# What is the Ideal Moisture Percentage to burn wood



## katwillny (Jan 1, 2012)

Is there a set moisture content that wood should be burnt at? Do different wood types have different sweet spots that they should be burn at? There may be previous threads, but I figure I'd get the conversation started. 

thanks
Franklin


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## Pallet Pete (Jan 1, 2012)

I tend to go by sound and feel but 20% and under is generally acceptable to burn. 

Happy New Year
Pete


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## Loco Gringo (Jan 1, 2012)

I re-cut about 1/2 cord 2 yr split oak yesterday and checked each piece before removing from the frame, and 9 outa 10 were 14-17 percent. Im thinking thats pretty good yeah?


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## EatenByLimestone (Jan 1, 2012)

You burn whatcha got.  Sometimes you may have to clean the chimney often...

Ideally, you bang two pieces of wood together and they ring out loud and clear.   

Matt


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## NH_Wood (Jan 1, 2012)

Loco Gringo said:
			
		

> I re-cut about 1/2 cord 2 yr split oak yesterday and checked each piece before removing from the frame, and 9 outa 10 were 14-17 percent. Im thinking thats pretty good yeah?



Yes, real good Loco! And for the OP, with a standard moisture meter, I believe that 25% and less is considered fine for the stove. Measure from the face of a fresh split piece of wood. Cheers!


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## SolarAndWood (Jan 1, 2012)

KatWill said:
			
		

> Is there a set moisture content that wood should be burnt at?



The driest you have the time and space to get it.  You are not going to over dry wood if air drying in upstate NY.


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## rwhite (Jan 1, 2012)

Size of fuel is also important. These are commonly used charts for determining wildfire potentials:

Fuels are classified into four categories by which they respond to changes in moisture. This response time is referred to as time lag. The four categories are:
â€¢1-hour fuels: up to 1/4 inch in diameter.
â€¢10-hour fuels: 1/4 inch to 1 inch in diameter.
â€¢100-hour fuels: 1 inch to 3 inches in diameter.
â€¢1000-hour fuels: 3 inches to 8 inches in diameter

Granted these are based on round fuels but it is possible that the % moisture you measure may be different (especially on smaller splits) by the time you burn it even if it's only a few days. I burn a lot of 2x4 mill ends that are kiln dried and burn really well and usually measure 12-15% moisture. Even if covered a few days of rain and high humidity will make them harder to start and the moisture can go above 20%. So the moral is you can dry a smaller split quicker but it also reacts quicker to environmental changes. If we start having a few days of rain and high humidity I usually bring in a few days worth of wood and put it in the basement.


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## katwillny (Jan 1, 2012)

rwhite said:
			
		

> Size of fuel is also important. These are commonly used charts for determining wildfire potentials:
> 
> Fuels are classified into four categories by which they respond to changes in moisture. This response time is referred to as time lag. The four categories are:
> â€¢1-hour fuels: up to 1/4 inch in diameter.
> ...



Thanks Rwhite, this helps


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## RNLA (Jan 1, 2012)

Feels like dry like a popcorn fart, sounds like a bowling pin when you bang it together... All this is a good thing. I don't have a moisture meter but I will never burn wood less than a year old again either. I know well that I may not be burning the best wood but it is better by a factor of 10 compared to what I had done in the past! Thanks to Brother Bart and Backwoods Savage for telling and showing what seasoned wood is.


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## Backwoods Savage (Jan 1, 2012)

I have never been concerned with moisture content. I simply give the wood time to dry and it burns great.


EDIT:  Perhaps I should have worded that a bit different. I am concerned about moisture content but have never been concerned at what % moisture the wood is. We just simply dry the wood and burn it. It works amazingly well and is very simple to do with no special tools required.


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## katwillny (Jan 1, 2012)

Thanks Dennis. I think i was just trying to justify the expense and if it would be worth the money to get a MM. I do got a birthday coming and all so I have to give the missus ideas. But I understand the need to dry wood properly to eliminate creosote. Thanks all for your replies. 
Franklin


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## CTYank (Jan 1, 2012)

Loco Gringo said:
			
		

> I re-cut about 1/2 cord 2 yr split oak yesterday and checked each piece before removing from the frame, and 9 outa 10 were 14-17 percent. Im thinking thats pretty good yeah?



