Btu calculator

[boisblancboy]

Ok guys do you have a link that gives BTU's per cord of whatever species of wood?

Here is what I want to do this year since my winters can get boring. I want to keep track of the average temp of each day I'm burning along with what species of wood I'm burning and come up with how many Btu's I needed for a given season. I just think it would be interesting to see after a few years how closely related average temp and the amount of Btu's consumed are.

 

[amateur cutter]

All wood has the same BTU per pound. Some is way lighter than other species. Dry pine vs dry oak etc. I think you'd need to weigh how much wood you burned each day relative to temp to get an accurate number. Give it a little while & someone will be along with a better answer. There's some really smart people on here when it comes to this stuff, & I ain't one of them. A C

 

[boisblancboy]

I have been to a few sites that give you btu's per volume but don't know how accurate they are. I hoping someone has a site that is notably accurate.

 

[gzecc]

http://mb-soft.com/juca/print/firewood.html

 

[onetracker]

http://www.chimneysweeponline.com/howood.htm

i always liked sweeps btu chart. it seems to correspond with my own observations.

 

[begreen]

As a supplement to the btu chart, check out this nifty calculator for figuring out how this translates to burn times and stove output:

https://www.hearth.com/econtent/index.php/articles/burn_time_calculator

 

[Realstone]

I've checked out a few different BTU charts, including the ones recommended in the stickies in the Wood Shed. One thing I've noticed is that there is quite a disparity between the charts BTU ratings on different species. I wonder why?

 

[begreen]

I found the same disparities when checking out state agricultural sites.

 

[onetracker]

I've checked out a few different BTU charts, including the ones recommended in the stickies in the Wood Shed. One thing I've noticed is that there is quite a disparity between the charts BTU ratings on different species. I wonder why?

i don't sweat the differences too much. no one is doing a proper labratory assesment on 'this wood vs that wood'. its more of a weight-per-volume calculation which works just fine to let us know which species (in general) has the most energy per cord. no one will dispute that oak has more btu's per cord than poplar. i just use the chart as a guide.

OT

 

[Realstone]

i don't sweat the differences too much. no one is doing a proper labratory assesment on 'this wood vs that wood'. its more of a weight-per-volume calculation which works just fine to let us know which species (in general) has the most energy per cord. no one will dispute that oak has more btu's per cord than poplar. i just use the chart as a guide.

OT

I suppose you're right in the long run. Wood burning isn't an exact science But on the other hand, I saw one chart that put apple way above sugar maple, (perhaps 25%). Now apple is a lot more work but if the BTU's are significantly higher, then it is worth the effort.

 

[bogydave]

That's one of the good things learned here, BTU content of various woods differ greatly.
Makes members & readers of the forum, more educated & better wood burners

Charts vary with moisture content (20% is the norm) & how many BTU per pound ( 8000 to 8500) & volume in a given cord (80 - 90 cubic ft of wood)

* 8,000 to 8,500 Btu per pound for non resinous woods. 8,600 to 9,700 Btu per pound for resinous woods @ 12% moisture.

8,000 to 8,500 BTU per pound is quit a span, most charts use these numbers to calculate BTU per cord, so you get quit a range of BTU like: Douglas-Fir @23.5 - 26.5 Mil BTU/cord.
Important also, are charts that give weight per cord, dry & wet (green). Helps you not overload your rig too much


Bottom of this chart give some of the critera used to calculate the numbers: (Notice 12% moisture content used)
http://www.consumerenergycenter.org/home/heating_cooling/firewood.html

Mother nature is not perfect. Random is more realistic.
You don't see trees of the same species exactly the same, some have better soil, sun, water & climate than others & grow faster. Some grow slow & have tighter grain.
Seeing variances on BTU is "natural", even trees a few yards apart will vary.
I've thought of doing some testing with the birch here, called "paper birch" but has the BTU of "yellow birch" (test done by UAF) years ago.
But, would it mater? Birch would still bet the best BTU wood here.

Someday, wood might be sold by BTU instead of cord. Then more samples & testing would be important.
Here we ask, how many cords do you burn per year, maybe how many Million BTUs will eventually come along, (we have a member good at it, but has not been here for a while)
I know if prices per cord were all the same, I'd want a cord of birch over a cord of cottonwood

The charts get you close & let you know which species you get "the most bang from your buck"

Dry wood is the most important part of burning wood, 20% is minimum, less is "soooo" " sooo" much better. (Boiling water takes energy from the heat return & creates creosote)
The new catalytic stoves, really really like dry wood

I've learned "You burn what you got" , & the drier, the better

 

[begreen]

If it burns blue, the wood is true. (gold that is!)

 

[Realstone]

That's one of the good things learned here, BTU content of various woods differ greatly.
Makes members & readers of the forum, more educated & better wood burners

Charts vary with moisture content (20% is the norm) & how many BTU per pound ( 8000 to 8500) & volume in a given cord (80 - 90 cubic ft of wood)

* 8,000 to 8,500 Btu per pound for non resinous woods. 8,600 to 9,700 Btu per pound for resinous woods @ 12% moisture.

