# My firewood can be TOO dry!!



## soupy1957 (Aug 15, 2010)

This is an interesting article...........worthy of reading by all wood burning individuals.  It talks about wood that can be TOO dry, and the effects that brings on.

http://www.woodheat.org/tips/drywood.htm

-Soupy1957


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## EatenByLimestone (Aug 15, 2010)

Heard of it, never seen it... or should I say never noticed it.  

Matt


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## SolarAndWood (Aug 15, 2010)

Check back in January and see how many people are complaining their wood is too dry.


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## soupy1957 (Aug 15, 2010)

It makes sense of course, on some level.  Wood that is too dry will burn more quickly (almost evaporate before my eyes), not giving the fire the time it needs to really heat things up before having to add more wood.  There IS something to be said for hard woods, in that regard, as well; since a hard wood (like Cherry, for one example) will burn longer due to its density.

-Soupy1957


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## SolarAndWood (Aug 15, 2010)

I've found that the super dry stuff goes up pretty quick with a roar in the old smoke dragon at the camp.  At home, it lights off the cat just fine and burns perfectly.  I don't have a moisture meter but I doubt even the stuff that has been under a well ventilated roof for decades is as dry as a 2x4.


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## cmonSTART (Aug 15, 2010)

It can happen, but most of the time it's the opposite that is the problem.


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## vvvv (Aug 15, 2010)

simplified chemistry for woodburn=
C-CO-CO2
C-CO=1 HEAT UNIT
C-CO-CO2=3.5 HEAT UNIT
if the wood is too dry & it gassifies too fast for the available amount of combustion air, the CO will exhaust without combusting thus losing a significant amount of potential heat


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## Backwoods Savage (Aug 15, 2010)

In all my years of burning wood the only time we've had to be careful because of dry wood was when we've used cut-offs from kiln dried lumber. As for regular firewood we have never had a problem. The drier the better. Most folks on this forum are well aware that we have been burning 6-7 year old firewood for many years and it burns great. 

This year will be a bit different around our place though as we have less than a cord of that old wood and we'll be digging into the wood that was cut during the winter of 2008-2009. No worry though as it is very dry wood which is mostly ash with a small amount of soft maple.


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## summit (Aug 15, 2010)

thats the issue folks run into with the brick fuel (envio, bio, etc.)


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## Rich L (Aug 15, 2010)

Ya I had picked up about 3/4 of a cord of wood last year from my tree guy and that wood was so dry it burned really quickly.I'm thinking I should of mixed it with some semi seasoned wood to make the burn last longer.As I look at my wood from last fall it looks gray from all the heat we've been getting.It's uncovered and I hoped it's not too dry.Even the two month old wood when split gives off that dry wood sound like a crack rather than a thud.This summer has been so hot and dry the dirt is like dust and the wood is baking.Give me some rain.


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## oldspark (Aug 15, 2010)

summit said:
			
		

> thats the issue folks run into with the brick fuel (envio, bio, etc.)


 That's an interesting point.


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## rdust (Aug 15, 2010)

Only way I can see it happening is if you live in a desert or really dry area.  Last year my old man gave me some elm rounds that were 22 years old that he couldn't split by hand back when he cut it.  I split them and measured the m/c before burning them, I believe they were right around 14%.  I don't think wood can get much lower then that in my area.  Best burning wood I've put in my stove to date, Dennis wood is a close second though.


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## vvvv (Aug 16, 2010)

in the case of uncombusted CO, the "problem" cant be "seen" because CO is invisible


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## roddy (Aug 16, 2010)

i often burn the outs from our kiln dried maple production....at 6-8 % moisture ,all i can say is watch -out.just a couple of 1x6 x 12 inch peices and witha bit too much air,you get that weird smell  comming off your stove that tells you maybe your getting a might warm....


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## oldspark (Aug 16, 2010)

Rich L said:
			
		

> Ya I had picked up about 3/4 of a cord of wood last year from my tree guy and that wood was so dry it burned really quickly.I'm thinking I should of mixed it with some semi seasoned wood to make the burn last longer.As I look at my wood from last fall it looks gray from all the heat we've been getting.It's uncovered and I hoped it's not too dry.Even the two month old wood when split gives off that dry wood sound like a crack rather than a thud.This summer has been so hot and dry the dirt is like dust and the wood is baking.Give me some rain.


 What kind of wood was it and rain is not going to put any moisture back into the wood, I have some 2 year old oak that was dead on the ground when I cut it and the 5 inch rounds are 17% on the inside, as the article stated (I believe) he has never seen wood below 14%. Having rotton punky wood is a whole other issue.