That's typical of wood here, on bringing it in from pile. Mind that this year's drying season morphed into super-soggy season with all the rain.

Storing it near the woodstove for a while takes the MC down quite a bit more. The really good stuff gets more such time than the crap.

NO SUCH THING as "too dry." If you think so, I'll relieve you of it. Claims of such are purest BS, IMHO and that of my lil Morso.


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## RNLA (Jan 1, 2012)

KatWill said:
			
		

> Thanks Dennis. I think i was just trying to justify the expense and if it would be worth the money to get a MM. I do got a birthday coming and all so I have to give the missus ideas. But I understand the need to dry wood properly to eliminate creosote. Thanks all for your replies.
> Franklin


 If your trying to justify the expense put a new maul or chainsaw on the list of gifts for your B-day.


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## katwillny (Jan 1, 2012)

RNLA said:
			
		

> KatWill said:
> 
> 
> 
> ...


Already got me two Mauls, a 6lb and an 8lb. Also have my trusty Poulan 18 and the little Homelite 14 for smaller logs. The Homelite is always on the trunk of my car in case something catches my eye on the way to and from work.


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## oldspark (Jan 2, 2012)

I just took out a loan on my MM, I think the payment was $1 a month for a year.


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## maxed_out (Jan 2, 2012)

katwill, you need to do a search for some of the charts that battenkiller did.  theres one graph in particular that will help you understand the relationships between mositure, heat output and efficiency.  once I saw these, bingo, lights went off for me.  I think that thread may be titled "can my wood be too dry". not sure.


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## Lumber-Jack (Jan 2, 2012)

oldspark said:
			
		

> I just took out a loan on my MM, I think the payment was $1 a month for a year.


Glad to see you took on that financial commitment there Oldspark, I plan to follow suit as soon as I finish paying off my matches.  ;-)

Probably the biggest and most common failure new, and old, wood burners make again and again is burning wood that is not properly dried. The simplest, most accurate way of "measuring" the moisture content of wood is with a moisture meter.  Next to matches a moisture meter is one of the cheapest wood burning tools a person can buy.      nuff said


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## Ram 1500 with an axe... (Jul 14, 2013)

Anybody?


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## jdp1152 (Jul 14, 2013)

anybody what?


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## HDRock (Jul 15, 2013)

Lumber-Jack said:


> The simplest, most accurate way of "measuring" the moisture content of wood is with a moisture meter. Next to matches a moisture meter is one of the cheapest wood burning tools a person can buy. nuff said


I agree, and the $12 Harbor Freight meter works as good as the $30 General Tools meter. Yes there are more accurate more expensive meters but not necessary for fire wood.
If U are 3 years ahead I guess U wouldn't need one, If U have 30 years experience burning wood maybe U don't need one but , If just starting out, I think it's a must have tool and , I for one, would never be without one .
We have the technology ,and it is affordable , why not use it ?
Even if U have to burn what U got, at least U know what U got

EDIT 25% MC will burn 20% is better, _*Under*_ 20% is best.
Yes U can burn wood above 25% but U will have several problems


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## weatherguy (Jul 15, 2013)

20% and below, I burned some oak last year that was 22-23% and it was ok, higher than that and I really notice a difference.


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## Woody Stover (Jul 15, 2013)

weatherguy said:


> 20% and below, I burned some oak last year that was 22-23% and it was ok, higher than that and I really notice a difference.


I like the way it catches when it's down about 18% or less, but the EPA test wood is at 20% _wet-basis_, which would read 25% on a meter. When I burn 25% wood, it is hissing like a perturbed cat when catching.


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## blades (Jul 15, 2013)

My personal numbers, HF  MM w/ fresh battery

popcorn fart/ kiln dry = 8% ( this will float depending on ambient conditions) kindling
Optimum burn  12-15 %  ( this can take 3 or more years for Oak / Hickory or similar longer if using really big splits over 6-8"my area)
 15-20% will burn ok in my units but heat output reduced ( at this range sounds like a baseball bat but I can feel the difference when burning)
20-25% still wet behind the ears( not spiting but got to run with the primary almost wide open for a good portion of the time) only use if desperate
25% and above might as well pay the utility company or buy compressed wood logs, Generally defeats purpose of burning wood in the first place. Wallet deflaters.


