iDRY Vacuum Kilns

Sponsors:

pecan in kiln

Started by xlogger, February 09, 2019, 07:53:31 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

xlogger

I put some 3" thick wide pecan in kiln a week ago air dried to around 20 percent. Got a good steady drip for several days and started slowing down and finally stop yesterday. I check it a couple places at 16 percent. I was thinking about running the heat on up for a couple days to heat treat it. Any suggestions?
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

bkaimwood

I would run it up at least 20 degrees for 2 days, see what happens...should get some water moving...
bk

WDH

Just don't go over 133 degrees with the compressor running or you will trip the compressor.
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

YellowHammer

Run the heat up to 130 until I he wood stalls again.  Then turn off the ompressor and go to 145 and restart the compressor again when safe.  

When I recharged my unit with 134a, I can operate at 140.  High pressure switch trips at 145.
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

xlogger

Quote from: YellowHammer on February 09, 2019, 10:57:00 PM
Run the heat up to 130 until I he wood stalls again.  Then turn off the ompressor and go to 145 and restart the compressor again when safe.  

When I recharged my unit with 134a, I can operate at 140.  High pressure switch trips at 145.
I'll have to look into the 134a that sounds good. After I posted this I walked into kiln and my glasses fog up so I cut the compressor back on. I had it at 120° and cut it to 125°. I've got my vent closed and auto fan off (easy to keep warm in cold weather) so it worries me getting close to 130. I raised the filter cover and see water on coils but nothing dripping. This is the thickest slabs I've tried to dry so far.
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

YellowHammer

First, I assume the compressor is functioning normally?  I've had Freon leaks in the past and the first sign was compressor running but the evaporator coil wasn't cool.  Any time I'm in the vicinity, I raise the filter screen and feel the coil.  If it's cool everything is functioning properly.  It's just a routine check I do.

Tripping the high pressure switch is something I've done too many times for me to mention here.  It's easy to reset, the biggest problem is removing the screws on the kiln side panel.  Push the little red button, all is well.  There is a lot of additional drying potential between 120 and 130, but there is a certain amount of risk.  

I run my kiln hot, right in the edge of trip in instances like this.  Hotter air absorbs more moisture, the coils can remove it more efficiently with the higher delta T, and the heat will cause stalled wood to unstall.  Lots of benifits if done in the correct time of the cycle.  I had to reset my kiln just last week, some stalled walnut had me at 140 and I overshot and somewhere between 145 and 150 I tripped the safety.  Oops. I keep a power driver and socket in the kiln box for just such an occurrence. 

Also, you don't have to run the compressor to dry stalled wood.  The temperature drives the moisture out of the wood, and the higher temp air absorbs it.  So the only benifit the compressor serves is to remove the moisture from the air.  The same can be accomplished by simply removing the air from the chamber.  I do this two ways, I crack a vent and turn on the heat lamps, either 2 or 4, as well as the kiln heat strips, compressor off.  Run the setpoint up to 145 or 150 and add enough heat where the chamber can lose moisture laden air and maintain temps.  It's just like running the sterilization cycle early, except vent or door dump the air occasionally.  Check the wood with a moisture meter to keep track of the values.  I've walked entire loads of wood down using this technique, compressor off and safe.  

Since the wood and chamber are hot, doing a full kiln dump is not a problem because the mass of the wood will reheat the exchange air quickly.  Also, me having 3,000 lbs of concrete on top of the stack, acts like hot rocks and retains heat.

Don't run high temps when the wood still has a high enough moisture content to chance sticker stain.  


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

rjwoelk

Just a thought dont know how its set up. Could one not fabricate a door on the pannel ,to make access simpler.
Lt15 palax wood processor,3020 JD 7120 CIH 36x72 hay shed for workshop coop tractor with a duetz for power plant

YellowHammer

I'd hate to modify anything, it might detract from the resale. :D :D :D

Actually, I only have to remove a couple screws and I peel the sheet metal side back like a banana peel.  Sometimes I just leave its jacked up, sometime I screw it back down.  I just didn't want to sound like I was being hard on it. :D
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

