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Length of time from 12% moisture to 7%

Started by JamieK, October 17, 2022, 04:34:16 PM

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JamieK

Hey guys, I have the nyle l200m. I've only dried a few loads with it so my experience is limited. I have a load drying right now of black walnut. The moisture seems to be stalled at 12%. This morning I checked and the probes measured 12.8%. After 10 hours it went to 12.4%. I guess one question is can I trust the probes to give an accurate reading? and is the last few percent that difficult to remove?
Currently the dry bulb is set at 138 and the wet bulb is at 94. I'm getting about 1 gallon of water removed in 24 hours
Wood-Mizer LT70 full line, BMS250, BMT100, Moffet M5,Nyle L200M, Lucas mill model 7 with slabbing attachment and planer attachment

YellowHammer

The probes are pretty accurate, they measure the resistance between the probes through the wood based on several things, including moisture.

Walnut will characteristically stall right about where you are.  So that's normal for walnut. It takes time and heat to overcome.  

You are running above the high pressure freon shutoff temperature, I'm surprised it hasn't tripped already, it may have already except you say you're getting water out of the condensate line.  
YellowHammerisms:

Take steps to save steps.

If it won't roll, its not a log; it's still a tree.  Sawmills cut logs, not trees.

Kiln drying wood: When the cookies are burned, they're burned, and you can't fix them.

Sawing is fun for the first couple million boards.

Be smarter than the sawdust

Southside

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K-Guy


Your compressor is most likely off and you are venting the moisture you lose. The compressor can't run at those temps and you will need to reset the high pressure switch.

KilnTech Episode 10: High Pressure switch reset for L53/L200 - YouTube
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YellowHammer

Is water coming out of the condensate line?  Is the compressor tripped or is it actually running?  The controller will only show that it's commanded on, but doesn't give my active feedback to indicate if it is actually on and running.  Water coming out of the condensate line is a sure sign.  If not, feel the coils to see if they are cool and listen to see if the compressor is running.   

Walnut stalls and it generally takes heat to break it feee, but the compressor switch on the main panel should be flipped off anytime you have a set point above 120F.
YellowHammerisms:

Take steps to save steps.

If it won't roll, its not a log; it's still a tree.  Sawmills cut logs, not trees.

Kiln drying wood: When the cookies are burned, they're burned, and you can't fix them.

Sawing is fun for the first couple million boards.

Be smarter than the sawdust

JamieK

I use the sense energy monitor to make sure everything is working properly. The tall green area is when the compressor is running so i know the switch is not tripped. At the current settings the compressor is cycling on and off. If I lower the wet bulb just 2 degrees it runs constantly with no additional moisture removal.
I have a very slow drip of water coming out.
Is it possible that the compressor is not efficient that close to the cut off temp?
I removed a board yesterday that was 2 layers down. When it cooled down i checked the moisture with my lignomat and it measured 8% but the probes still say 12%. I have the wood group set to #3 per the nyle manual.
This is still puzzling to me
 
Wood-Mizer LT70 full line, BMS250, BMT100, Moffet M5,Nyle L200M, Lucas mill model 7 with slabbing attachment and planer attachment

Stephen1

I think you need more chickens :D I will follow along also
IDRY Vacum Kiln, LT40HDWide, BMS250 sharpener/setter 742b Bobcat, TCM forklift, Sthil 026,038, 461. 1952 TEA Fergusan Tractor

YellowHammer

With such a large Dry bulb wet bulb spread or depression your wood is not putting off any moisture.  The air is exceptionally dry.  Is the wet bulb set at 94 or is it reading 94? That's more than 40 degrees depression, which is way overkill.  Normally, 20 degrees or even 25 degrees is maximum needed.  

The first thing is to get a true mc level of a dry walnut board and I'm not sure I'd trust anything but a pin meter.  Is your lingomat a pin?  Otherwise do an oven dry check, and get the real number and check that against both meters, the kiln and the lingo.  Also check a board with all 4 probes, to make sure there isn't a wiring or resistance issue. You can use a previously dried piece of walnut to do this, as long as you know it's dry, such as one stored in your house.  It will be 7 to 8% list likely.  You can use an EMC chart to confirm. 
 
The species corrections on the N200 are not overly accurate, so I use different ones than the manual.  If you want to do an uncertainty check, scroll through each group and you can see how much the numbers will change on the same piece of wood.  
Once you are very confident in the actual mc of a piece of wood, scroll through the N200 settings until it's number matches the true mc number.  

You've really got two issues I think.  Is the moisture level is correct and setting the readout to match the readings you trust and next, why is the compressor able to operate at such a high temperature without tripping the high pressure cutoff?

Either way, first step is to get a moisture number you can trust.  

YellowHammerisms:

Take steps to save steps.

If it won't roll, its not a log; it's still a tree.  Sawmills cut logs, not trees.

Kiln drying wood: When the cookies are burned, they're burned, and you can't fix them.

Sawing is fun for the first couple million boards.

Be smarter than the sawdust

jimbarry

Just a side note on compressor running while air temp is +135ºF. A couple days ago I had a load running and I mistakenly shut off the vent on the control panel of our L200M. The next morning I checked in and the dry buld on the control panel was reading 138ºF. Realizing what I did I turned the vent back on and opened a manual vent on the oppostie corner. Didn't take long to cool down. I figured the compressor tripped but the drip line continued for another day at which time the cycle was done. Hauled it out, shoved in another load and fired it up as normal. Everything working as it should. My guess, the air temp inside the compressor cabinet had not yet reached the shut off temp.

JamieK

OK, I get it now. I thought the over pressure switch is set at 140f so I thought the operating temp would be just below that. Reread the manual for this and couldn't find anything except for page 26 where it shows the schedules and only shows it at a max of 120f. Then I did a search on the web and found the sales sheet from nyle showing a temp range of 70f-120f
Wood-Mizer LT70 full line, BMS250, BMT100, Moffet M5,Nyle L200M, Lucas mill model 7 with slabbing attachment and planer attachment

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