cmsmoke
ArboristSite Operative
How about the overdraft question?
I'm not sure if it's overdraft, but I can see if you have a lot of draft and a stove where the secondary air can not be controlled it could contribute to coaling. You could get too much air on top with not enough primary air to the bottom of the fire. The fire up top would generate ash while the bottom would smolder. If stacking methods block air flow through the wood it would make it worse.How about the overdraft question?
Do I have the power to dump this thread?
It's been so far blown off topic and there's no chance bouncing back. I remember well now why I don't post much over here. I feel much better over in the chainsaw forum.
Thanks to you guys who added great on topic discussions.
I'm not sure if it's overdraft, but I can see if you have a lot of draft and a stove where the secondary air can not be controlled it could contribute to coaling. You could get too much air on top with not enough primary air to the bottom of the fire. The fire up top would generate ash while the bottom would smolder. If stacking methods block air flow through the wood it would make it worse.
I had a manometer hooked up to my pipe a couple years ago and my pipe hardy drafts cold and is normal during a fire but naturally it's high when it's colder outside with a hot fire in the box.How about the overdraft question?
As the original poster you can delete the thread. Look under thread toolsDo I have the power to dump this thread?
It's been so far blown off topic and there's no chance bouncing back. I remember well now why I don't post much over here. I feel much better over in the chainsaw forum.
Thanks to you guys who added great on topic discussions.
Not all fires on the ground burn to fine ash. But in the stove there are a couple of different issues with coals. Number one on the list is not that the coals don't burn down all the way. The primary issue is that when secondary combustion stops and there are only coals left, the stove does not put out enough heat to maintain temperature. If more wood is added so secondary combustion starts and heat output increases, eventually there are only coals again and heat output decreases. This happens so often that eventually the firebox is filled with coals and there's no room to add more wood. Comments about the coals being smothered because ash is produced on top of the coals, and about coals being left over unburnt, are evidence that airflow in the firebox (or another factor) doesn't encourage the coals on the bottom to burn.I don' understand why you can build a fire on the ground and it burn to fine ash, but these few can't make it happen in a stove.
A leaf blower would blow away ash as it is produced so only coals would remain in contact with air.Granted you have to keep the pieces together to burn completely. Now put you leaf blower across the top of it...what would happen?
If there is no secondary combustion because all of the volatile gasses have been burnt off already then the excess secondary likely only serves to cool down the stove resulting in reduced heat output.
I had a manometer hooked up to my pipe a couple years ago and my pipe hardy drafts cold and is normal during a fire but naturally it's high when it's colder outside with a hot fire in the box.
I'm not sure why a strong draft would make coaling worse. I would think that primary and secondary air would get more air in a high draft situation. If anything make the coals disappear faster. So much heat is generated in my secondary fire that I almost completely shut my stove down then after the gasses burn up there's not enough air to burn coals fast enough. More air would make my secondary fire to hot and short. This is why I think an actuator wired to a timer would be perfect. I could get a efficient secondary fire then five hours later the timer would open the primary air with an actuator and effectively burn the coals and heat more effectively in the coal stage.
On some secondary combustion stoves the secondary air cannot be controlled - it is always wide open. Therefore if you stop down the air only the primary is reduced. So the balance changes. With good draft you could burn the top too fast while the bottom burns too slow.Chris I don't see why over draft would only be affecting the secondary air. Over draft probably affects both primary and secondary air.
But in my barn stove there do not seem to be separate sources of primary and secondary air. They appear to be delivered through the same plenum. "Primary" air is only distinguished by the path it takes... down the inside of the glass door and presumably over the floor. To get primary air from a separate source you're forced to open the door.
I will say that it takes some practice (with my problem stove) to find the balance between coals and wood. There's a tendency to try and fuel for max heat output but that just doesn't work. If I maintain the balance between coals and wood/secondary then eventually the stove gets pretty dang warm. But it takes time. Overfueling in an attempt to generate more heat in less time results in more coal buildup and greater high to low temperature variations.
On some secondary combustion stoves the secondary air cannot be controlled - it is always wide open. Therefore if you stop down the air only the primary is reduced. So the balance changes. With good draft you could burn the top too fast while the bottom burns too slow.
I have have one that is this way, but it's on a shorter flue. The other has a single control that limits both primary and secondary. I much prefer this system.
Well heck man, you had a better idea in that other thread (can't remember which one)...Trying to think of a way to lift the coals so you can add wood underneath them, then let the coals back down.
I've read the posts from chadihman several times, and I can not find where he states such a thing. He does speculate that opening the air after secondary combustion will resolve the issue (that was the point of his thread, he was asking for opinions)... but he hasn't posted where it has been verified in any way, shape or form. And, even though what you say has been brought up a couple of times, and I've pointed out it's only speculation at this point (based on available posts)... the OP has not clarified. It may resolve the problem... it may not... but at this point, we just don't know.The way I understand it... the OP doesn't have this issue or the issues of ash covering the coals, as long as he opens the air feed back up after the secondaries are done.
I like these kind of responses.Here's a really good article on over-draft and dealing with it that I've linked to before.
http://www.gulland.ca/florida_bungalow_syndrome.htm
It indicates the fire burns too fast with an overdraft condition... which I suppose (actually at one time I was convinced) could build excessive coals. I believed it was my problem after much frustration and research... but closing the flue damper (one method of dealing with it described in the article) to a dozen different setting didn't make any difference on the excessive coaling. Although, closing it about 2/3 did lengthen the effective heating time some. I also have a flue damper on it out in the shop, and I've determined I get the best heating results with it closed just short of ½ way... but it hasn't done anything to reduce the coaling issue.
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