Can you cement a piece of refractory back on?

SonOfEru

Member
Jan 11, 2018
126
Sanbornton NH
I got a new catalytic element for my Encore 0028 and opened up to replace it, and discovered a piece of the refractory on the left end of the old one was broken off. The old one had warped and I figure it pushed the piece off. Rats!

Broken off end.jpg


I found the piece in the ashes below.

Broken piece.jpg


It would fit fairly well back into where it came from, or at least be a whole lot better than nothing, if I could attach it to the end of the catalytic.

So - is there a cement that I could use that would adhere and would stand the heat?

I see "Refractory Cement" online, but not sure it's what would work for this, where the catalytic surface will get red hot. Reading the online product links they sound more like cement you would but into a joint in a stove, or something like that. Not sure if they would actually bond something onto a stainless steel surface.

I do realize that the refractory is not originally bonded to the catalytic, you just slip the cat in there. But there is no hope of cementing the broken off piece onto the edge where it broke off from. The edges are dusty and there is precious little room to maneuver. If I cement it onto the cat, I can reach down from above and brace it from the back opening and do a fair job of getting it oriented right.

Of course, I also realize this would only work one time. Next time for replacement, the cemented piece would not come off nicely and be able to reuse with the next cat.

Is there any other solution? If I do nothing, there will be a small gap where flue gases coming up and over into the cat can get past it and straight out into the passage to the exit flue. I sure dont want to replace the whole refractory box for a small "leak". At least it looks like it would be a small leak.

So I would be ok with some other way to block the leak. I dont worry that much about the end of the cat not being insulated enough to fully function catalytically, I just need to make all the flue gases go through and not around it.
 
Last edited:

Chuck Pate

Member
Jan 8, 2014
2
Cincinnati, Ohio
As a potter and VC stove owner I can offer a solution. the refractory assembly is made from rigid kaolin fiber or kaowool. Koalin is a primary clay and is very refractory. I suggest getting yourself some Kaowool which the soft blanket version of the refractory assembly and filling the gaps around your catalyst, just be sure not to block the flow. Be sure to wear a mask when handling the kaowool as it contains silica and is not something you want breathe in. Good Luck
 

SonOfEru

Member
Jan 11, 2018
126
Sanbornton NH
As a potter and VC stove owner I can offer a solution. the refractory assembly is made from rigid kaolin fiber or kaowool. Koalin is a primary clay and is very refractory. I suggest getting yourself some Kaowool which the soft blanket version of the refractory assembly and filling the gaps around your catalyst, just be sure not to block the flow. Be sure to wear a mask when handling the kaowool as it contains silica and is not something you want breathe in. Good Luck
Very interesting idea! Can I ask, did you mean to tuck a small piece in there to fill the gap? I was able to use a high temp sealant from Rutland that held the piece sort of in place. Being dusty on the surface, it was hard to get any kind of adhesion, but after multiple applications of just a little more each time, and holding my breath being careful not to knock loose what I already had on, I was able to build up a junction between the broken piece and where it got knocked off from. After I held my breath one more time when inserting the catalytic, it still stayed there and has been there since. but still there is a small gap. no longer the gaping hole that I was afraid of but enough of a small passage that I can see the flue gases can get through and directly out past the cat. It definitely gets hotter there, because of that leak point. When the temp runs up over 1000* and the whole cat starts to glow, it glows brighter at that spot.

I looked online for Kaowool and it looks like it's sold in a rolled up blanket of it. Would I just snip off a small piece and gently snuggle it in there at the leak point? Of course I dont want to tuck it too hard, for fear of breaking the broken piece off again.
 

Chuck Pate

Member
Jan 8, 2014
2
Cincinnati, Ohio
Exactly, you can just tuck it in to “replace” the missing refractory. Also if I remember correctly when I rebuilt my VC encore the refractory assembly sat on two strips of kaowool. So if you look around I’m sure you could find a smaller quantity than a whole roll. Glad you got it to stay together with the cement. Hope this helps.