You guys ought to be ashamed

[planman]

Some of the old timers may be right.

Im only burning wood for 3 years now but when I first started I questioned everything. I neither have the time or desire to cut or stack wood myself as my time is more valuable. Ive found very little scientific research supporting an optimum 20 % moisture content or that dryer is better. I did find the following : http://www.fs.fed.us/pnw/pubs/pnw_rn450.pdf which supports my non stacking as just as effective as stacking for drying wood. I have also found numerous studies that support a 3 month drying time in most areas as being sufficient. So in the interest of time and money, I dont stack but I do buy my firewood in March of each year and cover the pile with a tarp. Works for me:msp_thumbup:

 

[brianmorgan17]

Good article. I stack because it looks neeter and takes less room. I'm not real excited about having to move all the seasons wood into the barn in the spring. I need to find a way to NOT handle the wood so much.

I cut the tree and cut to length. If I have more than a load, I unload and get more. Then I have to pick it back up or otherwise move it to the splitter log lift. Then I split and either carry each piece to the stack or throw it in a pile that I have to move again to stack.

I'm wore out and haven't burned any yet.

Brian

 

[MrWhoopee]

Im only burning wood for 3 years now but when I first started I questioned everything. I neither have the time or desire to cut or stack wood myself as my time is more valuable. Ive found very little scientific research supporting an optimum 20 % moisture content or that dryer is better. I did find the following : http://www.fs.fed.us/pnw/pubs/pnw_rn450.pdf which supports my non stacking as just as effective as stacking for drying wood. I have also found numerous studies that support a 3 month drying time in most areas as being sufficient. So in the interest of time and money, I dont stack but I do buy my firewood in March of each year and cover the pile with a tarp. Works for me:msp_thumbup:

From the U.S. Forest Service study (which is a study of drying wood using a solar kiln) which you referenced above:

"Unsplit paper birch cut to 16- to 18-inch lengths will not air dry to 20 percent moisture content in a single season. Any system that would accelerate drying to permit burning of dry wood the same year it is cut would be useful."

The clear implication being that 20% is the target number for suitable burning, if you can achieve close to that MC in 3 months, so much the better. The study also states:

"High moisture content in firewood results in less effective burning of the wood and in a loss of energy in evaporating the water during burning. A cord of paper birch (Betula papyrifera Marsh.) firewood with 15 percent moisture (dry weight basis) would be expected to use an energy amount equal to 470,000 British thermal units (Btu) during burning to evaporate this moisture. An equivalent cord of paper birch that had a moisture content of 80 percent would be expected to use 2.5 million Btu (Ince 1979). The dry cord will produce more than a 12-percent increase in usable heat."

No need to clarify that.

Regarding stacking, the study goes on to state:

"Each stack was about 18 inches wide, 8 feet long, and 5.5 feet high and contained approximately one-half cord. In two of the piles, individual pieces were oriented north-south and conventionally stacked. In the third pile, alternate tiers of pieces were oriented east-west to provide for better air circulation."

This clearly describes a single row of stacked wood (which the diagram also shows). Though they frequently use the word "pile", the pile they descibed was stacked. I did not find any reference to a pile, in the sense of a heap of wood with no organization or alignment of the individual pieces.

Again, this study was comparing drying stacks of green paper birch using a simple solar kiln as compared to air drying the same type of stack. They did not compare loose piles to organized stacks. I do NOT maintain that one dries better than the other. I do maintain that I can stack more wood in a given footprint than can be loosely piled in the same, which is frequently the reason for stacking.

Referencing scientific studies is only helpful if they studied and supported the methods you espouse.

I do not wish to convince you that your methods are wrong. If they work for you, that's all that counts.
However, if you wish to convince others.....

 

[planman]

Firewood drying in 3 months in a pile not stacked

Sorry forgot to include this study which has pictures !!!! I myself have found no difference in stacking vs pile and as per this study a simple cover will do in about 3 months you should be down to a good moisture %

http://www.aqfairbanks.com/wp-content/uploads/Wood-Storage-Best-Practices-Final-Report-2.pdf

 

[MrWhoopee]

Sorry forgot to include this study which has pictures !!!! I myself have found no difference in stacking vs pile and as per this study a simple cover will do in about 3 months you should be down to a good moisture %

http://www.aqfairbanks.com/wp-content/uploads/Wood-Storage-Best-Practices-Final-Report-2.pdf

This study also specifies 20% MC as the target. In looking at the pictures, I saw lots of stacks (organized piles) but I didn't see any heaps (unorganized piles) unless they were under tarps. I suspect that a dense pack stack (no space between rows) probably dries at the same rate as a heap of similar size. Stacks with space between the rows, to allow air circulation, will dry more quickly.

