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Heating element rust
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bbognerks




Joined: 10 Jan 2011
Posts: 51
Location: Wichita, KS


PostLink    Posted: Mon Feb 07, 2011 6:14 pm    Post subject: Reply with quote


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Well that was a massive failure. I can tell that the anode is attracting something as any foam in the pots migrate right above them if let sit for a while. The problem is that they aren't preventing rust. So, plan B it is. I pulled the element out yet again and applied the POR 15. I had to let it sit and dry/cure. I will fill the keg again tonight and let it sit for a day again. I'll report back with the findings. If this doesn't work, I guess it's silicone every few months as needed... *sigh*
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crush




Joined: 28 Dec 2010
Posts: 709
Location: Telemark, Norway


PostLink    Posted: Mon Feb 07, 2011 6:59 pm    Post subject: Reply with quote

Oh, futtocks. It's a pity it didn't work. Do you have any ideas why??

I share your frustration that this doesn't want to work since it would be nice to have a solution that allows us to be forgetful or have the convenience of leaving water in the kettles. But could plan B be a simple as not leaving water in the kettles?

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kal
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Joined: 12 Dec 2010
Posts: 10895
Location: Ottawa, Canada

Drinking: Pub Ale, Electric Creamsicle, London Pride, Wit, Janet's Brown, Russian Imperial Stout, Black Butte Porter

Working on: Belgian Quad, Belgian IPA


PostLink    Posted: Mon Feb 07, 2011 7:03 pm    Post subject: Reply with quote

Your anode wasn't in contact with the heating element was it? I thought it had to be in contact for it to work best.

I simply don't leave water in the kettle overnight, but will be trying with the aluminum locknuts I'm going to be sent anyway. They're in direct contact with the heating element.

Kal

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crush




Joined: 28 Dec 2010
Posts: 709
Location: Telemark, Norway


PostLink    Posted: Mon Feb 07, 2011 7:22 pm    Post subject: Reply with quote

kal wrote:
Your anode wasn't in contact with the heating element was it? I thought it had to be in contact for it to work best.


I'm not a metallurgist, but from reading bits here and there, it seems it should be sufficient with an ion path and an electron path. The ions flow through the water, and electrons flow through the case of the kettle. So, as long as water is touching both the locknut and the element, and they are electrically connected, then this should work.

After all, most sacrificial anodes in water heaters are screwed to the tank, separate from the element.

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kal
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Drinking: Pub Ale, Electric Creamsicle, London Pride, Wit, Janet's Brown, Russian Imperial Stout, Black Butte Porter

Working on: Belgian Quad, Belgian IPA


PostLink    Posted: Mon Feb 07, 2011 7:48 pm    Post subject: Reply with quote

I'm not sure but I thought that most water heater sacrificial anodes were magnesium which is a much better material to use and works well when not in contact with the heating element. I admit I haven't followed this closely but I could have sworn I read that ALU is much worse and while it will work a bit when not in contact possibly, to have it work best it has to be in contact. I may be wrong though!

Kal

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happysacbrewing




Joined: 20 Jan 2011
Posts: 34
Location: Edgewater, MD


PostLink    Posted: Mon Feb 07, 2011 11:01 pm    Post subject: Reply with quote

This might be completely unrelated, but I don't think so. On boats, we use zinc as a sacrificial anode to prevent galvanic corrosion, which I think is the same phenomenon that we are worried about here. With a zinc, it definitely needs to be connected directly to the thing you are trying to protect. Don Casey, who is the guru for dealing with electricity and boats explains it this way:

"Electrical contact is essential There is an unfortunate misconception that a sacrificial anode can be mounted anywhere, even hung over the side on a string, and it will still perform its appointed duty. That is dead wrong!

For a zinc anode to provide any protection, it must be in electrical contact with the metal being protected. The conductivity of the water is not adequate. We need low-resistance, metal-to-metal contact-either by mounting the zinc directly to the metal being protected or by con- necting the two with a wire. A hanging anode can provide protection if it is connected by a wire to the metal being protected.

Where the zinc is mounted directly to the protected metal-bolted to the side of a metal rudder, for example-it is essential to make sure the surface under the zinc is bare and bright before the anode is installed. This is to ensure good electrical contact."

