Idea for drying lumber

[rbdoby]

I need a cheap way to finish drying small amounts of wood for projects. My wife will kill me if I drag anything else into the house. I can only wood down to about 12% to 14% moisture in my workshop. All my lumber is stored in racks under a shed. Here's my idea.

I have a stairway in my shop leading to the loft. It's pretty much wasted space. If I close it off the area is about 150 cubic feet. Harbor Freight sells GoldenRod dehumidifiers for $35 that will handle up to 300 cubic feet of enclosed space. It's a metal tube that heats up to about 150° and drives the moisture out of an enclosed space. There is info on GoldenRod dehumidifiers at www.drytheair.com.

OK guys, tell me why this won't work so I won't waste my time and $50 bucks to build me a small kiln.

 

[jeff...]

I need a cheap way to finish drying small amounts of wood for projects. My wife will kill me if I drag anything else into the house. I can only wood down to about 12% to 14% moisture in my workshop. All my lumber is stored in racks under a shed. Here's my idea.

I have a stairway in my shop leading to the loft. It's pretty much wasted space. If I close it off the area is about 150 cubic feet. Harbor Freight sells GoldenRod dehumidifiers for $35 that will handle up to 300 cubic feet of enclosed space. It's a metal tube that heats up to about 150° and drives the moisture out of an enclosed space. There is info on GoldenRod dehumidifiers at www.drytheair.com.

OK guys, tell me why this won't work so I won't waste my time and $50 bucks to build me a small kiln.

Not sure how golden rod works but your 100% correct the lowest MC one could hope to archive is around 12 ~ 15% stacked outdoors. I think you may be on to something, don't forget about airflow through the stacks and insulating the area to make it tight. After all your trying to dehumidify 150 cubic feet of air not the air from your shop. You didn't hear me say your idea would work, because I don't know if it will. But it seems like your investing very little money to try out an idea. The old saying applies nothing ventured nothing gained. I still think the best method is kiln drying it's proven, repeatable and can sterilize (bug kill) a load. Granted your not looking to dry a few 1000 BF, your looking to dry a few hundred BF. There are lots of ways to dry lumber, yours may be another way that no one has thought of yet, you might just be paving a new road...

I'm sure folks more knowledgeable than myself will chime in here. I used to dry my own lumber but it was quite dangerous and a fire hazard, so I'm not going to share how I used to do it.

Thanks

 

[Robert Arrowood]

Sounds like a good plain too me as well.Like Jeff said "nothing ventured nothing gained".I've been thinking about trying to use an old camper shell off my brothers pickup.I don't need anything too large myself.All I want to dry is my walkingsticks (for now)LOL.And if nothing else you would have a nice insulated hiding place.:eusa_danc

 

[DIYGUY]

Jeff pointed out that you are trying to move the moisture laden air - that air will enter your shop presumably. My garshop does not have nearly enough good ventilation and I am almost always finding rust on something, and I don't have anything drying out in my shop.

Another concern I would have is about the impact on your stairs. I know they are utilitarian leading only to the loft, but adding and removing moisture in a confined space is bound to impact them somehow. Perhaps you can seal the underside of them with some plastic sheeting.

Is it a lack of resources (space, time, money) that is the inspiration for this project? There are lots of good plans around for solar kilns that could be readily modified for your needs. That might be a better long term investment.
Good luck with whatever you decide and I hope all goes well ...

 

[newtonc]

I agree it's a start,and on to a good idea.
My only concern would be sealing up the area under the stairs and then using a dehumidifier, that only heats up.Yes you would be creating a little low-temp oven.But by heating up the area and having green wood,wouldn't you be creating a little greenhouse of heated moisture where the moisture couldn't escape?
Which I think would lead to a lot of bigger problems,mold and decay being a few of them.It would be one thing if it was in a shed not attached to your house,but to experiment in a shop(maybe attached to the house?) and with structure and stairs involved...I think it would make me nervous.
I think a dehumidifier that collects(and drains) water would be best.

 

[Mark Anderson]

i'm going to be the odd ball, waste of money. all it is is a heater, you need something to actualy remover moisture.

this may help to keep condensation off of metals by heating them up above the due point. but that is about it. and here in north carolina that can mean heating an area up above the comfort range.

thier therry of expanding air just don't cut it for your application. air is only going to expand so much. after that your wood will be sitting in warm moist air.

you would be much better off going with a real dehumidifier. one with a drain hose so you can see the watter is actualy being removed.


another hought on the stair thing is the fire hazard. are these stairs the only excape route from an area? do you realy want a stickered pile of kindling under them?

 

[jglord]

My vote is for something solar powered - possibly around or in the current shed. Long ago, when I heated exclusively with wood, I rigged-up some 6 mil polly to cover the wood, but was held off the wood. I had a south facing deck raised off the ground by about six feet. I nailed the poly to the underside of the deck with strips of wood and held it down on the ground - end turned out with some logs. I had poly on the ends with provisions to allow ventilation.

