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Is there such a thing as too dry wood?

Post in 'The Wood Shed' started by ohlongarm, Nov 29, 2011.

  1. Backwoods Savage

    Backwoods Savage Minister of Fire

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    Quit yelling Thistle. :lol:

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  2. Battenkiller

    Battenkiller Minister of Fire

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    Had 'em both in the 60s, but never the flowers in my hair because I don't have any hair... as you well know. :mad: :lol:

    I'll leave you all guessing about that other 60s substance.
  3. Thistle

    Thistle Minister of Fire

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    :lol: Sorry Dennis.
  4. tymbee

    tymbee Member

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    I'll buck the concensus and suggest that-- at least in theory-- yes, wood can be too dry.

    Not something that I worry much about here and doubt that this "objectionable" level of dryness could ba achieved without extraordinary measures, but I did manage to find at least one source that supports this in theory:

    http://www.energysavers.gov/your_home/space_heating_cooling/index.cfm/mytopic=12570
  5. oldspark

    oldspark Guest

    Hello tymbee, your first post and you want to stir some crap. I tend to stay out of these posts but yes it can be too dry in a way but still burnable. :)
  6. tymbee

    tymbee Member

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    Yikes-- didn't mean to do any crap stirring! :)

    I've been reading posts here for awhile just happened to have read that article recently as well as having a similar firewood moisture conversation with local friends. Very interesting to read about all the different approaches to cutting & burning firewood.

    Also, I'm interested in the moisture meters I've seen mentioned here. The General instruments moisture meter seems to be one of them. But I see they make many different models. Would appreciate hearing any specific recommendations as to which might work best?
  7. oldspark

    oldspark Guest

    A lot of us like the cheap Harbor freight ones (Bk did some testing and for the most part are accurate) but they eat battries left and right. Cheap batteries are availible on ebay.
  8. Slow1

    Slow1 Minister of Fire

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    I suspect that same article is a bit out of date. Note their reference to "Advanced combustion woodstoves" which is what they call stoves with secondary burn (i.e. just about any stove we call EPA stoves here that doesn't have a cat). So, the reference to "airtight modern stove" may be talking about the prior generation stoves that didn't have secondary air and thus the design to burn that smoke. Current "modern" stoves are designed to burn wood below 25% MC, not "just over" as that statement is calling for. So something isn't adding up - and I think that article is simply out of date.
  9. oldspark

    oldspark Guest

    I dont think that article is out of date, it talks about EPA stoves and I have burnt real dry wood and it does exactly what they say, it goes ballistic.
  10. oldspark

    oldspark Guest

    They test the stoves at 25% I believe, the quick off gassing is gonna happen no matter what type of stove you have, the problem is you can not catch all of the gasses in that situation, this has been argued many times before. The wood (outside) only gets so dry anyway, you can get it much dryer by bringing inside in the stove room. Everything I know (for the most part) I have learned from BK. :lol:
  11. ISeeDeadBTUs

    ISeeDeadBTUs Guest

    As others have typed, most wood is best after it's been dried the most.

    But you should be very careful with that Oak . . . If you tried to burn that, you'd find it much too dry, which is quite dangerous. Just go through your stash and throw that crappy over-dry Oak in a pile. Next time I'm out your way I'll get that mess out of there B4 you do some serious damage with it!
  12. CTYank

    CTYank Minister of Fire

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    Sure seems outdated to me. The bit about "If you place wood that is too dry on a bed of coals, it will instantly give up its gases as smoke, wasting unburned smoke and producing creosote buildup." is purest BS for an EPA stove; I've NEVER seen anything of the sort. EVER.
    Might be true for some sub-optimum stove designs. With my little Dane, I'd crack the door for whatever seconds it takes to light, then set draft accordingly and sayonara. For ballistic, I'd have to leave the door cracked with lots of sugar maple, or remove door gasket. Not gonna happen.

    "Instantly" is also a giveaway. Note also that it's "instantly giving up ... smoke", NOT instantly roaring off in flames. I'd say find better references- written by scientists or other knowledgeable folks. Not some hack parrot.

    Dennis, please note: no allowance is made for the extra time needed for air-dring oak. Anyone who's burnt oak should pick up on that.
  13. oldspark

    oldspark Guest

    Well Yank I have seen it to an extent with really dry wood.
  14. tymbee

    tymbee Member

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    Amazingly generous offer. I am truly touched by the altruism demonstrated by members of this group! :)
  15. Battenkiller

    Battenkiller Minister of Fire

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    I have provided several articles written by scientists who provided both the actual increased creosote accumulation and the efficiency loss data from their studies, and they all fell on deaf ears here and pissed a lot of people off. Several modern stove manufacturers have made similar claims which have then been ignored by the users. John Gulland, the leading Canadian wood burning authority, has written about this phenomenon (and he was talking about EPA stoves) and was made out to be an idiot on this board.

