Wood size and BTU's - a silly question

[KYrob]

If you split a round of white oak in half and another of the samesize into quarters, will you get the same amount of BTU's from both pieces? What I am getting at is, should I split my rounds in halves or quarters to obtain the most/best burn time. I scrounged 4 truckloads of white oak for 2012/2013 but whoever cut the tree up cut it into 20" and 24" pieces. My stove likes em' 14 or 15 so I have been cutting them down and have a bunch of odball sizes and was wondering how I should split them, as in half or quarter.

The tree was standing dead for about 3 years so I am hoping it will be good to go in 2012/2013.

Hope this makes sense,
Rob

 

[mywaynow]

Smaller the piece, the quicker it will heat up, the hotter and faster it will burn. As an example, it you took that round log, split it into 8ths, and put all 8 in the stove, you may over heat the stove because of the rate of burn. On the other hand, split it in half and put both halves in, and your burn will last a long time and burn relatively even the whole time. White Oak is really good, high BTU wood. You just need to determine how it needs to burn for your use. If you are burning 24/7, I would leave'm large for the most part.

 

[mywaynow]

Thinking about my post, I believe I did not address the question. BTU's, when applied to wood, take into effect burn time and temp. So, I don't think the size of the wood will affect the BTU output. It will only alter the temp x time ratio.

 

[CTYank]

If you split a round of white oak in half and another of the samesize into quarters, will you get the same amount of BTU's from both pieces? What I am getting at is, should I split my rounds in halves or quarters to obtain the most/best burn time. I scrounged 4 truckloads of white oak for 2012/2013 but whoever cut the tree up cut it into 20" and 24" pieces. My stove likes em' 14 or 15 so I have been cutting them down and have a bunch of odball sizes and was wondering how I should split them, as in half or quarter.

The tree was standing dead for about 3 years so I am hoping it will be good to go in 2012/2013.

Hope this makes sense,
Rob

All else being the same, smaller splits will burn faster with a higher flue temp, and thus deliver less of the chemical energy as heat into the house. The chemical energy released by combustion will be the same. But then, you do reduce the primary air, no?

Pushing the limits to extend burn time increases the probability of depositing poo in the pipe, and sending aerosol of nasties to folks downwind to breathe.

I've found that splitting into a mix of sizes is best, with a range from kindling to largest practical to share firebox with another piece of that size.

 

[Backwoods Savage]

Thinking about my post, I believe I did not address the question. BTU's, when applied to wood, take into effect burn time and temp. So, I don't think the size of the wood will affect the BTU output. It will only alter the temp x time ratio.

Same btu's no matter which way you split. The larger splits will give you a longer fire but the smaller splits will give you a shorter but hotter fire. In the end you get the same btu out of the wood so it is just a matter of what you want.

I would also take into account what type of wood you are splitting. For example, if you are splitting a soft maple then you do not want small splits because it simply will burn too hot. But if you want to mix this with some other wood then perhaps small splits are okay. If you are burning oak, then some soft maple mixed into the oak will help the fire get established quickly while the oak will give you the longer burns. This is why most folks will save their oak for burning during the night. That way the house stays warm through the night without having to get up to stoke the stove.

So, always consider what type of wood you have and what your needs are and let that be your guide. Even folks in Southern PA or Ohio will burn a lot different than what we burn here in MI. Still, folks in northern MI will have different needs than the more Southern MI folks. The climate just is not the same.

 

[WoodPorn]

I think if you are burning only Oak you are going to want a mix of split sizes, you won't be starting too many fires in a cold stove with 6 or 8 inch splits. I'd do 3/4 of the pile large and the remaining small to kindling size.

As far as the odd ball lengths, try cutting the longer pieces at a diagonal in the middle, instead of a 20" long round giving you a 16" and a 4" or 2 10" you can effectively get 2 16's.

 

[woodchip]

Pushing the limits to extend burn time increases the probability of depositing poo in the pipe.

Only if you burn crappy wood ;-)

 

[Danno77]

One way to think about it is this. Lets assume that flame is consistent. Now lets assume that you have a coffee table on fire on only the top. Now lets assume that you have a conference table on fire (also, only on the top). Which fire is likely to be hotter? I guess the conference table.

What you do when you split wood up is increase the surface area that can be on fire at any one time. (let's ignore MC). You are gonna burn through the smaller splits faster, because you have a greater amount of wood on fire at any given time. So, longer burns will be achieved with larger pieces, even if the larger pieces have the same MC.

Chances are, however, that the MC of your larger pieces isn't as good as the smaller.

If you don't believe me then have your kids collect branches from an oak tree and cram those all in your stove. Then borrow some 8 year old oak from BackSav. tell me which one overfires your stove faster, and then which one is dead faster.

 

[Battenkiller]

[del][/del]Oh, man... not the old coffee table/conference table argument again?

 

[Danno77]

[del][/del]Oh, man... not the old coffee table/conference table argument again?

lol

 

[billb3]

You probably need to find what your particular stove / chimney and temperature conditions like best..

I like to throw both sizes in at night.
If I throw just two huge chunks in I might find a couple huge cold coals in the A.M. and I've even found a few end pieces not burnt at all.
If I put all smaller ones in the stove is cold in the morning but everything is gone.
A mix seems to be good company and there might even be some hot coals in the morning.


Surface area with flame on it is what you might be contemplating, not BTU.

 

[CTYank]

Pushing the limits to extend burn time increases the probability of depositing poo in the pipe.

Only if you burn crappy wood ;-)

Nope. The lower your operating temp, the higher the probability that the secondary flames will go out. Don't need crappy wood for that. Simple enough.

Life is seldom black/white. Lots of gray too. Cheers.

 

[mayhem]

If you split a round of white oak in half and another of the samesize into quarters, will you get the same amount of BTU's from both pieces?

You will get the same BTUs out of one half of a round or two quarters. The wood has a certain amount of BTUs in it and its by the volume of the wood. The smaller pices will present a greater surface area to the flame and will tend to release their BTUs more quickly than the half...thus a hotter fire, but shorter lived.

What I am getting at is, should I split my rounds in halves or quarters to obtain the most/best burn time.

Mix em up. I like to keep some of my stuff big for longer overnight burns...smaller stuff when I wake up to get the temps up quickly.

 

[Battenkiller]

My feeling is that, although there will always be the same amount of BTUs in the wood, larger pieces will burn cleaner for a longer duration because they will burn more controlled and predictably. If you are talking about heat output from the stove, smaller splits will burn at a faster rate, so those BTUs will get used up faster and you will get more heat from the stove per unit of time. That's why wood is rated in BTUs, but stoves are rated in BTU/hr.

I say leave them bigger and season them longer. You can always split wood smaller later on, but is hard to split it larger.

 

[woodchip]

If you are talking about heat output from the stove, smaller splits will burn at a faster rate, so those BTUs will get used up faster and you will get more heat from the stove per unit of time.

I suspect there is a maximum amount of heat that you can get from any stove, and any excess heat may well go up the flue.