Tons of smoke upon startup after a long low burn

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Rangerbait

Feeling the Heat
Dec 17, 2016
456
Shepherdstown, WV
I brought this up before somewhere, but I have young children and suffer from short term memory loss as a result...after a long low burn in my BK King stove, when I load it back up in the afternoon it spews smoke like crazy. Normally it’s after dark and not an issue, but now that the days are getting slightly longer, I’m starting to get embarrassed about the amount of smoke. Is this entirely normal, or am I doing something wrong?

[Hearth.com] Tons of smoke upon startup after a long low burn
 
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Are you leaving the door cracked for a little bit after you load it? It seems to help.
I assume you have the air on high after a reload?
 
What happens when you close the bypass? Tons of creo burn out of these cat stoves boxes, especially BKs, after burning an entire load on low, then firing up a new load at high temp. That's why I question how clean the cats really run overall. It's one thing to test a clean, new stove in a lab but a whole 'nother kettle of fish in real life with a creo-coated box. And I'm also not sure that even when the bypass is closed, that the cat is capable of handling all that creo smoke, especially on high.
 
I guess you also have to factor in that a cat stove uses less wood when figuring overall emissions.
Yeah, it's embarrassing for me as well, but not as bad since I only have one close neighbor. :rolleyes: I try to fire up before or after they go for their walk. ;lol
 
To answer your question, no it’s not normal. It’s not creosote burning out of the firebox or the chimney. No... it’s the wood smoking. If you give it a little extra air by cracking the door it helps. Just don’t walk away from it.
 
My bk smokes heavy like that during warm up. It makes a lot of white smoke for quite a while. Once the cat is engaged it tapers down pretty fast to blue and then clear over about an hour.

The noncats are far superior about low startup smoke. They can burning clean much faster.
 
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Are you leaving the door cracked for a little bit after you load it? It seems to help.
I assume you have the air on high after a reload?

Leave the door cracked u til the fire is good and established, and yes, full air. The issue happens when the fire is going well, so that leads me to believe it’s creosote burning off.
 
That’s excessive smoke. I would not consider it normal. I’ve had 3 BKs, none smoked like that. Do you have huge pieces of wood? Moisture content? Is the stove down to only a few coals when reloading?
 
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Looks like the weather pattern is pushing the smoke down and not letting it go up and away. That will happen to me on damp/wet days when the air is “heavy”.
 
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There might be some tricks. Like starting with a partial load of loose stacked small stuff that will get everything hot fast and then loading the big load on top of the coals.

Top down fires might help you.

I use the propane torch to quickly ignite the load and get the cat engaged ASAP.

I have a single story home so the smoke plume is often at ground level. It’s embarrassing but doesn’t last forever. I’ve been known to delay starting a fire if guests are arriving or if the school bus will drop off the kids during the plume period. At my latitude, there is lots of darkness during the burning season.
 
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Looks totally normal to me. It’s not creosote burning off, it’s just a cold fire ramping up. There is a lot of steel cooling off the fire, slowing draft, and preventing a clean burn.

No ceramic baffle in the bk!
 
That’s excessive smoke. I would not consider it normal. I’ve had 3 BKs, none smoked like that. Do you have huge pieces of wood? Moisture content? Is the stove down to only a few coals when reloading?

Pretty small pieces of sub-15% Ash on this load...down to a pretty low coal bed, although still active enough to start without matches.

The smoking continues after the stove’s reaches the active zone and I engage the cat, but after about 30 minutes, the smoke’s invisible.
 
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Pretty small pieces of sub-15% Ash on this load...down to a pretty low coal bed, although still active enough to start without matches.

The smoking continues after the stove’s reaches the active zone and I engage the cat, but after about 30 minutes, the smoke’s invisible.
And that’s with the door cracked for a bit? Hmmm. Everything makes sense, except the amount of smoke.
 
To answer your question, no it’s not normal. It’s not creosote burning out of the firebox or the chimney. No... it’s the wood smoking
It’s not creosote burning off, it’s just a cold fire ramping up.
The issue happens when the fire is going well, so that leads me to believe it’s creosote burning off.
Not sure how webby and Highbeam are making their determinations. If you go outside when the smoke is blowing down like that, does it smell like wood burning or like creosote?
 
