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New to the forum, trouble drying cherry

Started by CLinLogs, July 20, 2017, 04:39:42 PM

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CLinLogs

Been lurking and reading for a couple years here but finally upon finishing my dehumidification kiln, decided I needed to become a member.

I have small test load of cherry in the kiln right now that seems to be stuck. It was air dried to 20-25% before going in the kiln and I've gotten it down to around 12-14% MC since... and that's where it sits. I'm not getting any more than a few drops out of the dehumidifier hose the last few days. I've held at anywhere from 90-115 degreesF and its not giving up any moisture... where do I need to go from here?

Joey Grimes

Sounds like you need a little more heat our final setting on 4/4 cherry would be 120 dB 90 wb .What type of kiln are you running ?
94 woodmizer lt40 HD kabota 5200 ford 4000 94 international 4700 flatbed and lots of woodworking tools.

CLinLogs

Ah, I need to bump the temp up a bit, I see. It's a homemade kiln made from old walk-in freezer panels with duct fans for airflow, 50 pint dehumidifier, heat bulb for more heat if necessary (gets to 115 easily with the fans and dehumidifier in this weather), and some instruments controlling and monitoring temp and humidity. I don't have the real wet bulb/dry bulb set-up yet, just temp and relative humidity... I was hoping to prove I could dry something with the equipment to prove the concept before going further. So kick up the temp to 120 until final mc is achieved? Yes, I'm working through reading DHL, trying to get it to sink in. It's a lot to process!

CLinLogs

So if my dry bulb is 120°, my relative humidity is 30%, and my barometric pressure is 30 in/HG... my wet bulb temp should be about 90 right? I've had it running this way for about 12 hours now and not a single drop of water has come out ???

needless to say I'm confused

YellowHammer

Are you sure your moisture meter is correct?  Most times, cherry gives up its moisture relatively easily.  What thickness is it?
Where are you getting your relative humidity from? 
Sorry for the questions, just trying to get an understanding of the situation. 
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

CLinLogs

No, questions are great and I know you know your stuff. It's 5/4 thick. I have two different temp/RH probes in the kiln and they both read about the same on both measurements... Could the dehumidifier be shot? It's still "running" but as I said no water is being removed.. I have a "general" brand pin meter, I'm reading on nails about 1/2" deep in Two different areas. I believe the better to be at least very close, I've checked it against a delmhorstj2000 and they were within .1-.3%. That's on my list to buy as soon as I can (j2000).

YellowHammer

Dry bulb 120F
Wet Bulb 90
RH 31%
EMC=5.6
What load size?

Looks like you are doing things right.  The cherry should be coming down to about 6%, but you don't want to go down that far.
 
The dehumidifier isn't putting out much water because there isn't much in the air, but that doesn't mean the wood isn't drying out.  It will be coming down from the 15% to about 5.6%.

I would be checking the wood with the moisture meter daily.  Or use the oven dry method to confirm and track.  Its always a good way to confirm the meters are working correctly.

If you can raise the heat, bring it up further.  Or wait it out and let the wood come to the conditional EMC value.

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

GeneWengert-WoodDoc

The nails measure the wettest spot along their length.  Right after measuring the kiln lumber, Take a dry piece of wood in your shop and measure the MC.  You should see under 9%.  Then take this piece into the kiln.  It is possible that you have moisture in your cable of the meter.

Many compressors have an auto shut off at 112 F or so.  Their fan may still run.
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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