Catalytic stove operation questions

[Jasper]

Have had some cooler weather here and have gotten to light up my buck 91 insert and play with it some and I have a few questions for some of the more experienced burners.

I start a fire and get the cat up to temp and close the bypass and it climbs up to around 1400 -1500 degrees as I slowly close it down. Once I get it closed down pretty good I get these crazy flames just off the wood that go all the way to the top of the stove and across the glass. They are not roaring just look ghostly and float around. The cat stays up to temp but the flames I'm talking about seem to get near the catalyst area and I'm worried it may be flame impigminataion that damages catalyst. It looks pretty awesome but I don't want to damage anything. Is that how these stoves are supposed to look when you close them down?

My other question is how low can I close the fire down to. Should there be some flame or is it ok as long as the cat is working and the wood appears red and smoldering? Thanks for any help anyone can offer.

 

[fire_man]

That's exactly what the my old Fireview cat stove looked like when I snuffed down the air control: Lazy ghostly and floaty. They were definitely not a cause for concern. Flame impingement happens when you open the draft up and are sucking flame which is burning off the wood into the catalyst. It's more of a "high speed" flame that shoots into and contacts the cat for a long time. The floaty flames you are talking about are nothing to worry about.

Each stove is different regarding how low you can close it. The Fireview was not supposed to be snuffed so the draft was shut all the way. But absolutely it was ok to close it down enough to get the red and smoldering burn with no flames. You just had to make sure you were at least slightly open on the draft lever. Modern cat stoves are mostly designed to protect the cat from flame impingement - the cat is further back and protected by a screen on the FV.

 

[HotCoals]

Yep ghost flames are cool and I can get them at times also. You're doing nothing wrong..burn on my friend!
To try and answer your second question,
I hardly ever have flame in my stove unless it's really cold out...just a orange glowing blob most of the time unless I want or need flame.

 

[Jasper]

Thanks for the help guys.

 

[Charles1981]

My stove does the same when it is shut down to an appropriate level.

If you shut it down too much too fast you get those ghost flames for a bit then they go out for 10-15-30 seconds ...then re-appear in huge whooshing fashion almost like an explosion and then go out once more. That would be back-puffing...if it back puffs hard enough...you get smoke pushed out the stove into the room.

But as long as you can maintain them and not get the back puffing you are good especially if you are closely monitoring the cat probe.

 

[Charles1981]

That is a video I made of my stove cut back all the way. You have the dancing ghost flames. And I was able to catch 2-3 times the flame go out, then woosh back in. This is actually pretty close to perfect operation for my stove as the wooshing actually doesn't cause back-puffing of smoke into the room at this rate...but if the flames went out longer than they do (only out about 7-10 seconds in the video) then the force of the explosion would probably shoot smoke back into the room.

If I turn it down to fast and the flames go out for like 20-30 seconds...smoke builds up than ignites with so much force it belches the top loading plate out with the explosion and instant smoke...blech. Thankfully it has rarely done this and tends to happen on either warm wet days, or a few times when it was super cold with wind gusts of like 50+ mph.

 

[Jasper]

I had a back puff Sunday night, which I believe is because I was trying to close it down too fast. It flashed and a puff of smoke came out. I was standing right in front of the stove when it happened and scared the crap out of me till I realized what happened.

 

[Woody Stover]

I get the floater flame burns quite a bit in the 91, no problem. I will sometimes burn a more vigorous flame right after I've closed the bypass, to make sure the cat takes off strong. But it's possible to look above the lower heat shield through the holes in the front airwash channel and see how far flames are being sucked around the shield. I would think you would have to have the air open pretty far for the flame to get near the face of the cat. The thing to keep an eye on with this stove is that the cat temp doesn't get up around 1800, which it can do if you have a bunch of small stuff burning in there, off-gassing all at once. They say that extended operation over 1800 can shorten the life of the cat....the last thing you want since the cost of a new one pushes $300. I've read the manual several times; Lots of good info in there.
It's hard sometimes to get just the right angle, but you can see the cat glowing through the hole where the bypass rod enters the stove. Once the cat is blazing, you can see orange reflected off the top of the heat shield.
I generally run the air pretty low once the stove is in cruise mode, with the left shotgun air slider closed and the right airwash slider out maybe 1/4".

 

[MJFlores]

Those ghost flames you're seeing are a sign that you're doing everything right. The cat is lit, the stove is at the proper temp, not much water vapor coming off the wood. usually when you're in this condition if you go out and look at your chimney you'll see nothing but heat shimmy and no smoke. You'll keep your chimney clean burning like that, and are efficiently burning your wood. My Fireview does that all the time..starts with roaring flame until I engage the cat, and then they slow down and the ghost flames come on. I also have lots of secondaries (when a small flame slinks up to the cat and then a rolling flame washes down and then disappears...those are the mini explosions someone else mentioned. Keep doing what you're doing...the cat is actually operating at hotter temps than the flame in the stove so no worry about damaging it unless prolonged flame is washing over the unlit cat which can shorten it's life. Cats are replaceable and consumable so not much to worry about there.

 

[Jasper]

I get the floater flame burns quite a bit in the 91, no problem. I will sometimes burn a more vigorous flame right after I've closed the bypass, to make sure the cat takes off strong. But it's possible to look above the lower heat shield through the holes in the front airwash channel and see how far flames are being sucked around the shield. I would think you would have to have the air open pretty far for the flame to get near the face of the cat. The thing to keep an eye on with this stove is that the cat temp doesn't get up around 1800, which it can do if you have a bunch of small stuff burning in there, off-gassing all at once. They say that extended operation over 1800 can shorten the life of the cat....the last thing you want since the cost of a new one pushes $300. I've read the manual several times; Lots of good info in there.
It's hard sometimes to get just the right angle, but you can see the cat glowing through the hole where the bypass rod enters the stove. Once the cat is blazing, you can see orange reflected off the top of the heat shield.
I generally run the air pretty low once the stove is in cruise mode, with the left shotgun air slider closed and the right airwash slider out maybe 1/4".

What is the highest temp to safely get the stove up to. I have been taking readings with IR gun in the top next to the cat prob, as it was the hottest spot I found. It got up to 460 Sunday night. I could not locate anything in the manual about over fire temps.