iDRY Vacuum Kilns

Sponsors:

Using Fans for the initial Air Drying

Started by Glenn1, October 18, 2014, 03:10:59 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

WDH

I do the same thing as Robert.  I run the kiln at 150 degrees for 24 hours, and usually let the load sit for a while with all the vents closed and all the fans running.  I have let the load sit for 24 hours after sterilization, and the temp in the kiln will still be above 130 - 135 degrees with every thing including the fans shut down and the vents closed. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

OneWithWood

I do the sweat-em-in-the-sauna thing for most of the hardwoods, but I still flood the floor with about 20 gallons of water before running the temp up for oak.  My kiln chamber is 21'x10', the DH unit is a Nyle 200 and controller is a Honeywell (Woodmizer sold this setup as a DH4000 back in 2002).  I have had good results with the oak doing this, especially the 8/4. 
One With Wood
LT40HDG25, Woodmizer DH4000 Kiln

Glenn1

Quote from: OneWithWood on November 11, 2014, 02:05:53 PM
I do the sweat-em-in-the-sauna thing for most of the hardwoods, but I still flood the floor with about 20 gallons of water before running the temp up for oak.  My kiln chamber is 21'x10', the DH unit is a Nyle 200 and controller is a Honeywell (Woodmizer sold this setup as a DH4000 back in 2002).  I have had good results with the oak doing this, especially the 8/4.

How are you containing the water on the floor?  Are you keeping it away from the walls or not worrying about it?
Vacutherm IDry, Nyle 53 Kiln, New Holland Skid Steer, Kaufman Gooseneck Trailer, Whitney 32A Planer

GeneWengert-WoodDoc

Air dried lumber has very little, if any, stress.  However, when running the stress test with prongs, if there is a moisture gradient, the prongs will show stress.  The prong test must be made with no gradient.  So, keeping the vents closed with heat may actually be eliminating the gradient, which would have shown stress.

A commercial kiln will use 180 F and very high humidity for 18 - 24 hours.  It is hard to understand how a very mild condition (heat and vents closed) would be just as effective.  For this reason, I suspect that the amount of stress in many instances is very low.  Adding a great deal of humidity will cause the surface to gain moisture and swell (or try to swell) so that even a piece with stress will show no stress, until the moisture on the surface (moisture gradient) is dispersed.

To get a good reading with the prong tests when there is a gradient, put an individual prong in a microwave on high power for 15 seconds.  Then take it out and wait a couple of minutes before reading the results.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

WDH

Quote from: GeneWengert-WoodDoc on November 11, 2014, 06:25:08 PM
A commercial kiln will use 180 F and very high humidity for 18 - 24 hours.  It is hard to understand how a very mild condition (heat and vents closed) would be just as effective. 

Is 150 degrees for 24 hours considered a 'mild condition"?

Another question.  If the wood going into the kiln is already air dried to 15%, will much additional stress develop between drying from 15% to 8%?
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

GeneWengert-WoodDoc

Yes, 150 is mild.  We know that stresses are not removed well at 150 compared to 180.

Virtually all stress develops during the loss of the first 1/3 of the moisture, from green.  So, no stress develops at low MCs.  Short answer...need more?
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

WDH

No.  Mostly what I am drying in the DH kiln has pre-air dried.  I am not getting much stress at all, therefore the question about the "mild" 150 degree sterilization. 

I still hate white oak.  All thicknesses  :).
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

Peter Drouin

Thanks for the info guys. It will help in the spring when I can get my kiln together. :D
A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

OneWithWood

Quote from: Glenn1 on November 11, 2014, 02:28:35 PM
Quote from: OneWithWood on November 11, 2014, 02:05:53 PM
I do the sweat-em-in-the-sauna thing for most of the hardwoods, but I still flood the floor with about 20 gallons of water before running the temp up for oak.  My kiln chamber is 21'x10', the DH unit is a Nyle 200 and controller is a Honeywell (Woodmizer sold this setup as a DH4000 back in 2002).  I have had good results with the oak doing this, especially the 8/4.

How are you containing the water on the floor?  Are you keeping it away from the walls or not worrying about it?

