Finished Kiln-

[EZland]

 

 

This is my finished Kiln.  I am testing my posting pictures skills. 

[Den Socling]

You did well with the kiln and the posting. 

[EZland]

 

 



  

  

  

  

 

I built this Kiln in a week.  It hold about 500 BF although it will only take a 10 foot board.  I have a extension cord powering two fans.  I am moderning temps and humidity with a remote set up. 

[EZland]

Ok I guess I can prove I can post photos,but not spell check or even the correct word.  lol  I meant "Monitoring"  temps and humidity.  I have had about 300 BF of pine in there for two weeks, it has dropped form 40% ish to 18% in 15 days.  Oh, and no splits or cracking. 

[Riggs]

Love it, thanks for sharing.

[John_Haylow]

Very nice job, looks great. 8)
John

[ancjr]

Definitely looks like a quality build.   

Is that a steep angle roof angle for GA latitude?

[WoodenHead]

That looks great!

Did you insulate the walls?

[WDH]

Excellent.  I may want to come see it  ;D.

[EZland]

I did insulate the walls with R13 and  the roof angle I guessed/built it at  45 degrees. Not really sure if the angle is the best, but way easier on the carpenter skills. 

WDH, you are welcome to come see it.  It really is a fun project.  As far as cost I think I have $400 into it.  I would have to think to itemize the list.  Most of the cost was the roof $140, stain about $110,2 fans $34,  hinges, insulation, remote thermometer and other fasteners are the rest the total. Lumber free, all of it came down in a tornado.  I did set it up on two utility poles that I sawn in half.  It weighs about 3000 lbs or so, I know I tried to lift it with my tractor and the front wheels came off the ground,but I can drag/ roll it to a better location on my property if needed. 

The high temps are not as high as some kilns out there, but so far in has been easy to control the humidity.   I may have to add a flea market dehumidifier to drop it to 6-8%, but this is the first run with 300 BF of pine.  I will keep you posted on the results. 

[thecfarm]

That does look like it will work. Good luck.

[pineywoods]

Nice job on the build. I see you opted for the full width doors. Your back will thank you. Go for the de-humidifier. It will cut the drying time considerably. If you need more heat, fasten some black painted roofing metal to the bottom side of the rafters. Solar radiation hitting a lumber stack at 45 degrees makes a very poor collector, black metal perpendicular to the sun is a lot more efficient.

[EZland]

Piney,   You can't see it very well in the pictures, but I did use black painted metal on the bottom side of the rafters.  Do you know what the angle of the roff should have been for Ga latitude?  Later I might build a second for longer lumber. 

Those full length back doors are the way to go.  Much easier loading.  I also added a small door in one of the large doors for access to check the lumber. 

If I place a dehumiditfier in it I guess I should close all the vents?  I like the idea of using solar as much as possible,but at what point will the outside humidity have a no return effect? 

[ancjr]

Do you know what the angle of the roff should have been for Ga latitude?

I remember reading about the angle of the roof being factored in, but re-read last night and decided from what I read that it isn't critical.  When the roof angle is made to match the latitude (39 degrees for me) and the building oriented to maximize its facing the path of the sun in the sky, you'll get maximum solar radiation into the kiln during the summer.  Winter radiation is optimized by adding a few degrees.  That said, it's not critical unless you're extremely limited on materials and/or available sunlight.   8)

[GeneWengert-WoodDoc]

The best roof angle for year-round performance  is equal to the latitude.  Make it steeper as you move north to get more heat in the early winter, but a slight loss in the summer.  Likewise, a little flatter will give better summer performance.  However, 45 degrees is so easy to do, that I have suggested 45 degrees for most of the US.

The key to the angle is the shadow that the collector makes; the larger the shadow, the more energy that is intercepted.  So, if you think about it, small changes in the angle at noontime will not have a big effect on the shadow cast.  Even if the angle is off so that you collect 10% less energy, that only means around 3 or 4 extra days in the kiln.  If you are in a hurry when drying, then solar is not the way to go.

Regarding pine, the moisture comes out so fast that the kiln will be like a sauna.  So, open the vents wide and keep the fans running 24 hours for the first week.  Then as the MC drops, close the vents partially and build up some heat, etc.

