Author Topic: firewood red oak vs white oak  (Read 5955 times)

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Offline 3.1416

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Re: firewood red oak vs white oak
« Reply #25 on: January 31, 2013, 05:34:28 PM »
All cellulose (wood) contains the same BTU's. It's just that some woods are denser and pack more cellulose into a tighter space. So, we say white oak has more BTU's than red oak. But that implies that we are talking about per cubic foot or cord or some given volume.

Green wood uses up a lot of its BTU's in drying the wood before it can burn.

An easy chart to find would be specific gravity of various woods. This will tell you instantly which has the most BTU/cubic ft. The higher the specific gravity the more BTU/volume.

If covered, wood will air dry at a rate of about 1" per year on each surface. It will eventually dry down to around 12 to 14 percent moisture. It won't go any lower than that in outside ambient conditions. At least that is true for where I live. Dryer climes may go lower. So split your wood quickly. Also cut it in the winter while the sap is down to gain a little advantage. Plus it warms you twice. When you split it and when you burn it.

By the way I believe that red oak has a S.G. of around 0.96 and white oak is up around 1.04. One floats and one doesn't. For 2 cubic feet the weight difference would be around 10 lbs. Which gives you an idea that you would need to burn 10 lbs more r.o. to get the same BTU from 2 cuFt. of w.o. These figures are from memory from 10 years ago when I ran a hardwood sawmill. Take into consideration that I have CRS. (Can't Remember Sh..) Hope this helps those who weren't raised with a woodstove for heat.

Oh, one more trick. Frozen wood splits a lot easier than warm wood. Red Oak easiest of all.


Offline TXCraig1

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Re: firewood red oak vs white oak
« Reply #26 on: January 31, 2013, 06:39:16 PM »
All cellulose (wood) contains the same BTU's. It's just that some woods are denser and pack more cellulose into a tighter space. So, we say white oak has more BTU's than red oak. But that implies that we are talking about per cubic foot or cord or some given volume.

Green wood uses up a lot of its BTU's in drying the wood before it can burn.


I don't remember anyone discussing BTU's - rather BTU/cord or BTU/lb - nothing was implied.

FWIW, all cellulose may have the same BTU, but wood is not all cellulose. The cellulose/lignin content is not the same for all woods (lignin is 15-20% for typical hardwoods), and lignin is a higher energy fuel than cellulose. This is probably not particularly important in the larger picture.

Green wood doesn't use up any of its own energy in drying. The total available energy in the wood doesn't materially change as it drys. Dry wood burns better because it doesn't require heat, that would otherwise go to pyrolysis, to drive off the moisture. It also burns more efficiently due largely to the higher temperatures possible without the water and water vapor present. 

In most cases, there probably isn't enough difference in BTU/lb to overcome the cost difference. The bottom line when picking [hard]wood for the WFO is #1 - dry, #2 - cost. For all practical purposes, the BTU discussion is meaningless.
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Offline vincentoc13

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Re: firewood red oak vs white oak
« Reply #27 on: March 13, 2013, 08:39:21 PM »
Theres a guy in my area selling avocado wood, just wondering if anyone has tried it?

Offline Woodfiredovenpizzero

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Re: firewood red oak vs white oak
« Reply #28 on: March 20, 2013, 01:58:00 PM »
Vincent:

I have found avocado to be too soft and retains a lot of humidity, therefore not much heat output.

Edgar