The kiln is very well sealed along the floor wall boundary and the walls are coated.  With a 3000bf charge of 6-7% wood the water does not stay on the floor long enough for me to worry about it. 
One With Wood
LT40HDG25, Woodmizer DH4000 Kiln

OneWithWood

I am quite fond of white oak, all thicknesses.  It brings out my more caring patient side  :D :D :D ;D
One With Wood
LT40HDG25, Woodmizer DH4000 Kiln

WDH

 :D :D :D

Actually, I love everything about white oak except for drying it. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

kantuckid

I have two stacks of 2x6x10&14' of (mostly SYP) pine on sticks under the open roof on the front of my shop. Each stack is a bit over 1,000BF stacked 3.5' wide.

 I have one 20" box fan on the end of each stack blowing 24/7 into the end.

 In my area, about how many days will these fans serve an effective purpose toward drying this lumber? 
Thanks!
Kan=Kansas;tuck=Kentucky;kid=what I'm not

customsawyer

Quote from: kantuckid on June 06, 2021, 10:10:01 AM
I have two stacks of 2x6x10&14' of (mostly SYP) pine on sticks under the open roof on the front of my shop. Each stack is a bit over 1,000BF stacked 3.5' wide.

I have one 20" box fan on the end of each stack blowing 24/7 into the end.

In my area, about how many days will these fans serve an effective purpose toward drying this lumber?
Thanks!



If I am reading it right your fans are blowing against your stickers instead of through your lumber. I don't think your fans are going to help much. Look back at the pictures of YH fans and lumber. Bigger fans will help more and have them moving the air parallel to the stickers. 
Two LT70s, Nyle L200 kiln, 4 head Pinheiro planer, 30" double surface Cantek planer, Lucas dedicated slabber, Slabmizer, and enough rolling stock and chainsaws to keep it all running.
www.thecustomsawyer.com

kantuckid

I see what your say & it's true and I considered that when I placed them but not smart enough huh? ;D I'm gonna move the fans to the open walkway between the stacks and opposite ends from each other, then move them along the stack a bit as they'll be pretty close to the wood-maybe 24" from the stacks. I have these box fans sitting on milk crates to position them above the base. 

Now, back to my question? 
Kan=Kansas;tuck=Kentucky;kid=what I'm not

Southside

If it's framing lumber you are after I bet they would be under 20% MC in a couple weeks. 
Franklin buncher and skidder
JD Processor
Woodmizer LT Super 70 and LT35 sawmill, KD250 kiln, BMS 250 sharpener and setter
Riehl Edger
Woodmaster 725 and 4000 planner and moulder
Enough cows to ensure there is no spare time.
White Oak Meadows

kantuckid

I wouldn't doubt that %, but since I'm still waiting on wall logs I have some time. My tractor remains dead so the p[ines I dropped have laid since Early May when the first guy managed to not work on it at all and only been moved bit over a week now to 2nd guy. I can hear the bugs eating as past few days the heats been on in the woods. I've got a bunch of 4x6 pine beams to saw yet if those trees stay OK.
 About half the stacks were in place early April but the last were month later. I moved my fans this afternoon. They are blowing oppositely which also mean they are sucking air through the stack beside them and ones doing a middle the other an end for now. I've about got my shop arranged for dead stacks and planning operation plus T&G-ing. I own too many MC's and got several still in the way of lumber milling. ;D
 
Kan=Kansas;tuck=Kentucky;kid=what I'm not

GeneWengert-WoodDoc

Fans are used for air drying usually in a shed.

The issue is the operating cost.  Let.  For example, if you have a small fan that uses 12 amps or 1500 watts, or 1.5 kWatts, and you run fit 12 hours a day for 25 days, and your electric useable is around 400 kW.With an electric rate of $,15 per kW, the cost is $60.  Is it worth $60 to have drier lumber in a shorter time? Of course, multiply $60 by the number of fans.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

kantuckid

There are another few localized factors: Electricity is cheap in E KY, plus I'm using box fans that don't draw 12 amps (more like half that) plus my shops on it's own meter and the shop minimum applies given that this time of year I tend not to be inside as much using that electricity. Once that planer kicks on that meter whirls!
My particular stacks were done in roughly two stages as I logged more trees to finish, so this fan thing sort of catches the top up with the bottom as I'll pull off the top when I walk boards to the planer, etc.. 
Kan=Kansas;tuck=Kentucky;kid=what I'm not

Don P

This time of year drying faster also reduces stain.

WDH

I use air drying fans constantly, especially this time of the year. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

Thank You Sponsors!