Post in 'The Wood Shed' started by sw mariner, Feb 12, 2010.
Used dehumidifier to dry"green" wood in the basemant.........within 2 weeks had good dry wood.
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OK, I will bite. :vampire: How dry was it? Was it split into 1/4" by 1/4" pieces? How much wood? How many litres of water did you collect over the two weeks? What type of wood?
Only problem I see is getting rid of that much water, my 6 cords probably has a few gallons. sump pump?
How did you force the moisture from the wood, 4 - 6" thick pieces usually release moisture pretty slow. Heated to what temperature?
Note the use of "green", not green.
Was it a tree you jsut took down that was living and you bucked and split it in the last week or so?
Or are you now in the business of selling "seasoned" firewood?
I'd like to hear more. Do you mean that the firewood is dry the whole way through - or 'seasoned' - or was it just dry on the outside? How green was it when you started? All the dehumidifier does is lower the humidity in the room, so how does this method dry wood faster than any other stack of firewood in dry air? I don't think firewood stacked in Nevada dries in two weeks. I don't think firewood stacked indoor in the winter dries in two weeks.
1 cord of newly cut harwood,yellow birtch,maple,neatly stacked and packed in the basement with the temperature hovering around 25-30 celcius.dehumidifier removing aprox.2 gallons per day.Not the proper way of doing things i'll admit;but when works great if your in a pinch
OK, doing a bit of quick math with rounded numbers...
A cord of "green" Oak = ~6000 lbs
A cord of seasoned Oak = ~3000 lbs
A gallon of water = ~8 lbs
3000 / 8 = 375 gallons
2 gallons per day = 187.5 days
Now that would only be true if the last gallon left the wood as fast as the first gallon did but we all know that it doesn't work that way, so I have to say this is a false claim.
End of story but of course there will be many others that spout this unsubstantiated claim.
Oh come one, let's not let facts get in the way of a good story! ;-)
Seriously, I agee with your rough calculations. There is an awfull lot of water in green wood. I don't think a cord would dry in two weeks in the middle of a 120 degree Arizona summer. Maybe the outer surface would feel dry though...
I took one year seasoned splits and put into a basement room with a dehumidifier. Stacked with plenty of air gaps between each split. One medium cherry split lost 100 ml. of water 3-4 weeks. That's a lot of water.
Don't factor in what the dehumidifier is collecting. That's coming from the room. But with my room's humidity running 25%-30%, I'd say those splits lost some quick moisture.
love the calculations ...........but according to my calculations it's burning like gasoline............reality is i can't say how high the moisture content was before i started the process,just know it was newly cut wood .........i heard the rumor that the process worked ........so i tried it.......now i'm a beleiver.
As for me, I'll stick to doing things "the other way." That is, I'll stack it out in the sun and wind and let Mother Nature do her thing. It won't even cost me a cent for the electricity to run Mother Nature's dehumidifier.
As for the calculations, I'm perhaps not up to date on things but here is what I came up with:
Room 25-30C = 77 - 86 F That is a pretty wide range of temperatures.
2 gallons per day = A lot of water! How much from wood and how much from basement is not known but most basements around here are pretty damp places.
One medium cherry lost 100 ml in 3-4 weeks. 100 ml = 3.381 4022701 ounce [US, liquid] Am I wrong here?
I am always amazed how people try to get around this seasoning thing. Instead of doing things the easy and time-proven way they try to work around it and these are usually the folks who end up with big problems. Better to relax and let time and Mother Nature work as they are our friends....if we will let them be.
Burger King mentality.
Gotta have it now and "my way".
I guess I wouldn't swallow these "facts" any faster than the story. From green/dry wts at this site: http://extension.missouri.edu/publications/DisplayPrinterFriendlyPub.aspx?P=G5450
(I have no reason to think these aren't accurate) the wt. difference between a cord of green/dry(20%) maple is 810 lbs., 1379lbs for Oak, Birch isn't mentioned. So for Maple that would mean losing 97 gallons of water (810lbs/8.345 lbs/gal) or 48.5 days if the humidifier captured 100% of water lost at 2 gallons/day. BUT (yeah I know....) if one assumed that the humidifier only captured 1/4 of the water lost and the rest was lost by vapor exchanging through the house, windows, heating etc. it would fit with a couple of weeks.
The firewood kiln manufactures claim to dry firewood in 24 hrs and I guess I don't have any problem believing you could dry a split in the oven over 24 hrs, why not in 2 weeks at 77-85 °F (as claimed), with a dehumidifier lowering the RH and circulating the air through the wood. If his splits had sat around for a few days before getting loaded into the basement, they could have easily lost 5-10% moisture by weight before even starting depending on his local conditions. It would have been helpful to weigh the splits before and after to have a better idea how much water was really lost. Certainly simple enough to do next time.
In my own experiment as I have reported on this site, I have lost over 31% by weight in 28 days on fir and 45% by wt. in 21 days with Alder with just a fan, no heat. My temperatures averaged 45.6 °F and RH 85% with normal daily fluctuations each. And 50-90% of that loss was in the first week. I have to think with dry air and warmer temperatures it would have been lots faster. I'll be glad to send along the data file to anybody that wants it.
I haven't found what the limiting speed on moisture moving out of wood is. No doubt it's slower in dense woods like Oak verses Alder, and increases at higher temperatures.
I'm thinking ultimately the moisture in the center of a split can't move until the moisture around of it moves out of the way... which can't move until the moisture outside of it moves and so on. But as long as the outside surface is under dry conditions, moisture should head that way as fast as the cell structure and temperatures allow.
skyline, you raise some good points. But it seems to me that there are locations where day time summer temps are in that range with very low natural RH and we don't hear about wood seasoning that fast.