The most significant feature of this study is the wood used. The study having been performed in Alaska, there are no hardwood species included. Birch, aspen, cottonwood and spruce are all softwoods, which dry much more quickly than hardwoods. I can cut green pine, fir or cedar in spring and they will burn fine come winter (though I do get substantial creosote accumulation). I cut standing dead lodgepole pine that is below 20% MC when it hits the ground. The 3-year-cure that is so commonly recommended applies generally to hardwoods and specifically to oak. Many of the other hardwoods will reach an acceptable MC in a year or two, but oak is extremely slow to dry. 3 years guarantees that all of your wood is dry. If you find a way to get oak to 20% in 3 months without a kiln, patent it.

 

[brewmonster]

This study also specifies 20% MC as the target. In looking at the pictures, I saw lots of stacks (organized piles) but I didn't see any heaps (unorganized piles) unless they were under tarps.--MrWhoopee

That's right, MrWhoopee. I think you read this study more carefully that the fellow who cited it in the first place. You made some good observations about the study's limitations and here's another one: it was conducted in Fairbanks, AK where the average annual precipitation is 10.9 inches. That's about one-fourth of what we get in the East. Also, mid-summer days in Fairbanks are up to 20 hours long. Maybe not too hot and sunny, but still.

Seems to me someone was eager to find a justification for handling his firewood in the easiest possible way and latched onto this article without even reading it carefully.

 

[planman]

Stacking vs piling -- once again

Guys, ive both stacked and piled my oak here in NEPA and have observed no material difference Ive also burned 3 month old oak with noproblem once Ive gotten a nice bed of coals going. Once I get my inglenook ZC EPA fireplace up to temp I can burn just about anything. This year I had my wood guy dump 10 cord of hard maple in June and it already burns great.

I observe the the law of diminishing returns. The question is, does your investment of time and money drying and stacking pay off ??? Certainly not for me as I charge $250.00 hr. for my time. If any of you find a study or other proof that stacking makes any difference whatsoever please post. As for moisture, the argument of a 20% optimum also makes no sense to me. Why is 20% optimum ?, is 10% too little ??. Ive yet to find a study explaining the correlation between moisture %, burn time and heat output, but I suspect heat output is probably more dependent on your stoves heat transfer efficiency than wood moisture content. Best of luck. :msp_wub::msp_w00t::smile2:

 

[TreePointer]

I've played around with moisture meters but never found the need for one. Most wood will fully season if properly c/s/s in one full year. The exceptions, like oak, will season in two years.

If you are selling wood, a moisture meter can help settle disputes, but that's the extent of its usefulness to me.

 

[Sourdough54]

Alaskan Study

I just thought I’d mention, as MrWoopee pointed out there are no “true” hardwoods listed in the Forest Circus Alaskan study. This is because the woods listed are the best that are available (white birch, white spruce and aspen). One that wasn’t mentioned was tamarack which has (relatively) high BTUs similar to white birch (I assume that is because it is less common and only available locally).

I thought I’d point out that the interior of Alaska is very cold country with no natural gas available and with temperatures commonly in the minus 40° F and colder range and as the paper stated approximate 59% of the homes heat with wood.

Brewmonster also correctly stated that the Interior is fairly arid country with very intense summers.

Anyway, I just thought I’d point out that we somehow stayed warm in spite of heating with wood that some of you wouldn’t burn if it was dropped it off in your driveway and that you in the lower 48 should be grateful to have a vast array of species to chose from.

P.S. When I lived on the islands in the rainforest of southeast Alaska all we had to burn was Sitka Spruce, western hemlock and cedar, fortunately the temperatures were temperate, but we did get an average on 164 inches of rain a year.

 

[planman]

moisture in wood and heat output

This statement makes no sense to me:

"High moisture content in firewood results in less effective burning of the wood and in a loss of energy in evaporating the water during burning. A cord of paper birch (Betula papyrifera Marsh.) firewood with 15 percent moisture (dry weight basis) would be expected to use an energy amount equal to 470,000 British thermal units (Btu) during burning to evaporate this moisture. An equivalent cord of paper birch that had a moisture content of 80 percent would be expected to use 2.5 million Btu (Ince 1979). The dry cord will produce more than a 12-percent increase in usable heat."