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## Rich L (Aug 16, 2010)

oldspark said:
			
		

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  That wood was oak.It was solid but light in weight and burnt fast.This years wood that is graying is maple.I just went out and lifted some splits and they have good weight to them.So the graying is just a cosmetic thing.This wood will give a good long burn.Rotten punky wood I stay away from.I tell folks to smash it up with a sledge and use it as a peat moss or put it in the compost pile.Not a good burner at all.


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## Rich L (Aug 16, 2010)

rdust said:
			
		

> Only way I can see it happening is if you live in a desert or really dry area.  Last year my old man gave me some elm rounds that were 22 years old that he couldn't split by hand back when he cut it.  I split them and measured the m/c before burning them, I believe they were right around 14%.  I don't think wood can get much lower then that in my area.  Best burning wood I've put in my stove to date, Dennis wood is a close second though.


 Your one of the few that I've read about who've had the same experience as me when it comes to burning dry seasoned Elm.It was the best burning wood I've ever had.I'll take Elm all day long even though I know the splitting by hand will be the hardest of the other woods I deal with.


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## firefighterjake (Aug 16, 2010)

SolarAndWood said:
			
		

> Check back in January and see how many people are complaining their wood is too dry.



Excellent point . . . in the two plus years I've been hanging around here I can't ever recall reading a thread about anyone complaining that their wood was too dry . . . now threads from folks complaining about wood still being unseasoned, difficult to ignite, creating creosote and blackening the glass front . . . yeah, seen more than a few of those threads.


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## oldspark (Aug 16, 2010)

Rich L said:
			
		

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 Been burning oak for 30 years and the only "light" oak I hve run in to was punky, so not sure what you had.


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## spirilis (Aug 16, 2010)

summit said:
			
		

> thats the issue folks run into with the brick fuel (envio, bio, etc.)


dunno, I burn those and I've noticed they seem to gas a little slower than cordwood, or at least the kiln dried variety I've tested.  I think the compressed configuration of those bricks make them burn a little differently than you think (slower, I've found).


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## vvvv (Aug 16, 2010)

spirilis said:
			
		

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gotta consider amount of surface area exposed, surface area is where the wood or brix will offgas when heated


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## benjamin (Aug 16, 2010)

[/quote]gotta consider amount of surface area exposed, surface area is where the wood or brix will offgas when heated[/quote]

exactly, you can take a big elm round that's been close to the furnace the whole winter and it won't burn too fast in any stove I've seen.  Not splitting your wood will cure that problem real quick.


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## johnnywarm (Aug 16, 2010)

the smaller the split the more it will season.


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## spirilis (Aug 16, 2010)

BLIMP said:
			
		

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ya there's that, but with the splits I always noticed outgassing at the ends through the grain, whereas bricks only seem to burn at the outer edges it always seemed splits (once at full blazing temperature) shoot flames out the ends a lot, as if the smoke gasses were being produced deep inside and making their way out the end.  might have an influence in the burn rate.


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## vvvv (Aug 16, 2010)

water boils @ 212*f, woodgas @~600*, fire@~1200*


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## Rich L (Aug 16, 2010)

oldspark said:
			
		

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  Now you got me thinking.Maybe it wasn't oak.The wood guy said it was oak.It was all split and had a nice golden color to it.I couldn't tell what it was.It cost me $50.00 and I just moved on it quick.One thing for sure it wasn't pine.


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## Backwoods Savage (Aug 16, 2010)

Maybe it was popple.


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## Pagey (Aug 17, 2010)

Backwoods Savage said:
			
		

> Maybe it was popple.



Or cardboard.   :lol:


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## Rich L (Aug 18, 2010)

Pagey said:
			
		

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  Now that's funny.Thanks for the chuckle.It might of been Popple however fifty bucks for almost a cord still worked out for me.It lasted about ten days.


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## Hiram Maxim (Aug 18, 2010)

roddy said:
			
		

> i often burn the outs from our kiln dried maple production....at 6-8 % moisture ,all i can say is watch -out.just a couple of 1x6 x 12 inch peices and witha bit too much air,you get that weird smell  comming off your stove that tells you maybe your getting a might warm....




Not trying to high-jack the thread :roll: 
Roddy,

At what temperature do you use when kiln drying?

I spoke to a guy that has a cedar lumber mill and he told me 100 °F for three days in the kiln.

Thought seemed pretty low temp?

THx, Hiram


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## North of 60 (Aug 18, 2010)

BLIMP said:
			
		

> water boils @ 212*f, woodgas @~600*, fire@~1200*



Those #s are only good at sea level. People that are at 4000+ are gonna have a different story along with results. Time to de-rate those #s. Oil and gas #s will show significant change at 2000 and up.
Just saying.