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## oldspark (Jul 15, 2013)

Blades numbers are off of what mine would be, any thing below 20% seems to be fine in my stove, not sure if I can get much below 15% any way.


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## thewoodlands (Jul 15, 2013)

katwillny said:


> Is there a set moisture content that wood should be burnt at? Do different wood types have different sweet spots that they should be burn at? There may be previous threads, but I figure I'd get the conversation started.
> 
> thanks
> Franklin


 Since we don't have any Oak, our firewood is stacked for a minimum of 2 years then it's ready for burning, I never use the M/M anymore. When we did it was 20% or under.


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## oldspark (Jul 15, 2013)

I only use mine to post results on here.


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## Ram 1500 with an axe... (Jul 15, 2013)

Me being a rookie an just accumulating wood this spring, I just got my $30 general yesterday, I split a round of red oak, it was at 45, I then split a split that's been split for a week. That came out at 29, I have maple  and black locust that I split  in march and April both reading 17 and 18. I also split a skinny piece of honey locust, I couldn't believe it was 26. So I should be fine with the maple and black locust?


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## ScotO (Jul 15, 2013)

Ideally, anything below 20% is very good for the stove.....that said, I've burned wood that was in the low 20's with no problem, too.....
I don't own a MM, all of my wood seasons 3 years and I don't have any problems with it that way.  Before, though, I burned moister wood and cleaned the chimney a lot more frequently because of that.


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## Ram 1500 with an axe... (Jul 15, 2013)

Great, thank you all very much for the input, I'm feeling better for the upcoming season..


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## Woody Stover (Jul 15, 2013)

blades said:


> 15-20% will burn ok in my units but heat output reduced ( at this range sounds like a baseball bat but I can feel the difference when burning)
> 
> 20-25% still wet behind the ears( not spiting but got to run with the primary almost wide open for a good portion of the time) only use if desperate


I "liked" your post but not sure that something at 18% would result in decreased heat output, it might just burn a bit slower so that the heat isn't released as fast up front. And I don't have to open the air up that wide on the low 20s stuff, but it might hiss a bit at the start....


Ram 1500 with an axe... said:


> Me being a rookie an just accumulating wood this spring, I just got my $30 general yesterday, I split a round of red oak, it was at 45, I then split a split that's been split for a week. That came out at 29, I have maple and black locust that I split in march and April both reading 17 and 18. I also split a skinny piece of honey locust, I couldn't believe it was 26. So I should be fine with the maple and black locust?


That Oak will really slow down once you hit the upper 20s, and won't burn well for a long time. The Maple and Locust at 18% is good. Hopefully that wasn't just a couple of splits that were drier than the rest. But it sounds like you'll probably get by OK, though.


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## blades (Jul 15, 2013)

There is always room for numbers up and down the scale and of course a hf meter is not what one would call a piece of high end equipment,  I do not know if it could be recalibrated or not but it gets me where I need to go. I have some pieces of furniture (Oak, Maple)  that I keep in the shop as a test reference.


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## brakatak (Jul 16, 2013)

I just got the General MM today..   are you drilling small holes into the splits and stick the MM pointers in the hole?   When I do that I get 40% on my freshly split oaks.    When I just put the MM pointers against the split side I get about 20%.     Big difference when I drill holes and stick the pointers in.      Just wondering what is correct method to use?


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## Ram 1500 with an axe... (Jul 16, 2013)

I stick mine in so the meter can stand straight up without touching it. I never thought of drilling holes, lets see what others do


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## HDRock (Jul 16, 2013)

brakatak said:


> I just got the General MM today.. are you drilling small holes into the splits and stick the MM pointers in the hole? When I do that I get 40% on my freshly split oaks. When I just put the MM pointers against the split side I get about 20%. Big difference when I drill holes and stick the pointers in. Just wondering what is correct method to use?


When U check a split for moisture, U must split the piece first, and check it right then N there ,check it smack in the middle , if U split it and wait till the next day U will not get an accurate reading what the MC, (moisture content) is inside the piece.


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## Ram 1500 with an axe... (Jul 16, 2013)

To brakatak and all,
I just read the directions. It says to drill the holes to get a more accurate reading so that the tips touch inside. But that doesn't take into consideration that you are splitting the split just before you take the reading. Therefore it is the tips that are reading the MC, not the entire spike. It clearly says not to use force when trying to take a reading.
So the correct method is what HDRock said to do.....
But thanks for making me read the directions, so I know I am doing it right.....