It completely ignores the first law of conservation of matter and energy. They simply minus out the BTU necessary to evaporate the moisture in the wood without any further accounting. The heat contained in this steam don't just magically vanish, it goes through my stoves heat exchange the same way the rest of the combustion gasses do So in the above I should only loose 12% X 1-(stove thermal efficiency %) in my case about 3% or so, or am I missing something ???

 

[Whitespider]

This statement makes no sense to me:

It completely ignores the first law of conservation of matter and energy. They simply minus out the BTU necessary to evaporate the moisture in the wood without any further accounting. The heat contained in this steam don't just magically vanish, it goes through my stoves heat exchange the same way the rest of the combustion gasses do So in the above I should only loose 12% X 1-(stove thermal efficiency %) in my case about 3% or so, or am I missing something ???

You're missing a lot.
First of all, combustion gasses do very little to heat your stove, those gasses must come in direct contact with the steel in order to conduct some of the heat to it. Heat radiation is what mostly heats the stove steel... for the most part, heat contained in the combustion gasses is lost through the flue because it radiates very little. Nearly all the heat radiation is absorbed by the steel and conducted to the outer surface, whereas only a portion of the heat held in the gasses is conducted to the steel. The more efficiently and completely the fuel is burned, the more of it is converted into radiation and less of it into combustion gasses (some amount of combustion gas is unavoidable)... when more heat radiation is produced by the fire, more heat is conducted through the steel and radiated into the room. Heat radiation is like sunlight, it travels in a straight line until it contacts something that will either absorb it (like steel) or reflect it (like aluminum)... it does not follow the gasses out the flue. Burning wet wood decreases combustion efficiency and increases the amount of combustion gasses (which includes, but is not limited to steam or water vapor)... and most all of the heat held in those gasses is lost out the flue. The "stove thermal efficiency %" will not change the percentage of heat lost because of burning wet wood... it is not a factor.

 

[brianmorgan17]

There's a lot of science going on here now!!!:biggrin:

 

[planman]

moisture in wood and heat output

I understand the difference in radiant vs convective heat, that's why I bought ZC fireplace instead of a wood stove. My firebox is wrapped inside an insulated box and a large portion of the radiant heat is used to heat the air blowing around and out of the unit. I also get radiant and ultraviolet heat though the front of the stove and through the 40X26 glass. Wet wood does produce more smoke, but once my stove reaches temp it its designed to burn that smoke. So im back to the first law of conservation of energy and matter. If I put 1 lb of wood in the stove I should get about 8000 BTU less any residual ash and combustion gasses. Unless you telling me that wet wood produces more ash, I should get the same amount of heat from wet wood than from dry. All of this makes me believe that the whole "only burn seasoned wood" campaign is a bunch of B/S by the green thumb patrol. Ive burnt wet wood and it does burn slower but once my stove is hot no more smoke.

 

[Whitespider]

Your stove may be designed to burn a certain portion of some combustion gasses (not all of it, that's impossible), but it can not burn water or water vapor, and the heat contained in that water vapor (as well as excessive combustion gasses) is lost... heat lost that would otherwise not be lost.

You're still missing a lot.

 

[planman]

forgive me, I only minored in Physics. Please be kind enough to explain to us all how this heated water vapor goes through the same heat exchange pathway as all of the other combustion gasses but magically does not get conducted into the room ?????opcorn:

 

[planman]

water in fuel

Here's a link to a bunch of guys who must also not understand physics or my other major chemistry, but they figured out how to burn wood with 50% moisture. Go figure :yoyo:

VTHR Green wood Chip Furnace Page 2

 

[Whitespider]

My firebox is wrapped inside an insulated box and a large portion of the radiant heat is used to heat the air blowing around and out of the unit.

forgive me, I only minored in Physics. Please be kind enough to explain to us all how this heated water vapor goes through the same heat exchange pathway as all of the other combustion gasses but magically does not get conducted into the room ?????

Well, first-of-all Mr. Physics Minor, the “heat exchange pathway” is the air blowing around the outside walls of the firebox proper; that’s where the heat is “exchanged” from the outer steel walls of the firebox to the air via “conduction” (not radiation). The water vapor does not pass though the “heat exchange pathway”. “Radiant” heat does not, as you stated above, warm air (well, not much anyway)… it simply travels through it until it contacts something of higher density, which is then warmed by the radiation, which in turn warms the air around it by the conduction/convection process (“heat exchange”). “Radiant” heat is what heats the steel walls of the firebox from the inside (not conduction) and then the outer walls of the firebox “conduct” that heat to the air contacting it (again, “heat exchange”).

