Backpuffing/flames on top of heat shield

[crater22]

Had backpuffing happen again this A.M the flames on top of the heat shield. Opened the by pass for a short period to get the flames out. Did this do any damage to the cat? The manual says not to allow any flames to come in contact with the cat.

Also, was opening the by pass the correct way to get rid of the flames? Other ideas?

Many thanks in advance

 

[begreen]

Hopefully you caught this quickly and no damage done. What stove is this? Can you add it to your signature?

 

[crater22]

Thanks. It is a Buck 91. I thought it was showing in my sig line. If not I will update my info.

 

[begreen]

Good deal, it's there now. Calling @Woody Stover to the front desk with a Buck cat question.

 

[crater22]

Kinda thought he would be involved. He has helped me so much in the past. Don't let this guy leave the forum.

 

[Jags]

Flame above the cat is going to be a relatively "cool" flame. It would probably take some time to cause an issue. The bigger question is WHY and why the back puff. Flashbacks are usually caused by not enough oxygen being supplied to the fire causing a backdraft to come down the stack. Just guessing but I suspect weak draft is causing a. "Pool" of gases to form above the cat causing the flame where it shouldn't be. Maybe trying running the draft a small percentage above where you had it set.

 

[Woody Stover]

Had backpuffing happen again this A.M the flames on top of the heat shield. Opened the by pass for a short period to get the flames out. Did this do any damage to the cat? The manual says not to allow any flames to come in contact with the cat.
Also, was opening the by pass the correct way to get rid of the flames?

When they mention "flame impingement" on the cat, they are talking about a roaring fire forcing big flames into the face of the cat. The flame above the shield is just the heat of the cat igniting smoke that gets near it, and isn't anything to worry about, like Jags said.
When it's cold outside, draft will be stronger, and you might have had more smoke in the box when using your normal air setting. Remind me of your chimney setup. Fireplace, or straight up through the roof? How tall from the top of the stove to the top of the cap?
What was your cat temp when this was happening? When you say "backpuff," was it a sudden, almost explosive ignition, or just a "flash-over" where a dark box fills with flame for a second, then goes out?

 

[crater22]

When they mention "flame impingement" on the cat, they are talking about a roaring fire forcing big flames into the face of the cat. The flame above the shield is just the heat of the cat igniting smoke that gets near it, and isn't anything to worry about, like Jags said.
When it's cold outside, draft will be stronger, and you might have had more smoke in the box when using your normal air setting. Remind me of your chimney setup. Fireplace, or straight up through the roof? How tall from the top of the stove to the top of the cap?
What was your cat temp when this was happening? When you say "backpuff," was it a sudden, almost explosive ignition, or just a "flash-over" where a dark box fills with flame for a second, then goes out?

Woody, sorry for late reply. I have a inside setup with the flue straight up about 16'. It was more of a flash back. Cat temp was about 1200. It was about 6 degress and only a breeze not really windy. It happened during a cold start up. When my flame goes out and the wood starts to coal, that is when the cat temp starts to climb and that is what happened. Should I always try to keep a flame going? Also, should the air controls be set ahead of closing the bypass. I might be doing it wrong by waiting until the cat gets at 600 and then make my final adjustments on the air. That is when things are going good for awhile but then the flame goes out and things start to coal and up goes the temp in the box.

I really appreciate all your help along with everybody else who has replied.

 

[Woody Stover]

I have a inside setup with the flue straight up about 16'. It was more of a flash back.

OK, you should have good draft, especially with the cold weather we've been having. Sometimes weak draft can cause smoke to build up in the box, leading to a backpuff, but that doesn't sound like it's the case with your setup. As long as it's just a 'flash-over' and not a full-blown backpuff, where smoke comes out of the stove into the room, everything is OK in my book. I kinda like the flash-overs...they look cool.

Cat temp was about 1200. It was about 6 degress and only a breeze not really windy. It happened during a cold start up. When my flame goes out and the wood starts to coal, that is when the cat temp starts to climb and that is what happened. Should I always try to keep a flame going?

That all sounds good, and normal. Good cat temp, and yeah, you might get a couple of flash-overs or floating ghost flames when you first cut back the air. As long as you are able to level off the cat temp where you want to, you are doing well. I like anything from 1000-1500. If you are still having trouble with the cat temp going higher, you may see a gap between the plates and the air inlet holes when the sliders are all the way in. To see this, you have to have the ash pan door and fan control door open, and you have to lie down and look up under the "hearth" (ash lip.) @WranglerBowman had a good idea for fixing those gaps, in the "too hot cat temp" thread; He just removed the screws holding the plates to the right slider, then pulled the slider rod all the way out and bent it up slightly in the middle, which will position the plates up higher so that they seal the air inlets better. https://www.hearth.com/talk/threads/too-hot-cat-temp.158662/#post-2129651

Also, should the air controls be set ahead of closing the bypass. I might be doing it wrong by waiting until the cat gets at 600 and then make my final adjustments on the air. That is when things are going good for awhile but then the flame goes out and things start to coal and up goes the temp in the box

I was running the probe up to 700-900 before closing the bypass, but if you can get the cat lit and probe temp rising quickly from 600, that's great...whatever works. But no, I didn't set the air prior to closing the bypass; I would close the bypass and run some flame in the box until I was sure the cat was lit, then I would close the air to the final setting in maybe three steps. My final setting was with the shotgun closed, right slider maybe 1/4-3/8" open.

I really appreciate all your help along with everybody else who has replied....Don't let this guy leave the forum.

OK, I'll make a note of that...there's at least one member who doesn't wish I would go away.