How do you split wood for maximum burn times?

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begreen

begreen

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Staff member
Nov 18, 2005
104,680
South Puget Sound, WA
Last week I experimented with different splits to see what gave the best burn time. I had a variety of wedge shaped splits, slabs (around 3-4" x 10-12" rectangles), rounds (3-6" limbs) and big chunks (around 6"x6"x9"). I loaded N/S and E/W. The hottest and spikiest burn was loaded N/S with mostly rounds and some odd filler pieces. The temp went up quickly, but the fire pretty much was consumed and done within 5 hrs. The best times I've gotten are with the big slabs loaded E/W. The stove only goes up to about 650 (softwood) and keeps that temp for several hours. But the large chunks, if packed tightly, did fairly well too.

For folks with a large firebox, how do you split your wood (size and shape)? How do you usually pack the stove for good long burns?

PS: Yesterday I did a mixed packing with doug fir slabs on the bottom, then quarter logs and rounds of madrona (hardwood) on top. The stove took off and burned hot. Hit a bit over 800 and held that for almost an hour. I reloaded about 7 hrs later, the stove was down to 350 at that point. FWIW, it seems to me there's still too much air getting to the fire which leads to a hot initial spike and shorter burn times. But we'll see next season when I have pure hardwood to burn.

Also, when burning slabs I saw a funny phenomenon. The big PE stoves have a row of secondary holes in the manifold running center N/S. About halfway through the burn there'd be a deep V notch cutting through the top center of the slab. The heat and flames from the secondaries would saw the top slabs in half every time.
 
My firebox is a 2.14 sq ft, so its probably on the large size of medium. I get my longest burn times out of minimizing the wood surface areas and maximizing the log size. If I can barely get it through the door its a good overnight piece...then I stuff the biggest wood I can fit into the open spaces without putting undue pressure on the secondary manifold (don't want to crack it for an extra 20 minutes of burntime). If I put a load of hard maple or oak in there I can get upwards of 7-7.5 hours of flames and a good 8-9 hours or good usable heat out of it...less than that for wet, green or softer woods of course.

Its interesting that you get that sawing action wiht the secondaries...that doesn't happen to me, but I can't easily stuff wood up into the area in front of my burn tubes.

I alwals load everything E/W, but it should be noted that its a side loading stove.
 
BG, My results are pretty similar to yours. I like the big thick slabs for long burns both because they burn longest and the slabs are easier to stack tightly. I do get the saw effect, but on the bottom from the primary rather than the top from the secondary. The only thing I have not tried is large rounds like some people will recommend for an overnight burn. Any rounds I have are generally smaller than most of my splits, which is why they weren;t split in the first place. I don't really notice the burn time being longer with the rounds than the splits in this case. I actually get longer burns with n/s loads, but only because my wood is cut to perfect length for loading n/s, and if I do it e/w, I end up with about 2-4" of space on each end of the logs, so I can't actually cram as much in as if I'm loading n/s. If the wood were cut to a longer length to necessitate e/w loading, I'm sure the burn time would be a bit longer.

You also need to factor that my wood is less than perfect, and I get about 30-45 mins of sizzle on each load. It's a pretty good testament to my stove that even with this wood I can burn hot after the initial boil-off and I have a really clean chimney.
 
I've got a big pile to split up. So far I have been splitting mostly into radial wedges, but now I'm thinking of trying to create more slabs.
 
I have a small stove (especially compared to most of you) but I seem to get the best overnight burn with 2 large splits (approx. 7 lbs) placed E/W with the narrow side to the middle and then fill in the V with 4" rounds.
 
I get the saw action too but really can't load the stove E/W to experiment with the Pacific, its just too narrow E?W and a big PIA to cut down my 18" splits to 12" to get em in. Interenting how the slabs go longer than the rounds, my guess is because with the PE when you damp 'er down almost all the air comes from the secondaries and cant penetrate to the bottom slabs therefore the sawing action. If I get a bunch of shorts i'll try and E/W load one night, but like the old addage says, if it aint broke don't fix it.
 
My night burns have mostly been big oak slabs. Four across fill the 30-NC firebox N/S. They are as tall or a little taller than the brick retainers. I make no effort, in fact try to avoid, filling the combustion space above the firebrick. I leave a little space between them but I burn'em cigar style at 450-500 or so stove top and body temp with the blower running instead of ramping up to secondary combustion temp and scorching them from the top down. I load it at 8-9 o'clock and have a 250-300 degree stove at six or seven o'clock when I get up after the blower has been running all night at 1/3 to 1/2 speed. I have no idea what temps would be if the blower wasn't running. Air is set at about one third open since my "zipper" intake is blocked off and the "doghouse" is sitting on a shelf in the garage.
 
Interesting. It looks like slabs are the way to go. I will adjust my splitting accordingly. The blower a factor I don't have (yet). My temporary experiments with the air control have become semi-permanent. I bent the stop so that if I want to (and do) the primary air can be completely closed. That improved burn times noticeably and without a lot of negative side effects. The glass still stays reasonably clean and the stove has less tendency to spike. Burn times have gone up by 1-2 hrs. I'm still experimenting with the EBT. Yesterday I kept it temporarily blocked off and found this morning that there were a few cold charcoal chunks among the glowing ones. It could be that when we start burning hardwood that I will need to rejigger my setup, but for softwood, I'm getting a more even-temperature, longer burn with the current setting.
 