WDH

I like the idea of a little access door to re-set the little red button :).  Good one, RJ.
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

xlogger

Thanks, I'll check to see if the coils are cool first thing in the morning. I did check them earlier and they had moisture on them but didn't put my hand on them.
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

GeneWengert-WoodDoc

From DRYING HARDWOOD LUMBER


What To Do When Drying Apparently Stops
What can be done when drying seems to stop in the middle of the kiln run? Drying will never actually stop if the EMC of the kiln atmosphere is lower than the core MC of the lumber, but the drying rate is extremely slow. To correct this problem of "slow drying," the dry-bulb temperature can be slightly increased (perhaps 5 F to 10 F) during the intermediate stages of drying (under 25%MC). Higher increases at higher MCs are not recommended because of the risk of degrade. If a kiln operator decides to increase temperature above 30% MC, the operator should make sure that the kiln controller is properly calibrated.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

123maxbars

What meter are you using? Checking a sample board or the wood in the kiln?
My meter will always read high if I take it inside the kiln to check for MC. Usually about 4% higher than the actually MC of the wood
Note: I use the Wagner pinless meter. I rely on it for a basis of MC but when I get a deviation of 30% between the dry and wet bulb my wood is dry usually. 
Sawyer/Woodworker/Timber Harvester
Woodmizer LT70 Super Wide, Nyle L53 and 200 kiln, too many other machines to list.
outofthewoods
Youtube page
Out of the

YellowHammer

Delmhorst J2000 is a mainstay.  Pin style meter, has shunt calibration, temperature and species compensation.  
 For thick wood, get the slide hammer option.  The same meter can use both.  

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

123maxbars

Quote from: YellowHammer on February 10, 2019, 10:46:37 PM
Delmhorst J2000 is a mainstay.  Pin style meter, has shunt calibration, temperature and species compensation.  
For thick wood, get the slide hammer option.  The same meter can use both.  
accurate when taking readings inside kiln? that's my only gripe about the wagner, 
Sawyer/Woodworker/Timber Harvester
Woodmizer LT70 Super Wide, Nyle L53 and 200 kiln, too many other machines to list.
outofthewoods
Youtube page
Out of the

YellowHammer

Sure, that's what the temperature compensation is for.  It's a resistance meter, it won't care.    

How else do you check the wood with a meter except inside the kiln?  Typically, I'll probe a half a dozen random boards to get an average.  The Wagner won't read correctly in a kiln because of the heat and humidity?  
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

xlogger

Quote from: 123maxbars on February 10, 2019, 10:40:59 PM
What meter are you using? Checking a sample board or the wood in the kiln?
My meter will always read high if I take it inside the kiln to check for MC. Usually about 4% higher than the actually MC of the wood
Note: I use the Wagner pinless meter. I rely on it for a basis of MC but when I get a deviation of 30% between the dry and wet bulb my wood is dry usually.
Delmhorst J2000 with hammer.
Robert, I like the idea of using 134a so I can up temp. Why doesn't Nyle do this? Come in Stan and tell us. 
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

K-Guy

Hi Guys
Stan from Nyle.

Yellowhammer call me when your compressor fails, I think soon. The reason you can get up to 140°F is that you are undercharged and the compressor shouldn't run at that temperature. 
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

One risk of using a moisture meter in the kiln is that the meter is often cooler than the wet-bulb or dew point temperature.  Moisture then condenses on the probe, wires and connectors, meter surface, and possibly inside the meter.  Readings will often not go under 12% MC, then, even though the wood is drier.  Some people report that Drying seems to stop at 12% MC, but it is the meter that stops working correctly.  This is true for pin and pinless meters.

If you are using a pin meter, bring the samples outside the kiln for testing.  Do net test inside the ion.

Another way to use a pin meter is to put the pins into the wood (specially made pins for in-kiln use) and the run wires to the outside and keep the meter outside of the kiln.  One way to do this with commercially built equipment is Delmhorst's Kiln-Mo-Trol.

Incidentally, the temperature used for correcting readings is the wood temperature, which is often the dry-bulb temperature, even when the samples are brought outside the kiln.

Note that a pinless meter cannot read accurately when there is a large moisture gradient, which does happen when kiln drying.

