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heating kiln

Started by xlogger, September 09, 2019, 04:53:00 AM

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xlogger

I was wondering when I use my Nyle to dry wood if seems like I get good drips for the first few days and then it slows down. Like the load of Maple I have in it now. I put it in about 5 days ago MC was around 20%. I check it last night with a very slow drip around 12-16%. If I go ahead and turn up the heat and cut off DH I believe it drys faster. I open up the doors a few times a day when I do this. Heating the kiln is at really no cost to me, I use my OWB for that.
Stan if you see this can I use my exhaust fans set to come on and not worry about opening the doors to let humidity out. Or maybe just start using high heat to begin with for faster drying and saving electric power not running DH.
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

K-Guy

@xlogger 

No. The vents operate on the dry bulb as over-temperature protection. To do what you want the vents would operate off of the wet bulb.

Higher heat and venting by opening the doors would be similar to how a conventional kiln operates. The big thing to watch there is whether or not the wood you are drying will react in the early to middle stages of drying. It also makes it difficult, if not impossible, to control the drying rate.
Nyle Service Dept.
A common mistake people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.
- D. Adams

GeneWengert-WoodDoc

From a more technical viewpoint, the outside fibers dry first and this is done quickly, so you see lots of water.  However, the water on the inside has to move through the wood, which is a slow process, to get to the surface where the air carries it away.  Two things make this happen faster...heat and lower humidity.

Sometimes, a short burst of heat followed by DH operation when the temperature is back to a safe value is all it takes to get the moisture moving.  However, you also need the humidity to be 30% RH or lower as it passes through the lumber.  Getting this low humidity can be hard if the compressor is low on the refrigeration gas or if the temperature in the kiln is so,low that the coils in the DH ice up.  So, 115 F is a good target temperature minimum near the end of a cycle, and hotter, if allowed by the DH unit, is even better.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

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