# Drying wood indoors using a dehumidifyer



## MOHAWK1

Hello everyone I was looking for some insight an information on drying wood indoors using a dehumidifyer, I currently have 8 bush cord of almost seasoned wood, 70 percent of it is all red oak which was cut down 2 years ago but not opened up till this june, its all stacked up with plenty of space between the rows and is off the ground stacked on skids, I split a piece today just to see what the inside moisture was at, the wood looks nice and seasoned, ends are all cracked bark is loose etc, however when I split a few pieces today and the inside moisture was off the charts on the moisture meter and it felt wet still, so I got the idead of moving it into my quonsa hut and turning on my 2 70 pint dehumidifyers, if this option dries wood out quickly what would the dehumidifyer have to be set at and what should the room tempature be, my quonsa hut is 30x50 and 15 ft high spray foamed insulated and is super super tight, any information on this issue would be greatly appreciated, thankyou


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## firefighterjake

I'm thinking the cost to run the dehumidifier could add up . . . but I could be wrong.


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## Hass

Yeah, dehumidifiers pull quite a bit of juice.
When I was gutting my house, I wasn't living here and my elec bill was $80-90 a month running the dehumidifier (65 pint) 24/7.

When I stopped using it, my bill dropped to about $45/month. (have to include basic cost of service and what not)
So I figured about 40/month it cost me to run it.
and 2/3 of the time it was full and not even running since I didn't have the drain set up on it.

So figure out how many amps both are, and figure out what you pay per kwh to see if it's really worth it or not.
Hell, if you want to go all out put some space heaters in there while you're at it. (more $$$)
But most dehumidifiers make heat as they remove moisture.

Might be better off finding some "DRY" wood on craigs for the cost/effort it would take.


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## maple1

I don't think a dehumidifier would help you much there - that's a huge air space, and those things eat electricity. If you can get the wood under cover, while at the same time allowing or promoting air movement through from prevailing winds, you would be further ahead IMO.

I've got a 40 pint dehumidifier going in my basement right now, right up against the woodpile, after moving in my winter supply last week. Not intended to season wood, just get the basement humidity levels back down to reasonable after loading it up (7.5 cord) with slightly-surface-damp wood. It's been going for 2 days now and it's down from 90% to 75%. I usually only run it for a week or so, maybe intermittently a bit after that - then having the basment windows open should keep things good, until it gets too cold for open windows.


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## MOHAWK1

Hello again and thanks for the input, the dehumidifyer in my quonsa hut only has to be emptied every 3 days or so and works good at keeping the humidity levels at the desired setting, my wood pile gets sun and a lot of wind all day as I live out on a point along the lake, however I am concerned that the wood will not be ready to burn in the next 4-6 weeks, aside from the extra hydro bills associated with running 1-2 dehumidifyers etc, can this option work in theory ?? Thanks


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## Reggie Dunlap

Yes it can work, especially if you have a few box fans blowing air through the wood. I've done it with hard maple, cherry, and yellow birch. Oak dries slow, so it may take some time and electricity to get it to where its burnable.


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## maple1

Here's another suggestion. Since you have it on skids outside, when you move it inside put some ductwork down first, then use skids etc. to create an airspace on the bottom of the woodpile where the end of the ductwork is. Run the ductwork out to one end of the pile & hook up a fan to it that can exhaust outside. The fan will pull air from the bottom (where it should be most humid - moisture falls?) & inside of the woodpile, and hopefully thru the pile eventually, and spit the moisture outside. Or create some kind of cavity under the woodpile when you put it in that your humidifiers can draw from. The main problem with humidifiers though, aside from their current draw, is they pretty well quit working at not much below 20Â°c - I suspect that would be a bigger problem here.


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## joefrompa

Good heavens - do dehumidifiers eat that much?

I've got one in my basement stuck on 45% and it runs nearly non-stop 6-7 months of the year. Drains automatically and keeps the basement at a reasonable level....but if it's costing that much, maybe I should just put a wood burning stove down there  It'd pay for itself in a year!


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## My Oslo heats my home

Interesting idea...I wonder how much wood you could put in there to try it out. I have a dehumidifier in my basement and I have a short section of gardent hose running to my sump well, when it fills up the pump pushes it out to the dry well. Meaning, I don't have to worry about emptying. The  large sized dehumidifiers require about the same amount of electricity as a 10,000 BTU air conditioner, it can get expensive if they run alot.
If you have a sealed place to put the wood, your hut, and can possibly put a couple of fans in there along with at least one dehmidifier you could try it out. The electric bill will be two pages long next month but it's worth a try. 
Test a couple splits with the MM and then try out your idea and see what happens


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## jimbom

140 pint/day dehumidifiers will remove 140 pounds of water per day.  If your seven cords have 7000 pounds of extra water, you should get there in 50 days.


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## Backwoods Savage

The dehumidifier will take the moisture out of the air.....but won't take it out of the wood. Sitting outside in the wind will do much more for that wood than trying to dehumidify it. 

Your findings are just one more case where it proves that wood doesn't dry worth a hoot until it is split. Lots of folks seem to put a lot of faith in the ends cracking but that only shows the ends. It does not show the inside.


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## maple1

Backwoods Savage said:
			
		

> The dehumidifier will take the moisture out of the air.....but won't take it out of the wood. Sitting outside in the wind will do much more for that wood than trying to dehumidify it.
> 
> Your findings are just one more case where it proves that wood doesn't dry worth a hoot until it is split. Lots of folks seem to put a lot of faith in the ends cracking but that only shows the ends. It does not show the inside.



Agreed - it's one thing to suck water out of the air, quite another to suck it out of the middle of a piece of wood. Gradual steady flow of air is the best.


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## jatoxico

maple1 said:
			
		

> Backwoods Savage said:
> 
> 
> 
> 
> The dehumidifier will take the moisture out of the air.....but won't take it out of the wood. Sitting outside in the wind will do much more for that wood than trying to dehumidify it.
> 
> Your findings are just one more case where it proves that wood doesn't dry worth a hoot until it is split. Lots of folks seem to put a lot of faith in the ends cracking but that only shows the ends. It does not show the inside.
> 
> 
> 
> 
> Agreed - it's one thing to suck water out of the air, quite another to suck it out of the middle of a piece of wood. Gradual steady flow of air is the best.
Click to expand...


My intuition is the same, the moisture you are trying to remove is 2-3" from the surface. Sounds like an expensive way to go.


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## jatoxico

maple1 said:
			
		

> I don't think a dehumidifier would help you much there - that's a huge air space, and those things eat electricity. If you can get the wood under cover, while at the same time allowing or promoting air movement through from prevailing winds, you would be further ahead IMO.
> 
> I've got a 40 pint dehumidifier going in my basement right now, right up against the woodpile, after moving in my winter supply last week. Not intended to season wood, just get the basement humidity levels back down to reasonable after loading it up (7.5 cord) with slightly-surface-damp wood. It's been going for 2 days now and it's *down from 90% to 75%.* I usually only run it for a week or so, maybe intermittently a bit after that - then having the basment windows open should keep things good, until it gets too cold for open windows.



 :bug: Yikes


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## Woody Stover

If the MC in the middle of this Oak is "off the charts," I would write it off until next year and leave it stacked outside. No way it can dry in time, unless you have a stove in there too, and can jack the temp up to about 120* (Fahrenheit...Centigrade would be better.)  :smirk: 
Time to go to plan B.


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## golfandwoodnut

I run my dehumidifier all summer and spring and fall,  I would rather have a dry basement than a wet one.  My laminate flooring would bulge in the summer from the moisture.  In the winter, when the heat is on I do not need the dehumidifier.  Now that probably did not answer you question.  My first winter I did bring some cherry into the basement and ran the dehumidifier and the furnace and it did seem to dry it out quickly.  But then again cherry does tend to dry quickly.  I supplement my heat with an insert so I still do run the furnace.


