Can wood be too dry?

[BrianK]

Been up to Kitko, eh?

Yep, got about 5 cords of it stored in the basement now. And I have about a half cord of well seasoned ash and 3-4 cords of c/s/s combo of cherry, ash, birch, and maple that won't be ready to burn this season. I'm picking up 4 cords of 2 year old c/s/s combo of apple and oak this weekend from a local who is no longer burning for $75 a cord. This year we should be fine, and I've got lots of dead standing oak to get in for 2013/2014 season ;-)

 

[ScotO]

I've got lots of dead standing oak to get in for 2013/2014 season ;-)

If we get a snow weekend this winter, we'll drop and buck those big oaks up.

 

[Woody Stover]

"It should have a moisture content of 20% to 25% by weight. Some well-seasoned wood can in fact be too dry for today's airtight modern stoves. 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."

I think the wet-basis MC calculation is what the EPA uses for their woodstove tests. 20% wet-basis wood will read 25% on a moisture meter. I get a lot of hissing when I burn wood that wet, but that may not be a concern, except for possible increased creosote build-up. As far as uncontrolled off-gassing with dry wood, I try to let the coal bed burn way down, then build a top-down load with the big stuff on the bottom and the kindling on top. I think this will keep the top of the stove hotter and allow for sooner reburning of the smoke. JMO, may or may not be fact. Seems to be less smoke coming out of the stack with the top-down build, from what I can see...

Here is an interesting link I came across:
(broken link removed to http://www.epa.gov/burnwise/workshop2011/WoodCombustion-Curkeet.pdf)

I ran the first fire with the primary intake wide open since I wanted to make sure the flue temperature was hot enough.

Be careful though, you don't want to heat-stress your chimney pipe. I've got a flue thermo but you may have a harder time monitoring flue temp with an insert. Maybe some type of thermocouple setup at some point...
Yes, I would grab a bunch of Pine. If you split it on the small side, it will dry faster than just about anything else. It should help you to get through with the less-dry wood you have. I have a bunch of Pine split really small to start top-down loads. A couple of small pieces of newspaper are all I need to get the Pine on top going.

 

[Todd]

Nothing wrong with pine.

Doesn't burning pine make you go blind?

 

[bogydave]

Here is an interesting link I came across:
(broken link removed to http://www.epa.gov/burnwise/workshop2011/WoodCombustion-Curkeet.pdf)

Was BackwoodSavage their consultant? (Well Dennis uses old metal roof to top cover)

 

[Backwoods Savage]

Not me Dave!


Looks like the guys have answered your questions rather nicely so I'll just write, welcome to the forum Bryan.

 

[ScotO]

Doesn't burning pine make you go blind?

No, you're confused. PLAYING with your pine, that will make you go blind!

 

[allhandsworking]

I am currently burning (cold and wet over here) wood from the village pub which was knocked down this year, bone dry as its from about 1850 !
Some great beams 14" x 6" , made great splits
Burns lovely, and all free.
View attachment 75230
pic of pub being knocked down
Just checked on MM 14% !, guess it wont go any lower in the damp climate.

It's a shame Ireland and England are loseing so may pubs!

 

[bryan]

The problem that arises from TOO dry of wood (say kiln dried lumber) is that the wood can actually outgas FASTER than the stoves reburn system can consume them

Thank you Jags that was the answer the chemist in me was looking for. So it isn't the lack of temp and it isn't simply that they out gas faster, but rather too much out gasing at once overwhelming the ability of it to be consumed by the reburn. So limiting the amount of kiln dried in the stove at any one time would help alleviate that issue.

As for stack temperature I was monitoring it with an IR thermometer. I'm running the stove without a surround (not a fan of them) so I can aim up about a foot up from the insert and get a temp. The single wall pipe was measuring in the 280 range with the smallish fire I was burning.

 

[husky345 vermont resolute]

anyone here ever use bark to help build ur new fire up. i find it works great. as my white oak is drying the bark falls off and i figure why not burn it. anyone have any concerns? is it to dirty?

 

[bogydave]

I use birch bark as fire starter. But that's a whole different bark, lights easy & burns hot .

Oak bark, if dry, will work good. It' BTUs
Wish I had some to try.

 

[begreen]

Yer barking up the wrong tree for Alaska Dave. Birch bark is great for fire starting.