All stoves smoke on reload. Sometimes more than others.

It is definitely not creosote burning off. This white smoke is in a cold/warm stove.
 
Not sure how webby and Highbeam are making their determinations. If you go outside when the smoke is blowing down like that, does it smell like wood burning or like creosote?
Because we both actually have a Blaze King and lots of experience burning them. Ya, there’s some creosote that builds up in the box on these low burns. To burn it out it takes a long time on high, it’s not all going up in flames with each reload.
 
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I will recommend to reload on a hotter coal bed, don't let it go too low. Also what i see that helps a lot is drag everything back and bring just the coal to the front as much you can leaving the ashes in the back. That way the wood don't outgas too quick and it starts burning on front first. The combination of hot stove and rake the coals to the front make/gives you the least amount of smoke. I know the manual says to burn it high for 20-30 minutes after reloads, and i do but not at wide open throttle. I wait a few minutes that the front catch good and start to dial down to the point that the flames are not too active, i do a few steps to control the flames and wait till they start to slow down on their own. At this point i can dial it to my magic setting for a long burn.:) I noticed that controlling the flames and letting it catch at front fist instead of all at the same time, minutes later there is no smoke coming out. In my second install i have to go by that or it is a train. STRONG DRAFT. The other installed is more forgiven, but still.
Another option like HIGHBEAM mentioned, is to help with a few small pieces on top and do top/down. with a hotter coal bed i don't see the need.
 
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Because we both actually have a Blaze King and lots of experience burning them. Ya, there’s some creosote that builds up in the box on these low burns. To burn it out it takes a long time on high, it’s not all going up in flames with each reload.
I'm not talking about the older cooked-out creo "charcoal" that sometimes builds up in a cat stove. You might melt your stove trying to burn all that stuff off (I had that more in the Dutchwest, not much in the Keystone for whatever reason.) The creo I'm talking about which may be burning off in @Rangerbait's stove is the fresh, gooey stuff that is deposited over the course of the "long, slow burn" he is describing. This is the same stuff that is on your glass when it is black, but burns off in a while with a hot fire...that stuff is on the walls of your firebox as well. That is the stuff that can cause quite a bit of smoke, even after a good while with a hot fire. If he's got the bypass closed at this point, wood smoke would be burning in the cat. But like I said, I don't think the cat can handle all of that dense creo smoke. Now, I'll grant you that some regular wood smoke could probably make it through the cat unburned, if you have the air open quite a bit. To catch all of that wood smoke requires the "residence time" in the cat that BKVP has talked about, which you don't have if you are blowing the smoke through the cat at high speed. Hopefully Ranger can soon get the right conditions again where the smoke is blowing down off the roof, and he can tell us if it smells like wood smoke or creo smoke. And for sure, he can tell us how far he had the air opened up when he got this smoke.
Next load I fire later today, I'll get a load of Red Oak gassing and see just how much I can have the air open before the cat is unable to handle all the wood smoke..
 
Also what i see that helps a lot is drag everything back and bring just the coal to the front as much you can leaving the ashes in the back. That way the wood don't outgas too quick and it starts burning on front first. The combination of hot stove and rake the coals to the front make/gives you the least amount of smoke. I know the manual says to burn it high for 20-30 minutes after reloads, and i do but not at wide open throttle. I wait a few minutes that the front catch good and start to dial down to the point that the flames are not too active, i do a few steps to control the flames and wait till they start to slow down on their own. I noticed that controlling the flames and letting it catch at front fist instead of all at the same time, minutes later there is no smoke coming out.
Yeah, we would have to be there to see what is actually happening. Sometimes, like you say, big flames just in the front of the box will burn up all the smoke. But when the walls of the stove get hot with flame throughout the box, I have smoked out the hood with thick smoke...I go outside and it's definitely thick, stinky creo smoke. When the walls of the stove get hot, that is when the creo starts burning off. With the type of startup fire you're describing, I think the creo burns off more gradually, not all at once. You can still smell creo when you go out there, but the smoke isn't visible, only steam.
 