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## vvvv (Aug 18, 2010)

north of 60 said:
			
		

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http://www.newton.dep.anl.gov/askasci/chem00/chem00182.htm


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## roddy (Aug 18, 2010)

Hiram Maxim said:
			
		

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for hard maple  we start at about 39 degrees celcius and over about a 10 day span,we bring the temp up to 62 degees celcius for the last day,which is the conditioning period(thats the time we put moisture to he wood to get rid of the stress in the lumber that has occured during the drying period....ive never done cedar,but for pine the times and temp are close to the same as maple.you are right in assuming that those temps you heard seem a bit low.(again i,m not absolutely sure about cedar)also we are taking the lumber to 6-8 % moisture,which maybe different than what your cedar guy is doing.....rod


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## Battenkiller (Aug 18, 2010)

north of 60 said:
			
		

> Those #s are only good at sea level. People that are at 4000+ are gonna have a different story along with results. Time to de-rate those #s. Oil and gas #s will show significant change at 2000 and up.



Everything changes up high.  

Most easy to measure would be draft.  A chimney at 1 mile high will have 20% less capacity and a lower static draft than the same chimney at sea level.  What would that mean regarding super-dry wood?  I'm not at all certain, but I can think of one scenario.  With reduced draft, residence time for flue gases would be longer.  Adding a bunch of small splits of extremely dry wood onto a raging bed of coals could lead to a system packed with smoke.  

Even if you opened up the air all the way (which can lead to some nasty backpuffing), there would still be denser smoke in this system than in the same one operating at sea level.  It's totally possible that not enough air could be introduced to completely burn off this smoke.  As well, there is less oxygen at those levels, so you would need even more air volume introduced for combustion to be complete.  This could exacerbate the problem.  Lower draft will also mean lower intake velocity, reducing the mixing effect of turbulence on air and wood gases, leading to incomplete combustion.  If you can get the fire hot enough, the higher flue temps will increase the draft (and therefore, the intake velocity), resulting it improved combustion, but then more heat goes up the chimney.  All things considered, not an efficient and controlled burn.

All hypothetical, I've never burned above 2000'.  Maybe Beetle-kill can give us his observations at 8000'? ;-) 

My feeling on the subject it that if you put a big load of kiln-dried pine cutoffs or split 2x4s into a hot stove, you are going to have problems, like creosote formation, lower temperature burns, severe backpuffing, and wasted fuel.  If you put large splits or rounds of dense super-dry hardwood into the same stove, pyrolysis will occur much slower and the stove should be able to handle it no problem if you give it enough air.  The answer lies in experience and observation, and not in a set of absolutes.  But I personally think it's good to let new burners know that dry wood alone won't solve all their burning problems, and that in some instances, drier wood wastes more wood through smoke than less-dry wood.  

Stoves are designed for wood around 20% MC, stoves are tested with wood around 20% MC, so it stands to reason that 20% MC should not be considered to be merely adequate, but rather, the ideal.


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## Battenkiller (Aug 18, 2010)

roddy said:
			
		

> for hard maple  we start at about 39 degrees celcius and over about a 10 day span,we bring the temp up to 62 degees celcius for the last day,which is the conditioning period(thats the time we put moisture to he wood to get rid of the stress in the lumber that has occured during the drying period..



What's the RH of that air at 39ºC?  I can go from fresh cut cherry to <20% MC in my stove room in less than 2 weeks.  Temps are up around 86ºF (30ºC) and RH about 20-25%, fans blowing directly on the wood.

I'm curious about the kiln schedule you use.  I've read that most commercial kilns start at high temps and high RH until the FSP (about 30% MC for most woods) is reached, and then humidity is gradually dropped.  This is supposed to prevent case hardening and other internal stresses from occurring.  If I understand what you are saying, you allow them to occur and then condition them out later?  Correct me if I misunderstood.


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## dannynelson77 (Aug 18, 2010)

I got some wood last winter (mostly Red Oak) from an old farmer that had it stored in his barn for years.  It was definitely oak, but I do have to say it was so dry it was very light for Oak.  And it did burn much faster than any Oak I have burned.  Too fast IMO.  My moisture meter read it was 9% when i split a piece.  IMO, it was too dry.  Put out greaat heat but I had to keep feeding the stove way more than I normally do.


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## oldspark (Aug 18, 2010)

dannynelson77 said:
			
		

> I got some wood last winter (mostly Red Oak) from an old farmer that had it stored in his barn for years.  It was definitely oak, but I do have to say it was so dry it was very light for Oak.  And it did burn much faster than any Oak I have burned.  Too fast IMO.  My moisture meter read it was 9% when i split a piece.  IMO, it was too dry.  Put out greaat heat but I had to keep feeding the stove way more than I normally do.