If you want to believe your stove obeys the “first law of conservation of energy and matter”, yet ignores all the other laws of physics… well… whatever… I see no reason to continue with this… I be done.

Oh… and just for information and qualification… I didn't “minor” in anything; I dropped out’a school during the 10th grade because of sheer boredom.

 

[haveawoody]

Well lets think of it this way.
Steam will depart the woodstove at a consistent temperature.
Once a woodstove is at temperature the steam will not get and hotter so decreasing the temperature of a potential fire with moisture content.

If you burn wood at 20% moisture you are burning away 20% of the potential energy of wood that could combust at much higher temperatures.

Steam at it's temperature Vs burning wood temperatures carry away potential warming of steel and radiant heat.

10% burns away 10%, 5% at 5% etc.

Same reason kiln dried wood tends to burn like paper since the combustion temperatures are shedding very little water and increased combustion temperatures of very dry wood are experienced.
Kiln dried wood also has a runaway burn problem for the same reason.


Creosote deposits are a direct result of moisture content of wood, quality of wood and burn temperatures.
Any one of the 3 is poor and you get proportional creosote amounts.

You can prove it to yourself.
Have a look at your chimney deposits or glass deposits.
Start a fire with nice cured wood, get it going nice and hot.
Then feed it only greenish wood for a couple hours.
Let the fire go out and go cold.
Re look at the chimney deposits and even the front glass itself.
Or if you have a stack temp meter it's even easier to tell how poorly greenish wood combusts with 2 simple readings, one when the nice cured wood was burning and one when the greenish wood was burning.

 

[H-Ranch]

This statement makes no sense to me:

"High moisture content in firewood results in less effective burning of the wood and in a loss of energy in evaporating the water during burning. A cord of paper birch (Betula papyrifera Marsh.) firewood with 15 percent moisture (dry weight basis) would be expected to use an energy amount equal to 470,000 British thermal units (Btu) during burning to evaporate this moisture. An equivalent cord of paper birch that had a moisture content of 80 percent would be expected to use 2.5 million Btu (Ince 1979). The dry cord will produce more than a 12-percent increase in usable heat."

It completely ignores the first law of conservation of matter and energy. They simply minus out the BTU necessary to evaporate the moisture in the wood without any further accounting. The heat contained in this steam don't just magically vanish, it goes through my stoves heat exchange the same way the rest of the combustion gasses do So in the above I should only loose 12% X 1-(stove thermal efficiency %) in my case about 3% or so, or am I missing something ???

You're right about 1 pound of wood supplying the same amount of heat when burned whether it is wet or dry. (Remember that you're talking about the weight of the wood - a 1 pound log with 10% moisture content will be larger than a 1 pound log with 50% moisture content since water is making up more of the overall weight.) The energy from burning the wood is not being used to heat the combustion chamber or even the flue. Some of the energy is used to heat the water from ambient to the boiling point. But by far the largest amount of energy used to get the water out of the wood is not in heating it, but from converting it from a liquid to a gas. The more water in the wood, the more energy is used for this conversion. And this energy does not raise the temperature of the water at all - the energy input is not "lost", it is used to break the bonds of the water molecules. So in your model there is no added heat to the combustion gasses even if you could recover it. Your refresher course is to read up on latent heat of vaporization.

It is not a conspiracy theory - it's science. Burning wet/green wood may be the single biggest reason the government is involved in regulating wood heat (because of people complaining about smoke.) OK, so the number one reason is to figure out how to tax it... don't get me started on either - I'm not going down this rabbit hole any more than this.

 

[planman]

Green wood

Unfortunately I had to learn how to burn green wood the first year I was burning as my ex firewood guy gave me a really green load. My solution was to get a hot bed of coals going then add the green wood on top and pop open my ash pan just a crack. Using the ash pan I could regulate the amount of air entering from under the wood.

This guy seems to have learned how to burn green wood as well Burning Green Wood Cleanly - YouTube

I get that if the wood is 50% water 1lb of wood is really only 50% combustible but I by my wood by volume not weight. Regardless, this should not effect the combustion efficiency or the heat transfer efficiency of my stove. So I should benefit from the super heated water vapor as it travels through the inside heat transfer path of my firebox. I posed a link to a couple of VT researchers that burn green wood and do a good job explaining how the heat loss is not directly proportional to the moisture content of the wood. please see my above posting. Price of a cord of wood in NEPA $ 150, pissing a guy off who claims to have a pulsating brain, Priceless !!!