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Drying wood quickly for heating  RSS feed

 
Davis Bonk
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I bought a farm house this spring and the furnace died so I had to finish the year with electric space heaters. I have been bucking logs I felled this summer and have now begun to split them. I have several cords of ash that I am processing.

I am also in the process of building (gathering materials for) a RMH. I would like to build it upstairs but I am unsure of the floor holding all that weight in the center of the house so it looks like its going in the basement and I am going to have to insulate as much concrete as possible.

The real kicker: will my wood be dry enough? or should I invest in a new propane furnace?

right now I am seeing two options. The first is a solar kiln. Ive got a dozen or so glass sliding doors so I could make a greenhouse lean to kiln thing

The second is to use the mass to finish drying the wood. I would welcome the moisture in the winter. Or is this going to be a huge headache?

am I in a pickle or does anybody have some optimism based in reality to throw my way? everyone says that wood should age at least a year that i have come across.
 
R Scott
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Location: Kansas Zone 6a
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Drying it with the mass is a good way to finish off the drying.

You could also buy a little dry firewood to get you started.

It takes a lot of structure to hold up a mass whether on the second floor or first floor over a basement. Build it on top of a load bearing wall.
 
Davis Bonk
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Thanks. I trimmed a few big limbs of dead apple this summer and gleaned a grove for all the dead buckthorn so I hope that should get me started. I know that that is not enough dry to get me through the winter, but hopefully I can make a rack over/around the mass for drying and get a system down. It'll be an extra step in the middle, but well worth it if it works. I'm gonna have to dry out the mass too, but I should squeak by.
 
Mike Sved
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Location: Geraldton, Ontario -Zone 1b
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http://www.hearth.com/talk/threads/drying-wood-quickly-indoors.61783/

The discussion linked above goes into great detail about one guy's experiments with indoor quick drying. I've tried it and it works just the way he claimed. The key ingredients are a low relative humidity outside, a source of heat nearby and constant air movement through your wood rack. I took green, dripping birch and was burning it safely a month later. People found it bizarre that I regularly weighed pieces of firewood and used a marker to write the details of their drying progress on the logs. I thought it was perfectly normal. The one possible problem is the potential for bugs to crawl out of the wood. I only experienced a dozen or so over a winter while drying 3-4 full bush cords inside.
 
Cj Sloane
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You can burn Ash green. I've recently read that Birch will burn ok green due to the oils.

I did have a solar drier for 10 years and it did work great. Get yours up & running. Smaller logs will obviously dry quicker.
 
Michael Cox
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We have been short for dry wood at various points and have tried to quick dry it indoors with limited success. All I can suggest is to ensure good airflow, split it smaller than normal and leave it as long as possible.

We aim to get 2 full years ahead - I'd like to be 3 years ahead but we are short on storage space - to give our oak and chestnut time to dry well. You really notice a difference after an extra year.

I suspect you will be in for a frustrating year - cool fires that don't really throw out lots of heat and need more tlc than normal. I'd buy in some dry wood and save the semi dry stuff for the following year, otherwise you will be in the same situation next year too!
 
Cj Sloane
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I'm more than a little surprised people haven't included built in wood storage for their RMH. Here's a masonry one:
.

Even my woodstove (soon to be replaced) has a spot for kindling:
 
Matt Walker
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Location: North Olympic Peninsula
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That's what I do CJ, my RMH has two little alcoves with venting that convect air from front to back then up behind the mass. I fill them with wood, about two days worth, and they will go from 25% to 15% overnight typically. I also wonder why more rocket mass heaters don't include this feature.

This photo is dark, but you can kinda see the wood drying alcoves there:



Hmm, let's see if I can find a better one....Well, I guess this is as good as I have right now...

 
Michael Cox
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I like that - making use of convection from the heat of the stove surely makes a big difference. I'm surprised by a drop in moisture content from 25% to 15%. That is a big difference in terms of how well it will burn, and doesn't tally with my experiences of trying to dry wood next to our stove at home. I suspect the planned convection is the key.
 