 

[dafattkidd]

anyone here ever use bark to help build ur new fire up. i find it works great. as my white oak is drying the bark falls off and i figure why not burn it. anyone have any concerns? is it to dirty?

I regularly burn bark with my kindling. Just make sure it's dry. I've found that bark dries faster than the wood it fell off of, but retains rain water for longer periods of time.

 

[Huntindog1]

Last year with my wood with a little too much moisture, i would have a couple wheelbarrows loads stacked a couple feet from the stove and the stove would dry it some.

 

[jharkin]

Yes was very sad to see it go, had some good times in that old place, only place for a beer nearby is now in the local sports centre, not quite the same as an old country pub.
Sadly no one could make it pay, so they knocked it down to build some new houses.

Ok, now I know we are in big trouble. If a pub cant make money in recession then we are really and truly doomed.

Back to the main topic Im sure that wood burned nice. When we had to replace a section of insect damaged sill beam here I burned the salvaged chunks. 200 year old oak that measured 7% on the MM - lit up like a firecracker.

 

[save$]

Just be careful with the bark. Make sure it is dry when you bring it in. Also only bring in what you are putting in the stove. Bark is often the home of bugs. Lots of bugs. Bugs that will become active when they get warmed up.
Bark still soundly attached to the wood may be less apt to be home to as many bugs as that of loose bark. Bug like dark moist places to hide and feed in. Another reason why we are now burning pellets.

 

[Jags]

Thank you Jags that was the answer the chemist in me was looking for. So it isn't the lack of temp and it isn't simply that they out gas faster, but rather too much out gasing at once overwhelming the ability of it to be consumed by the reburn. So limiting the amount of kiln dried in the stove at any one time would help alleviate that issue.

Bingo! You may pass to the next level.

 

[Huntindog1]

This is from the Wood Heat Website:

Can Firewood Be Too Dry?

Yes, although it is not a common problem

Properly seasoned firewood still has a fair amount of water in it, say 15 to 20 percent of its weight. That water regulates the combustion process along with a few other factors like piece size, load configuration and combustion air supply.
The higher the fuel moisture, the slower the wood breaks down when heated because of all the heat energy soaked up in boiling the water out of the wood and raising the temperature of the steam.
Conversely, the dryer the wood, the more quickly it breaks down when heated. By breaking down, I mean the vaporization of the volatile components of the wood; that is to say, it smokes. The dryer the wood, the more dense is the smoke at a given heat input rate.
Since wood smoke is fuel, we want to burn it as completely as possible and that means mixing with adequate oxygen in the combustion air. The problem is that a firebox load of very dry wood produces far more smoke than the air supplies of stoves are designed to provide. Besides, even if you could supply enough air, you would produce an inferno that would howl in the stove and make everyone in the house nervous. Fires that intense can seriously damage the stove's innards. Wood that is very dry produces a fire that is hard to control without making a lot of smoke.
Kiln-dried wood is down around 10 percent moisture. Depending on climate and conditions of storage, normal firewood won't dry down to kiln-dried moisture because of normal outdoor humidity. For example, I've never measured wood below about 14 percent in my firewood supply. But I suppose that firewood could get very dry by natural seasoning in desert conditions. Or firewood stored in old barns, which are like kilns in hot summer weather.
The right band of firewood moisture is between 15 and 20%. When you get much over 20% you start to see symptoms of sluggish ignition and the inability to turn down the air without extinguishing the flames. Towards 30% the wood sizzles and fires are very sluggish and it is hard to get a clean burn until the wood is almost to the charcoal stage. Above 30% water bubbles from the end grain when the wood is heated and it is very hard to burn at all. Species like poplar/aspen, which have very high native moisture content are virtually non-combustible when not adequately seasoned.
The main difference between EPA low-emission certified stoves and conventional stoves is that you can turn down EPA stoves for a long burn without extinguishing the flames. That is, they are better at producing a clean, controlled fire. But they are designed for wood that has a moisture content of twenty percent plus or minus one or two percent. Once you go far outside this band, their emission rate goes up. So even the best wood stove's performance will suffer if the wood is not in the right moisture range.
If you have some very dry firewood, like kiln-dried cut offs or old wood stored in a hot place, mix it with regular firewood to raise the moisture content of a full load.
JG

 

[Billybonfire]

It's a shame Ireland and England are loseing so may pubs!

Yes its very sad, think with the economic downturn people are having a beer at home instead of going to the pub

 

[Jags]

JG

John Gulland can get a bit wordy.

