Chimney Smoke

[aaron1]

I am wondering the causes of chimney smoke.

As I get my stove running the chimney smokes a bit as it gets going on newspaper and kindling and then stops smoking once I get it going strong and put on a few more pieces of wood.

If I reload my stove onto a thick layer of coals with stovetemp at 400F, the chimney smokes just a bit and then stops.

Is most of the smoke coming from A) incomplete combustion in the firebox, B) cooling of flue gasses or C) a combination of both? I am assuming that any smoke I see is coming from incomplete combustion in the firebox, as I can eliminate chimney smoking when I first start the stove within a few minutes if I keep it good and hot so I must not have to put much heat up the chimney to get rid of condensing flue gasses.

When I damper down my stove a little to fast (when it's b/w 400-500F stovetop temp) it might start smoking out of the chimney. This is due to incomplete combustion in the firebox, not a too low flue temperature right?

 

[Big Dan]

sounds like you got the gist of it

 

[Slow1]

Smoke is, by definition, due to incomplete combustion. All combustion should be happening inside the stove (otherwise that is a new topic).

Now, if you see something coming out of your chimney it is either smoke or steam. Steam is white and dissipates very quickly, smoke hangs around.

IF you have smoke exiting the stove and it condenses (cools sufficiently) in your chimney/flue then you will have creosote build up which as you know can lead to other issues (see "combustion outside the stove").

So the real question, which you seem to have down pretty well, is how to minimize the amount of smoke. Burning good dry wood is the best start there.

 

[rdust]

Gonna get smoke at start up and reloads no way around it. Once the stove gets warm enough for secondary combustion(cat or non cat) to happen the smoke should clean up if you're running the stove correctly and your wood is dry. Top down fires at start up help reduce start up smoke from what I've read but I've never messed with them.

You're burning wood, it's gonna smoke at some point don't sweat it.

 

[aaron1]

It's hard to believe that just opening the damper a little more reduces the smoke. I guess the wood is constantly seeping off invisible gases that I don't see and can't tell if they are being burned. If they aren't being burned, I get smoke, and if they are, I don't. I'm pretty sure my flue is hot.

Creosote accumulation would then be a separate issue from smoking, right? Creosote would be created from cool conditions in the chimney flue rather than incomplete combustion in the firebox?

 

[Sprinter]

Creosote would be created from cool conditions in the chimney flue rather than incomplete combustion in the firebox?

Creosote is actually released from the wood as gasses in the combustion process, but then if the flue is cool enough, it condenses on the surface as the solid (or liquid) creosote you see. That happens at around 250F.

Here's a link that explains the combustion process http://www.heartheat.com/flameworksOLD/index_WoodComb.htm