My favorite "sustainable" burn, or, how to lick the dreaded "coaling" problem

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
  • Hope everyone has a wonderful and warm Thanksgiving!
  • Super Cedar firestarters 30% discount Use code Hearth2024 Click here
Status
Not open for further replies.

precaud

Minister of Fire
Hearth Supporter
Jan 20, 2006
2,307
Sunny New Mexico
www.linearz.com
Every season there are always many questions/comments/people pulling their hair out over how to maintain a continuous sequence of load burn cycles while avoid coals buildup. The best technique will vary by stove, wood species, piece size, etc. But I thought I'd show how I've learned to do it best with my Quad 2100.

Every time I burn this stove by stuffing it full-up, getting the whole thing burning, adjust the burn rate down, and burning through the load, I'm left with a huge pile of coals when it's time to reload. I then waste 20-30 minutes burning down the coals (which isn't very efficient) before I can reload it.

So I've developed another approach. It attempts to answer "Can I adjust everything so that, as each load burns, the previous load of coals burns completely down too?"

The basic trick is to adjust the piece size, load size, and burn rate that the stove can maintain so that the coals will burn down in the same time that the load burns. As you know, coals require exposure to air and time to burn. So that's the variable that determines how I'll load the stove. And, as it turns out, the load size must be smaller. Then, the size of each piece in the load can be larger to extend the burn time.

The pic below shows what works best in the Quad. It's really simple. Two large pinon rounds (no bark) loaded N/S, 15" long, as big in diameter as can fit in the stove, is all it takes. These will give an amazingly steady flaming burn of 2.5 to 3 hours. Look at it 30 minutes in and then again two hours in (when this photo was taken) and the flame looks the same. The thermometer on the pipe sits at 350º the whole time, tailing off to 300º toward the end. When it's done burning, chunk them down into a new coals bed, reload, and repeat as often as desired. I call it my "sustainable burn."

As you can see in the pic, the rounds shrink as they burn. When first loaded, butted right up against each other, these two had about an inch of space on each side. Once or twice in the cycle, I have to open the door and nudge them back closer together, otherwise the flame diminishes due to the widening gap between the rounds.

If I use splits instead of rounds, the burn is hotter, not as long, and not as easy to control. It tends to 'take off' toward the end of the cycle.

The downside to this method is that the heat output, while constant, isn't adjustable. Each stove will have an output rate that comes with this sustainable burn cycle. So if you're going to use this technique, choosing a stove size based on it's "cruising" burn rate is the way to go, not on it's maximum output.

I haven't yet been able to optimize this same technique for the Nestor Martin. It's a completely different animal. On it I just use the underfire air control, which feeds air up through the grate, to burn the coals down, just like a coal stove does. It works really well. My hunch is, sustainable burns are trickier to pull off with an E/W burning stove.
 

Attachments

  • [Hearth.com] My favorite "sustainable" burn, or, how to lick the dreaded "coaling" problem
    quadburn.webp
    24.1 KB · Views: 717
What works for me is raking all the coals forward so they burn down first then the split in the back becomes the next coal bed.
 
Todd said:
What works for me is raking all the coals forward so they burn down first then the split in the back becomes the next coal bed.

+1 but sometimes let the coals build up before an overnight burn.
 
Todd said:
What works for me is raking all the coals forward so they burn down first then the split in the back becomes the next coal bed.

Yes, I didn't mention that detail, most of the coals get raked forward but still leaving a bed under the rounds.

The other thing I didn't mention, I do not "char" the whole load with a hot burn at the start. Once the flame maintains itself, I throttle it down right away.
 
Same way I burn in the 30. Rake the coals to the front and load the splits N/S and the coals burn down front to back just like the rounds or splits do. And you obviously rake the coals up tight to block that freakin EPA hole in the center front. I just did away with the damned thing.
 
Hum........ Pyro explain.. I maintain a deep bed of coals for lighting the reload and keeping a constant stove top temp thru the burn cycle. Are you saying you try to have no hot coals then reload? Why?

Tom
 
Yup BB, with splits, I cover the doghouse. But with the rounds I leave it clear.
 
xman23 said:
Hum........ Pyro explain.. I maintain a deep bed of coals for lighting the reload and keeping a constant stove top temp thru the burn cycle. Are you saying you try to have no hot coals then reload? Why?

No, I'm not saying that. How can you burn a load and not have hot coals at the end? You might say what I'm trying to get is new coals being created at the same rate the old ones burn off.
 
precaud said:
Yup BB, with splits, I cover the doghouse. But with the rounds I leave it clear.

Try covering it with the rounds too and just use the primary air. To cover my doghouse I would have to take a rag out to the shelf in the garage where I stored it. You and me know how to adjust a primary air intake. Don't need no stinkin open holes to do it for us. :lol:
 
BB, I've tried it both ways and the rounds like to see more air down the middle. On the Quad, the doghouse air is controlled by the primary air control. I have about 40% of it blocked off by a piece of metal. Without it, the stove is difficult to control.
 