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## brakatak (Jul 16, 2013)

Ram 1500 with an axe... said:


> To brakatak and all,
> I just read the directions. It says to drill the holes to get a more accurate reading so that the tips touch inside. But that doesn't take into consideration that you are splitting the split just before you take the reading. Therefore it is the tips that are reading the MC, not the entire spike. It clearly says not to use force when trying to take a reading.
> So the correct method is what HDRock said to do.....
> But thanks for making me read the directions, so I know I am doing it right.....


 
Good to know... thanks for reading the directions and sharing.   i'll try that method tomorrow.


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## Ram 1500 with an axe... (Jul 16, 2013)

Woody Stover said:


> I "liked" your post but not sure that something at 18% would result in decreased heat output, it might just burn a bit slower so that the heat isn't released as fast up front. And I don't have to open the air up that wide on the low 20s stuff, but it might hiss a bit at the start....
> That Oak will really slow down once you hit the upper 20s, and won't burn well for a long time. The Maple and Locust at 18% is good. Hopefully that wasn't just a couple of splits that were drier than the rest. But it sounds like you'll probably get by OK, though.


Thanks I will be testing more in the upcoming future...


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## oldspark (Jul 16, 2013)

I just push the pointed pins in hard, no need to drill holes with the HF unit.


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## HDRock (Jul 17, 2013)

oldspark said:


> I just push the pointed pins in hard, no need to drill holes with the HF unit.


I push in hard to,  with the HF unit, and I have used it a lot , nothing has broken


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## Sprinter (Jul 17, 2013)

HDRock said:


> I push in hard to, with the HF unit, and I have used it a lot , nothing has broken


I have noticed a difference of a couple % between pushing in moderately hard and very hard (1/8" to 1/4"), but sometimes it made no difference at all.

I'm in the "get a meter" camp. Anything else is guesswork. Wood with 30% MC has 50% more water than wood with 20% MC and that makes a big difference.


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## Paulywalnut (Jul 17, 2013)

I use my MM on scrounged wood that I just split to see where I am starting from. I just let it season 3 years
like others have said previously.


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## infinitymike (Jul 17, 2013)

I push it in hard too,  oh wait wrong forum... sorry 

But seroiusly, its like a cheap tire pressure guage, gotta take a bunch of readings and take an average.
In the end, if its 3 years old it  will be just fine.

However in a Wood Gun gasifier things are a bit different. They actually recommend 25-30%
If its too dry (20% and below it can start puffing. 
Thats where there isn't enough 02 to burn well and so it gets starved and then can suck more air into the firebox.
Kinda like when you take a plastic gallon jug of water and dump it out, you get that chugging thing going on.


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## Ram 1500 with an axe... (Jul 17, 2013)

Being ahead 3 years and those that are not is what separates those that should use a moisture meter.... And by the way, I just heard a commercial that said " why don't you pick on your own size" too funny but true, you guys are seasoned, we are trying to get seasoned......does that make any sense?


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## infinitymike (Jul 17, 2013)

I wish I was three years ahead. 
I only started burning full time 2 winters ago. 
The wood I'll be burning this winter will only be just under 2 years old. 
NOW, I do have enough drying that will get into the 3 year dry bracket in about 2 more years. 
Then I'll be coasting real fine.


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## Sprinter (Jul 17, 2013)

infinitymike said:


> I wish I was three years ahead.
> I only started burning full time 2 winters ago.
> The wood I'll be burning this winter will only be just under 2 years old.
> NOW, I do have enough drying that will get into the 3 year dry bracket in about 2 more years.
> Then I'll be coasting real fine.


Don't forget that drying time depends on factors like species, climate, covered or not, etc.  Last season I burned 20-25%alder that was less than a year old.  But I also have some big leaf maple that is still 35% after more than a year.  I don't know if I'll ever burn that stuff.  Oak is notoriously slow, as are others.  Splitting small can make a huge difference.


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## Ram 1500 with an axe... (Jul 17, 2013)

Sprinter said:


> Don't forget that drying time depends on factors like species, climate, covered or not, etc.  Last season I burned 20-25%alder that was less than a year old.  But I also have some big leaf maple that is still 35% after more than a year.  I don't know if I'll ever burn that stuff.  Oak is notoriously slow, as are others.  Splitting small can make a huge difference.