Matt Walker
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Michael, I imagine the convection plays a big role, but also keep in mind the wood is split quite small compared to normal cord wood. 3" on the largest face, typically, and most is smaller. I think that's the largest factor, lots of surface area and not much volume per piece of fuel. Oh, I almost forgot, I also burn soft wood almost exclusively here in the PNW of the US. It's a different story with hard wood, for sure.
 
Bert Vinyl
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Remember that most woods dry through the ends after surface water is gone. So ends should have air flowing past them and the ends should face a heat scource for best drying in the house... Stack it for best air flow past the ends, use the prevailing wind direction at the site to best advantage to get airflow past both ends, and keep the rain off the top of the rows.. The tree fluid goes from ground to air through these tubes in the wood, so use this info to help dry the wood. Oak is used for barells because water doesn't go through it sideways, but you can suck air through endgrain of that stuff. Warm wet wood is still wet, but it's better than cold wet wood. And cold winter air dries wood much better than moist warm air. Weigh a piece, keep it in the middle of your pile and weigh it later to check progress maybe.
I once was working at a job where the boss wanted this new cut down tree gone. Well, i got it gone into my 2500 chevy truck. I had a rounded load, and didn't unload it but drove around for a few days with it in the back and the stuff on top was noticeably drier after that. i figure the air blowing on it really helped out.
thinking about these facts, maybe a row or 2 in the back of a pickup,under a cap with no windows would dry quick enough to be worth the effort. Or fill the cab and keep the heater on to help dry it. Or under hood kilning a batch a day.I can see it now.
,
 
Michael Cox
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Bert Vinyl wrote:
I once was working at a job where the boss wanted this new cut down tree gone. Well, i got it gone into my 2500 chevy truck. I had a rounded load, and didn't unload it but drove around for a few days with it in the back and the stuff on top was noticeably drier after that. i figure the air blowing on it really helped out.
thinking about these facts, maybe a row or 2 in the back of a pickup,under a cap with no windows would dry quick enough to be worth the effort. Or fill the cab and keep the heater on to help dry it. Or under hood kilning a batch a day.I can see it now.
,


I'm not sure that the added fuel cost for the truck is worth the drier wood. Carrying 100kg of firewood a few 100km is going to hit your fuel consumption.
 
Bert Vinyl
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Of course thats right, but I was just raving on. We have a wonderful retired professor around here in Maine USA who stresses wood being in a woodshed for a yr or so as being the best thing you can do to reduce wood smoke pollution.All the epa rules in the world don't help any where near what woodsheds do. All the best, Del in Maine.
 
Jim Fisk
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Location: Smoky Mountains of E Tennessee
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We got caught last Winter with enough dry wood to last about til December and then had the worst Winter here in the Smokys in years with temps at 20 below on more than one occasion. We spent months dropping 80-100' trees, cutting, splitting and drying the days wood on racks above the stoves. We run 4 woodstoves with 2 in the main house and one in the cabin and one in the aquaponics greenhouse. Somehow we made it and the drying wood gave off lots of moisture which always helps in the dry heat of Winter. Had a few logs get a bit glowing on occasion but the smoke gave them away in time for no flare-ups. The 2 homemade gasifier stoves will get a welded up drying rack for just this purpose in the future and that will assure the wood never makes contact with the actual stove surface. Not that I plan on ever going thru that again but who knows with this crazy weather we have had. The year I broke ground in January for the AP GH it was 60F here while last year, just 2 yrs later, we were at 20F below zero during that same period. Makes it a bit hard to judge just how much wood we will need per year going forward. The Native Americans around here are calling for a "black squirrel" Winter this year which means a whopper and I am still building the new gasifier boiler and hydronic heating system for the new house. Yikes!!
 
Russell Davis
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Jim Fisk wrote:Somehow we made it and the drying wood gave off lots of moisture
I recall it being said that 1 lb propane has about the same heat as 2 lb of air dry wood having 20% moisture. Does anyone know if those to points are true?
And that plus or minus 10% moisture is worth about 15% of the woods heat either way?
Does anyone know if those to points are true?
Seems that it can be a lot easier to force dry wood (to minus about 20 to 30% of the wood's moisture ) than it is to cut split and haul about a third more wood.
Does anyone know if those to points are true?