    As well, I have never read anywhere any information from any stove manufacturer that claims wood must be seasoned for 2 to 3 years to get satisfactory burns. Many claim 6 months is sufficient for hardwood (and don't exclude the oaks), most say a full year. A full year seems right to me, but it has been shown and reported here that most of this outside drying occurs only during the most advantageous times of the year, the rest of the time it sits and waits for good drying days to come along.

    I brought this up several times merely to help folks optimize their burns. I included charts and efficiency figures from world-class scientists. I have read just about every lame reason that exists to try to debunk these scientific findings, from "that wasn't an EPA stove", to "those guys are typing that up from their heat pump warmed office". Me, I trust the scientists. They explain quite clearly what occurs in the stoves and in the flues while burning wood at various moisture contents, and the evidence is pretty compelling to me, so I attempt in vain to share.

    Then along comes some "expert" who claims he gets his wood to 0% MC, and I say to myself, "Do I really care to educate this person?"

    So, burn on, my friend. My own personal experience tells me that it all burns if you know what you are doing, both too dry and too wet. So, you burn your 0%, I'll burn my 20-25% and we'll both stay warm come February. I've been accused of being obsessed with this "too dry wood" thing, but that's a load of baloney. It's not a contest to me, it's just about staying comfortable when it's 10 below. The fact is that playing around with varying moisture contents allows you one more variable to tweak.

    What I find particularly amusing is this Holy Grail of 20%, like wood burns for chit at 22% and needs to wait another year, but magically burns like gasoline the minute it crosses that 20% MC threshold and then stays good at 18%, 16%, 14%, 12%, 10%, 8% and on down to 0%. Where are the references from credible sources that you speak of that supports this notion? I have never seen them, and I have done a whole lot of reading on the subject. What I have found is a lot of studies that show that, because of the way a batch-loaded cordwood heater works, there will always be a "sweet spot" regarding MC for any particular load, in a particular stove, running through a particular flue, in a particular climate, and run by a particular operator. In fact, there is a MC where the stove reaches maximum burn efficiency (cleanest burn) and another one (lower MC) where is achieves maximum overall efficiency. This will be true in any stove, not just pre-EPA stoves. What are these sweet spots? I haven't a clue for you, but I can pretty well assure you that it ain't at 0% MC.
  16. tymbee

    tymbee Member

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    Hi Batten,

    I tend to agree. That is, if I cut trees in the fall/winter, then split and stack in early spring, by burning time the following winter the wood is going to be sufficiently dry. If it sits there for another year, I don’t see that much difference. Of course the critical factor, and an important variable, is just how the wood is stored during the optimal drying period of summer/fall. Given the hygroscopic nature of wood, the moisture content at any period of time is not solely dependent on how old it is. It can lose or absorb moisture relative to ambient conditions. Wood stacked off the ground with sufficient air space and with a southern exposure and favorable climate will obviously dry quite well over time. Wood tossed in a heap in a moist wooded area won't dry and can even gain moisture. Saying "3 year old firewood" doesn't mean much without some kind of qualifier.

    I am new here and I didn't realize that this seems to be a subject of some contention. I would like to think that folks can discuss their own particular theories based on whatever evidence they bring to the table and either come to a consensus, or simply agree to disagree.
  17. CTYank

    CTYank Minister of Fire

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    Hard to tell what you're aiming at me in your post. And why the volume of the data-dump, again.
    Just maybe, it'd be better if we ratchet down the "vocal" intensity. For one, I've never participated in any of the hatchet-jobs you've mentioned.
    If you're alleging I'm talking BS about getting MC down to/near 0%, it's not that difficult according to my HF MM, given that the splits I burn are very small (typically 8"l x 3"across) and dry very nicely in the low-temp kiln that exists a foot or so from my little Morso.

    You'll notice that I still avoid text-dumps. (As an aside, I tend to gloss over such stuff- other things to do, people to listen to.)

    Lumber-processing references that I've read clearly indicate that oaks take twice as much time as other hardwoods to air-dry. Dennis is onto something.
    Personally, I ignore most any such claims made by stove mfg. I trust local experiments much more, and am fussy about "satisfactory burns."

    If you ever think you have wood that's too dry, I'll be happy to bring a p/u for you to load it into, even rent a trailer. No charge for disposal.