I'm not talking about the older cooked-out creo "charcoal" that sometimes builds up in a cat stove. You might melt your stove trying to burn all that stuff off (I had that more in the Dutchwest, not much in the Keystone for whatever reason.) The creo I'm talking about which may be burning off in @Rangerbait's stove is the fresh, gooey stuff that is deposited over the course of the "long, slow burn" he is describing. This is the same stuff that is on your glass when it is black, but burns off in a while with a hot fire...that stuff is on the walls of your firebox as well. That is the stuff that can cause quite a bit of smoke, even after a good while with a hot fire. If he's got the bypass closed at this point, wood smoke would be burning in the cat. But like I said, I don't think the cat can handle all of that dense creo smoke. Now, I'll grant you that some regular wood smoke could probably make it through the cat unburned, if you have the air open quite a bit. To catch all of that wood smoke requires the "residence time" in the cat that BKVP has talked about, which you don't have if you are blowing the smoke through the cat at high speed. Hopefully Ranger can soon get the right conditions again where the smoke is blowing down off the roof, and he can tell us if it smells like wood smoke or creo smoke. And for sure, he can tell us how far he had the air opened up when he got this smoke.
Next load I fire later today, I'll get a load of Red Oak gassing and see just how much I can have the air open before the cat is unable to handle all the wood smoke..

It definitely smells like nasty creosote smoke, not like the campfire-esque smell I recall from the wood stoves of my youth. In fact, it almost never smells like wood smoke, no matter how clear the smoke...the air currents draw the smoke down near my front door when there’s no wind, and it’s never a pleasant smell.
 
It definitely smells like nasty creosote smoke, not like the campfire-esque smell I recall from the wood stoves of my youth. In fact, it almost never smells like wood smoke, no matter how clear the smoke...the air currents draw the smoke down near my front door when there’s no wind, and it’s never a pleasant smell.

During the clear clean phase that smell is the great smell of fully combusted smoke. I liken it to car exhaust. Campfire smoke doesn’t get to go through a catalyst where most of the “campfire smells” are broken down into heat.

The creosote accumulation in the firebox was deposited during a long burn while the stove was fully at operating temperature. You won’t be able to burn that creosote off until you raise the firebox temperatures well above the initial deposit temperature. That doesn’t happen during warmup.

The white smoke after a reload is not the burning off of the firebox creosote accumulations regardless of the smell. Those accumulations don’t burn off until way into a very hot burn. But what is creosote? It’s just condensed wood gas. Fires always burn wood gas so in a way you are always burning the ingredients of creosote.
 
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The creosote accumulation in the firebox was deposited during a long burn while the stove was fully at operating temperature. You won’t be able to burn that creosote off until you raise the firebox temperatures well above the initial deposit temperature. That doesn’t happen during warmup.
The hottest part of a cat stove during the cruise is the top of the stove around the cat. I'd wager that when you are ramping up a fresh load, with the heat and radiation of big flame in the box, the sides may be quite a bit hotter than at cruise. I can't really test this theory on my stove because of the buffering/lag effect of two layers of stone..but steel stove guys should be able to verify weather this is the case.
The white smoke after a reload is not the burning off of the firebox creosote accumulations regardless of the smell. Those accumulations don’t burn off until way into a very hot burn. But what is creosote? It’s just condensed wood gas. Fires always burn wood gas so in a way you are always burning the ingredients of creosote.
I'm not sure we can ascertain the color of the smoke from Rangerbait's picture on the internet. We'd have to be there to say for sure. But to me, it looks kinda heavy and dirty. White, wispy smoke is steam, gray or blue smoke is wood smoke. This creo smoke has an almost brown look to it. When I have a bad 'smoke out the hood' episode (doesn't happen every time) after a long, low burn, there's a thick, billowing cloud of foul-smelling creo smoke blanketing the area like a heavy fog. I mean, birds are falling out of the trees. ;lol I think this is the condensed, concentrated creo on the walls of the stove burning off..hours worth of deposits being burned off in a relatively short period of time. Yes, later in the burn you will still get a little creo smell but I think that even though the majority has burned off the walls, I think the creo-burning continues at a lower level. It's a much worse smell than you would get just burning a few splits at your fire pit.
So if you have company coming over, or the neighbors are out, make sure you burn out your stove beforehand, then throw on some Black Cherry splits and you'll have them saying "What a lovely fragrance, we should get one of those wood-burners!" >>
 
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