Baking Firewood

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Is it OK to shut down the air supply?


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Burn Time

New Member
Nov 30, 2015
38
Wisconsin
I've a 25 year old Vermont Castings Resolute Acclaim cast iron model and recently installed an additional new Hearthstone Mansfield soapstone model. Can I use the same burning practice with the new EPA non-catalytic as with my old stove?

Here's how the Resolute Acclaim works, in a nutshell: It has a rear chamber that is separated by an iron or steel divider from the front firebox. The flue collar is at the top of the rear chamber. From top to bottom, the divider does not quite reach the floor of the firebox, leaving an inch or two open across the width of the firebox. At the top of the divider is a damper that can be opened or closed from the outside. When the damper is open, the smoke flows into the top of the rear chamber and straight up the flue pipe. After building up a bed of coals that covers the opening at the bottom of the divider, I close the damper, forcing the smoke to exit downward, through the live red coals for secondary combustion, under the divider and into the rear chamber, then up the flue. The rear chamber is filled with a refractory material with vertical channels. The refractory material becomes very hot, providing tertiary combustion. That's it. Apparently the current Vermont Castings operation still makes Resolute Acclaim stoves on the same design, although I am not certain of that.

My practice with the old stove has been to build up a heavy bed of coals, get the gasses passing through the secondary and tertiary combustion, stoke the firebox with cord wood, then crank down the air intake. Essentially, that bakes the cord wood. There is very little or no flame and no smouldering or smoke or creosote. The effect on the cord wood must be something like making charcoal, although not exactly because the cord wood in time turns to live red coals. This produces a very long burn.

OK, the new EPA stove is designed entirely differently. But I have been able to build a heavy bed of coals, stoke it full of cord wood, turn the flue damper down about 7/8 and close the air intake (at least as far as the EPA allows air intakes to be closed). The effect is nearly the same as with the old stove. With very little flame the cord wood bakes down into live red coals and takes the stove up to 600 degrees. Then, I repeat the process. I've been able to use this method to get the longest burn time in the 300-600 degree range and get the most out of my cord wood.

I use dry cord wood. I move the cord wood from my wood shed to a one-cord wood box in my basement, which allows it to dry roughly to a moisture range of less than 10 or 12 percent. Sometimes it gets too dry.

I've not read for a long time of anybody recommending an oxygen deprived method to cook off cord wood. I think it used to be common. Any comments are welcome. Wood burning is an art and a constant learning experience.
 
Hi Burntime. When you Stoke your EPA stove with cord wood and bake it, as you describe, getting stove top temps around 600 deg, I'm guessing you must be letting the wood ignite and flame for a while first, to get the stove up to those temps? Are you getting secondary flames? If not, there must be quite a lot of smoke going up your flue, as it wouldn't be burning off in any way, so it wouldn't be the same effect as your old VC and for sure the 'EPA police' will be on their way....

If you are getting secondary burn, then it sounds like you're getting the same as I do sometimes, when my primary air is able to go as low as it will go, and the stove top is around 600, the secondaries seem to need all the available air in the box and there is no fire around the wood at all. The stove will go on like this for quite some time and I watch the wood 'bake' away... Looking for a while like charcoal and eventually turning into glowing coals, just as you have described.

But there must be secondary flames, or you've just turned your stove into a smoke dragon.
 
As long as you have that pillow of fire at the baffle cleaning things up before it heads out the pipe it seems like you are flirting with the best case burn. It sounds like you are using the pipe damper to control the air to the secondary tubes by restricting draft. That is one thing some of us struggle with. Too much draft pulling in more secondary air through the tubes shortening our burn times. With colder drier weather I often have my primary control all the way closed with a solid secondary burn at the top. as stated above, If you are losing the secondary flames before you get to orange coals, then you are likely smoking out the neighborhood while you sleep::P 600f is the max you want to see on the top center stone so I would not target that as a cruising temp or you may spike higher and hurt something.
 
If the secondary tubes aren't firing early in the process then you're billowing smoke out the chimney.
 
Hi Burntime. When you Stoke your EPA stove with cord wood and bake it, as you describe, getting stove top temps around 600 deg, I'm guessing you must be letting the wood ignite and flame for a while first, to get the stove up to those temps? Are you getting secondary flames? If not, there must be quite a lot of smoke going up your flue, as it wouldn't be burning off in any way, so it wouldn't be the same effect as your old VC and for sure the 'EPA police' will be on their way....

If you are getting secondary burn, then it sounds like you're getting the same as I do sometimes, when my primary air is able to go as low as it will go, and the stove top is around 600, the secondaries seem to need all the available air in the box and there is no fire around the wood at all. The stove will go on like this for quite some time and I watch the wood 'bake' away... Looking for a while like charcoal and eventually turning into glowing coals, just as you have described.

But there must be secondary flames, or you've just turned your stove into a smoke dragon.
Fiona your description was more complete than mine. The firebox quickly goes to lazy, plasma-like flames that "bathe" the secondary tubes. Finally, it reaches the stage where everything is red, live coals. I check the chimney for smoke just after I refuel. With this method, there is no smoke. But if I leave the air supply open, I do sometimes get smoke. Just to be sure I'm clear, I do this only on a deep bed of coals that is capable of quickly igniting new cord wood. If I wait too long, until stove top temperature is below 200, I will use kindling to re-ignite.
 