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## Battenkiller

I heartily disagree with the above posters who claim that wind is all you need.  Even sustained hurricane-force winds won't help wood dry in the slightest if the relative humidity is at 100%.  At 100% RH, water molecules from the air will be landing on the wood surfaces as fast as they are leaving.  Until the outside gets drier than the inside, no moisture gradient will be established within the wood, and the water will stay inside the wood forever.

_Relative humidity is what drives the entire wood-drying process._  Yes, all the dehumidifier does is to suck the water out of the air, but that dry air is what dries the wood... ALWAYS.

There are numerous large-scale dehumidification kilns all over the country that work on the same principle - lowering the relative humidity inside a controlled space, and using fans instead of wind to keep the dry air circulating over the wood surfaces.    All wind/fans do is to make sure that the low RH air is constantly coming into contact with the wood surface.  These kilns greatly speed up the drying process of the lumber inside them, otherwise, why would anyone use them?

The question is not whether or not it will work, because kiln operators know that it will.  What is important is to figure out how much money it will cost to dry a relatively low-value item such as firewood.  My guess is, "more than it saves".  To drive that last bit of water out of your wood will cost a lot.  The heat you will lose through evaporation by burning it in its present state is really not that much, certainly not hundreds of dollars worth (which is what it will cost to run those two puppies).  The advantage of drying wood outside in the wind instead of inside a kiln isn't that it will dry faster, because it won't - it will dry much slower.  The real advantage of outside wood drying is that it is free.  Lumber is expensive, so it is worth it; firewood is cheap, so it ain't.

Besides, I don't think those cheapy home units will really pull that much water out of the air, at least not once the RH inside the hut drops lower.  You'd need a big commercial dehumidifier to do the job efficiently.  Now you're really talking some big bucks.  Leave it outside is my feeling, but cover it up soon to keep any more rain from soaking it so close to burning season.


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## krex1010

I doubt your humidifier idea will work, yes they use humidifiers in kilns, but your situation is not going to give you the drying conditions you would see in a kiln.  Your oak is likely best served by saving it until next year.


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## Battenkiller

krex1010 said:
			
		

> I doubt your humidifier idea will work, yes they use humidifiers in kilns, but your situation is not going to give you the drying conditions you would see in a kiln.  Your oak is likely best served by saving it until next year.



You know, I think you're right.  A humidifier probably won't work at all.


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## krex1010

Battenkiller said:
			
		

> krex1010 said:
> 
> 
> 
> 
> I doubt your humidifier idea will work, yes they use humidifiers in kilns, but your situation is not going to give you the drying conditions you would see in a kiln.  Your oak is likely best served by saving it until next year.
> 
> 
> 
> 
> You know, I think you're right.  A humidifier probably won't work at all.
Click to expand...


You think I'm right? Could you maybe tell my wife that? Show her that it may be possible every once in a while. Lol


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## woodchip

joefrompa said:
			
		

> Good heavens - do dehumidifiers eat that much?
> 
> I've got one in my basement stuck on 45% and it runs nearly non-stop 6-7 months of the year. Drains automatically and keeps the basement at a reasonable level....but if it's costing that much, maybe I should just put a wood burning stove down there  It'd pay for itself in a year!



We used to use a dehumidifier to keep our house dry in the damp autumnal weather (I suffer from quite bad rheumatism), but the cost of running the dehumidifier was about the same as all our other electric appliances added together, and when we started using the woodburner, it dried the air down nicely by itself. 

If I had several cords of unseasoned wood, I'd be tempted to run the furnace to keep warm for this winter, and allow the wood to season naturally for another year. 

I'd still have the wood to burn next year, and would not be thinking about drying next years wood yet...............

However, I might be planning seasoning some wood for 2013-14 soonish  ;-)


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## My Oslo heats my home

krex1010 said:
			
		

> Battenkiller said:
> 
> 
> 
> 
> 
> 
> 
> krex1010 said:
> 
> 
> 
> 
> I doubt your humidifier idea will work, yes they use humidifiers in kilns, but your situation is not going to give you the drying conditions you would see in a kiln.  Your oak is likely best served by saving it until next year.
> 
> 
> 
> 
> You know, I think you're right.  A humidifier probably won't work at all.
> 
> Click to expand...
> 
> 
> You think I'm right? Could you maybe tell my wife that? Show her that it may be possible every once in a while. Lol
Click to expand...


+1 for BK.


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## onetracker

i quickly browsed thru the responses here....

what's a bush cord??

so now we've got face cords, ricks, and bush cords? :grrr: 

please advise

OT


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## woodchip

Sounds like some sort of made up measurement to sound like a cord, but sold at a more expensive price.

Probably a bit like when we stopped selling petrol here in gallons, and started using litres. 

Might as well have called them bush gallons, we got well short changed on that one.......  ;-)


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## Hunderliggur

First, dry wood (20% MC is better).  What do you loose for wet wood?  Based on http://www.engineeringtoolbox.com/weigt-wood-d_821.html there is approximately 15 pounds/cf of water "extra" in fresh cut wood versus seasoned (20% MC) wood.  Given the BTU requirements to heat the water to 212 then the 944 BTU/pound to turn it it to steam (lets approximate at 1000 BTU/pound), you have to have 15LB/CF * 128 CF = 1920 LB * 1000 BTU/LB = 2M BTU to use that wet wood (if you can get it burning).  Cord wood has an energy range of 10 to 16M BTU / cord https://www.hearth.com/econtent/index.php/articles/heating_value_wood so that means using wet wood is costing about 15 to 20% more wood to be burned.

Don't bother with the dehumidifier.


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## oldspark

Battenkiller said:
			
		

> krex1010 said:
> 
> 
> 
> 
> I doubt your humidifier idea will work, yes they use humidifiers in kilns, but your situation is not going to give you the drying conditions you would see in a kiln.  Your oak is likely best served by saving it until next year.
> 
> 
> 
> 
> You know, I think you're right.  A humidifier probably won't work at all.
Click to expand...

 What if your wood is too dry?


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## kettensÃ¤ge

Why don't you just try to burn some. If the end grain drips water or it hisses, no good. 

Could be an issue with the meter or your technique.


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## maple1

jatoxico said:
			
		

> maple1 said:
> 
> 
> 
> 
> I don't think a dehumidifier would help you much there - that's a huge air space, and those things eat electricity. If you can get the wood under cover, while at the same time allowing or promoting air movement through from prevailing winds, you would be further ahead IMO.
> 
> I've got a 40 pint dehumidifier going in my basement right now, right up against the woodpile, after moving in my winter supply last week. Not intended to season wood, just get the basement humidity levels back down to reasonable after loading it up (7.5 cord) with slightly-surface-damp wood. It's been going for 2 days now and it's *down from 90% to 75%.* I usually only run it for a week or so, maybe intermittently a bit after that - then having the basment windows open should keep things good, until it gets too cold for open windows.
> 
> 
> 
> 
> :bug: Yikes
Click to expand...


BTW, I meant the air in my basement is down to 75 from 90 - I didn't mean the wood itself, if that was what was read. The wood is fairly well seasoned, just had some exterior dampness when it went in that immediately started migrating to my basement air.

Roughly speaking, that is - sometimes I am suspicious of my super cheap humidity/thermometer unit.


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## oldspark

90% humidity in the basement, does not seem right.


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## maple1

Battenkiller said:
			
		

> Until the outside gets drier than the inside, no moisture gradient will be established within the wood, and the water will stay inside the wood forever.



If that is truly the case, how do we ever get wood seasoned to 20% m/c? Relative humidity is rarely below twice that here - I suspect there are not that many places that have relative humidity below 20%. Actually, I think the air humidity here is always above wood m/c even when the wood is green & fresh cut - right now it is nice & sunny out, wind at 22km/hr, and rh is 72%. I think air movement serves to wick moisture away and is the primary requirement - but of course will not wick anything away while the wood is being rained on. And yes, it will take time - most times lots of it.


