Heat source for a small sterilizer box - small DIY home shop use

[Aeromister]

I am new to the Forestry Forum but have really been impressed with the information I have found here.  I have a question of some of the well educated - experienced members;

I recently built a solar kiln for some live edge cherry 8/4 lumber (I have about 200 bd ft in the kiln right now - stickered and stacked).  The cherry was allowed to air dry to the 11-14% range before I got it.  I know it is a little late in the year for a solar kiln but I am getting RH values in the 25% range inside the kiln and it does seem to be working in getting the moisture level down. However I am not able to increase the temperature high enough to sterilize the wood.  I am thinking of assembling a temporary foam insulated box around the wood and heat it to around 150 degrees (F) to accomplish the sterilization process.  My kiln is 4' X 12' and I intend to assemble the foam box around the stack of lumber in the kiln.  I was thinking of using a heater-blower like one of these inside the foam box (with a baffle to direct the air flow through the stack of lumber) https://www.amazon.com/dp/B018DJ7UDO/ref=psdc_3735251_t1_B00GXV84BM.

The heater has a 185 degree switch on it but I thought I would use a controller like this to control the heater-blower to keep the temperature in the 150-160 range.  

https://www.ink-bird.com/products-outlet-thermostat-c909.html

I thought I would give it a good 4-8 hours at 150-160 degrees to make sure the wood was well heated.  Any comments would be appreciated.

Thanks

[samandothers]

Welcome to the forum!

Check out, search for the thread Hot Box: Hot Box in Drying and Processing
by Caveman.  It has some good detail for you.

[GeneWengert-WoodDoc]

In my foreign travels, much of the world uses a hot box to sterilize lumber instead of doing it in the kiln.

[Aeromister]

Gene 

Thanks for the information.  I think I am going to try to make a hot box in the garage to sterilize a couple of pieces of wood and then stack the pieces in the basement to continue to acclimate.  I did check the moisture in a few pieces of wood.  There just has not been enough sun to generate heat and do much drying.  I ordered a fireplace heater and a temperature controller.  When they get here I will assemble a hot box and post a couple of pictures.  I am a little concerned about case hardening from the heat but hopefully the cherry is dry enough that it should not be a problem (highest moisture I have found to be 11.0%).  

Thanks again,

Jim

[thecfarm]

@Aeromister welcome to the forum. What ya using the lumber for?

[mredden]

Gene

Thanks for the information.  I think I am going to try to make a hot box in the garage to sterilize a couple of pieces of wood and then stack the pieces in the basement to continue to acclimate.  I did check the moisture in a few pieces of wood.  There just has not been enough sun to generate heat and do much drying.  I ordered a fireplace heater and a temperature controller.  When they get here I will assemble a hot box and post a couple of pictures.  I am a little concerned about case hardening from the heat but hopefully the cherry is dry enough that it should not be a problem (highest moisture I have found to be 11.0%).  

Thanks again,

Jim

If you are going to use the wood in the basement, then acclimate it there. But, if you are going to use it elsewhere, you might want to check the humidity in the basement. Around here, basement humidity moisture can be very high. Maybe not in your locale. I'm putting smaller pieces in my attic where it's much warmer and drier.

[GeneWengert-WoodDoc]

Aeromister,
  Just a small bit of education...casehardening is caused the first few days or so of drying from green.  What you are concerned about is oversrying the outside because of low humidity, which is not casehardening.  Low humidity is caused when normal air is heated...25 F of heat with 100% RH air can drop the humidity to under 30% RH, so heat lamps or other hot source will create super low RH.  It is important to mix this hot air with the cooler air in a kiln or hot box before it contacts the lumber, which will assure more reasonable humidity, but you still need to be careful,  so measure the RH electronically with a $30 digital device.  This will be accurate enuf if you are within the sensor's temperature and humidity range.  Replace after a year or two.