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Drying wood indoors using a dehumidifyer

Post in 'The Wood Shed' started by MOHAWK1, Sep 26, 2011.

  1. MOHAWK1

    MOHAWK1 New Member

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    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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  2. firefighterjake

    firefighterjake Minister of Fire

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

    Hass Minister of Fire

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    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.
  4. maple1

    maple1 Minister of Fire

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    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.
  5. MOHAWK1

    MOHAWK1 New Member

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    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
  6. Reggie Dunlap

    Reggie Dunlap Feeling the Heat

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    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.
  7. maple1

    maple1 Minister of Fire

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    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 20°c - I suspect that would be a bigger problem here.
  8. joefrompa

    joefrompa New Member

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    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!
  9. My Oslo heats my home

    My Oslo heats my home Minister of Fire

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    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
  10. jimbom

    jimbom Combustion Analyzer

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    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.
  11. Backwoods Savage

    Backwoods Savage Minister of Fire

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    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.
  12. maple1

    maple1 Minister of Fire

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    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.
  13. jatoxico

    jatoxico Minister of Fire

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    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.
  14. jatoxico

    jatoxico Minister of Fire

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    :bug: Yikes
  15. Woody Stover

    Woody Stover Minister of Fire

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    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.
  16. golfandwoodnut

    golfandwoodnut Minister of Fire

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    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.
  17. Battenkiller

    Battenkiller Minister of Fire

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    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.
    Cory S likes this.
  18. krex1010

    krex1010 Minister of Fire

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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.
  19. Battenkiller

    Battenkiller Minister of Fire

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    You know, I think you're right. A humidifier probably won't work at all.
  20. krex1010

    krex1010 Minister of Fire

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    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
  21. woodchip

    woodchip Minister of Fire

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    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 ;-)
  22. My Oslo heats my home

    My Oslo heats my home Minister of Fire

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    +1 for BK. :)
  23. onetracker

    onetracker Minister of Fire

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    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
  24. woodchip

    woodchip Minister of Fire

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    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....... ;-)
  25. Hunderliggur

    Hunderliggur Minister of Fire

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    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 http://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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