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## maple1

oldspark said:
			
		

> 90% humidity in the basement, does not seem right.



With a basement full of damp wood? That is always what happens here, with my experience - soon as the damp wood goes in (I can never seem to get it in when it is completely dry for some reason), the humidity skyrockets. It would likely go down on its own with a couple of windows open, after a while, but I don't want it at that level any longer than it has to be.

EDIT: Is there anyone else with a humidity measuring device in the area of their basement woodpile that has any more input?


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## oldspark

maple1 said:
			
		

> oldspark said:
> 
> 
> 
> 
> 90% humidity in the basement, does not seem right.
> 
> 
> 
> 
> With a basement full of damp wood? That is always what happens here, with my experience - soon as the damp wood goes in (I can never seem to get it in when it is completely dry for some reason), the humidity skyrockets. It would likely go down on its own with a couple of windows open, after a while, but I don't want it at that level any longer than it has to be.
> 
> EDIT: Is there anyone else with a humidity measuring device in the area of their basement woodpile that has any more input?
Click to expand...

 OK maybe you are correct, but man that is just about raining.


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## maple1

I have a feeling some would be surprised if they followed humidity levels. There are lots of nice summer days with RH over 90% - hence the 'humidex' talk on hot muggy days, i.e. the summer equivalent of winter 'wind chill' talk.

I will admit to being surpised when I first put my el cheapo thermometer/humidity meter thing up in my basement.


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## krex1010

Just throwing a fact out there that may generate some discussion here. I once saw a chart, I believe I saw it in a thread here, that peak combustion efficiency occurs at a about 22% moisture content.  Not sure if that means heat transfer peaks there as well, but I thought that was an interesting fact that goes against the common held opinion that you need sub-20% moisture levels to be able to burn efficiently.


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## Battenkiller

oldspark said:
			
		

> Battenkiller said:
> 
> 
> 
> 
> 
> 
> 
> krex1010 said:
> 
> 
> 
> 
> I doubt your humidifier idea will work, yes they use humidifiers in kilns, but your situation is not going to give you the drying conditions you would see in a kiln.  Your oak is likely best served by saving it until next year.
> 
> 
> 
> 
> You know, I think you're right.  A humidifier probably won't work at all.
> 
> Click to expand...
> 
> What if your wood is too dry?
Click to expand...



 :lol: 


Hadn't thought of that. 

Well, now you _really_ got a problem.  It's a lot harder to rehydrate wood through air alone than it is to dehydrate it.  Look at the chart below to see what I mean.

If your wood was somehow way down to 10% MC (like many claim after several years of outdoor storage) you might get it back up to 16% MC (low end of the EPA test procedure load) _if_ you could get the humidity in the storage room up to about 85% RH... but it would take a very long time.  And that could not be done too easily during the winter.  

The RH in my home drops to about 20% in January and February no matter what a I do.  Even tossing in a cord and a half of wet oak would only raise the humidity up to about 45-50% RH... and that would only last a couple days before it plummeted back down again.  Been there, done that.  Now, if you had several humidifiers running all at once, you _might_ get that wood back up to 12% MC if you could maintain the winter-dry air that constantly infiltrates your home at about 65% RH.  Super-tight new construction would be the best, but even that allows several air exchanges a day.  Doubtful, but if you want to try it, be my guest.

But... then there is the hysteresis effect at play (sorry, couldn't find a chart that shows that) when you are rehydrating dry wood.  You might need to keep the air at about 75% RH in order to overcome that and get the wood back up to 12% MC, or all the way up to 90% RH to get it back up to 16% MC.  You'd be living in tropical conditions, you'd have mold sprouting everywhere, and it would take all burn season to accomplish.  You'd end up burning all of the wood at a MC that was too low and lose about the same amount of useful heat (excessive smoking in the beginning of each burn cycle) as if you burned it a bit too wet, but with more creosote buildup.

Best bet if your wood is too dry is to soak it in the back pond for a couple weeks, then take it out, stack it, wrap it entirely in black plastic and hope for the best.


 ;-P   ;-P    ;-P


(I'm finding out that you can never add enough "tongue-in-cheek" emoticons)


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## maple1

That's an interesting chart - hadn't seen that before.

From that, one could maybe expect that putting 20% MC wood into a 70Â°F basement would put your humidity at 90%.

Huh.


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## krex1010

It is much much much easier for moisture to come out of wood than it is to go back into it.  I have soaked wood chunks (baseball sized) for several days and then split them open and checked the moisture content compared to unsoaked chunks and there is almost no difference, there is a small amount of water seeping back into the outer part of the wood ( like a 1/8 of an inch) but that's it.  I did this to see if soaking wood really is helpful in my smoker, I think it slows burning for a few minutes but that's it. So I don't bother soaking my wood before smoking anymore.  So my suggestion is that if your wood is too dry, do nothing and burn away!


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## Battenkiller

krex1010 said:
			
		

> Just throwing a fact out there that may generate some discussion here. I once saw a chart, I believe I saw it in a thread here, that peak combustion efficiency occurs at a about 22% moisture content.  Not sure if that means heat transfer peaks there as well, but I thought that was an interesting fact that goes against the common held opinion that you need sub-20% moisture levels to be able to burn efficiently.



Yes, Krex, I have found a ton of research online and in wood burning manuals that supports that.  This may be the chart you are referring to (see below).  It is taken from a book written by one of the most highly regarded solid fuel experts in the world, Dr. Jay Shelton.  Dr. Shelton did much of the pioneering work that evolved into the EPA standards used today.

Peak combustion efficiency in non-cat wood burning appliances usually occurs way up around 28% MC using a _dry-basis calculation_ of moisture content - the same MC calculation used in the standard moisture meters used by homeowners.  That is equivalent to about 22% water by weight (wet-basis calculation).  Considerable excess air is required to get that combustion efficiency up there.  That means a lot of heat goes up the flue and is lost to the outside environment.  About 8-10% of the heat produced is lost up the flue compared to wood burned at the MC that gives the greatest overall efficiency.

Peak heat transfer, however, occurs at around 0% MC.  That is because the stove needs to be choked down so far that basically no heat goes up the flue.  At that MC and very low airflow, massive amounts of unburned fuel will cling to your cold flue walls and you will lose about 20% of the heat value of your wood as smoke or accumulated creosote.  Therefore, burning wood at 0% MC is not only much more inefficient, it is downright dangerous.  Not only will you leave massive creosote deposits in the chimney, 0% MC wood has incredible potential to runaway if too much air is added, dramitically increasing the risk of igniting the creosote.

Overall efficiency comes at the point where combustion air best matches the heat-retention characteristics of your system.  For most non-cat stoves, that would mean using wood at around 20% MC as read on a standard moisture meter, or at about 16% water by weight (wet-basis calculation).  Isn't it interesting that the EPA chose 16% MC wet-basis (20% MC dry-basis) as the low end of the acceptable MC range for its test loads?  It's because, below that point, many EPA stoves will actual create higher emissions rather than lower emissions and they might not even pass the test.

BTW, if you look at the MC scale on the chart, you will see the difference between the two methods of expressing moisture content.  The scale at the top (ranging from 0-55% MC) represents the dry-basis MC expression used by the lumber industry (and in just about every moisture meter sold today).  The scale at the bottom (ranging from 0-35%MC) represents the wet-basis MC expression used by the wood heating industry.  Use the top scale if you are trying to use the ideal wood MC by checking with a moisture meter.  The author probably used both scales just to confuse folks and make himself appear even smarter.   ;-)


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## Wood Duck

oldspark said:
			
		

> 90% humidity in the basement, does not seem right.