Attachments

  • [Hearth.com] My favorite "sustainable" burn, or, how to lick the dreaded "coaling" problem
    qf11.webp
    28.8 KB · Views: 667
Pyro, it didn't. make sense, but you never know when your going to learn something new. To maintain the bed I break up the last bit of the burn with a poker. Then reload
 
The way I licked the problem was with my Doghouse mod. Opened up the zipper air from 3/8" to 3/4" and I made it adjustable. Combined with good dry firewood, I can have a long slow clean burn with coal preservation, or I can have a fast burn with lots of heat and no coaling. What I still can't have is a long slow burn and no coaling.

As others mentioned, the choice of splits (or rounds), their orientation and spacing, their species, and their MC, are all valid points. If the doghouse air isn't on your side, their validity wanes.
 
simpler solution - pack the firebox full - burn her hot - reload - repeat

glowing coals are good - they throw lots of heat
 
cycloxer said:
glowing coals are good - they throw lots of heat
No, and no. Coals take up too much space in the firebox and don't throw nearly as much heat as a good load.
 
cycloxer said:
simpler solution - pack the firebox full - burn her hot - reload - repeat

That approach never worked for any stove I have ever owned.
 
LLigetfa said:
cycloxer said:
glowing coals are good - they throw lots of heat
No, and no. Coals take up too much space in the firebox and don't throw nearly as much heat as a good load.



I stir up a big pile and leave the door open.
Throws incredible heat and right in front of the blower.
 
LLigetfa said:
Coals take up too much space in the firebox and don't throw nearly as much heat as a good load.

I don't dread red coals at all - they throw plenty of heat. Shoot a thermo at them sometime. How do you think a wood stove heats overnight? It turns your wood into coal that then burns and releases heat. Have you ever cooked on a charcoal grill? If you let your coals turn black, then you aren't burning it hot enough. I will agree with you that black coals don't throw any heat.
 

Attachments

  • [Hearth.com] My favorite "sustainable" burn, or, how to lick the dreaded "coaling" problem
    Coals.webp
    27.6 KB · Views: 403
BrotherBart said:
Same way I burn in the 30. Rake the coals to the front and load the splits N/S and the coals burn down front to back just like the rounds or splits do. And you obviously rake the coals up tight to block that freakin EPA hole in the center front. I just did away with the damned thing.

Did you just take the doghouse off and cover the hole up with a piece of metal? Does this give a longer burn or just reduce coaling? I assume this would work on a 13 as well?
 
blel said:
BrotherBart said:
Same way I burn in the 30. Rake the coals to the front and load the splits N/S and the coals burn down front to back just like the rounds or splits do. And you obviously rake the coals up tight to block that freakin EPA hole in the center front. I just did away with the damned thing.

Did you just take the doghouse off and cover the hole up with a piece of metal? Does this give a longer burn or just reduce coaling? I assume this would work on a 13 as well?

Experiment first by putting a magnet over the two holes that feed the doghouse. They are right behind the front legs. Then if you don't like the way it burns you just remove the magnets. And remember that you will then be providing all of the primary air so you can not shut the air all the way down. Some people like it, some don't. Whether it gives longer burns or not is not the issue for me. What it gives me is a nice controllable five to six hundred degree burn for a long time instead of sitting biting my fingernails while the thing zooms up to seven hundred and finally decides to settle down.

I burn north/south and reload when the stove is back down to around 350 to 400 degrees by dragging the remaining coals in a line at the front of the firebox and loading the splits with the front of them sitting on the coal bed. Having a box full of coals hasn't ever been an issue for me. People that keep putting a new split on every hour or so or that choke the stove down too much end up with huge piles of coals. I load three huge splits N/S, set it and forget it till morning. None of this wide open to 500 and then clamp it down for a light show. Just nice flames for hours and hours.

Different strokes for different folks. And yes, one member is running his 13 modified this way and loves it.
 
blel said:
Did you just take the doghouse off and cover the hole up with a piece of metal? Does this give a longer burn or just reduce coaling? I assume this would work on a 13 as well?
It is a generally held opinion that less air gives longer burn but at the expense of more coaling.

Of course my stove is very different than what you and BB are discussing but I think the same principle probably applies. In case you didn't follow the link I posted above, to reiterate, I fashioned a sliding valve that I could best describe to be like a piston on a 2 cycle engine. As the piston slides down, it exposes ports on the sides allowing more air in and sliding it up closes them. It really does work well and I grin ear-to-ear every time my hand touches the control. I think it is intuitive enough that my wife caught onto how it works without a long technical dissertation from me.
 
Status
Not open for further replies.