 

[Obadiah]

What I find interesting is the fact that your moisture content of your wood will depend on where you live. For example, friends in Oregon are lucky to get their wood dried to 25% after even after several years, because the humidity levels are so high there, it’s always raining. A few hundred miles to the east in Montana where I live, I can cut down a standing dead lodge pole and have readings in the teens. Most of my stored firewood has single digit readouts. The wood I am burning now test at 3-4% it has been stored for approx. 5 yrs. When I lived in Michigan it would take me a longtime (5yrs) to get wood down to the teens. In Montana there are no hardwoods, when we first moved here I was a little perplexed on what I would use for wood.........yeah I know, I'm a little dense sometimes......after 15 yrs. of burning Lodge Pole, Tamarack and Fir, I do not even miss hardwoods, we still get plenty long burn times too. If the wood is dry and seasoned there is no more creosote than what I remembered back when all I burned was hardwoods. So in my humble opinion, wood can never be too dry. It takes three things to make fire, fuel, spark, and air. Take away anyone of those three parts of the combustion triangle and your fire will go out. Woodstoves and hearth products that burn wood for heat are usually air tight; if you shut the damper all the way down then the stove will go out. On some of the latter EPA stoves they required the manufactures to open them up so you cannot shut them all the way down where they will smolder. With those stoves it’s a different story and I can see where it would make a difference if your wood was really dry, the stove would burn hotter, but fully closed down, I would doubt it would over fire. Really the only way to over fire a woodstove is to leave the door open and go to work or something like that. I have never seen anyone or heard of anyone over firing their stove because their wood was too dry, but that's what I love about this business, just when you think you have things figured out, someone comes along and throws a monkey wrench in......so you rethink what you thought you knew.

 

[David Tackett]

I use the bark that falls off my logs to get my fires started. Now if I only had a sure fire method to get the old lady's fire started.

 

[bag of hammers]

I am currently burning (cold and wet over here) wood from the village pub which was knocked down this year, bone dry as its from about 1850 !
Some great beams 14" x 6" , made great splits
Burns lovely, and all free.
View attachment 75230
pic of pub being knocked down
Just checked on MM 14% !, guess it wont go any lower in the damp climate.

Jealous. Was there any chance of salvaging 1 of those beautiful old beams, for some worthy project, or did the machine break them up?. Having a "chunk" of the old pub as part of a bar, for example...? A small bit of the pub history, and memories of pints raised there, preserved in the same room where the rest is fueling the fire?

 

[Jclout]

Bryan mixing the wood is what alot of people do to balance having some not so good wood. The smaller stuff will help out alot.

Learn this Rake Your Coals Forward Technique that alot of people use.
Notice the small stuff in the front on top of the hot coals will get your stove temps up more rapidly if your wood isn't the best.

The reason to rake the coals forward is to have more room in the back of the stove to load a bigger log on the bottom of the stove and not load it on hot coals. This gets you a longer burn time. It also gets you more head room to load more wood in the back of the stove were there are no coals to load on. Then the stove kinda burns in a front to back fashion and not all wood burning at once. The small stuff in the front takes off rapidly on the front hot coals up by the air inlet and gets your temps up quickly in the stove so as once the temps are up in the stove up can get the air shut back down and get the stove set for a long nights burn mode. With not so good wood sometimes it takes a while to get temps up before you can get the stove shut down for the night and by then you have just burnt up a bunch of your wood trying to get that temps up but you need all the un burnt wood you cant get so as to get a long over night burn.

https://www.hearth.com/talk/threads/rake-coals-forward-and-stove-start-up-pictures.80659/

Does all the wood in the stove have to burn off the excess moisture (this is so it will combust right?) before you can start shutting the air down while having the secondaries burning or is it just the wood in front near the coals that has to be hot enough to combust? My guess is the whole load right, that's why you burn allot of your wood up heating up the load if it has too much moisture content and are not left with enough wood for a long burn?

 

[SmokeyCity]

You can never be too rich, too skinny or have wood that is too dry.
but if it really is too dry then you have some good kindling/tinder.

The drier the wood the slower you can burn it ( less air). If you ever get your hands on a BK - it will gladly eat the driest wood you can feed it and it will burn it on a starvation air diet and let the CAT milk the smoke for all its worth.

Nah.....it cant be too dry.