I bet a large percentage of basements are close to 90% relative humidity, at least the unfinished damp ones that are common here. Any closed air space with moisture will tend toward 100% RH unless the temperature changes occasionally, and basements don't tend to change temperature. Caves also have very high relative humidity for the same reason.


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## Battenkiller

maple1 said:
			
		

> That's an interesting chart - hadn't seen that before.
> 
> From that, one could maybe expect that putting 20% MC wood into a 70Â°F basement would put your humidity at 90%.
> 
> Huh.



No, that's not what is going on.  

The concept of an equilibrium moisture content (EMC) assumes that the volume of air at a given RH is vast compared to the volume of wood.  This is almost always the case in the real world.  Even when stored inside, outside air is constantly infiltrating the building no matter how tight is may seem.  The wood reaches an EMC with the RH of the air in which it resides.  In a cool basement, that RH might be a lot higher than the outside air.  In a hay loft at the peak of a hot sunny day, it might be a lot lower.  Of course, the whole process is exceedingly slow, so the only thing you can go on is the _average_ RH in the storage place over a given time period.

Now, if you were to take a small quantity of wood at 20% MC and hermetically seal it with heavy plastic so not a trace of air could get in or out, the RH of the air spaces inside the package would go all the way to 100% RH and the wood would probably still be pretty close to 20% MC inside.  It all depends on the initial volume of air compared to the volume of wood, factoring in the air exchange rate and the temperature at which it all is stored.  Basically, there are several variables involved.


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## krex1010

I think that what all this means is that you should get a year ahead on your firewood stacks and burn away, problem solved .


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## Battenkiller

krex1010 said:
			
		

> I think that what all this means is that you should get a year ahead on your firewood stacks and burn away, problem solved .




 :lol: 


Revolutionary!  That just might work  But... we could still have fun here playing around with all the "what ifs".  Understanding is never a bad thing IMHO.


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## oldspark

krex1010 said:
			
		

> I think that what all this means is that you should get a year ahead on your firewood stacks and burn away, problem solved .


 Ah an epiphany!


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## maple1

So I guess the answer to the question is 'yes, but.......'.


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## krex1010

I agree 100% battenkiller

How's the trout fishing by the way?


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## Battenkiller

Wood Duck said:
			
		

> oldspark said:
> 
> 
> 
> 
> 90% humidity in the basement, does not seem right.
> 
> 
> 
> 
> I bet a large percentage of basements are close to 90% relative humidity, at least the unfinished damp ones that are common here. Any closed air space with moisture will tend toward 100% RH unless the temperature changes occasionally, and basements don't tend to change temperature. Caves also have very high relative humidity for the same reason.
Click to expand...


Considering that the mean yearly RH in most regions of the U.S. is up around 70-80% RH, that is not surprising.

To test your hypothesis, I just went down to the basement to measure the RH with a sling psychrometer. 

Basement floor is still wet from two major groundwater floods during Irene and Lee.  Sheetrock walls feel cool to the touch, and are still very wet at the bottom where the water soaked deeply.  Dehumidifier has been off for days because I am being forced out of here after 20 years and I no longer care how musty it gets down there.  Walkout basement door hasn't been opened in days, and I have hardly gone down there at all in the last three weeks.  Pretty damp feeling to say the least.  Stinks, too.

Results?

68ÂºF dry bulb temp, 65ÂºF wet bulb temp, 3ÂºF wet bulb depression gives me about 86% RH.  Of course, the outside air is still well above 70% RH, so there is not as much difference as you might expect.  Mostly due to the temperature difference, I'd guess.  Even with no activity in and out, air infiltration has prevented the air in there from rising to 100% RH, even during some of the wettest soil conditions in recent history.  Interestingly, my IR gun shows the temp of the sheetrock walls is 68ÂºF a few feet up and 65ÂºF down where they are still soaking wet - same as the dry and wet bulb readings.  Makes sense, eh?  Says a lot about how accurate my commercial-grade IR gun is as well.

Curiously, even at a very damp 86% RH, the EMC of the wood down there is still 18% MC, and at 90% RH in the basement all wood will be at 20% EMC.  Raise the RH all the way to 100% RH?  According to the EMC chart, it will never rise above about 28% MC... the water content that gives the highest combustion efficiency _and_ the MC that most wood reaches when all of the free water is gone and all of the bound water remains.  A few minutes of careful thought will make all this perfectly clear as to why.


----------



## Battenkiller

krex1010 said:
			
		

> I agree 100% battenkiller
> 
> How's the trout fishing by the way?



Been great this year.  The water's been so high on the 'Kill I can catch 'em in by back yard... 20 miles away.  %-P


----------



## Wood Duck

I think the wood will burn, so the question is whether it is more economical to burn the damp wood, run a dehumidifier, or run the furnace and save the wood for next year. I guess that burning the wood is the most economical way to remove the water. It would be more fun to burn the wood after it dries, but it will burn now. Check your chimney often.


----------



## krex1010

Battenkiller said:
			
		

> krex1010 said:
> 
> 
> 
> 
> I agree 100% battenkiller
> 
> How's the trout fishing by the way?
> 
> 
> 
> 
> Been great this year.  The water's been so high on the 'Kill I can catch 'em in by back yard... 20 miles away.  %-P
Click to expand...

That's a river I always wanted to fish.  Not sure about the 'kill but high water always equals big browns where I fish


----------



## woodchip

The talk has all been about the amount of moisture in a bit of wood so far. 

Surely the amount of moisture contained and percentage humidity will depend on the density of the wood, ie, lighter less dense wood will dry quicker, and give a higher reading even if the actual amount of sap/water inside is the same amount as a denser split, and will also release that moisture quicker. 

Putting dry looking wood into a basement might well increase the moisture level in the basement if the wood is not dry all the way to the centre of the splits, and is still in the process of moving moisture slowly from the middle to the ends of the splits (although the end will feel dry at this point), as air movement in a basement is likely to be lower than splits stacked in windrows out in the sun, even if the R/H of the air is showing something surprisingly high (air not being dense will mean a high R/H even if there is not much actual moisture there....... 

Just some thoughts from here........


----------



## Battenkiller

krex1010 said:
			
		

> Battenkiller said:
> 
> 
> 
> 
> 
> 
> 
> krex1010 said:
> 
> 
> 
> 
> I agree 100% battenkiller
> 
> How's the trout fishing by the way?
> 
> 
> 
> 
> Been great this year.  The water's been so high on the 'Kill I can catch 'em in by back yard... 20 miles away.  %-P
> 
> Click to expand...
> 
> That's a river I always wanted to fish.  Not sure about the 'kill but high water always equals big browns where I fish
Click to expand...


Oh, yeah, and the Battenkill is big brown water without a doubt.  The problem this year has been in finding them in the surrounding fields... literally.

Send me a PM.  Always glad to take people out on the 'Kill, be glad to fish with you if you ever get in my area.


