I have an idea on how to get rid of coals faster. What you think?

[cmsmoke]

How about the overdraft question?

 

[Chris-PA]

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.

 

[cmsmoke]

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. Granted you have to keep the pieces together to burn completely. Now put you leaf blower across the top of it...what would happen? I don't believe the coaling has anything to do with grates or secondary burn. No one with the problem wants to say if they had checked for overdraft with a reliable device.

 

[chadihman]

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.

 

[Del_]

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.

Don't give up on us yet! See my suggestion below:

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.

Chris I don't see why over draft would only be affecting the secondary air. Over draft probably affects both primary and secondary air.

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.

Due to the design of my Jotul the secondary air input if hard to get to as it's up inside the back of the stove a couple of inches.

I've blocked all secondary air testing to see if it does result in a hotter stove and a more rapid burn down of a large bed of coals.

It does.

So instead of leaving the door open if the original poster would see if he can find the secondary air input open and block it up it would be interesting to hear if his results are like mine, a faster burning and higher heat output of a 'coal only' fire.

 

[chadihman]

How about the overdraft question?

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.

 

[TBrown]

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.

As the original poster you can delete the thread. Look under thread tools

 

[cmsmoke]

OK, then your problem and the problem of others who have posted must not be the same. Sorry I got caught up in it. Why not go to a thermostatic spring type control. Closes of air when hot and opens as it cools off. It sounds like you have done the experimentation. Keep it simple. Plenty of stoves use them successfully.
Edit: This method may be more beneficial, because it would coincide with the heat output, not time. In other words, there may be times when the fire is out before the timer opens the air. Worse yet is if it would open while still going strong.

 

[Whitespider]

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.
*

 

[1project2many]

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.

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.

Granted you have to keep the pieces together to burn completely. Now put you leaf blower across the top of it...what would happen?

A leaf blower would blow away ash as it is produced so only coals would remain in contact with air.

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.

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.

 

[Del_]

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.

While you're experimenting you might want to try setting up the timer to close all secondary air input and see what that does. Secondary air when not needed for combustion not only takes heat from the stove.....it cools down the chimney some lowering draft.

 

[Chris-PA]

Chris I don't see why over draft would only be affecting the secondary air. Over draft probably affects both primary and secondary air.

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.

 

[Del_]

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.

Yes, it might be hard to shut of secondary air in some designs.

It would be better to have some experiment with easier designs to test if my theory holds true.

I know it works on my Jotul F600CB.

Secondary air in my Jotul enters the stove the same place as primary air, in the back bottom of the stove. There is a 3/8 X 3 inch slot up inside the stove that leads to the secondary combustion air input tubes. I controlled secondary air by inserting a piece of sheet metal up into this slot. By pulling a handle forwards or pushing it backwared(a stove poker handle) that was mounted to the bottom of the stove and ran to the back attached to a piece of sheet metal that went through the slot I was able to vary secondary air input. Secondary air input change results could be seen instantly when the stove was in high secondary air mode. After secondary combustion was over I would push the handle in and shut off almost all secondary air input.

 

[Del_]

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.

The Jotul F600Cb has secondary air that is always wide open. That doesn't mean mods can't be made to control secondary air input only. It took a second control.

 

[zogger]

Trying to think of a way to lift the coals so you can add wood underneath them, then let the coals back down. Closest I have come is fast bucket action via toploading.

Maybe a set of rods close together..hmm a two piece scoop with fingers, pick coals up with finger scoop, hold up for some clearance, shove in wood underneath, lay it back down, and gradually pull out the lower finger scoop while pushing a flat pusher thing on top.

 

[cmsmoke]

The way I understand it 1project2many, 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 have never saw a campfire not burn to ash when tended the way I explained.

 

[Whitespider]

Trying to think of a way to lift the coals so you can add wood underneath them, then let the coals back down.

Well heck man, you had a better idea in that other thread (can't remember which one)...
Remember?? Just flip the stove upside down‼

 

[Whitespider]

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'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.
*

 

[laynes69]

I do remember accumulating too many coals in the old furnace. It was something around 20 below and windy. We were pushing the thing to its limits, and there were so many coals, we could add little wood. The only thing we could do in that situation was to set an alarm clock, wake at 2am or wake to a cold house.

Initially when we installed our new furnace, we couldn't keep up with heating demand. We resorted to stuffing the box full on top of a huge coalbed, which just made things worse. I also choose to burn the largest rounds that were half seasoned thinking it would be okay. As time went on and year after year we buttoned up our home, the problem dissapeared. Instead of fighting it, it now benefits us. So in a home that's drafty and uninsulated, it's a nusciense. If the home is tighter and enough heat is taken from the coalbed, it's a benefit. In both scenarios they function the same, it's just for one it's the wrong tool for the job. Either way coals can and will burn down on grates or firebrick. It comes down to preference. Every year on numerous boards, when the weather turns for the worse, these threads pop up. And a large majority of complaints is the lack of heat and heavy coaling.

 

[chadihman]

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.
*

I like these kind of responses.