8,000 to 8,500 BTU per pound is quit a span, most charts use these numbers to calculate BTU per cord, so you get quit a range of BTU like: Douglas-Fir @23.5 - 26.5 Mil BTU/cord.
Important also, are charts that give weight per cord, dry & wet (green). Helps you not overload your rig too much ....

+++!

 

[boisblancboy]

Awesome guys thanks for all the good links and information. I'll give my idea a shot which should be fun since I have birch, beech, maple, hop hornbeam, and hemlock in wood pile split and ready to burn in the fall. It nothing less it will be interesting to see what comparisons I get.

 

[Backwoods Savage]

Ok guys do you have a link that gives BTU's per cord of whatever species of wood?

Here is what I want to do this year since my winters can get boring. I want to keep track of the average temp of each day I'm burning along with what species of wood I'm burning and come up with how many Btu's I needed for a given season. I just think it would be interesting to see after a few years how closely related average temp and the amount of Btu's consumed are.

Well, the Yoopers have to have something to do during the long winters.

 

[mywaynow]

I did a project with my son this past winter that involved tracking "warmth" factors of different species. We used 2 data points to chart the effectiveness of the species. First was temperature of the stove top, second was amount of water that steamed out of the pot. Both are similar outcomes of stovetop heat, but that is what we did. The loads were all overnighters so they had the ability to run their course. We used a camera/dvr to monitor the stove thermometer and then reviewed the temps each day. Outcomes were not really what I expected overall. The surprising wood was Maple. It came up to temperature quickly and held for a decent amount of time. I think we are going to do this again with more varieties. Seeing the time that the stove holds temp was interesting. Poplar did better than I would have guessed, based on BTUs charts.

 

[Realstone]

Awesome guys thanks for all the good links and information. I'll give my idea a shot which should be fun since I have birch, beech, maple, hop hornbeam, and hemlock in wood pile split and ready to burn in the fall. It nothing less it will be interesting to see what comparisons I get.

Mmm, hornbeam. If you have a lot of patience and a good chain sharpener, you're scoring high in the BTU's

 

[Realstone]

I did a project with my son this past winter that involved tracking "warmth" factors of different species. We used 2 data points to chart the effectiveness of the species. First was temperature of the stove top, second was amount of water that steamed out of the pot. Both are similar outcomes of stovetop heat, but that is what we did. The loads were all overnighters so they had the ability to run their course. We used a camera/dvr to monitor the stove thermometer and then reviewed the temps each day. Outcomes were not really what I expected overall. The surprising wood was Maple. It came up to temperature quickly and held for a decent amount of time. I think we are going to do this again with more varieties. Seeing the time that the stove holds temp was interesting. Poplar did better than I would have guessed, based on BTUs charts.

Did you chart the results?

 

[boisblancboy]

I

Mmm, hornbeam. If you have a lot of patience and a good chain sharpener, you're scoring high in the BTU's

I had four face cord of it a couple years ago and I've cut a lot of it over the years and it isnt that hard or your chain. The thing I disliked about it the most is that it is terribly messy cause of the flakey bark. I will probably like it more now that I have more draft control over my liberty now then when I bought it new.

 

[Gark]

Interesting project- would like to see the results. One factor to consider (unless I missed it, not mentioned yet) is the efficiency of your burning system. Not all the BTU' s available in the fuel will heat the home, since some goes up the flue and some boils off a little moisture. If those losses are not expected and figured, your results could look off. Perhaps figure about 70% efficiency (wild guess) for all calculations? IMHO

 

[boisblancboy]

Interesting project- would like to see the results. One factor to consider (unless I missed it, not mentioned yet) is the efficiency of your burning system. Not all the BTU' s available in the fuel will heat the home, since some goes up the flue and some boils off a little moisture. If those losses are not expected and figured, your results could look off. Perhaps figure about 70% efficiency (wild guess) for all calculations? IMHO

Great point! I wouldn't mind hearing from anyone how to get a rough idea at what efficiency I would be running at.

 

[Gark]

Whoa. I downloaded the users manual (Liberty) from Lopi website and page 6 specs say "Overall efficiency (Oregon method)" ... Is... 70%. I was just guessing, but there it is.

 

[boisblancboy]

Nice work. Now would your efficiency change depending on if your using single or double wall connector?

 

[Gark]

Yes, that is a good point. The length and single/double type connector would affect system efficiency. How to figure that in is way above my level. There are combustion wizards here who know - perhaps they will answer that question.

 

[boisblancboy]

It would interesting to know for sure and hope someone does answer. Not that I need the actual numbers as long as I'm being consistent throughout my experiment, but of course I would rather be more accurate if I can be.