----------



## gerry100

My basement is too damp in the non burning months when I use AC for comfort

During the burn season it gets so dry I like most others put a pan of water on the stove top

Could putting wet splits in the stove room help with the dryness and season wood

may be practical with some setup


----------



## pdxdave

Battenkiller said:
			
		

> Wood Duck said:
> 
> 
> 
> 
> 
> 
> 
> oldspark said:
> 
> 
> 
> 
> 90% humidity in the basement, does not seem right.
> 
> 
> 
> 
> I bet a large percentage of basements are close to 90% relative humidity, at least the unfinished damp ones that are common here. Any closed air space with moisture will tend toward 100% RH unless the temperature changes occasionally, and basements don't tend to change temperature. Caves also have very high relative humidity for the same reason.
> 
> Click to expand...
> 
> 
> Considering that the mean yearly RH in most regions of the U.S. is up around 70-80% RH, that is not surprising.
> 
> To test your hypothesis, I just went down to the basement to measure the RH with a sling psychrometer.
> 
> Basement floor is still wet from two major groundwater floods during Irene and Lee.  Sheetrock walls feel cool to the touch, and are still very wet at the bottom where the water soaked deeply.  Dehumidifier has been off for days because I am being forced out of here after 20 years and I no longer care how musty it gets down there.  Walkout basement door hasn't been opened in days, and I have hardly gone down there at all in the last three weeks.  Pretty damp feeling to say the least.  Stinks, too.
> 
> Results?
> 
> 68ÂºF dry bulb temp, 65ÂºF wet bulb temp, 3ÂºF wet bulb depression gives me about 86% RH.  Of course, the outside air is still well above 70% RH, so there is not as much difference as you might expect.  Mostly due to the temperature difference, I'd guess.  Even with no activity in and out, air infiltration has prevented the air in there from rising to 100% RH, even during some of the wettest soil conditions in recent history.  Interestingly, my IR gun shows the temp of the sheetrock walls is 68ÂºF a few feet up and 65ÂºF down where they are still soaking wet - same as the dry and wet bulb readings.  Makes sense, eh?  Says a lot about how accurate my commercial-grade IR gun is as well.
> 
> Curiously, even at a very damp 86% RH, the EMC of the wood down there is still 18% MC, and at 90% RH in the basement all wood will be at 20% EMC.  Raise the RH all the way to 100% RH?  According to the EMC chart, it will never rise above about 28% MC... the water content that gives the highest combustion efficiency _and_ the MC that most wood reaches when all of the free water is gone and all of the bound water remains.  A few minutes of careful thought will make all this perfectly clear as to why.
Click to expand...


Seasoning is sped up by drier air, but by no means is there a limit imposed at the RH% of the air.  Air has a higher moisture capacity than wood at the same pressure/temp, so there is a natural transfer of moisture from wood to air as the cells break down inside the wood. Lower RH accelerates the 'death' of the wood cells and this transfer.

100% RH means it is raining. So if you hit 100% RH in your basement, you've got alot more issues than just some dripping wet wood.


----------



## krex1010

It can very easily be 100% rh in your basement and not be precipitating inside your house.


----------



## oldspark

krex1010 said:
			
		

> It can very easily be 100% rh in your basement and not be precipitating inside your house.


You will have moisture condensing on everthing though.


----------



## pdxdave

oldspark said:
			
		

> krex1010 said:
> 
> 
> 
> 
> It can very easily be 100% rh in your basement and not be precipitating inside your house.
> 
> 
> 
> You will have moisture condensing on everthing though.
Click to expand...


Yup. 
I have actually experienced indoor rain in a hot, humid part of Mexico in mid-July. The A/C was running in the room next to me, and as the cold air leaked out from the top of the adjacent doorway, it cause the 95% RH air to condense, and little drops of 'rain' were landing on me.


----------



## maple1

That is likely due as much to the cold air leak than the rh level.

I have basement rain too once in a while - but that is condensation off an uninsulated cold water pipe feeding the washer a couple of loads in. Happens in all kinds of weather/rh levels.

I think you could see 100% rh in a basement without rain happening - mine gets over 90 at times and it only feels a little stuffy.


----------



## onetracker

oldspark said:
			
		

> 90% humidity in the basement, does not seem right.



if i don't dehumidify my basement it shoots up to 90% in summer.


----------



## onetracker

maple1 said:
			
		

> That's an interesting chart - hadn't seen that before.
> 
> From that, one could maybe expect that putting 20% MC wood into a 70Â°F basement would put your humidity at 90%.
> 
> Huh.



3 years ago i must have brought in some damp wood cuz there was water DRIPPING from the ceiling in my shop (its structural concrete) i thought that maybe it was soaking in from outside but it was the firewood causing it. i think that load was probably only seasoned for a few months.


----------



## Battenkiller

gerry100 said:
			
		

> During the burn season it gets so dry I like most others put a pan of water on the stove top
> 
> Could putting wet splits in the stove room help with the dryness and season wood
> 
> may be practical with some setup



I put up to 1 1/2 cord of unseasoned wood in my basement at a time and it only has a very minimal effect, and it only lasts for a few days.  I documented this all extremely carefully last year and presented the data here on Hearth.com.  I used a weather-grade sling psychrometer that has two thermometers in it.  They are attached to a carrier that allows them to be swung rapidly through he air.  One of them (the "wet bulb") has the mercury bulb encapsulated with a wick, which is dunked into distilled water, while the other one (the "dry bulb") sits right beside it. When the device is spun in the air, the distilled water in the wick of the wet bulb evaporates, causing the temperature to drop through evaporative cooling.  The difference between the two thermometers is recorded and then the relative humidity of the air is determined using something called a psychometric table.  This method is extremely accurate compared to the Home Depot dial-type humidity indicators most folks have.

OK...  what did I find?

Several hours from the time I'd first bring in the wood, the humidity would start to rise.  At the end of about 24 hours, the RH in the basement would rise from the low 20% range up to about 40% RH.  That is just about perfect for inside winter living conditions.  On the second day, however, the RH would drop down into the upper 30% range, them into the high 20% range after about five days.  The wood itself was drying rapidly, losing hundred of pounds of water in a  very short period of time.  This was confirmed by weighing various splits and recording their weight changes.  I kept one split and recorded all of the weight changes through the entire season.  It went from about an initial 57% MC all the way down to about 20% MC within three weeks.  Multiply that by a few thousand splits over the course of the winter and you can get an idea of how much water was being released into the home.

Where did all the water go?  It was definitely evaporating out of the wood and into the surrounding air.  Why didn't it raise the humidity level in my home?  Air exchange, as I mentioned before.  How much?



> *Ventilation rate*
> 
> The ventilation rate, for CII buildings, is normally expressed by the volumetric flowrate of outside air being introduced to the building. The typical units used are cubic feet per minute (CFM) or liters per second (L/s). The ventilation rate can also be expressed on a per person or per unit floor area basis, such as CFM/p or CFM/ftÂ², or as air changes per hour.
> 
> *For residential buildings, which mostly rely on infiltration for meeting their ventilation needs, the common ventilation rate measure is the number of times the whole interior volume of air is replaced per hour*, and is called air changes per hour (I or ACH; units of 1/h). *During the winter, ACH may range from 0.50 to 0.41 in a tightly insulated house to 1.11 to 1.47 in a loosely insulated house.*[4]
> 
> ASHRAE now recommends ventilation rates dependent upon floor area, as a revision to the 62-2001 standard whereas the minimum ACH was 0.35, but no less than 15 CFM/person (7.1 L/s/person). As of 2003, the standards have changed to an addition of 3 CFM/100 sq. ft. (15 l/s/100 sq. m.) to the 7.5 CFM/person (3.5 L/s/person) standard.



So, even in a very tight home, the air inside is being completely replaced by outside air every other hour!  Knowing this, it is hard to have faith in a pan of water making a big difference, never mind a few splits of wood.  HVAC experts say that the average tight home of 2000 sq.ft. needs about 5 gallons of water added every day in order to maintain a 40% RH level.  A leaky home will need twice that amount.  _My_ leaky home would need about 2100 gallons of water in a seven-month heating season in order to achieve that goal.  Five full cord of dense hardwood dried down from green to 20% MC would only add about 1/3 of that amount.

Now, there are some who claim to get satisfactory results by drying laundry by the stove.  They may think they feel better, but trust me, they would never fool my weather-grade instrumentation.


----------



## krex1010

oldspark said:
			
		

> krex1010 said:
> 
> 
> 
> 
> It can very easily be 100% rh in your basement and not be precipitating inside your house.
> 
> 
> 
> You will have moisture condensing on everthing though.
Click to expand...

Not unless your basement is cooler than the outside temperature.


