Buck 91 cat was on fire. What happened?

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New Member
Jan 23, 2017

I was burning my Buck 91 stove today and had just reloaded over coals putting in some splits. A while later, I saw no fire in the box, but a glow coming from the cat I've never seen before then. I observed more carefully, and noted a fire up above the firebox. I opened the bypass, and a large fire started briefly in the firebox, but the fire in the cat stopped. I closed the byoass and all went back to normal.

Never did the cat temp prob go near 1500 staying between 1000 and 1500.

What happened and how can it be prevented? Is it damaging if that happens since the cat didn't seem to get too hot? I could have easily been away from home and not seen it do that.

Thank you for any help.

Kind regards,
It sounds perfectly normal to me.
That is interesting. I've been happily using it for 2 months and have never seen a fire above the metal structure above the firebox. I thought fire directly in contact with the cat could damage it from other threads I've read.
Secondary flames are normal and inevitable. It happens.
I've had the weird cat on fire thing too. Not often but it happens. You just have enough fuel, heat, and air right there in front of the cat to support visible fire.
What happened and how can it be prevented? Is it damaging if that happens since the cat didn't seem to get too hot?
Nothing to worry about. In a fuel-rich environment (lots of smoke in the box,) the smoke will sometimes be ignited in front of a hot cat. I've seen it happen in all of the cat stoves I have run. Woodstock has stated that this doesn't constitute "flame impingement" and that it will not hurt the cat. I think that for true flame impingement to occur, you would need a roaring fire with flames slamming the front face of the cat, and that would be pretty hard to do on the 91, from what I've seen.
I've been happily using it for 2 months
Sounds like you are liking it so far. How much area are you heating? Is your wood pretty dry? How long split and stacked, and what kind are you burning?
I had a problem with the cat getting too hot (1800 range) on the used stove I bought, due to a frayed ash pan gasket that let air in through the ash dump, which I could see because the coals would glow more brightly over the dump lid. My stove also had a little too much air getting past the plates on the right-side slider, which I made an adjustment for. But the best tweak was one posted within the last year or so...I'd have to look back to find out who that was that came up with he. He simply took the plates off the right slider, slid the rod out, and put a very slight upward bow into the rod. That causes the plates to close the gaps a little more when the slider is in the fully-closed position. You don't want to over-do it or you will have friction when sliding the rod.