The rest of the article is here: http://www.boatus.com/boattech/casey/23.htm
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bbognerks




Joined: 10 Jan 2011
Posts: 51
Location: Wichita, KS


PostLink    Posted: Tue Feb 08, 2011 2:21 pm    Post subject: Reply with quote

Hmm, I had thought that the contact through the keggle wall would have been enough. I mean it seems it would be the same as a wire. Of course, it's going through like 4 different contact points to the base. As you can see in the picture of the anode, it has an inner ring of unknown metal. Then this is bolted to the keggle. The keggle wall connects to the Silver Solder which is bound to the SS locknut. Then the threads are what make the final contact to the element. After reading happysacbrewing's post, I guess there probably is too much in the way for a clean path. I don't really know how I could connect it via wire though... I can easily screw into the anode, but how in the world would I get electrical contact to the base? Maybe I can silver solder the wire to the base or something...
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crush




Joined: 28 Dec 2010
Posts: 709
Location: Telemark, Norway


PostLink    Posted: Tue Feb 08, 2011 3:52 pm    Post subject: Reply with quote

if you have a voltmeter, you can use it to measure the resistance between the locknut and the element face through the keggle wall. It should be close to zero. For comparison, you could also measure the resistance of the same length of copper wire to see if there is any significant difference. (Or calculate it - 24 AWG wire has a resistance of ca. 0.03 ohms per foot.)

If the resistance between the locknut and the element face comes out as "-1" or infinite or similar (different voltmeters vary how they represent an open circuit), then there is no electrical connection. You will either need to rework the setup so the locknut and element are electrically connected, e.g. maybe using less teflon tape, or use a wire to create a connection. (Sorry if this is pointing out the obvious, can't seem to be able to express myself today...)

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Feurhund




Joined: 01 Feb 2011
Posts: 89



PostLink    Posted: Tue Feb 08, 2011 7:25 pm    Post subject: Reply with quote

Does anyone know if the aluminum locknut is a workable solution. Also, as someone commented, will it be difficult to remove later? Just installing elements now and dont want to do it twice. Thanks
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happysacbrewing




Joined: 20 Jan 2011
Posts: 34
Location: Edgewater, MD


PostLink    Posted: Sat Feb 12, 2011 9:28 pm    Post subject: Reply with quote

I don't know if the aluminum locknut will work or not, but again from experience with boats, I have my doubts. Aluminum doesn't work well when used in a fresh water system because fresh water is more resistive than salt water and aluminum does not usually have enough negative electropotential to overcome it. In a marine environment, aluminum can be used as a sacrificial anode in brackish water but that is because there is some salinity making the water less resistive than fresh water. Zinc is also used in salt water, but doesn't work well if heated, so is basically out for use here. For fresh water like what we have in the HLT and BK, you should probably use magnesium and not zinc or aluminum. Magnesium has the most negative electropotential and can overcome the higher resistivity of fresh water.

This is a pretty good Wikipedia description of the uses for various sacrificial anodes:
http://en.wikipedia.org/wiki/Galvanic_anode

The other problem I see with using an aluminum nut as your sacrificial anode is that you might never be able to get it off. If you used teflon tape or tefgel between the bolt and nut that would take away the metal to metal contact you need to have it work well as an anode. If you didn't, you would have dissimilar metals attached to each other in a wet environment. On boats, that usually means that after any period of time at all, they will bond to each other so tightly that no amount of force will get them apart. I suppose you could use an aluminum bolt as well, but remember that the point of sacrificial anodes is that they degrade over time, so here you would have the thing that is attaching the heating element to the kettle slowly degrading, probably not a great option.

The most elegant method here would be to attach a small magnesium sacrificial anode to the face plate part of the heating element that is rusting. You could probably tap a small hole in the plate, and screw it in through a center hole in the anode. The problem with this option is from what I have been able to find on the internet so far, nobody makes a magnesium anode that is small enough to work here. There are places that make custom anodes that I am sure could do it, but I don't know the cost for that kind of work. If there are enough people interested in this, we could go to them for a group buy and see what they could do.

