I installed a stainless steel catalyst in a Vermont Castings Defiant Encore last winter. We had it out the other day for cleaning, and were surprised to find that the stainless core had sagged in the center (the metal cats are wound from very thin SS) maybe 1/4" so it sagged in some places and bulged in others. The very lightweight SS wrapping around the outside had also distorted in use so the cat is no longer square. Actually, it looks sort of like a loaf of bread, puffing up in the middle, and with rounded corners.
It can still be gotten in and out of its slot without too much trouble, but I am concerned that if it distorts any more it may not.
I'm trying to figure out whether to return it under warranty, or to clean it and put it back in and see what happens. There are some things in situations like this that distort a bit on first use, then stop once they are comfortable, and others that keep getting worse and worse until they fall completely apart. I don't know what category this catalyst falls into. The manufacturer offered to replace it under warranty with a ceramic one, but didn't have any more advice - they said they'd only been selling them for 2 years, and hadn't had enough come back to have a feeling for how they behaved in the field. I sort of hate to give up on it, because I really did want to give it a good run and find out if the steel cats are any good.
The SS cat is much lighter and less rigid than the ceramic ones - you could twist or flatten it easily with your hands. A bit disconcerting if you are used to the ceramic one. But is this necessarily bad? When I open up a really trashed Defiant Encore, one where the refractory box has started to disintegrate, I usually find the SS frame from the stock ceramic cat completley pretzeled by the heat, lying twisted and almost unrecognizable in the wreckage. My suspicion is that the standard cats may be what actually destroys the refractory box once they start distorting, since this could put a lot of stress on the surrounding refractory. The SS cats might actually be superior in this regard, as they are much flimsier, and not as likely to put stress on the refractory as a result.
I would be interested in hearing what kind of experiences others are having with these cats, and whether the sort of sagging this one is experiencing is normal.
It can still be gotten in and out of its slot without too much trouble, but I am concerned that if it distorts any more it may not.
I'm trying to figure out whether to return it under warranty, or to clean it and put it back in and see what happens. There are some things in situations like this that distort a bit on first use, then stop once they are comfortable, and others that keep getting worse and worse until they fall completely apart. I don't know what category this catalyst falls into. The manufacturer offered to replace it under warranty with a ceramic one, but didn't have any more advice - they said they'd only been selling them for 2 years, and hadn't had enough come back to have a feeling for how they behaved in the field. I sort of hate to give up on it, because I really did want to give it a good run and find out if the steel cats are any good.
The SS cat is much lighter and less rigid than the ceramic ones - you could twist or flatten it easily with your hands. A bit disconcerting if you are used to the ceramic one. But is this necessarily bad? When I open up a really trashed Defiant Encore, one where the refractory box has started to disintegrate, I usually find the SS frame from the stock ceramic cat completley pretzeled by the heat, lying twisted and almost unrecognizable in the wreckage. My suspicion is that the standard cats may be what actually destroys the refractory box once they start distorting, since this could put a lot of stress on the surrounding refractory. The SS cats might actually be superior in this regard, as they are much flimsier, and not as likely to put stress on the refractory as a result.
I would be interested in hearing what kind of experiences others are having with these cats, and whether the sort of sagging this one is experiencing is normal.