Sprinter, you better get with the program and get some 17% stuff.....


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## Ram 1500 with an axe... (Jul 17, 2013)

Sprinter, if you pay for the shipping, i will send you some maple and black locust....


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## MrWhoopee (Jul 18, 2013)

Woody Stover said:


> I "liked" your post but not sure that something at 18% would result in decreased heat output, it might just burn a bit slower so that the heat isn't released as fast up front. And I don't have to open the air up that wide on the low 20s stuff, but it might hiss a bit at the start....


 
As the MC goes up, more of the heat is used to boil water, which then goes up the stack. This results in less heat output from the stove. If you want heat, use dry wood. If you want to boil water, use a tea kettle.


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## oldspark (Jul 18, 2013)

MrWhoopee said:


> As the MC goes up, more of the heat is used to boil water, which then goes up the stack. This results in less heat output from the stove. If you want heat, use dry wood. If you want to boil water, use a tea kettle.


But his point was that 18% is in the prime range for firewood and not enough moisture to be an issue.


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## PapaDave (Jul 18, 2013)

Most stove manufacturers who actually put the info in their manual, suggest 20% or less. Having typed that, they also say that you should "season" wood for 6-12 months before burning. That's fine for some wood and areas of the country, but won't work for anything but soft hardwoods, and Pine around here.
When I started, the wood was really wet and didn't burn well...no MM needed to tell me.
The wood has gotten drier and burned better because I got ahead a little more each successive year.
Strive for that and be happy.
Pine, Poplar, Spruce, and others will dry well enough to burn in 6 months (longer is gooder), soft Maple, Ash take a year or more, Oak.......well, Oak is in it's own category.
No experience with BL, Hickory, or others.
I had nothing but Oak at first. If I'd known better (I didn't), I'd have gotten a bunch of Ash for the 2nd year.
The 1st couple years are the toughest. If you can learn early that wet doesn't burn, you've come a long way, baby.


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## oldspark (Jul 18, 2013)

PapaDave with all due respect, I can get Cherry, Silver Maple, and Ash (maybe more types but have not checked) to less then 20% in about 7 full months through the summer here in Iowa, saying wood has to be seasoned for a set periond of time does not always take into account it that includes the full summer months. This is why I always say your results may very. I dont consider the Ash to be a soft hardwood and not sure which ones you do.


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## oldspark (Jul 18, 2013)

This is of course cut to length and split in single rows for that 7 months.


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## oldspark (Jul 18, 2013)

I did cut some Cherry in March and it still feels heavy but by October it will be below 20%, wont burn it this year but I could, for fun I could see what the moisture level is now.


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## PapaDave (Jul 18, 2013)

PapaDave said:


> That's fine for some wood and areas of the country, but won't work for anything but soft hardwoods, and Pine* around here*.


Your "around here" is different than mine.
I just split some pine slab yesterday that's been sitting for almost 5 years. It was still a bit damp after being split.
You are correct...no absolutes.


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## oldspark (Jul 18, 2013)

My only guess is we have a lot more wind then you do.


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## PapaDave (Jul 18, 2013)

Sun too. It can be downright gloomy for days and days.
Not recently though.


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## USMC80 (Jul 18, 2013)

Ash where I am usually good in about 8 months


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## Sprinter (Jul 18, 2013)

oldspark said:


> My only guess is we have a lot more wind then you do.


That will help a lot along with the relative humidity.


oldspark said:


> This is of course cut to length and split in *single rows* for that 7 months.


Has anyone done an experiment to see how much single row stacking is better than multiple rows?  It seems like it would be better, but how much?


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## oldspark (Jul 18, 2013)

Good question sprinter but do not know if any one has tried it, its not going to get the wind on the wood like a single row but hard to judge how much better for the single row, I do not top cover my wood either but if I had multiple rows I would cover it for sure as the inside of the rows will stay wetter for longer which could lead to longer drying times or even rot.


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## Backwoods Savage (Jul 18, 2013)

There is a world of difference between the climate where PapaDave lives vs where oldspark lives! And yes, that can and will make a difference.