At about 62 cents a pound for propane and about $1.50 a pound for propane storage a well done wood heating system looks like a bargain to me.
 
Troy Rhodes
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I built a 12.5' x 28' hoop greenhouse, primarily for dying wood.

The results were extremely good. Here's a whole thread with pictures over on hearth dot com.

http://www.hearth.com/talk/threads/i-built-a-12-5-x-28-greenhouse-to-store-and-dry-wood-working-awesome.129149/page-2


It dries wood like gangbusters. It doesn't take years, it takes weeks. This assumes you have some sun and some heat.

There are a few unique details. The ground is sealed, actually sealed (Ok 99%) with plastic and mastic on all seams, overlaps and at the edge where it meets the framing. If you don't do this, moisture from the ground
will make this much less awesome.

There is a screened window on each end. One of those has a cheap box fan hooked to a cheap thermostat, so the fan comes on at about 90F. This guarantees that the fan only runs when there is hot humid air to pump out of the greenhouse, minimizing/optimizing electricity use.

I would be happy to answer questions.

troy
 
Troy Rhodes
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On a related note, it's hard to tell what the moisture content of wood is by....looking. Or....feeling. You would really like your wood to be below 20% for better efficiency and less creosote.

Under 10% is awesome and hard to attain unless you have a solar greenhouse wood dryer or something similar. Or you live in a dry hot dessert I guess.

4 pin moisture meters have gotten very cheap. 13-20 bucks gets you one on ebay, like so:

http://www.ebay.com/itm/4-Pin-LCD-Digital-Wood-Firewood-Moisture-Humidity-Meter-Damp-Detector-Tester-US-/201098218721?pt=US_Garden_Tools&hash=item2ed2634ce1



Nice, non-chinese meters can run 80-100 or more bucks.


It is a good lab exercise to verify the accuracy and precision of a cheap chinese moisture meter by using the weigh-heat-weigh method.

That's where you (as precisely as you can) measure the weight of a piece of wood, then you bake it in the oven at 300-325 for a while. Then weight it again. It will weigh less due to the boiled off water. Then bake it some more and weigh it again. When the weight stops changing, we can more or less assume all the water is gone.

(Orig. weight - final weight / orig weight) x 100 = the moisture content of the wood prior to baking. Then you compare that with what your cheapo moisture meter tells you prior to baking.

Mine was surprisingly accurate.


Note that you have to use the moisture meter on a freshly split surface to get the most accurate reading. The surface of an unsplit log will always measure drier than the wetter interior.



finest regards,


troy
 
r john
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Troy Rhodes wrote:I built a 12.5' x 28' hoop greenhouse, primarily for dying wood.

The results were extremely good. Here's a whole thread with pictures over on hearth dot com.

http://www.hearth.com/talk/threads/i-built-a-12-5-x-28-greenhouse-to-store-and-dry-wood-working-awesome.129149/page-2


It dries wood like gangbusters. It doesn't take years, it takes weeks. This assumes you have some sun and some heat.

There are a few unique details. The ground is sealed, actually sealed (Ok 99%) with plastic and mastic on all seams, overlaps and at the edge where it meets the framing. If you don't do this, moisture from the ground
will make this much less awesome.

There is a screened window on each end. One of those has a cheap box fan hooked to a cheap thermostat, so the fan comes on at about 90F. This guarantees that the fan only runs when there is hot humid air to pump out of the greenhouse, minimizing/optimizing electricity use.

I would be happy to answer questions.

troy



In the same thread is a description of my commercial solar kiln set up
 
Ian Petrie
Posts: 15
Location: Tuffnell, SK. Zone 3B
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I don't know how well forested the area is where you live, but standing deadwood and windkill from the forest definatly helped me make it through the winter two years ago, when I was stuck without a seasoned wood supply. Look for trees killed a year or two ago (if you know the history of the weather in the area you live, big wind storms, tornados, etc). If there is still bark on the tree but it peels off easy or has a bit of bark off in places it should be good to burn. Standing naked trees will be all punky and will burn with no heat.
I've also heard, although I haven't tried it myself, that submerging logs in running water (like a stream) for a time will wash the sap out of them and make for quicker drying once bucked and stacked.
Good luck!
 
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