----------



## Battenkiller

It's all about dew point.  If the temperature of the basement surfaces is lower than the dew point of the contained air, moisture (dew) will collect on these surfaces.  If not, then it won't.  Simple as that.

OK... not so simple.  Dew will have a harder time forming on porous surfaces and poor thermal conductors like wood, but it will definitely form on exposed pipes and come down like rain.


----------



## Swedishchef

Holy crap, what a post.
BK :  Are you an engineer? You sound like one! Lots of my buddies are P.Eng and sound like you! I agree with everything you have said. 

To get back to the OP, I think that a nice big fan, some heat in the basement and a DEhumidifier will certainly accelerate the drying process. I don't know where you live, but where I live we don't get wind 24/7. A couple of commercial fans (that run at about 100 watts a piece) and a dehumidifier will do a better job than mother nature can: you can control the climate inside but not so much outside. However, will it dry the wood quick enough for this winter? Will it be cost effective? The only way to find out is to try it.

Andrew


----------



## jatoxico

I think a major point of that is being missed is that the MC of wood is calculated on a weight basis eg. 30g water per 100g of wood = 30% MC.

Relative humidity is not calculated this way. From the attached chart notice that at 20 C (around 70 F) the actual amount of water on a g basis is only 8g/1000g air at 50% Rel Humidity and 15g/1000g at 100%.


----------



## Battenkiller

jatoxico said:
			
		

> I think a major point of that is being missed is that the MC of wood is calculated on a weight basis eg. 30g water per 100g of wood = 30% MC.
> 
> Relative humidity is not calculated this way. From the attached chart notice that at 20 C (around 70 F) the actual amount of water on a g basis is only 8g/1000g air at 50% Rel Humidity and 15g/1000g at 100%.



Yes, the RH of air is temperature dependent while the MC of wood is not.  Heating up a split with 50% MC will not change the amount of water it can hold.  I don't see how this fact changes anything.  Water molecules will leave the surface of the wood at a faster rate when the RH is low than when it is high.  That's where the dehumidifier comes in.

Since the only way water can leave the split is directly from the surface into the air, water inside the split must migrate to the surface across a diffusion gradient that is established by the water leaving at the surface.  Therefore, the faster the water leaves the surface (i.e. the lower the RH), the steeper the gradient becomes, and the faster water molecules will migrate out of the inner portions of the split, and the faster the entire split will dry.  That's why I said earlier that RH is what drives the entire process, not temperature _per se_.  

Heating up the air in the basement _will_ lower the RH and allow water to leave the wood surface faster.  That's why this process works so much better in the dead of winter.  The frigid outside air contains very little water even at a high RH.  As that air infiltrates into the heated spaces, the RH drops like a stone and rapid drying begins.  In a naturally ventilated system like a home, the moisture that leaves the wood soon exits the living space as new dry air moves in from the outside.  

With a dehumidifier, the water is removed from the air by the cold condensation coils of the dehumidifier (which are well below the dew point) and drips into a container to be removed, or is drained away continuously through a hose or pipe of some sort.  There is no need to continually introduce fresh air into the storage place because the air is continually being dried by the condensation process itself.

FWIW their are two principle methods for calculating the MC in wood.  The one you mentioned - wet-basis - is the most intuitive way, but it is not the way MC is expressed by wood technologists.  They use a method of calculation called _dry-basis_.  It is the weight of the water divided by the dry weight of the wood fibers themselves.  Wood that is 30% water by weight is 70% dry wood fiber by weight.  30Ã·70 = .429 X 100 = 42.9% MC _dry-basis_.  It is crucial to understand this point if you are using a moisture meter to judge the readiness of your wood.  After all, fresh-cut white ash that might read 42.9% MC on a meter (dry-basis) is durn near ready to burn just as it is (and some folks do burn fresh-cut ash with success), whereas wood that might be 42.9% MC wet-basis like red oak (70% MC dry-basis) will hardly ignite.


----------



## jatoxico

Battenkiller said:
			
		

> jatoxico said:
> 
> 
> 
> 
> I think a major point of that is being missed is that the MC of wood is calculated on a weight basis eg. 30g water per 100g of wood = 30% MC.
> 
> Relative humidity is not calculated this way. From the attached chart notice that at 20 C (around 70 F) the actual amount of water on a g basis is only 8g/1000g air at 50% Rel Humidity and 15g/1000g at 100%.
> 
> 
> 
> 
> Yes, the RH of air is temperature dependent while the MC of wood is not.  Heating up a split with 50% MC will not change the amount of water it can hold.  I don't see how this fact changes anything.  Water molecules will leave the surface of the wood at a faster rate when the RH is low than when it is high.  That's where the dehumidifier comes in.
> 
> Since the only way water can leave the split is directly from the surface into the air, water inside the split must migrate to the surface across a diffusion gradient that is established by the water leaving at the surface.  Therefore, the faster the water leaves the surface (i.e. the lower the RH), the steeper the gradient becomes, and the faster water molecules will migrate out of the inner portions of the split, and the faster the entire split will dry.  That's why I said earlier that RH is what drives the entire process, not temperature _per se_.
> 
> Heating up the air in the basement _will_ lower the RH and allow water to leave the wood surface faster.  That's why this process works so much better in the dead of winter.  The frigid outside air contains very little water even at a high RH.  As that air infiltrates into the heated spaces, the RH drops like a stone and rapid drying begins.  In a naturally ventilated system like a home, the moisture that leaves the wood soon exits the living space as new dry air moves in from the outside.
> 
> With a dehumidifier, the water is removed from the air by the cold condensation coils of the dehumidifier (which are well below the dew point) and drips into a container to be removed, or is drained away continuously through a hose or pipe of some sort.  There is no need to continually introduce fresh air into the storage place because the air is continually being dried by the condensation process itself.
> 
> FWIW their are two principle methods for calculating the MC in wood.  The one you mentioned - wet-basis - is the most intuitive way, but it is not the way MC is expressed by wood technologists.  They use a method of calculation called _dry-basis_.  It is the weight of the water divided by the dry weight of the wood fibers themselves.  Wood that is 30% water by weight is 70% dry wood fiber by weight.  30Ã·70 = .429 X 100 = 42.9% MC _dry-basis_.  It is crucial to understand this point if you are using a moisture meter to judge the readiness of your wood.  After all, fresh-cut white ash that might read 42.9% MC on a meter (dry-basis) is durn near ready to burn just as it is (and some folks do burn fresh-cut ash with success), whereas wood that might be 42.9% MC wet-basis like red oak (70% MC dry-basis) will hardly ignite.
Click to expand...


My only point was; from reading the thread there seemed to be a question among some as to how wood could apparently become drier than the prevaling RH. eg if RH is 50% how can wood ever get less than 50%? I was simply pointing out than RH and MC are not expressed in equivalent scales of measurement. So wood of 40% MC will dry even in conditions of high humidity and cool temp although the process will, of course, be slower than if temp is high w/ low humidity. It is also why you can put "dry" wood in your basement and still raise RH.
Apologies if I misread any posts.


----------



## Battenkiller

jatoxico said:
			
		

> My only point was; from reading the thread there seemed to be a question among some as to how wood could apparently become drier than the prevaling RH.
> Apologies if I misread any posts.



No need to apologize.  I was just going on in my usual verbose way, trying to help clarify the way wood dries.  I've gone through these concepts plenty here in the last few years, but there is a new crop of burners every year.  Only trying to help educate them, as I am sure you are doing yourself.


----------



## woodchip

jatoxico said:
			
		

> I think a major point of that is being missed is that the MC of wood is calculated on a weight basis eg. 30g water per 100g of wood = 30% MC.
> 
> Relative humidity is not calculated this way. From the attached chart notice that at 20 C (around 70 F) the actual amount of water on a g basis is only 8g/1000g air at 50% Rel Humidity and 15g/1000g at 100%.