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## Backwoods Savage (Jul 18, 2013)

PapaDave said:


> Most stove manufacturers who actually put the info in their manual, suggest 20% or less. Having typed that, they also say that you should "season" wood for 6-12 months before burning. That's fine for some wood and areas of the country, but won't work for anything but soft hardwoods, and Pine around here.
> When I started, the wood was really wet and didn't burn well...no MM needed to tell me.
> The wood has gotten drier and burned better because I got ahead a little more each successive year.
> Strive for that and be happy.
> ...


 
And most stove manufacturers also will tell you not to burn pine.....


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## oldspark (Jul 18, 2013)

Well for me and my stove, the 20% figure rings true and its not just the stove manufactors who use the figure, I had no idea what the %'s were until I joined this site and started reading up on it and believe me you will read things that dont make any sense once in a while, wood does quit drying after it reaches a point and it wont get any dryer after that to speak of.
 Most of the moisture is lost in a short period of time (tests by posters and some wood sites have found this to be true) and the last part of the seasoning comes slower,  so most of what I have read is either true or close to true when I compare it to my real world findings.
Best thing is keep track of your own seasoning and then you know.
For the new wood burners and ones who have little storage space a MM is your friend.


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## Ram 1500 with an axe... (Jul 18, 2013)

oldspark said:


> Well for me and my stove, the 20% figure rings true and its not just the stove manufactors who use the figure, I had no idea what the %'s were until I joined this site and started reading up on it and believe me you will read things that dont make any sense once in a while, wood does quit drying after it reaches a point and it wont get any dryer after that to speak of.
> Most of the moisture is lost in a short period of time (tests by posters and some wood sites have found this to be true) and the last part of the seasoning comes slower,  so most of what I have read is either true or close to true when I compare it to my real world findings.
> Best thing is keep track of your own seasoning and then you know.
> For the new wood burners and ones who have little storage space a MM is your friend.


I agree and I'm finding it out now that depending on the wood, some mc drops quickly the first few weeks, then I'm sure it takes more time the lower it gets....all wood was not created equal...


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## Trilifter7 (Jul 18, 2013)

I would guess that split size also plays a big part in drying time as well.


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## oldspark (Jul 18, 2013)

Trilifter7 said:


> I would guess that split size also plays a big part in drying time as well.


 Very much so, if you are in a bind for wood split it a little smaller and even shorter and it will help in the drying.


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## Sprinter (Jul 18, 2013)

Trilifter7 said:


> I would guess that split size also plays a big part in drying time as well.


Very much so. Think of drying time in terms of mm per week or something like that. The thinner the split, the sooner it will dry all the way through.   I also try to split for the widest surface area.


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## Ram 1500 with an axe... (Jul 18, 2013)

I am splitting All of my beech 12-15 in long, I'm hoping this will help, it is at 28% when splitting the round...


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## oldspark (Jul 18, 2013)

Ram 1500 with an axe... said:


> I am splitting All of my beech 12-15 in long, I'm hoping this will help, it is at 28% when splitting the round...


Wont hurt that's for sure. Beech has fairly low moisture content on the stump so a good wood for drying quickly.


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## Sprinter (Jul 18, 2013)

Ram 1500 with an axe... said:


> I am splitting All of my beech 12-15 in long, I'm hoping this will help, it is at 28% when splitting the round...


I'm not familiar with beech, but that should come out fine next season.


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## Trilifter7 (Jul 18, 2013)

Sounds like there's lots of variables making it hard to estimate the average drying time but i think we can all agree that anything below 20% and you're good to go!


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## Sprinter (Jul 18, 2013)

Trilifter7 said:


> Sounds like there's lots of variables making it hard to estimate the average drying time but i think we can all agree that anything below 20% and you're good to go!


That's the bottom line.  But even if you can't make that ideal, there are ways to handle it.  Some supplement with pallet wood, mill ends, Biobricks (or similar). etc.


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## MrWhoopee (Jul 20, 2013)

oldspark said:


> But his point was that 18% is in the prime range for firewood and not enough moisture to be an issue.


 
You are correct, but he questioned the idea that moisture content reduced the heat output of the stove. I was attempting to clarify that concept. Anything under 20% is perfectly acceptable, but less moisture is always better, with the possible exception of OWBs and other new-fangled devices.


