What creates more heat

Every pound of wood yields (approximately) the same BTU output. Doesn't matter what part of the tree it comes from...or even what species it is.

Wood is wood as long as it's seasoned. I just got done cutting a trailer load of dead small trees myself tonight. It will work great in the shoulder season and when I fill my I jøutl f55 for the night or day when I go to work the small rounds fit well in the air pockets around the big splits

It's not about the wood creating more heat but the amount of heat created for the energy expended. It's a lot more work to process limbs and tops than trunks and the trunks yield more wood quicker.

Chimney Smoke said:

It's not about the wood creating more heat but the amount of heat created for the energy expended. It's a lot more work to process limbs and tops than trunks and the trunks yield more wood quicker.

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I agree but if it's free or off your on land why let it go to waste

Jerhurt said:

I agree but if it's free or off your on land why let it go to waste

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Agreed. Easier to move and split, and the smaller pieces dry faster.

there has to be a difference, albeit small, as branches and trunks have different purposes.

If you consider total heat per given volume of wood (not weight), then there maybe some truth in the original premise. That is, there may be more BTU's in a cord of trunk wood than a cord of limb/small branch wood of the same species.

Ah it needs to be scientifically tested before any conclusion can be reached.

Av had a load of pine take the Paint off the walls then a load of fir that was disappointing.

If you think one part of the tree burns hotter then its probably a placebo. The only conclusion is that the top branchy part is drier.

I take everything north of 2" and it gets added to the piles, just a separate pile than all the big splits. It all creates heat in my book and if I spent the gas to cut it, its going in the stack

Jerhurt said:

I agree but if it's free or off your on land why let it go to waste

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Absolutely. I don't let any of it go to waste. When limbing I go down to about 1 inch diameter on branches as the limit of what I keep for firewood. They make good small stuff to start the fire with and are great fillers for in between splits on a full load.

D8Chumley said:

I take everything north of 2" and it gets added to the piles, just a separate pile than all the big splits. It all creates heat in my book and if I spent the gas to cut it, its going in the stack

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I do the same. They go in a seperate pile and get split in half or thirds for starting the stove and morning re-starts. I have roughly 1/3 of a cord for just that purpose.

More heat would equal more energy stored and I just cannot see how one part of the tree stores more energy than another for a given amount in mass?? If you ground all of it and created bio bricks I think this would prove out without question.

That said... there is something to surface area and burn time longevity as we all know a nice round or BIG square split(I like to call them yule logs) last better for over nights than a pile of 2" branches but the same amount of energy is being expelled in either case "all other factors being equal"

On woods such as oak that have alot of sapwood vs. heartwood I would take the trunk any day of the week. Heartwood is denser and has less rot. Other species this probably is a mute point as locust and mulberry which have very little sapwood. Trunks can generally give you more wood with less effort unless it is a huge monster. Neighbor down the road who has run two stoves to heat his whole house for thirty years really believes the trunk is best theory and was the first one getting me thinking about it. He gets big oak trunks and splits them in half with a fuse and gundpowder

I prefer trunk wood, but only because split wood stacks better than rounds. But when I drop trees myself I take anything down to about 1.5".

Oakwilt said:

So my neighbor was telling me to stop wasting time cutting all those tops, he says you get more heat from the trunk of a tree. My question is, who is right, I always thought a tighter grain is found in the limb of a hardwood tree therefore should create more heat pound for pound, he says not even close?

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I think Chimney smoke and others hit it, more work for less volume working the tops. That said, I don't really mind the extra work and I keep anything over 2" most of the time. I actually just lopped up a bunch of dead elm limbs I had laying around that were around 1" in diameter. Will use those soon for quick fires and kindling.

BTW - Density of sapwood vs heartwood was found to be statistically insignificant according to this study: hrcak.srce.hr/file/166363

The multiple
range test (95 % LSD method) (Table 2) showed
that the differences between [densities in] sapwood and heartwood
within white and red oak groups were not statistically
significant.

Table 2 Multiple range tests (95% LSD method) of sapwood and heartwood oven-dry densities of W_: white oak and R_: red
oak

I always thought the denser wood put out more btus. I'm not sure about the surface area stuff, but my grandad always told me were the tree splits for the branches is always the hottest burning part, or the longest. I forget

I thought that I learned way back in high school science that heat (energy) cannot be created or destroyed.

paul bunion said:

I thought that I learned way back in high school science that heat (energy) cannot be created or destroyed.

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Heat can be created, as all of us will demonstrate in our stoves this winter. Matter and energy cannot be created or destroyed, but can be converted to each other. So the wood (matter) will be converted to energy (heat).

As for the trunk vs. branches, I find a lot of time that the branches are not as dense as the trunk. So an armload of branches would weigh less, and have fewer BTUs, than a comparable armload of splits from the trunk. When you get into the larger more denser branches I would think the BTUs would be about the same. I agree with the others who have said they take fairly small wood down to an inch or two in diameter. It all burns, and the smaller wood has its uses too.

red oak said:

Heat can be created, as all of us will demonstrate in our stoves this winter. Matter and energy cannot be created or destroyed, but can be converted to each other. So the wood (matter) will be converted to energy (heat).

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Matter of semantics here. Create means to bring into existence. We are not creating heat (energy) because we are not bringing it into existence. It is stored in the wood. Nor are we converting matter into heat because we still have all the matter that we put into our stoves. Some is ash and the rest went up the stack as a gas. What is happening is we are changing the form of the matter releasing heat in the process.

And when the next tree pulls in the CO2 that we let off it will convert it partly into wood with the aid of some sunlight. That sunlight is where the energy that we get when burning wood comes from.

Yep, combustion is a chemical reaction. The breaking and forming of chemical bonds produces a net "release" of energy in the form heat and light. This energy had been stored as chemical bonds in the molecules that make up the wood.

A concise explanation of the combustion of wood at the molecular level:
http://www.whatischemistry.unina.it/en/burn.html

paul bunion said:

Matter of semantics here. Create means to bring into existence. We are not creating heat (energy) because we are not bringing it into existence. It is stored in the wood. Nor are we converting matter into heat because we still have all the matter that we put into our stoves. Some is ash and the rest went up the stack as a gas. What is happening is we are changing the form of the matter releasing heat in the process.

And when the next tree pulls in the CO2 that we let off it will convert it partly into wood with the aid of some sunlight. That sunlight is where the energy that we get when burning wood comes from.

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So what I'm getting from all this is, sunlight is the main ingredient in all this wood we talk about. It makes all of it Big and healthy, hard and dry, a fire fuelling fire.