The cheaper option that wouldn't look as nice, but should work just as well, is to solder a copper wire onto the heating element plate, run it up and over the top of the pot and wrap it around a small off-the-shelf magnesium anode sitting behind the kettle. There are plenty of small reasonably cheap magnesium anodes that would work for this, like the kind available here or other marine supply stores -http://www.boatzincs.com/mercruiser-magnesium.html.

Of course, the problem can also be eliminated by making sure there isn't any water up to the level of the heating element, without water there can't be galvanic corrosion.
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happysacbrewing




Joined: 20 Jan 2011
Posts: 34
Location: Edgewater, MD


PostLink    Posted: Sat Feb 12, 2011 9:31 pm    Post subject: Reply with quote

Actually, the more I think about it, option two in my previous post won't work because the anode would be out of the water. Sorry about that.
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bbognerks




Joined: 10 Jan 2011
Posts: 51
Location: Wichita, KS


PostLink    Posted: Wed Feb 16, 2011 2:10 pm    Post subject: Reply with quote

People have suggested using the magnesium fire starters as anodes. Maybe I'll replace the aluminum ones I got. I did go ahead and paint the bases with POR 15 and that seems to have taken care of the problem. But it never hurts to have more protection, and magnesium is good for beer anyways. Thanks for the analysis of why my aluminum anodes didn't seem to work. I appreciate it!
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Feurhund




Joined: 01 Feb 2011
Posts: 89



PostLink    Posted: Sat Feb 19, 2011 10:24 pm    Post subject: Reply with quote

Where do you put the magnesium?
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bbognerks




Joined: 10 Jan 2011
Posts: 51
Location: Wichita, KS


PostLink    Posted: Sat Mar 19, 2011 1:08 am    Post subject: Reply with quote

UPDATE!!!! I finally found a solution that works. I was still getting some rust even after using POR15. The threads just scratched it off and were rusting still. Just as I was about to buy some magnesium fire starters, a friend of mine found the holy grail.

See: http://www.theelectricbrewery.com/sacrificial-magnesium-anode

I did a test run on this and it was perfect. 18 hours of being submerged and no rust. I didn't even need a connecting wire. The kettle wall was good enough.
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Sparky




Joined: 17 Dec 2010
Posts: 221
Location: Muir Beach, California


PostLink    Posted: Thu Mar 24, 2011 9:34 pm    Post subject: Reply with quote

So, you mount by drilling another hole in the tank?
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crush




Joined: 28 Dec 2010
Posts: 709
Location: Telemark, Norway


PostLink    Posted: Fri Mar 25, 2011 12:17 am    Post subject: Reply with quote

I'm using blichmanns, and Kals weldless design. I'm not sure I need to sacrifice an anode - won't be leaving water in the kettles, but for someone that does I wonder if they could be mounted above the element, so they can be housed by the same conduit box as the element?

With magnesium being active, maybe it's just enough to throw it in the bottom of the kettle - contact with the base of the kettle might be enough?

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milldoggy




Joined: 23 Dec 2010
Posts: 570
Location: Pottstown, PA


PostLink    Posted: Fri Mar 25, 2011 12:34 am    Post subject: Reply with quote

Please tell how you mounted, what size was the threads
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bbognerks




Joined: 10 Jan 2011
Posts: 51
Location: Wichita, KS


PostLink    Posted: Mon Mar 28, 2011 6:06 pm    Post subject: Reply with quote

It uses standard 1/2" NPT. So I just silver soldered in a half coupling and screwed it in to that.


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milldoggy




Joined: 23 Dec 2010
Posts: 570
Location: Pottstown, PA


PostLink    Posted: Mon Mar 28, 2011 7:10 pm    Post subject: Reply with quote

Do you think this would help prevent rust on my welds when the keggle is dry. I think not, but I wanted to ask. I have scrubbed them with BKF and they have not rerusted, so hopefully I passivated them. I have a 1/2 coupler in my BK that I have plugged, I could try one of these. Just seeing if anyone thinks it would make a difference with a dry pot.
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bbognerks




Joined: 10 Jan 2011
Posts: 51
Location: Wichita, KS


PostLink    Posted: Mon Mar 28, 2011 7:53 pm    Post subject: Reply with quote

You are probably forming the rust while there is water in the kettle. Then when it dries you can see it easier. If you have the means to try one of these, you might as well. If it doesn't work, then you have an extra coupling in there is all.
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