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## oldspark (Jul 20, 2013)

MrWhoopee said:


> You are correct, but he questioned the idea that moisture content reduced the heat output of the stove. I was attempting to clarify that concept. Anything under 20% is perfectly acceptable, but less moisture is always better, with the possible exception of OWBs and other new-fangled devices.


His point was (and I agree with him) its not enough to amount to any thing below 20%, reduced heat out put is mostly associated with higher %'s of moisture, might be an interesting test though.


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## HDRock (Jul 21, 2013)

Dead standing trees ,on the ground , fresh cut, time of year cut, and other variables determine when wood is dry
Edit  How long it takes to dry


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## chvymn99 (Jul 21, 2013)

oldspark said:


> PapaDave with all due respect, I can get Cherry, Silver Maple, and Ash (maybe more types but have not checked) to less then 20% in about 7 full months through the summer here in Iowa, saying wood has to be seasoned for a set periond of time does not always take into account it that includes the full summer months. This is why I always say your results may very. I dont consider the Ash to be a soft hardwood and not sure which ones you do.


 
I've got some ash that I just split this spring, which was cut last year.  But it'll be ready this fall.  But then again, I'm in Kansas, kinda of like you.  We get the heat, sun, and wind which helps tremendously in the drying process.  I had some Oak that will be three years old, it was drying but at a slower pace.  It was against my fence with partial sun and partial wind (blocked by my rows of my hedge perpendicular to it).  I burnt some of the top layer this late spring.  It was Ok, so I went and laid some skids out in the wind and sun of my yard. What a world of difference it has made to that Oak.


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## MrWhoopee (Jul 21, 2013)

oldspark said:


> His point was (and I agree with him) its not enough to amount to any thing below 20%, reduced heat out put is mostly associated with higher %'s of moisture, might be an interesting test though.


 
This discussion made me curious about the actual amount of heat required to boil-off the water content of firewood, so I did some calculations:

A BTU (British Thermal Unit) is the amount of heat required to raise 1 pound of water 1 degree Fahrenheit. Using an ambient temperature of 70 deg. F. (YMMV), it takes 142 BTU to raise a pound of water to the boiling point (at sea level) of 212 degrees. A cord of Red Oak, at 20% MC, weighs 3570 lbs. and contains 22.1 million BTU/ cord. http://chimneysweeponline.com/howood.htm
The amount of water in a cord (20% of 3570 lbs.) equals 714 lbs. To vaporize that water: 714 lbs. x 142 BTU/lb.=101,388 BTU. This amounts to less than .5  percent of the total heat available. (101,388/22,100,000)x100=.458%

So, yes, the amount of heat required to dry wood at 20% MC is insignificant. For that matter, the amount of heat required to dry wood at 30% MC is also an insignificant fraction of the total amount available.

None of this has anything to do with the effect of the moisture content on the combustibility of the wood or creosote formation, it only describes the reduction of heat available.


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## Sprinter (Jul 21, 2013)

MrWhoopee said:


> This discussion made me curious about the actual amount of heat required to boil-off the water content of firewood, so I did some calculations:
> 
> A BTU (British Thermal Unit) is the amount of heat required to raise 1 pound of water 1 degree Fahrenheit. Using an ambient temperature of 70 deg. F. (YMMV), it takes 142 BTU to raise a pound of water to the boiling point (at sea level) of 212 degrees. A cord of Red Oak, at 20% MC, weighs 3570 lbs. and contains 22.1 million BTU/ cord. http://chimneysweeponline.com/howood.htm
> The amount of water in a cord (20% of 3570 lbs.) equals 714 lbs. To vaporize that water: 714 lbs. x 142 BTU/lb.=101,388 BTU. This amounts to less than .5 percent of the total heat available. (101,388/22,100,000)x100=.458%
> ...


But you need to factor in the most significant factor which is the latent heat of vaporization. After reaching the boiling point, it takes an additional 970 BTU to actually vaporize that same pound of water. It's the change of state from water to vapor that takes so much heat.


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## MrWhoopee (Jul 21, 2013)

Sprinter said:


> But you need to factor in the most significant factor which is the latent heat of vaporization. After reaching the boiling point, it takes an additional 970 BTU to actually vaporize that same pound of water. It's the change of state from water to vapor that takes so much heat.


