mm stainless steel strip by a lagging contractor at work, very kind of him, he said he has plenty of it back at his workshop.

I think I have come up with a good idear for the former, but this progect will need to go on the back burner for a while as i have a few other things on the go. But getting the parts together is half the battle.

All the best Dean.

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