As long as you have that pillow of fire at the baffle cleaning things up before it heads out the pipe it seems like you are flirting with the best case burn. It sounds like you are using the pipe damper to control the air to the secondary tubes by restricting draft. That is one thing some of us struggle with. Too much draft pulling in more secondary air through the tubes shortening our burn times. With colder drier weather I often have my primary control all the way closed with a solid secondary burn at the top. as stated above, If you are losing the secondary flames before you get to orange coals, then you are likely smoking out the neighborhood while you sleep::P 600f is the max you want to see on the top center stone so I would not target that as a cruising temp or you may spike higher and hurt something.
Good point Smoked. I just installed the flue damper (just above the collar) because I have a 30 foot flue with a strong draft. Burn times were far too fast. Now the stove produces excellent secondary burn. The stove just touches 600 degrees after reloading. Before, with a full north-south load, I had to open the cleanout at the base of the masonry flue to prevent the stove from overfiring, not a good thing.
 
I'm still trying to get a handle on what you're saying here, Burn Time... But clearly I'm intrigued....cos I want to understand better :cool:

....So what I think I'm hearing is that the difference between the standard practice with EPA stoves of burning in long cycles and what you're doing is that you are adding some more wood, when the stove is still relatively hot, onto a large bed of coals - and that you are NOT opening up the primary air at all at that point. I also think you're saying that, when you do that, the new-loaded wood doesn't flame (?at all?) but secondary flames are present, is that correct?
 
I'm still trying to get a handle on what you're saying here, Burn Time... But clearly I'm intrigued....cos I want to understand better :cool:

....So what I think I'm hearing is that the difference between the standard practice with EPA stoves of burning in long cycles and what you're doing is that you are adding some more wood, when the stove is still relatively hot, onto a large bed of coals - and that you are NOT opening up the primary air at all at that point. I also think you're saying that, when you do that, the new-loaded wood doesn't flame (?at all?) but secondary flames are present, is that correct?
Not exactly Fiona. Before I add wood to the bed of coals, I open the primary air and the stack damper all the way. Two things happen. The increased draft pulls ash and any smoke up the flue. The increased draft fans the coals, and, after I add the new cord wood, accelerates the ignition. After adding the new wood and getting rapid ignition, I quickly close the stack damper down about 7/8. I leave the primary air supply full open for as long as it takes to achieve good bright flame. Then I close the primary air. If I don't have time to wait, I will close the primary air completely. If I've placed some smaller pieces larger than kindling (one or two inches on the side) on top of the coals before adding the cord wood, I get the flames much faster and I won't get any smoke. If I've added large pieces of split cord wood, I may get smoke for a few minutes before the flames recover, but not for long. Usually I do this when the stove top temperature is at 200 to 300 degrees. The temperature rises to between 500 and 600 degrees. The time it holds at that temperature depends on the volume of wood I've added, but it's between two and three hours before beginning to decline for another one to three hours back down to the 200 to 300 degree range. So, I'm getting cycles of three to six hours depending on the volume of wood. I would rather refuel when I have a large bed of live coals, and add only two or three sticks of cord wood than wait until I have to use kindling to refire the cord wood. I find that waiting to refire from weak coals and kindling tries my patience. Does that make sense?
 
I can add a few splits to a 350 or 400 degree stove and not touch the air but I can't load it up that hot or the result an hour later will be something that scares me!!! Burn Time, what you are doing with the damper is adding a second control to what is normally a single control stove and it is cool that you are making it work for you. I added a damper to the snouts of my tees but it has not been cold enough here yet to do anything but have a long running big fire. With my damper being where it is, it will be hard to play enough to dial it in like you have but I may try if one of our colder spells fall on a weekend or a time when I am off from work. I mainly put the damper in so I could dial the draft back when it gets really cold and dry here and for some emergency overfire insurance.
 
I can add a few splits to a 350 or 400 degree stove and not touch the air but I can't load it up that hot or the result an hour later will be something that scares me!!! Burn Time, what you are doing with the damper is adding a second control to what is normally a single control stove and it is cool that you are making it work for you. I added a damper to the snouts of my tees but it has not been cold enough here yet to do anything but have a long running big fire. With my damper being where it is, it will be hard to play enough to dial it in like you have but I may try if one of our colder spells fall on a weekend or a time when I am off from work. I mainly put the damper in so I could dial the draft back when it gets really cold and dry here and for some emergency overfire insurance.
Before I added the damper just above the collar I did have an overfire scare. It makes a big difference in overall control because I have such a strong draft. In the EPA stoves, you can't shut down the primary air far enough if you have a strong draft. But I believe the damper would be helpful even if my draft wasn't so strong.
 
Fiona your description was more complete than mine. The firebox quickly goes to lazy, plasma-like flames that "bathe" the secondary tubes. Finally, it reaches the stage where everything is red, live coals. I check the chimney for smoke just after I refuel. With this method, there is no smoke. But if I leave the air supply open, I do sometimes get smoke. Just to be sure I'm clear, I do this only on a deep bed of coals that is capable of quickly igniting new cord wood. If I wait too long, until stove top temperature is below 200, I will use kindling to re-ignite.
Sounds ok to me. If you are not seeing smoke out of the chimney and just lazy flames in the stove you're doing ok.
 
Sounds ok to me. If you are not seeing smoke out of the chimney and just lazy flames in the stove you're doing ok.
I'm sitting in front of the stove now. Lazy flames in the back, 370 degrees. Last stoked it two hours ago, seven hours before that, five hours before that. Doesn't always work the same. It's foggy here, not the best for a draft. Burning wood is an art, doing you agree?
 
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