That was what I was trying to get at on the previous page, but probably not very well........  ;-)


----------



## Swedishchef

We should all have kilns inside out houses! I wonder if anybody does...

Andrew


----------



## maple1

I don't think I've seen any out houses that would hold more than a couple of armloads though.


----------



## Battenkiller

I'd try that, but I don't even have an out house. Put a flusher in back in '03.


----------



## woodchip

Our greenhouses now have 2 cords in them spread out, we are having an unusually warm spell (120f inside them today with the doors open) and a nice drying breeze. 

No power being used to dry the wood, just a simple solar kiln that's empty now the tomatoes are finished. 

Long may this continue, drying wood and not burning it  ;-)


----------



## My Oslo heats my home

woodchip said:
			
		

> Our greenhouses now have 2 cords in them spread out, we are having an unusually warm spell (120f inside them today with the doors open) and a nice drying breeze.
> 
> No power being used to dry the wood, just a simple solar kiln that's empty now the tomatoes are finished.
> 
> Long may this continue, drying wood and not burning it  ;-)



I have noticed the same effect on the tops of my stacks in the backyard, the clear plastic covers the row (tops) and the top 8-10 inches is much dryer than the lower uncovered sections of the stack. I wonder if black plastic covers would be more effective?


----------



## Battenkiller

My Oslo heats my home said:
			
		

> I wonder if black plastic covers would be more effective?





Just curious... why do you think black would be better?  I believe clear plastic would be better because you want the sunlight to go through the plastic to warm up the inside.  Just like a car on a sunny day... or a greenhouse. ;-)


----------



## My Oslo heats my home

Battenkiller said:
			
		

> My Oslo heats my home said:
> 
> 
> 
> 
> I wonder if black plastic covers would be more effective?
> 
> 
> 
> 
> 
> 
> Just curious... why do you think black would be better?  I believe clear plastic would be better because you want the sunlight to go through the plastic to warm up the inside.  Just like a car on a sunny day... or a greenhouse. ;-)
Click to expand...


Black would create more heat


----------



## cptoneleg

onetracker said:
			
		

> i quickly browsed thru the responses here....
> 
> what's a bush cord??
> 
> so now we've got face cords, ricks, and bush cords? :grrr:
> 
> please advise
> 
> OT





128 sq.ft of bushes don't buy them they burn really fast


----------



## Battenkiller

My Oslo heats my home said:
			
		

> Battenkiller said:
> 
> 
> 
> 
> 
> 
> 
> My Oslo heats my home said:
> 
> 
> 
> 
> I wonder if black plastic covers would be more effective?
> 
> 
> 
> 
> 
> 
> Just curious... why do you think black would be better?  I believe clear plastic would be better because you want the sunlight to go through the plastic to warm up the inside.  Just like a car on a sunny day... or a greenhouse. ;-)
> 
> Click to expand...
> 
> 
> Black would create more heat
Click to expand...


Only on the outside surface.  You want all of the energy from the sunlight to get _inside_ the plastic barrier.  As I said, like a greenhouse.


----------



## MOHAWK1

Hello everyone and thanks for all the input on this issue, I had originally posted this on monday, that day i split open a piece of red oak that sat in the log form for 2 years and was opened up and stacked this june to test the moisture content. Th meter read 35 percent which is as high as it goes so I thought this wood will never be ready in 4-6 weeks. I had the idea of bringing the wood into the quonsa hut to finish drying, using fans a dehumidifyer and being able to control the temperature. With the ability of being able to control these 3  elements of wood seasoning I thought i would post it on here get some input and give it a try. I brought in 3 wheel barrel loads on the monday turned on 2 fans set the dehumidifyer to 35 and let it sit till today. I split open 9 random pieces and they were all between 22-25 percent mc,


----------



## Swedishchef

Hey mohawk.

Glad to hear that it worked!  That is good news!

WHere in Ontario do you live? I am in QC.

Cheers!

Andrew

PS, pics are always nice!


----------



## benjamin

JimboM said:
			
		

> 140 pint/day dehumidifiers will remove 140 pounds of water per day.  If your seven cords have 7000 pounds of extra water, you should get there in 50 days.



... @ 80 degrees F and 80% humidity.  Problem is the wood won't give up water that fast at a high humidity or lower temp. I'm guessing you're better off moving it into the basement a few weeks before you burn it and letting the wood heat do the work for you.


----------



## Battenkiller

MOHAWK1 said:
			
		

> Hello everyone and thanks for all the input on this issue, I had originally posted this on monday, that day i split open a piece of red oak that sat in the log form for 2 years and was opened up and stacked this june to test the moisture content. Th meter read 35 percent which is as high as it goes so I thought this wood will never be ready in 4-6 weeks. I had the idea of bringing the wood into the quonsa hut to finish drying, using fans a dehumidifyer and being able to control the temperature. With the ability of being able to control these 3  elements of wood seasoning I thought i would post it on here get some input and give it a try. I brought in 3 wheel barrel loads on the monday turned on 2 fans set the dehumidifyer to 35 and let it sit till today. I split open 9 random pieces and they were all between 22-25 percent mc,



Sounds like you're going ahead with this.  Glad to see you got some quick results.  If it was me I would bring about a cord inside the hut, then erect a makeshift shelter around it and put the dehumidifier and fans right inside with it.  No use dehumidifying the air inside the entire hut when all you want is to get the air in contract with the wood at a lower RH.  

Several pallets could be set up with tarps to enclose it all, making a real cheap but highly effective low-tech kiln.  Plus, by enclosing it within a small space, the temperature will go up from the heat produced by the dehumidifier itself.  That will further lower the humidity since RH is temperature dependent. This is what the big commercial dehumidification kilns do, and it will speed the process up dramatically.

FWIW the drying rate will slow down a lot once the wood hits about 20% MC.  At that point, you can bring in another cord and moved the pallets and tarps and everything over to that pile and start all over again.  In my basement (which I jokingly call the "Battenkiln"), wood dries to completion from green to 20% in about 3 weeks, but that is at a very low humidity (~20-25% RH).  In my case, it is the constant infiltration of dry winter air that gets heated up to about 85-90Âº by the stove in the basement that does the trick.  You won't be able to get the RH that low using dehumidifiers, but you should still be able to get a cord dry in 4-5 weeks... maybe sooner, I have no direct experience with artificially drying firewood in any other way but the way that has worked for me for 21 years now.  Dehumidification of the air - by whatever means - definitely works, and it works faster than outside in all but the driest outdoor environments.


Below is the data and chart from last year's controlled experiment.  The shape of the curve gives an indication of how slow the drying goes after a while.  No use going on after that point, it just will not be cost effective.

Good luck, and keep posting the results.  Then post your electric bill when it is all dry. ;-)


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## Heartwood

Battenkiller said:
			
		

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> I doubt your humidifier idea will work, yes they use humidifiers in kilns, but your situation is not going to give you the drying conditions you would see in a kiln.  Your oak is likely best served by saving it until next year.
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> You'd end up burning all of the wood at a MC that was too low and lose about the same amount of useful heat (excessive smoking in the beginning of each burn cycle) as if you burned it a bit too wet, but with more creosote buildup.
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> You're saying you'll get MORE creosite build up with wood that's too dry?  It's not safe to burn wood that's too dry?  I've always been under the impression over-dry may be a little less efficient, but all the safer.
Click to expand...


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## Heartwood

I had to speed things up a few years ago.  Maybe what I did will help your process go even faster.  

Using some logic related to the sciene that Battenkiller shared about surface area, I split my splits.  In my simple mind, I was just figuring that a little log will dry faster than a big one.  It didn't cut the time in half (bet Battenkiller has some big formula for that), but it did get my moisture down quicker.  

You then have issues with buring smaller, faster splits.  But if you're like me, I had other wood to mix in.  