Here is what I do for best performance and burn time:

The stove has to be already hot (over 700 top temp) with a bed of 2 to 3 inches of hot coals

On top of that I use large 4" -6" rounded logs or if I don't have round ones I use half or squared ones in a N/S configuration and few inches away from the glass so 18" long.

Let it burn on Hi for about 10-15 minutes or until the top temp is over 800

Add smaller splits 2-4 inches on top of the large ones already burning to fillup the box to the top (I carefully make sure I do not hit the Baffle)

Then Close the air to one quarter for 10 more minutes

Then close it completely for the night after assuring a good secondary is On.

I use a pedestrian ventilator point it right to the stove body on Low to circulate the air arround.
 
Split it lengthwise :lol: really I split all different sizes. To me a packed stove burns the longest. Different sizes allow me to pack it full.
 
I find the really big splits burn longer, but they take twice as long to season. So if I am splitting now for next season the large splits will not be ready for next year. I am splitting a mix now but usually leave the largest one more year to dry.
 
BG, even in my small stove slabs seen to work better. I really think it is because you are creating a longer path for the flame to have to follow (kind of like a wood baffle plate)
 
BG,
If the round of wood is just right, I like to cut the center out which leaves me a big slab and 2 giant half rounds.
I pack my Oslo for overnight fires depending on the big chunks I find in my pile.
Slabs work best, but are few and far between for selection......usually for me it's 2 big chunks on the bottom and either a slab or half round on top.
Sometimes its like putting a puzzle together ...a work of art one might say.....2 medium triangular chunks on the buttom (bark down) and a massive triangular chunk on top (bark up)
Last week I posted a picture of 2 massive chunks of Hickory I packed in the Oslo. I put those 2 slabs on a red maple coal bed at about 10:00pm, by 10:30 bedtime it was rolling at 600. By the time I got to tend the stove in the morning after 7am the temp was still at 275.

Only Hickory, Redoak and White oak make an overnight appearance in my Oslo if I can help it.....

WB
 
Well, now you all have me intrigued. Although a slab for me is probably kindling for many of you :) I think I'm going to give this a try. Unfortunately, I just finished splitting so I'm going to have to find some more wood.
 
My small to medium splits lay in the 4-6" x 18-20". and large overniters are 8-10" x 20-22". The box is 4 plus cubic feet, so stuffin 80 lbs of hardwood in there routinely occurs on cold nites. Rounds give off the longest times. I have had great success layng down a course of E-W, then N-S, then E-W, etc. This will put temps at 600-700 for the first couple hours, 500-600 for a few, and 300-400 for two or three more.
 
WOODBUTCHER said:
BG,
If the round of wood is just right, I like to cut the center out which leaves me a big slab and 2 giant half rounds.
I pack my Oslo for overnight fires depending on the big chunks I find in my pile.
Slabs work best, but are few and far between for selection......
WB
Click to expand...

Your avatar shows it pretty well. I have some nice big rounds to split and will strive to get more slabs out of them. Previously I would just work my way around and radially split the round.
 
I mix 'em up as I split. I try to have roughly the same amount of big stuff as small stuff. I also mix up slabs, squares and wedges. I like to have an assortment because then I can fire based on the outdoor temp. I never load E/W (I assume this means left/right) I always load N/S (assuming this means front to back). But I also run a Woodchuck furnace (with a fire chamber capacity of almost 8 cubic feet) not a stove.
 
So cc, you may be the one guy that can answer the timeless question: How much wood can a woodchuck chuck if a woodchuck could chuck wood? :)
 
LOL I guess that depends on the temp. If its cold it'll eat it up. When its moderate it chokes it down really well and makes it last.

But i think the answer you're looking for is. A woodchuck would chuck as much wood as a woodchuck could chuck if a woodchuck could chuck wood. He he!!
 
BG - if you got the rounds that make slabbing them fairly easy, then go for it. I find a few big slabs on top of a nice bed of coals to be the ticket for longevity and heat output.

Minimizing the exposed surface area, allowing the stove to be "packed" tighter (i.e. more pounds of fuel) is the key. Slabs allow for this to happen easier when compared to rounds or radial splits.

Edit: short story - Friend was over, admiring the fire when it came time to reload. I grabbed a slab that HAD to have weighed greater than 30 pounds (white oak of about 8x12 and 21" long). His eyes got pretty big and asked "you gonna stuff that thing in there?". My response- "heck yeah, it'll fit won't it?".
 
I don't have much evidence from experimentation like you do. When I split, I just vary it quite a bit. Sometimes I split the log in quarters, sometimes I split it in slabs, large and small, sometimes I try to get it as big as 6x6. I like having plenty of thinner slabs to help pack the box or to slide on top of 2 splits to get a good burn in the AM. I don't have many rounds as I usually split them all unless they are very small.

In conclusion, I think I like the flexibility of wood split to square or rectangle and am moving away from wedge shaped - though it is virtually impossible to eliminate it. I dont really have much use for the wedge shaped in the big Olympic - and in the Castine, you need as much wood as possible in that smaller firebox, as well as stability when you pack it in there.
 
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