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conpewter 02-10-2009 03:16 AM

Rusting water heater element
Has anyone else had issues with the base of the water heater element rusting? If so what can I do to prevent this?

conpewter 02-10-2009 04:07 AM

I think I'm going to use silicone sealant. Since the element is under water it shouldn't ever get much above 212* Also this is the base of the element, not the actual element itself.

7327A21 Underwater Silicone Sealant 2.8 oz Tube, Clear $5.72 Each

... Sealant is FDA CFR21 177.2600 compliant when it reaches full strength and is washed. Meets ASTM C920, Class 25. This product is VOC compliant in all 50 states as of October 1, 2008.

From FDA
FDA CFR21 177.2600
Rubber articles intended for repeated use may be safely used in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food, subject to the provisions of this section.

So it is food-grade underwater sealent (used for aquariaums) and good up to 400*F

Guess I'll take my element off the keg and sand off the rust, re-install and then silicone over the exposed part.

AiredAle 02-11-2009 01:55 AM

I have the same problem with my Corny keg eHLT element base. I'm going to get a magnesium anode from a marine store and bolt it into the keg. This should work like the anode in a domestic water heater or a boat, and protect the steel from corrosion. I would guess that the silicone will be water proof but won't stop the rust, since it's oxygen that is the issue not the water. Plus if it keeps rusting the silicone will delaminate.

Interested in how it works out, though, let us know. Oh, if you do try the anode idea, don't use a zinc one, be sure to get magnesium.

conpewter 02-11-2009 12:35 PM

Thanks for the tip. I didn't know if I wanted to use an anode since I know those work by corroding instead of the other metals, so it may release magnesium into the water (not sure about this).

The idea with the high-temp waterproof silicone is to get rid of all the rust that is on there, then put the silicone over it to keep out the water and oxygen. This stuff is the same as stuff used for fish tanks to seal them together.

I'll keep this thread updated with what I find. I'd like to hear back on how the anode works as well :) Thanks!

conpewter 03-09-2009 03:05 PM

OK so the silicone sealant works somewhat. I was hoping to have a solution where I could leave water in the HLT for a day if I wanted (Wanted to try some Sous Vide cooking as well.)

So the silicone sealant worked but after a while the water either got under it, or I had not completely covered it and there was some rust after 24 hours of water exposure. I'm looking into food-safe / temp safe paints now.

I'm worried that the magnesium anode will put way too much magnesium into the water and change the water profile I'm trying to build. Other thoughts? (suggestions on paint/coatings?)

conpewter 03-09-2009 03:52 PM

Thinking about

POR-15 Inc. - Support - Por15 FAQ - Usage Tips

I emailed them to ask if it is food-safe (This would be similar to how JB-Weld is "Food safe")


Hello Dave. POR-15 is not approved by the FDA so I really can not recommend this application. Let me tell you though, POR-15 is completely inert when fully cured. It gives off no chemicals or vapors.

XXguy 03-09-2009 04:12 PM

Wow - when you say it started to rust within 24 hours... I'm thinking the previous rust was still there. Did you consider doing something like naval jelly or a rust preventative phosphate wash? Something that would nuetralize the existing oxidation & help to prevent future rust?

I'd think if you seal it well with the underwater silicon, there's little chance for new water intrustion.....though a few heating/cooling cycles might break any seal, and allow water to creep in.

I seem to recall reading online in a link in VT Brewer's thread about a guy who made his own heat sticks & he had tried to use aquarium silicone, but it couldn't stand up to the heat. I believe he was trying to "pot" the electrical connections though, and the heat was too much.

Found the link: Look at his notes on Image 16 & the story below all that.
How to Build an Electric Homebrewing Heatstick Audio Tutorial Podcast and Step by Step Photo Instructions

conpewter 03-09-2009 04:23 PM


The silicone I had was good to 500 degrees and it didn't seem to have any issues. The problem is that I need to thread the element into the nut still so I couldn't coat the whole thing with sealant until it was installed, at that point there is still bare metal exposed in the threads, I think this allowed water to get behind the silicone sealant and work it's way between the sealant and metal. (This was after 24 hours with water in the keg). It did actually work fairly well on the metal I was able to coat with it.

This was all inside the HLT so it never saw temps above 210 degrees as far as I can tell.

Also I did not use any phosphate wash to neutralize what was there (I don't have any of that) I just used a grinder wheel on my dremel and sandpaper for between the element posts. I got a lot of it but I bet there could have been a few specs left in the crevices.

conpewter 03-09-2009 04:26 PM

Looked at the web-site posted. I agree that JB weld would work, I was just looking for something that would allow me to remove the element later if I need to replace it.

ACorral 03-19-2010 11:52 PM

Conpewter, did you ever find a solution to the rusting problem. I'm having the same issue with my electric element. I can remove the rust, but it returns after each session.

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