Bottom line, after many tests and real-world attempts, a pinless meter cannot be used in the kiln to run a kiln.  Used in the kiln, the pin meter often has errors of 4% MC and larger. :)
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

YellowHammer

Quote from: K-Guy on February 11, 2019, 08:28:26 AM
Hi Guys
Stan from Nyle.

Yellowhammer call me when your compressor fails, I think soon. The reason you can get up to 140°F is that you are undercharged and the compressor shouldn't run at that temperature.
Stan, your killing me!   :D :D  
It could be undercharged,  :D but I like it this way. ;D Works better!   You could market it as the "Hammer Charge"!

Actually, if its undercharged, its marginal, as its a weighed in charge and generally, if there is low freon, there is frost on the evaporator line, which I'm not seeing.  Also, if there was very low freon, the low pressure safety with would trip.  So I'm operating within margins.  If I burn up the compressor, oh well,  I've had to replace compressors before, it was relatively inexpensive.  The only time I had to replace one on this unit was years ago, I think 2014-2015, when running the OEM RS-24 the unit was shipped with, which is unavailable in the South.   However, its a blend of other refrigerant, with a large fraction of 134a, available from any automotive store, which is why we switched.  This unit works great on 134a.  We use this L53 25/7 :D and has been an excellent unit.  Tough as nails.



Gene, not being contrary, but I don't take wood out of the kiln to test, except oven samples.  I hear what you are saying, and am always up for a good experiment.  Maybe the studies were for large scale kilns where the operator spends significant time on the kilns, and the user situation is different for small kilns, where the wood is tested by opening the door, testing a few boards and then shutting the door.    

So as an experiment, just a few minutes ago, I checked my Nyle 200M with wired, screwed in remote moisture probes.  I just happen to have a load of 4/4 red oak finishing in the kiln, dry bulb at 123 F and I set the auto shut off at 7% on the kiln unit, which it now reads.  However, the number on the front of the 200M display has no decimals, so I don't know the round off error for the integer value of 7 on the display, which may mean 6.6 to 7.4.  I just went inside the kiln a few minutes ago and checked 6 boards randomly in the stack to see if the Delmhorst pin meter corroborates the Nyle 200M remote probes.  For the 6 readings, I had a low of 6.1, and a high of 7.2.  The Nyle read 7.  Pretty close, actually surprisingly accurate. 

Anyway, I'm not telling people not to take samples out of the kiln if its more accurate, I'm just letting people know how I do it, and the actual experimental data to back up my reasoning, with an error of remote probes to checking in the kiln with a pin meter of well less than 1% MC.    

The meter reads 7.2, below


Pack 1 in the kiln, in the photo and displayed on the Nyle 200M wired remote moisture probes, as PRB.1. shows 7%, as an integer, no decimals.
 

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

xlogger

hard to unstack and move out a 200 pound slab to test it.
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

rjwoelk

Quote from: WDH on February 10, 2019, 07:05:18 PM
I like the idea of a little access door to re-set the little red button :).  Good one, RJ.
Should be able to install some piano hinges and maybe a magnite to keep it closed. 
Lt15 palax wood processor,3020 JD 7120 CIH 36x72 hay shed for workshop coop tractor with a duetz for power plant

WDH

The best thing is to not run the temp up too high and trip it in the first place ;D. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

xlogger

Quote from: WDH on February 11, 2019, 08:25:18 PM
The best thing is to not run the temp up too high and trip it in the first place ;D.
True, I've been lucky so far and not had to do it yet!
Talked to Stan yesterday and I'm going to run temp up to 145-150° for a couple days and then cool it down and cut compressor back on and see what happens.
Timberking 2000, Turbo slabber Mill, 584 Case, Bobcat 773, solar kiln, Nyle L-53 DH kiln

GeneWengert-WoodDoc

If you do get temporary condensation on a meter whensed inside the kiln, you will see that the meter will read 12% MC or similar value right AFTER you leave the kiln with the needles not stuck into a piece of wood. At he end  drying, the dew point in the kiln is low enough that the risk of condensation is small.  It is at high moistures when this is an issue.

This condensation is also why some people report that drying slows or stops during drying...their MC reading is the issue.

The kiln samples are removed from the kiln, and not entire pieces of wood.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Thank You Sponsors!