UAF did some testing drying firewood with different techniques. Solar kiln was impressive. Interesting read, charts & graphs &stuff for you wood nerds like me Tests were done in Fairbanks, 20 + hours of sun in the summer, Link http://www.uaf.edu/files/olli/CCHRCFirewoodStudies.pdf
Very interesting, thanks for posting. Confirms some of what is frequently said and done here on the forums.
I am having a really, really hard time with that study. Something is amiss as top covered wood is not going from 75%mc to less than 20% in 6 weeks. It just is not going to happen, sorry. My best guess at the failure in that study judging by the results is that they measured with a mm on the outside of the wood.
Yea Split & stacked off the ground, In a sunny location with good wind & good air flow between rows out of the rain (top covered) Hummmmmmm, Where have I heard that before ? blwn Not sure how they measure , but sounds right, I bet they measured the outside. Temps in the 80s & the sun is out almost all the time, helps some but not that much But does show which way is the fastest way to dry wood. I don't have a MM, but I know 2 full years here is a lot drier than 1 year, birch has water tight bark, so that side of the split don't dry, it has to wick to the cut edges. That takes time, more than 6 weeks here.
I think it is Oslo. We were there only once and it seemed to be very dry but this was in the summer too. Winter naturally will be drier yet.
The study doesn't say whether they used a wet basis or a dry basis for moisture content. I saw a post a while back on another forum that explained the difference: There are different ways of expressing moisture content, which don't at all have to do with the method of determining them. The EPA test loads are Douglas fir that is between 16 and 20% wet-basis. That is expressed by taking the weight of the water present and dividing it by the weight of the entire split. Your moisture meter is calibrated for Doug fir as well, but the calculations done by the chip inside of it (or the width of the scale divisions if you are using an analog meter) are done using the dry-basis method of expressing moisture content. That is expressed by taking the weight of the water and dividing it by the weight of the dry fiber that would be present in the wood after all the water has been theoretically driven out (as would be done in a 215º oven in a lab). Naturally, you get very different numbers, and this effect grows increasing more substantial as MC rises. It's a mathematical thing, and has nothing to do with the actual wood, which always has the same amount of water in it. If you want a real easy way to convert dry-basis meter readings to the wet-basis used by the EPA tests, just divide the number on the meter by that same number plus 100, and you will get the correct wet-basis MC every time. For example, the meter says the wood is 25% MC. Add 100 to 25, then divide that number (125) by the original reading. 25/125 = 20% MC wet-basis. The high end of the EPA test range... perfect for you stove. In another case, the meter says the wood is 19% MC. Add 100 to 19, then divide that number (119) by the original reading. 19/119 = 16% MC wet-basis. The low end of the EPA test range... perfect for your stove. As far as a definite cutoff number, I don't believe it exists. The way you load the stove, the type of wood, the way the wood is split, the amount of coals in there, the internal stove temps, the timing and size of wood additions, the strength of your draft.... all things that can and sometimes do have a more profound effect on the burn then just MC and draft opening. For me, the theoretical cutoff is 25% MC wet-basis (33% MC on the meter). That's 5% more water in the wood than the maximum allowable MC in the EPA test loads. Above that, you will likely have a progressively harder time burning your wood without micro-managing the stove.
"As far as a definite cutoff number, I don't believe it exists. The way you load the stove, the type of wood, the way the wood is split, the amount of coals in there, the internal stove temps, the timing and size of wood additions, the strength of your draft.... all things that can and sometimes do have a more profound effect on the burn then just MC and draft opening. For me, the theoretical cutoff is 25% MC wet-basis (33% MC on the meter). That's 5% more water in the wood than the maximum allowable MC in the EPA test loads. Above that, you will likely have a progressively harder time burning your wood without micro-managing the stove" There we have a good idea of what it's all about, burning wood is an art not an exact science so it takes a while to get a feel for it but one thing you don't want kicking your azz is wet wood.
I agree. Putting it on paper is a lot different than the real world experience . Their shortfall was not burn testing. But by now you'd think the "science of burning wood" would be exact. Humans started using fire hundreds of thousands of years ago. Seems logical that these "college boys/girls" that did the test, don't burn wood for their heat. Maybe their professor don't either. Professor Backwoodsavage needs to teach the class. He has a "Masters degree" in wood burning. I'm betting that their 6 week seasoned birch will not burn as good as mine @ 3 years seasoned
I like that they set up all the test methods in the area & it all was the same weather. I should send them some questions & reference this thread.
I believe students pay to take the course, students do most of the work for the testing. Hopefully the students are learning several things. Don't think it's a course that you take to get a" liberal arts" degree. Quit a bit of work involved to have all those different stacks , cut at different times & using several different methods. Got to be several cords of CSS wood there. That's real work.
Definitely. Battenkiller sent me his schematics and dimensions for his log arch at one time and I used them to build my own. He was great to talk to.
I wonder what they used to test it and how they tested? The way I test is split it fresh and check on the face. Like this: The numbers don't really seem to agree with my experience. Wrapping the pile in a tarp with it on the ground, I'm surprised it dried at all. Very surprised it would dry better than wood uncovered. I don't cover my wood and it doesn't soak up moisture like that chart is showing. Even if it rained nearly 24/7 the pile stays fairly dry other than the top foot or so. The wood I'm burning this year I c/s/s last fall. It was wet enough it maxed my meter out (60% I think). I tested it a few times through late spring-summer and it was at around 15-17%. When I brought a bunch up from the yard to the house this fall (VERYwet fall) I checked a few pieces and it was still reading about the same.
I believe that is how most all of us consider accurate testing: on a fresh split face. And I have seen <20% on the outside and 40%+ on a fresh split face. If you want to do an accurate comparison with multiple data points like the study I would say the only accurate way would be by weight. Which I believe bogeydave is doing a similar test like that as we speak.
