Finished Kiln-

[LeeB]

Did you use a drop curtain/divider above the stack to direct airflow through the wood?

[EZland]

I did  not have my curtain hung up to force the air in the right direction.  Yep, kicking myself, but learning.  I plan on putting in another load later in the week and I will install it then.  I may add another fan also. 

I believe it all has to do with airflow. 

Kingcha- I do have two  lower vents.   

[EZland]

Piney,
Would you want the DH on full time or just during the evening?  If so putting on a timer would be more cost effective , correct? 

[beenthere]

I did  not have my curtain hung up to force the air in the right direction

Found your answer. Have to force the air to go through the stickered pile, otherwise it just takes the easy route around the pile.

[Planman1954]

I run my fans with the dehumidifier. I let it go all day and night. Mine has run for about 4 days on a load of pine right now...I'll run out and check the mc........
OK. Looks like the average is around 10%. The top of the stack has dried more quickly than the bottom. There were higher readings I think due to less air flow near the bottom.

[pineywoods]

EZ, these little de-humidifiers don't consume enough power to worry about. The compressor is usually the same as a small refrigerator. Also, they will have a desired humidity setting. When the air gets above that setting, the unit will cycle on and run until the humidity drops below the desired setting and then shut off. Some will have a hight temp shutdown also. I just set mine for about 20% desired humidity and leave it on 24/7. A baffle to force the air through the stack is absolutely essential. Mine is a chunk of old canvas tarp hanging from the fan support down to the top of the stack.

[amgont75]

Great looking Kiln....How big is it? 

[SAWMILL BUDDY]

I keep the bottom vents wide open until the end of the cycle. Then close them up to get the heat. My kiln is 8x19 with 3 fans

[GeneWengert-WoodDoc]

Mold forms because drying at high MCs was too slow.  to speed up drying, we need to add more heat, lower the humidty, and or increase air flow.  it is hard to say what went wrong for sure, but in a solar kiln without DH, I suspect that venting was too little, causing increased RH.  Venting can be low because the vents are too small or the circulating fans do not create enough venting.  The rule of thumb of 1 sq ft of solar collector are (south facing, perpendicular to the sun at noon) per 10 BF of lumber is for oak.  For pine that dries much faster, more solar input is needed and more venting to avoid slow drying.

A little info about dehumidifiers.  A 50 pint per day unit will draw 5 amps about and remove 50 pounds of water per day.  A 1000 bf load of oak will have about 2000 pounds of water to be removed from green to 6% MC. 

At 5 amps and 110 volts and 24 hours and 12 cents per kWh, that is $1.50 per day for a reduction in MC of about 2% MC.  That would be around $ 40 for the load per 1000 bf of green oak.

Without a DH unit, but using solar or using air drying before solar, you can save $40, but it might take a bit longer.  In the Virginia Tech kiln, solar drying of 4/4 green red oak takes about six weeks in warm weather.  A 100% DH kiln with no solar would indeed go faster no matter what the outside weather.

[EZland]

Thanks Gene for the comments,
I am trying to use only only solar and a couple of fans due to my kiln is only powered by a 150 extention cord.  I have added another fan that oscillates blowing air directly into the stack and the tarp as the curtain to control the air flow.  Seems to help.  I just loaded in with a some 8/4 slabs and increased the stickers to 1 1/2  increase air movement.  Also if I wanted to dump RH should the venting be increase on the top or bottom of the kiln.  I still might have add a DH for hte winter, but trying to be low cost as possible.  It has been a tough summer to dry anything here in the south. 

amgont75, my Kiln is 8'x 10' 6" in the inside.  I was limited on the size due to the lumber lengths I cut on my mill.  My master plan is to build a 16' at a later date.  I am going ot need to buy an extention for the mill.  The great thing about the size of this kiln is I can drag it to another location with my tractor. 

Does any one know what temp do you have to get to to kill PBB?  I have heard several numbers out there, 133, 140, 160?  My high temp is about 160. 

[Deese]

I have GOT to build one of these. 

[LeeB]

I been saying the same thing for 14 years.  :D

[GeneWengert-WoodDoc]

To kill insects in wood, including the PPB, the WOOD needs to be 133 F (a politically determined number).  To reach that temperature through and through, the air would have to be perhaps 160 F for 5 hours or so.  If the air were only 140, it would take a very long time to achieve the 133 throughout the pieces.