 I knew there was something I was forgetting. That makes an additional 692,580 BTU, raising the total percentage to 3.59 percent. A significantly larger percentage than my original calculations. Thanks for that correction


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## Sprinter (Jul 21, 2013)

MrWhoopee said:


> I knew there was something I was forgetting. That makes an additional 692,580 BTU, raising the total percentage to 3.59 percent. A significantly larger percentage than my original calculations. Thanks for that correction


Just a theory, but I think another thing that happens to make the problem worse than the raw numbers would suggest is that all that water vapor is going to interfere with secondary combustion by the tubes or the cat, which steals from the stove's design efficiency and compounds the loss of heat transferred into the room.  If you were burning the wood in an open fireplace or old stove, the losses would probably be more in line with the BTU numbers.


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## blwncrewchief (Jul 21, 2013)

If we are going to get a little technical we are also raising that water to allot higher temperature that 212* in a modern wood stove. So if we take a secondary stove and say we are achieving 1000* firebox temp it would be a total of 930 + 970 = 1,900 Btu per pound x 714 pounds would be 1,356,600 or 6.1%. And we would get some of that back thru the heat transfer back out of the stove. However the real problem is the moisture stifling the burn rate and absorbing enough heat to cause inefficient combustion by keeping the burn out of the optimum combustion range. So the real loss is the far lower combustion efficiency by the lower combustion temperature. Most anyone that has burned higher and lower moisture wood in a modern stove has seen very clearly that there is a much greater difference in the real world than a couple percent that just the heat lost from the moisture would show.

I remember a member stating a year or so ago that once he changed to a modern stove how one bad piece of wood in a load ruins the whole party.


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## oldspark (Jul 22, 2013)

Bottom line for me I can not tell any difference in my stove after it gets below 20 percent, the secondaries work the same, this winter I could do some more testing but once the wood gets so dry it wont dry any more so most of my wood is at that level of moisture unless I make it a point to find some at 20%, as a test I did burn some at 22 to 23% and it seemed to burn fine with no sizzlers.


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## Holzstapel (Jul 25, 2013)

I tested a few splits last night with my new MM from Lowes.

Sassafrass from Sandy (C/S/S in November) 15%
Oak from Sandy (S/S in November) 25%
Birch from Sandy (S/S in June) 22%
Oak C/S/S 4 years ago (not much tho) 16%
Tulip from Sandy (S/S in June) 21%

The Oak, Tulip and Birch above were bucked back in November and stacked, I only S/S them in June

Oak from Sandy (C/S/S in June) 43%
Maple (i think) (C/S/S in June) TBD

Unfortunately, I have very little of the Sassafrass and 4 year old Oak.


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## Bluezx636 (Jul 25, 2013)

Holzstapel said:


> I tested a few splits last night with my new MM from Lowes.
> 
> Sassafrass from Sandy (C/S/S in November) 15%
> Oak from Sandy (S/S in November) 25%
> ...


Hey just wanted to know do you top cover your wood? I have wood split from sandy also but my moisture content is much higher. I probably should have covered from the start.


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## Holzstapel (Jul 25, 2013)

Bluezx636 said:


> Hey just wanted to know do you top cover your wood? I have wood split from sandy also but my moisture content is much higher. I probably should have covered from the start.


 
None of this wood has ever been covered.  I'm still figuring out what I want to top cover it with this winter.

Also of note - I resplit every split i tested so the meter was in the middle of a fresh split.


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## KenLockett (Jul 25, 2013)

infinitymike said:


> I push it in hard too, oh wait wrong forum... sorry
> 
> But seroiusly, its like a cheap tire pressure guage, gotta take a bunch of readings and take an average.
> In the end, if its 3 years old it will be just fine.
> ...


 

MIke, been down that road if you recall my series of posts last season. Contemplating MC as I wait for this coming heating season.


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## Holzstapel (Jul 31, 2013)

I tested a fresh split from the Oak stack* last night that fell during Sandy in the neighbors yard (C/S/S in June): 43% 

Birch from Sandy that was stacked in rounds but I split one last night: 24%
Beech from Sandy that was stacked in rounds but I split one last night: 34%

*the stack was on the ground last night when we got home from work.  We did stack a little high, but determined that the pallet sunk which caused the topple.  Good times stacking it all again.


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## Ram 1500 with an axe... (Jul 31, 2013)

I would get that birch split and stacked in sun and wind in single line ASAP.


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