[xlogger]

Looks great EZland, after my add on to my sawmill shed I'm thinking I want to build a solar kiln. Questions for Doc or anyone. I first want to use it to dry or kill any insects in cedar slabs probably mainly 2-4" thick and 6-8 ft long.  Any suggestions? Wonder how long it will take to dry, I'm brand new at drying. My plan will be for selling slabs, I'm not a wood worker. I printed out the plans for the Va tech kiln and it has the open door on the side. I want to have it like EZland's to load with forklift on rear wall, so a little change in plans there.  Ricky

[drobertson]

Looks real nice ezland, good price too!  david

[Kingcha]

Very nice job.   I just started on my kiln yesterday.   Still have to work on a few details

matt

[EZland]

Thanks all for the comments.  I am a huge copy cat. So be flattered that I studied and copied the other kilns on here.  No sense in reinventing the wheel or Kiln. 

Thanks Gene, for the tips on the humidity for pine. 
As far as close Monitoring of the humidity?  Love me some sawmill time, shop time, building fence time,horse riding time, garden time,  but..... it is summer time too. POOL.... and a cold one.

Life is  a balance act, love it.  and keep Jesus and Family at the top. 

[GeneWengert-WoodDoc]

Radio Shack has a humidity measuring device for about $30 that will work just fine for this use.

The so-called Virginia Tech solar kiln design that I developed in 1978, and goes by a bunch of names now, work's very well, and is a good compromise between cost and performance.  Lumber requires heat, humidity and air flow in order to dry and these three can be developed by many different designs and at many different costs.  So, this VT design considered all the needs for drying and tried to keep the cost under control.  Further, this VT design is fairly efficient...bf dried per month...and will achieve 7% MC final MC if desired.  The kiln can also be used to store dried lumber.

As mentioned, when the fans are off, the heat will build up (over 180 F) and go to the top and can melt fan components, hurt roofing, melt insulation, and damage motors.  So, keep fans moving, keep vents open and/or cover the collector when not in use during the heat of the day.  Note that this heat is only hot air and if you were to blow the heat through lumber, the lumber will use the heat and maybe get a bit warmer, but not 180 F.  The maximum temperature with lumber in the kiln will be 40 F hotter than outside.  This is true for any kiln design with insulated walls and clear roof collector.  The heat losses will be large enough to prevent the kiln of any design from getting hotter.  (Sometimes we hear of kilns that get hotter when the fans are running, but it is a temperature measurement error.

The key for any kiln is the amount of energy (the shadow cast) per BF of capacity.  This kiln uses 1 sq ft per 10 BF.  The shadow should be measured at noon on March 21 or Sept 21 (that is, facing south and  perpendicular to the sun at noon.  Note that any increase in area increases losses and also solar input.  More input means more heat and might be too much on a sunny day for some species. 

To minimize collector losses, two layers of plastic are used.  Also, the walls and floor are insulated.  Some people think the vertical south wall should be a collector, but the energy input is less than the heat losses from this wall unless three plastic layers are used.

Incidentally, glass is ideal, but strong glass has a lot of iron in it (green edge on the glass) and this reduces efficiency greatly.  So, the corrugated material in the kiln shown here is really ideal...long life and very good efficiency at a very good price too.

[EZland]

Update on my moisture percentages 24 days and down to 10% on the center of a 4/4 pine board.  Its 5% on the ends......of course.  I still have not put the dehumidifier in yet.   I was sidetracked (on vacation).  We have had a lot of rain in the last 24 days.  Today it was 139 in the kiln.  I have a remote in my garage to  monitor and the humidity was a 40 % lower  from the outside.  My wife's hutch is almost done.

[EZland]

Little discouraged tonight. Finally pulled the pine out of my kiln and 2/3 of it was molded.  The edge I could see from the door side was good, about 4 inches of every board.  Also the bottom 4 layers and top two were good.  The middle yuck. A few are totally blue and the rest blue here and there. 

I had two fans powering it, but I am not sure if I had the air flow I needed. Do I need more fan power? Its a 9x 11.

The good news I do have enough good pieces for my wife's hutch. Thank God. 

[pineywoods]

EZ, now you know why I use a de-humidifier. With no dh, did you vent the moist air out every evening ? The water that comes out of the lumber gotta go somewhere, otherwise it justs grows mold.

[Kingcha]

Sorry to hear about the mold.   I have a few items left to finish my kiln(back panels and get power) but have my first load stack and ready to go.   My first load has been air dried for almost 3 months so hopefully I won't have a mold problem.

matt

[Kingcha]

I  see your 3 vents at the top......do you have lower vents as well?

matt