I just so happen to have a dehumidifier gathering dust here and a cord of semi-green doug fir at about 30% MC. Not sure I'd want to lug the whole cord in for an experiment but maybe I can find some way to contain a decent pile of splits and give it a test. Weighing before/after of course. I wonder if covering the splits and the dehumidifier with visqueen plastic sheeting would work or just overheat the thing...
+1! Get 3 or more years ahead with cut, split, stacked and don't worry about any "methods" for creating properly seasoned ready to burn wood. Time (seasons) does it for you.
I know what you mean, and if we did, we wouldn't believe it anyway! I guess I just figure 2 weeks solid of 80-85 °F with air movement and I'm guessing 5-20% RH at those temps is going to dry wood really fast.
I'll be interested in your results since you're in my "neck" of the woods. I don't know where you're bringing the wood into (house, garage or basement) but I'm pretty sure that most dehumidifiers quickly stop working as the temperature heads below 60°F. I don't think I'll ever have a place inside to store wood that gets much above 50°F for 6 months out of the year so I'm not sure the extra energy cost using a dehumidfier provides any more benefit that just a fan especially if your wood is in a warm open room. Of course, outside a fan would work better than a dehumidifier and use lots less energy.
You might put a few splits under a piece of visqueen as a control. That's is what I should have done with my fan experiment as I'm sure the pieces that are out of the path the fan are still drying out relatively faster because of the air movement around them.
The other aspect of the original post is that the outside majority of his wood might be really dry and lights easy. From there, the extra 5% moisture that still hasn't dried one may never notice.
It just seems to me that there are the two extremes expressed here in drying wood, outside for 2-3 years if oak or 24 hours in a kiln with lots of heat and air movement added.
I think they both work but we can probably improve on the first method considerably without having all the expense of the second method.
Maybe one day when the kids are grown and gone I'll have 3 years worth of wood all stacked and dried ahead of time and won't have to worry about it. In the mean time I'll keep looking for ways to dry wood faster without having to buy a kiln.
No, this isn't something I'm going to make a habit of doing. I'm a first year burner with below average wood. But for anyone in a pinch that has a place to try this, I think it does help.
And you're right, my split went from 5lb. 9oz. to 5lb. 5oz. Most of that in the first two weeks. About 100 ml. of water, give or take.
Next year's white ash is stacked waiting on sunshine.
2012's oak is stacked and waiting on sunshine.
23º wet bulb depression at 84ºF = 24% RH in my shop just minutes ago. Actually was 25º depression at 86º = 20% RH, but I couldn't get the photo shot in time, so this is what I have to show. Have taken readings with a 31º depression back when outside temps were -15ºF, with a RH of about 8%. The result of this low humidity can be clearly seen in the photos of splits on the scale.
- Cherry split: cut down live, split and delivered to me in early November. Brought in and placed on scale, weighed at 7 lbs, 12 oz. and marked on 12/28/09. Removed to outside on 2/1/10 weighing 5 lbs, 6 oz. Gained 1 oz in the last two weeks (I thought it'd gain more). Weighed just now at 5 lbs, 7 oz for a total loss of 2 lb, 5 oz in four weeks.
- Oak split: cut down live, split and delivered to me in mid-December. Brought in on 1/13/10. Placed on scale, weighed at 13 lbs, 15 oz (probably lost several ounces that first day but I can't show that) and marked on 1/14/10. Weighed just now at 10 lbs, 3 oz for a total loss of 3 lbs, 12 oz in four weeks (also proof that oak dries much slower than cherry in the same conditions).
Don't shoot me, I'm only the messenger.
As you know, I use the heat from my stove to drive down the RH in my basement, but if you really want to use valuable electricity to do the job:
Very interesting link. Thanks!
I notice they went to a lot of trouble not to overdry the wood which presumably wouldn't be a big problem for firewood.
remember kids ..dry wood is NOT seasoned wood
Yes, quite true. I take great pains to season my kiln-dried wood with lemon pepper and butter and a hint of habanero sauce for extra heat. Otherwise, it just sits there and smolders.
Holy crap...someone takes their wood burning seriously! That's a very nice experiment. I love it! I believe the key is keeping the RH down. In the summer, where I live, it can stay in the 80s for weeks on ends. That does not help whatsoever. It takes a good combination of wind, sun (heat) and RH to help wood dry properly. Removing 1-2 of those makes it harder.
I'm glad I'm not the only one who's obsessed with wood burning ! I just put 4 pieces of fresh cut Oak in my basement which has a dehumidifier in it. In a few weeks I will attempt to burn it and I will post my results....I will be shocked and impressed if this works.
Should we be doing more productive things with our time ? Just asking.
I don't ice fish, so "No" is the answer for me.
Don't expect ground breaking results with a dehumidifier in the basement. Lots of air to dehumidify. Containing the wood within a smaller volume of air, and heating that air (actually, the dehumidifier will do that) to further lower the RH is the key.
I use a 50 pint (6.25 gallon) per day dehumidifier all summer long so my musical instrument wood doesn't get mildewed and ruined. Once that RH gets below about 70% in the basement, the dehumidifier gets progressively less moisture out of the air. I've never been able to drive it below about 45% running it day and night. After a while it takes a couple of days just to fill the holding tank (about 2 gallons). Dehumidifiers use a lot of electricity, and as mentioned above, at low temps they stop working altogether (the coils ice up). Building even a temporary enclosure will make it work much better.
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