Things we do in the middle of night

[Gavman]

will have a winter of burning just maple next year coincidentally, stay tuned for my review lol,
I burned a beech tree last winter and it was amongst the nicest wood I have ever used, super hot, nice coals and lasted great....

 

[Jim Timber]

Yeah, keep the beer and give me another party size bag of peanut M&M's.

 

[Whitespider]

Throughlly dry non resinous wood will have the same btu per pound regardless of the species.

Well... that's sort'a my point. For nearly any species of wood there is an accepted, engineering standard, specific gravity at 0% moisture content. If the specific gravity (SG) is known, then weight per ft³ can easily be figured. For example, the SG of (dry) White Ash is o.62, which can be calculated to 38.7 lbs/ft³. There’s also an engineering standard for the heating value per lb of (dry) wood… 7000 BTU. So, a ft³ of (dry) White Ash has a heating value of 270,900 BTU (38.7×7000).

Stay with me now…

There’s also a formula to figure the heating value of wood at any given moisture content… but at 20% or less that (complicated) formula can be replaced with a short-cut (you’ll just have to trust me on that… or research it yourself). Just subtract the moisture percentage from 100% and multiply by 7000. If your White Ash has a moisture content of 20%... 100-20=80%… o.80×7000=5600 BTU/lb… or, 216,720 BTU/ ft³. (Note; the “short-cut” isn’t perfect, but damn close enough at moisture levels ≤20%)

If we allow for the air space and whatnot in a stacked cord of White Ash, and use the standard of 80 ft³ of wood in a cord, air dried to 20% moisture… 38.7 lbs × 80 × 5600 = 17.34 mBTU/cord (rounded). Well, none of the 9 charts I found showed anything less than 21.6 mBTU. If I still use 20% moisture content (that’s what most charts claim to be based on) and figure 100 ft³ in a stacked cord I come up with 21.6 mBTU/cord. But one of those charts listed White Ash at 25.0 mBTU, and several listed 23.6 mBTU.

Still with me??

OK, so variables such as moisture content and how much air space allowed in a cord of wood can explain the BTU differences between charts… that I understand. But if the formula used to create the chart is based on accepted values; and variables such as moisture content and air space remain consistent throughout the entire chart, for all species… than all charts should end up in the same order. Yeah, BTU per cord values may be different from chart-to-chart, but ranking order should be the same… and the relative difference between species should hold constant. If actual science (i.e. standards and values) is used to create them, then there ain’t no way Elm, Walnut and Hackberry (for example) can swap places on the list from chart-to-chart… well… unless, of course, the creator is an idiot, biased or worse... and that makes the chart(s) flat BS‼

 

[c5rulz]

When I have looked at those charts I see they are split up into geographical locations. I wonder how much the same species of wood changes when grown in different location?

 

[Whitespider]

Certainly there are differences within species as geographics changes... heck, there's likely small differences in two trees growing 10 feet apart.
Still, I don't see how geographic differences can account for disagreement between BTU charts. Think about it... who has the time, resources and finances to test dozens of samples from a certain geographic area?? It would require oven drying each sample down to 0% moisture, as well as access to a lab and expensive equipment to determine specific gravity. That's why there's an engineering standard... the "testing" has already been done, likely using hundreds of samples (maybe thousands) from all over a species growing range. Unless we're talkin' some critical rocket science engineering project, the engineering standard is used... just as the speed of sound changes with altitude, atmospheric pressure, temperature, frequency and even wind speed/direction the generally accepted speed of 340 m/s (760 MPH) is used in near all non-critical equations/applications.

Besides, when the differences within a species because of geographics become great enough to actually matter, it is normally divided into two separate species... as in the Northern Red Oak/Southern Red Oak or the Eastern Cottonwood/Western Cottonwood.

 

[philoshop]

I'm totally trackin' with ya here Whitespider. People who do statistical analysis will invariably ask their clients,before they begin, what they'd like to see those statistics show.?
You want me to put any sort of faith in a chart, you'd better show me the background. Otherwise it's just an idea you've come up with that may or may not resemble what my world is like.