 Maybe RichL did have some old oak that was light, I remember reading other posts about very old wood that was inside and they thought the wood was fine but maybe it burnt too quick and they did not realize it was too dry. I burnt some wood while we were camping that was very old ash and it seemed like it still had a "normal" amount of moisture in t when I split it, had to be a good 10 years old, plus the wood was a normal  weight for white ash.


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## dannynelson77 (Aug 18, 2010)

Yea I think being in the barn, kept it get so low on the moisture scale.  In the hot summer it probably was like a kiln in there.....


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## Rich L (Aug 19, 2010)

dannynelson77 said:
			
		

> I got some wood last winter (mostly Red Oak) from an old farmer that had it stored in his barn for years.  It was definitely oak, but I do have to say it was so dry it was very light for Oak.  And it did burn much faster than any Oak I have burned.  Too fast IMO.  My moisture meter read it was 9% when i split a piece.  IMO, it was too dry.  Put out greaat heat but I had to keep feeding the stove way more than I normally do.


 Gee it's good to see another has had a similar experience as I.


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## North of 60 (Aug 19, 2010)

Battenkiller said:
			
		

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So I take it that you agree with me on elevation.
By the way, Blaze King prefers the MC of the wood for there Cat stoves to be between 12 to 18%.


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## Battenkiller (Aug 19, 2010)

north of 60 said:
			
		

> So I take it that you agree with me on elevation.



Not sure.  All you said is that things change above 4000'.  My position is that they may very well change for the worse regarding clean burns when using overly dry wood.  Do you agree with that?   


Here's the key points of the article as I view it:




> Properly seasoned firewood still has a fair amount of water in it, say 15 to 20 of its weight. That *water acts like a regulator of the combustion process* along with a few other factors like piece size, load configuration and combustion air supply.
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Note the initials at the bottom.  This article was written by none other than John Gulland.  I don't know about his personal experiences using old wood stored in a barn or in the desert, but here is his CV:


http://www.gulland.ca/abtjohn.htm


The least of your worries with overly dry wood is that it burns too fast.  It's the excessive smoking that can cause problems - in your burn, and in your flue. :zip:


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## vvvv (Aug 19, 2010)

Battenkiller said:
			
		

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it aint necessarily smoke, it can be uncombusted CO which is a significant energy source of heat & is invisible!


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## dannynelson77 (Aug 20, 2010)

Yea with the dry Oak I had I did not have a smoke problem.  Only problem I had was it burning too quickly!


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## vvvv (Aug 20, 2010)

north of 60 said:
			
		

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you're right about altitude changing the boiling temps.  question is= does it also change the flash point? got it posted on scientific forums but no answers yet.


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## Battenkiller (Aug 20, 2010)

BLIMP said:
			
		

> it aint necessarily smoke, it can be uncombusted CO which is a significant energy source of heat & is invisible!



Right.... all that carbon monoxide again. :ahhh: 

Pook, the gist of the article is about increased particulate emissions (smoke) as you deviate either way from the ideal moisture content band of 15-20% MC, not about heat loss through unburned CO gas.  CO never clogged anybody's flue with creosote and set their house on fire.

Not that there isn't significant heat loss going on as well.  CO has one of the highest ignition temperatures of all wood gases, and it is one of the more abundant products of pyrolysis.  It also has a lot of potential heat energy locked up in it, so making too much CO too soon is a waste of good wood.  

I think it's a lot more important to properly size the pieces of wood that you add to the fire.  Highly seasoned wood should be used in larger pieces than less seasoned wood.  However you do it, pay attention to the top of the stack.  If you don't see smoke, pyrolysis is proceeding at the rate it should for the wood you are using, and for your particular stove.  If the rate of pyrolysis isn't excessive, you're not making excessive CO either.


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## vvvv (Aug 20, 2010)

Battenkiller said:
			
		

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lol the point of the article is to challenge folksy wisdom thru education so u respond with folksy wisdom about the burn which i'd believe if u had some actual data to back it up. If a fire develops from the coals up, its an accelerating phenomenom as the woodload heats up & produces more outgassing.
the excess CO wont plug a chimni but in a concentrated area of "clean burning" woodstoves with weather inversion factors ....


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## Rich L (Aug 21, 2010)

dannynelson77 said:
			
		

> Yea with the dry Oak I had I did not have a smoke problem.  Only problem I had was it burning too quickly!



 Me Too !


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