PJ


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## MOHAWK1

Hello again and thanks for all the comments, to maintain 18-20 MC and not overdrying the wood, what would be the optimum temperature and RH to get the stabilized EMC of 18-20 percent,


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## Battenkiller

MOHAWK1 said:
			
		

> Hello again and thanks for all the comments, to maintain 18-20 MC and not overdrying the wood, what would be the optimum temperature and RH to get the stabilized EMC of 18-20 percent,



If you look back on page 2, post #34, you will see from the chart that an EMC of 18-20% would be maintained at a RH of between 87% and 90%.


Intriguing, eh?  A very good argument against long-term storage of firewood.  


The question then becomes, "How long does it take to get there?"

I would say that for large splits (6" thick on average, 18-20" long) the wood would need to be seasoned for at least 18-24 months to get there.  4" splits only need about a year, depending on the length they were bucked to.  Shorter wood seasons a lot faster.

After that point, how long would it take to get down to as dry as it can get in your environment?  Using conventional wisdom from the air-dried lumber industry, I'd hazard a guess that it would take about one year per inch thickness of the split... minus a fair bit because firewood is a lot shorter than lumber and does a lot of its drying from the ends.  So maybe 3-4 years for 6" splits to get down to the EMC found in most of the continent - 12-14% MC.

Some areas around the Great Lakes, much of Michigan for example, may never see their wood dry below 16-18% MC come burn season no matter how long it is stored.  A quick look at their average monthly RH percentages will tell you why.

Then again, you have to take those combustion efficiency charts i posted with a large grain of salt.   There are a lot of variables.  Large dense splits of primo hardwood at 14% MC might actually outgas a lot slower than thin pine boards at 18% MC, so the combustion efficiency and overall efficiency would be better with the drier wood.  Most experienced burners like big splits or rounds of hickory, locust, beech, hard maple, and black birch that have had long seasoning times.  It is really all about knowing your stove, your wood, your draft, etc.  Like medicine, woodburning is based on science, but is practiced as an art.


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## Battenkiller

Heartwood said:
			
		

> You're saying you'll get MORE creosite build up with wood that's too dry?  It's not safe to burn wood that's too dry?  I've always been under the impression over-dry may be a little less efficient, but all the safer.




There have been at least a half a dozen rigidly controlled scientific studies over the last 30 years that show conclusively that wood that is too dry will produce more creosote in the chimney than wood that is too wet.  These studies have not been well received on this forum, though.   :blank: 

Consensus here is that the studies must be flawed because they contradict what folks seem to observe in their experience.  Give me a flue that is accurately weighed by scientists before and after each burn session over anybody's anecdotal observations.

"Too dry" and "too wet" are arbitrary terms anyway.  The wood used in these studies wasn't oven-dry on the dry end, nor was it fresh cut on the wet end.  I think the "wet" hardwood was semi-seasoned red oak at about 42% MC.  Interestingly, that's just about the MC of fresh-cut white ash, and everybody knows you can cut an ash tree down and throw it right in the stove in a pinch. So, it's not like they were using oak fresh off the stump (at over 70% MC).

That said, there are many ways to safely burn wood that is "too dry" once you really know your equipment.  Split size, wood density, draft control, load size, and stove packing are some of the controllable variables that may skew the outcome.

The most creosote I ever produced in one season was about 15 gallons  I did that by using kiln-dried pallet scraps from my buddy's pallet making operation.  I was doing everything wrong.  Splits too small, not dense wood, choking it down too far to control the fire, etc.  Boy, did my sweep ever read me the riot act about that!  If I ever had a runaway fire in the stove (easy to achieve with kiln-dried pallet wood) I would have likely gone up in smoke once all that creo ignited.  After that experience, I would never again use - nor would I recommend - pallet wood to try to heat with (although it makes awesome kindling)


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## My Oslo heats my home

Battenkiller said:
			
		

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> Just curious... why do you think black would be better?  I believe clear plastic would be better because you want the sunlight to go through the plastic to warm up the inside.  Just like a car on a sunny day... or a greenhouse. ;-)
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> Only on the outside surface.  You want all of the energy from the sunlight to get _inside_ the plastic barrier.  As I said, like a greenhouse.
Click to expand...


I still can't understand the logic here. Dark colored roofs create more heat than lighter colored roofs, both the surface and the space beneath them. Dark colored cars also do the same. Even dark colored t-shirts in the sun. I still believe the space underneath a black colored platic topper will create more heat in the space beneath it vs. clear platic will.


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## Battenkiller

My Oslo heats my home said:
			
		

> I still believe the space underneath a black colored platic topper will create more heat in the space beneath it vs. clear platic will.



Then do it your way. ;-)


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## maple1

Battenkiller said:
			
		

> My Oslo heats my home said:
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> I still believe the space underneath a black colored platic topper will create more heat in the space beneath it vs. clear platic will.
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> Then do it your way. ;-)
Click to expand...


If you go black, the suns rays won't reach past the black. If you go clear, they will get inside and heat everything up inside radiantly and the plastic will trap the heat. The black topper will absorb heat, but not as much heat as everything inside will if the suns hits that - and even then the black will give the heat up both ways, inside and out. Also, I think dark bark on the wood that is piled inside will absorb more heat from direct sunlight hitting it than from air that has been warmed a bit by warm air between it and a hot dark overhead surface.

A dark shirt is warm in the sun, but your skin will get a lot hotter without a shirt there. Similarily, using the car analogy, I think the air inside the car interior (where there is glass) will be a lot hotter than in the trunk, with all dark steel over it and no glass.

Or at least that's what the seat of my pants is telling me....


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## Battenkiller

maple1 said:
			
		

> If you go black, the suns rays won't reach past the black. If you go clear, they will get inside and heat everything up inside radiantly and the plastic will trap the heat. The black topper will absorb heat, but not as much heat as everything inside will if the suns heats that - and even then it will give the heat up both ways, inside and out. Also, I think dark bark on the wood that is piled inside will absorb more heat from direct sunlight hitting it than from air that has been warmed a bit by warm air between it and a hot dark overhead surface.
> 
> A dark shirt is warm in the sun, but your skin will get a lot hotter without a shirt there. Similarily, using the car analogy, I think the air inside the car interior (where there is glass) will be a lot hotter than in the trunk, with all dark steel over it and no glass.
> 
> Or at least that's what the seat of my pants is telling me....



Your pants are very well informed.  :coolsmile:


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## RyanB

Getting back to the original question about the dehumidifier.... in the fall of 2008 I was forced to do this very thing.  We moved to our new location that september and started cutting mostly ash almost right away. We burnt thru the wood we purcashed from the original owners (guy was cheap and wanted every last penny possible) by Christmas.  And started burning our amazingly dry, dehumidified wood!  Here is what I did.   For starters my "hobby shop" is very well insulated and has a brand new at the time, non EPA wood stove rated for 2000 square feet.   I stacked 12 face cords in the shop (floor to ceiling, stacked 16" inches appart from each other stack). The next part of the equation before the dehumidification was to get some heat in the shop!  I went out and cut down a totally dead stand of poplar with a moisture content of under 20%.  I put 6 face cords of the poplar in the shop away from the stacks of ash.   I started burning the poplar and landed up keeping a temperature of 35 degree's celcius 24 hours a day with 3 firings every 24 hours.   I then had two nice sized box fans pushing the heated air thru the piles. I then fired up my 140 pint dehumidifier with it draining into the floor drain.   Starting with 100% green ash, within 3 weeks I had the entire stack down to 25%MC in the middle of splits, 2 week later I had MC down to 15% and was ready to shut it all down and take it into the house.    I have yet to have any "seasoned" under normal methods burn as well that 12cord did and if it wasn't so much work to move it all into the shop prior to the house....I would be doing it all again in a heart beat!

Ryan


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