I was amazed at how quickly the wood dried. It made the winter heating a lot easier - wood was lighter to carry and gave off more heat, being dry.:lol:

I'm sure there are more sophisticated and better controlled methods, but the sun will provide cheep and relatively safe heat for wood drying.:icon_thum

 

[Tarhead]

Rick,
(Mark climbing up on his soapbox....uhem
The Goldenrod reduces Relative Humidity, not Absolute Humdity. This is probably not a good way to do dry wood unless you're drying very small pieces. The make-up air replacing the "heated moist air being forced outside" has the same humidity as the air where you are currently storing your wood so your net loss of water molecules is zero. They raise the air temperature enough to get the relative humidity down but do not really do anything to get rid of the water vapor other than slowly moving small amounts of heated air. This is fine for a closet or a cabinet where you want to control mildew. To dry wood you need to get rid of the water molecules (drop the dewpoint to below the temperature of the wood in this case or increase the temperature of the wood) and that takes energy...a lot more than 38 watts. Ask Scott and Kyle how much it costs to run their kilns. A regular light bulb will do the same thing and a lot cheaper but a lot hotter and heat and wood are not a good combination if they are too close. Regular dehumidifiers and air conditioners get rid of water by condensing the water molecules passing air over a cold surface. If you circulate the air by this cold surface over and over it drops the absolute humidity of the air and the water molecules leave the solid things in the space to try to equalize with the air.
(Mark climbing down from his soapbox....sorry, it's what I do for a living and 4 out of 8 hrs/day trying to get people with advanced degrees to understand why my humidifiers are causing condensation:slap

Check around on Craig's List. Dehumidifiers are a frequent item for sale for <$50. It seems that you could enclose the stack of lumber in plastic and connect a dehumidifier. It will cost more to run than the Goldenrod but it will get rid of the water. Another slower option is to cut your stock to rough size and find a place inside an air conditioned space (under a bed?) to dry it over a few months.

 

[jeff...]

your going to want that space to be tight and insulated with airflow that circulated between the layers of your stack. The fan will need to be able to withstand high heat and humidity / conditions. You'll also need to make recommendations for the humidity of the heated air to escape into an area that will no get damaged like the outside.

The way I understand lumber drying there are three factors that come into play, airflow humidity and heat. You'll need to be able to control all three and be able to set them in the right proportions or risk degrade or perhaps case hardening.

Remember each species of lumber has a different drying rate expressed in maximum safe moisture content loss per day, exceed the safe limit at any time during the drying cycle and you risk degrade fall to far below the safe limit and you run the risk of mold.

There are a few different schools of thought here. one thought is to air dry your lumber to equalliberum, around here that's around 12 ~15%, cull out the defect and kiln dry the rest. The other school of thought is fell the tree on day one, mill the lumber on day 2, load the kiln on day 3 and dry till 6 ~ 8%

I'm looking to use that goldenrod thing in a space I'm building to store already kiln dried lumber, I think it may help the lumber from picking up extra moisture which is what I want then again it may not, don't know till I try... Thanks for posting info on it it seems very inexpensive to not give it a try, I wonder if it really works like they say it does?

Thanks

 

[photog]

I have to agree with Mark that it’s too little. I have a Golden Rod in my gun safe. It’s meant to raise the temperature a degree or two and you can even hold on to it for a while before it gets uncomfortable enough to make you let go. I don’t worry about a sling or strap touching it because it’s not a fire hazard. I installed it to prevent condensation when putting a cold gun into a room temperature safe,( a refrigerator sized enclosure) but I would think that it doesn’t have the moxie for your application.

How GoldenRod Works GoldenRod® heats to a surface temperature of less than 150° F (which is almost too warm to hold) and circulates warm, dry air throughout an enclosure on a 24 hour basis. This increases the temperature of the air inside to several degrees above the ambient outside temperature. Expansion of the heated air forces the moist air outside through the vents or loose fitting doors leaving the dry air inside.

 

[rbdoby]

Thanks guys

Your input has been a lot of help. I'll let you know what I eventually do.

Rick Doby

 

[Howard Acheson]

What is the relative humidity in your shop? No point in drying lumber to a point below the Equilibrium Moisture Content that is relative to the shop relative humidity. If you dry it to an EMC of 7-8% and your shop is at a relative humidity of 75%, the wood will absorb moisture and the EMC will go back up to about 12% in your shop.

BTW, wood can be air dried to any EMC. As said above, wood will reach an EMC relative to the long term relative humidity of it's environment. If you like in Arizona or some other desert-like area, wood can be air dried to 6-8% EMC.

 

[DaveO]

Along the lines of what Howard said here is good EMC calculator to help determine how dry you need your wood for the environment it will be in-

http://www.ncwoodworker.net/forums/downloads.php?do=file&id=150

Dave

 

[Gofor]

The Golden Rod appears to be the same thing that was available in Vietnam to fight the mildew, etc in clothing lockers. Didn't work there, but with a lower ambient temp around here, may do something. All it is is a heat rod that lowers the relative humidity. Air circulation is by convection.

Not for large items, and I am not a turner (yet) but one method I have not seen suggested here for small items like turning blanks is packing it in salt. When I was in FL, we used to stick fresh cut bait into salt to cure it for later use. A 50 lb bag of salt is cheap, and can be dried out in a microwave for reuse (wouldn't do that for cut bait salt tho:rolf::rolf. Dry salt will suck the moisture out of about anything.

Just a thought. Haven't tried it on wood.

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