    There are only degrees of expertise out there, and EVERYBODY has aspects of same, not just some high-priests.
  18. SolarAndWood

    SolarAndWood Minister of Fire

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    don't see either of those options happening :lol:

    You have to find a system that works for you. There are way too many variables, preferences and practical considerations there to say there is one way to do it. I dedicate enough space for a heap size sufficient for 3 years of wood and then get my seasons burn under a roof before the snow accumulates the year I want to burn it. Not too common a solution but produces dry wood for me with what I consider to be the least amount of work.

    Could I dry it faster? Yes. Could I reduce the amount I need to keep on hand at any given time? Yes. Could it be prettier? Yes. Do I care? Not really.
  19. ISeeDeadBTUs

    ISeeDeadBTUs Guest

    As usual, I have very little - if anything - useful to contribute. Other than . . . I didn't expect this post to go incendiary!! :zip:

    I've never seen the point of a MM. My BELIEF is that you'd have to keep all the wood from the same tree together. Then you'd have to measure the MC from the trunk to the tips. Do some sort of regression analysis realtive to time of year severed from the stump, diameter, species, yada, yada, yada. Or else put the MM to EVERY piece before deciding whether to burn it.

    My experience is MOSTLY with 8-10 yo Oak. No question in my mind that the single biggest factor in drying this stuff out is getting the bark off, keeping it out of ground water, getting it into the sun. Most of the wood I burn has not had ANY of that done, and is only chunked about a week B4 it is burned. But my boiler is claimed (and from my observation, this is somewhat a true claim) to be able to 'bake off' MC during idle, due to the refractory mass. Yet another statement that can start WWIII in the right circles :wow:

    Having seen scientist lie from time to time - like most nearly all humans - I am wary of 'new', counter-intuitive claims. IMHO part of the fun with burning wood is the variability of the fuel and the burn.

    Can you imagine sitting in www.weRfatOilBurners&proudOfIt;.com and discussing the variations in firing rates between three different local fuel oil suppliers??!?!?
  20. oldspark

    oldspark Guest

    Hey Yank can you take a picture of your MM stuck in a piece of wood reading 0%, I for one would like to see it. Two by fours that have been laying in my house are not that dry.
  21. Battenkiller

    Battenkiller Minister of Fire

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    Mine's packed away somewhere, but I believe it will read 0% if the MC is below 6%, which in the low end of it's range. I remember when I did the Denniswood thread that the wood took a long time to rehydrate back up from 0%. That whole time it read 0% until it got above 6%.

    Doesn't really matter, all you have to do is take the relative humidity of the room the wood is stored in and look up what the EMC is at that RH. Wood can only reach 0% MC when the RH is 0% humidity in the air. You need to get the room up above 212 degrees for that to happen. Even at that temp it would take many days for a split to reach 0% MC. In other words, it just ain't happening... even inside a real kiln.
  22. oldspark

    oldspark Guest

    Yank must have a hell of a wood burner! :lol:
  23. Battenkiller

    Battenkiller Minister of Fire

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  24. tymbee

    tymbee Member

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    Sounds like a workable strategy to me! Especially the "before the snow accumulates" part. Big difference between wood wet from rain vs. snow. Your pile can get rained on one day, but will dry out pretty quickly if followed by dry days. With snow covered wood, even if the weather warms and sun shines, the snow just continues to melt keeping things wet.

    I expect previous generations would get a chuckle out of discussions like this given that they didn't have the luxury of doing much "tinkering" with various wood burning theories. Back on the farm we would cut all kinds of wood when the opportunity presented itself, toss it in a big pile, then transfer it to the basement ideally before the snow came. My father did this for many years without such things as chainsaws and splitters, but rather crosscut saws, axes, and horses. Don't even remember seeing a moisture meter around anywhere. :)
  25. Battenkiller

    Battenkiller Minister of Fire

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    Well, it ain't happening three feet away from my Vigilant with fans blowing on the wood all the time, and that is a serious heater. Goes from about 60% MC down to 20% in three weeks, but takes three more weeks to get down to under 10%. At that point it basically sits just below 10% until spring, at which point I take it and put it outside and it slowly goes back to about 14%. And no questionable moisture meters here, I'm oven-drying and weighing the stuff.

    My experience is that once it gets down to about 10% MCdb the weight drops extremely slowly no matter how hot the room is, or how many fans you put on it.

    With my stove, wood that low in MC burns too fast, but that's what I get stuck with at the end of every season. By the following fall it has rehydrated nicely outdoors into the 14% range. Which works OK for my stove, but I prefer 20-25%. Burns cleaner in my old stoves (just an observation from my "local" experiments"). ;-P

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