Accurate Firewood BTU Values | 100+ woods rated

[BCB]

99% of BTU ratings you see online of incorrect for firewood. I decided to see if I could come up with BTU values correct for firewood, it turned into more, a lot more.

Enough of a journey that I wrote a blog post on how I came up with the data in my firewood ratings tables. You can read the blog post here:

https://boisafeudunord.com/blog/how-i-built-my-firewood-btu-ratings/

The firewood rating tables holds data for over 100 trees, you can see it here:

https://boisafeudunord.com/pages/firewood-btu-ratings

Hope some of you find it useful!

 

[all night moe]

Saved and bookmarked.
Thank you for posting this. It has been known for most charts to not be the most accurate. This seems to be a more realistic expectation of wood values.

 

[Dieselhead]

I’ll give it a look. Thanks for sharing.

 

[stoveliker]

I find "burn time" to be an odd characterization.
Burn time is a function of how much BTU you load (so species and volume, scaled by moisture content) and by the rate of BTU release.
You only look at the former,.of course, because the latter depends on the stove and its operator.

So maybe that needs to be renamed into "energy content" or "heat content" or something like that?

Other than that it's good to have a BTU list that specifically includes how it dealt with moisture content, and doing so in a consistent way across many species. Even if not accurate, it results in being able to get ballpark fair comparisons.

 

[qwee]

I agree there needs to be a uniform measure of BTU ratings for firewood. The charts are all over the place. Some are really low others really high, and some inaccurate. West coast BTU charts will overrate western species like fir and pine. Just because Douglas Fir are enormous doesn't mean the actual wood is dense.

Wood species I'm familiar with on this chart, Douglas Fir BTU 28.3, Lodgepole PIne BTU 25.7, and Siberian Elm 26.2. I thought BTU rating was basically how dense a wood is. According to your chart these 3 wood species provide more BTU than some Oak species. On your chart Doug fir is right up there with Black Locust and Hickory. No way!

I cut up a big Doug Fir a few months ago - my chainsaw ran right through 30" rounds like a hot knife in butter. It was very easy. I cut some Black Locust, too. I kept checking my chain because I thought it was dull, but it wasn't - the wood is dense. Lodgepole Pine is even less dense than Doug Fir. There is a reason why it takes 6 months to dry Doug Fir and 3 years to dry Oak.

 

[Dieselhead]

I noticed you listed Norway spruce as a high ash wood, I find it to leave almost no ash. I’m burning alot of it this season and next. I think I’d maybe have to empty my stove 2 times after 4 cord with what I’m currently experiencing.

 

[begreen]

BTU content for the same species can vary a lot depending on the age of the wood and the environment it grows in. For example, spruce grows much slower at high altitudes and can be much denser than lowland spruce, especially when growing in a drier area.

 

[stoveliker]

Yes, that reminds me of a 80+ year old pine three I cut down recently. It was less than 9" dia.
Very tightly packed rings.

 

[all night moe]

BTU content for the same species can vary a lot depending on the age of the wood and the environment it grows in. For example, spruce grows much slower at high altitudes and can be much denser than lowland spruce, especially when growing in a drier area.

Yes, that reminds me of a 80+ year old pine three I cut down recently. It was less than 9" dia.
Very tightly packed rings.

Yes indeed. Mid summer we took down a badly damaged spruce. I forget which variety it was. At the stump cut it diameter was about 20''.
The growth rings were as large as the average man's pinky finger.....1/2''.

 

[begreen]

Back in the early days here, moderator MSG from Colorado ran his stove on high altitude spruce. He said it burned like hardwood, long and hot. It had very tight grain. When we built the bridge up in the North Cascades we used ~20", high-altitude spruce for the beams. Beautiful wood, that was some heavy duty timber.

 

[BCB]

The tables have been down for updates since Saturday as I found some issue in the formulas as well as in the front-end code that were throwing off the numbers. I thought at first just to fix and put back up but as I went I kept finding ways to improve things (I hope), and ended up completely rebuilding the tables. Better data, better formulas, better code, so it took awhile.

I also needed to completely rewrite the blog post that explains how I built the tables, sources, etc. So if you had previously read that post or are interested in seeing how the tables are done put on that firewood nerd hat and go here.

@stoveliker I'll think about the burn time thing, it was meant to be an easy to digest characterization for those that don't really know much about their firewood.

@Dieselhead If you check now you will probably see a difference. I believe the new way I calculate ash is better. But also need to keep in mind ash is really dynamic, age of tree, location, bark on/off, burn environment, moisture, there are lots of variables. So ash is just a rough estimate based on the properties of the wood not including bark.

@qwee Yes exactly, and I think it is doable after enough hair pulling :D The numbers w ill have changed I am sure for the trees you are familiar with, have a look and let me know what you think.

Overall I think it was a pretty succesful update, let me know what you think or if you see anything that looks off 🍻