nyle l53

[John C.]

hi, thinking about getting a nyle l53.looking for reviews of people running them.did you build chamber to their specs?can you set pitch when drying  pine?any feedback would be appreciated.thanks,john.

[YellowHammer]

I bought one recently, have been using it nonstop, and so far it has been a pretty good unit.  I built the kiln to the plans provided by Nyle, and everything works as advertised.  I have noticed that it puts out a good deal of heat, so I am having to run with my vents open to keep the temps in the kiln down.  I have been drying oak.
I don't know about setting pitch at 160, but it does have heat strips that let me reach sterilization temps of 140 with no problem.

Buy the Nyle gasket kit, it works pretty good, and get a cam clamp door latch kit for trailers to make shutting the doors easy.

YellowHammer

[John C.]

yellowhammer,are you useing the power vents?drying oak green?i'm planning on drying red oak mostly.what size chamber did you build?sounds well insulated, did you use polyisocyanurate for insulation?

thanks for your help,john

[YellowHammer]

I'm using the manual vents, which is not a problem because I check the kiln every day to get the sample board weights, and adjust the vents if needed. The kiln just doesn't change conditions so quickly that you can't catch it.  I used R30 in the walls and also a layer of 2 inch extruded polystyrene.  Six inch insulated concrete floor and aluminum paint on the inside. 

Here's a photo.




YH

[jim blodgett]

Yellow Hammer - You have to open vents to keep temperatures down? You can't control the heat on the unit?















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[John C.]

nice looking kiln yellowhammer.

thanks, john

[YellowHammer]

The kiln can control temperatures to some degree, but since there is no cooling capacity, the only way to reduce temperatures is to reduce the compressor cycle duration, or open the vents. 
Quoted from the Nyle manual, "If your chamber is well constructed and insulated, you will find that the motors in the system are providing excess heat, resulting in the temperature rising above the desired set point. How far it will rise will depend on the outside temperature, insulation, and tightness of the chamber. We provide two manual vents to "dump" excess heat. If the temperature rises above the desired set point, open the vents half way and check the temperature in a few hours to see if it is still rising or not lowering. Open further or close the vents accordingly. Keep in mind that any venting is also venting moisture, you need to watch the drying rate of the lumber. You may reduce the percentage compressor time to account for the venting. Reducing the percentage time will also reduce the heat being generated in the kiln, reducing the temperature rising."

YH

[jim blodgett]

I'm unfamiliar with your guages, thermometers, or whatever monitoring devices you use, so please bear with me.  I am very interested in that L53 unit, close to ordering one, and trying to understand all this (great looking kiln chamber).

Is there any consistancy with the amount overheated your system gets?  Like, is it 20% high, or something?  If so, have you thought about adjusting your target settings to compensate?

Just seems counter intuitive you'd have to leave vents open to release heat you've paid for.  I get it if there's no noticible trend, no consistancy.  But regularly?  I got to believe there'd be a way to anticipate consistant deviations from expectations.

Maybe I'm overthinking it.

[YellowHammer]

No, there's no over thinking it, you can get lost in this stuff, but there are a few rules that are consistent with this style of low temp dehumidification kiln. There's people with a lot more knowledge than me, but I'll try to explain how this operates. 
Temp, RH, vent dumping, heat strips, etc all are used to accomplish one thing which is to lower the moisture content of the chamber so that the wood will lose moisture at the coolest possible temperature and at its max allowable rate for that species to avoid defects.  For red oak, I have good results with no more than 2 percent moisture loss per day, or about 5 gallons of water per 1,000 bdft.  The L53 kiln will far exceed that rate if the temps are allowed to go up.  I did 6 percent MC loss by mistake one day and warped the heck out of some oak wood....The kiln comes with simple controller that sets heat strip temp and compressor duty cycle.

Increasing temperature, even slightly, allows the wood to release more moisture, and also allows the air to absorb more moisture, but has a significant penalty because the outer fibers in the wood weaken which allows the stresses of drying to cause the wood to warp more.  Best thing is to keep the wood fibers cool and strong, at least if the wood is above 40 percent MC.  For example, down to 35 percent MC, red oak should not get above 90 degrees, according the Nyle kiln schedule. So as long as the kiln can hit the max safe drying rate of the wood, heat is to be avoided in this style of kiln.

So the goal is to run the compresser at its lowest duty cycle to save money, to reach the maximum drying rate allowed by the wood, and at the coolest temp to minimize defects.  So in the case of red oak, you are not driving the kiln to max capacity, you are throttling it back to balance max allowable moisture removal rate of the wood at the lowest possible temp.  Today, with my compressor at 70 percent, the vents slightly open, the wood is at 87 deg and I had a 2.1 percent moisture removal rate, which is all I want.  As the wood gets dryer and less prone to release moisture, I will have to close my vents some to raise the temp of the kiln, but I dont want it to get to 100 deg until the wood is less than 25 percent MC, again according to a conservative red oak schedule.  I could also reduce my compressor duty cycle and close my vents to reach a lower temp, but then my drying rate falls off my target 2 percent because the compresser isn't running long enough to get rid of the moisture. 

So here's how I work the kiln.  With a fresh load of oak, I initially set the compressor to a low setting, say 60 percent, with the vents closed, and set the heat strips to 80 degrees, which is the minimum temp the compressor will need to kick on.  The next day I will check the kiln temp and try to target 85 degree kiln temp by increasing or decreasing the compressor duty cycle a little.  I check the MC loss of the wood by weighing and I personally prefer to target 2 percent MC loss per day, which is safe, and also happens to pump out about 5 gallons of water per 1000 bdft.  So now the goal is to keep the MC loss at 2 percent but not let the temp increase above 90.  But with the Nyle 53, the residual heat from the compresser will try to slowly drive the heat up a few degrees per day, and you don't need the extra heat because the wood is already drying at its max safe rate and the heat will cause defects. To reduce temperature, the only two knobs available to turn on the L53 are compressor duty and venting. Dial down the compressor too much and you drop you moisture removal rate below 2 percent.  Open the vents too much and the temp will decrease, again falling off the 2 percent.  Within a couple days of trial and error you hit a balance of 2 percent MC removal per day and at the lowest effective temp. These conditions are a balance of max safe removal rate at the minimum defect temperature.
Since the kiln conditions change slowly due to the mass of a couple tons of wet wood, checking the kiln once a day easily allows me to keep things balanced, and I don't see the need for automatic vents.  It actually a pretty easy thing to keep adjusted because the L53 won't over drive a full kiln load.

I also have a coupe of cheap digital hygrometers in the kiln to measure RH and calculate an EMC for reference purposes. 

A couple other comments, I have two lumber moisture meters, both expensive and well known, but by far the best way to measure MC is with a $20 dollar food scale to weigh kiln sample boards.  Lots of articles written on the tecnique, and it is simple and accurate.

Also, the published max safe moisture removal rate for red oak is up in the 3 percent range, but for whatever reason, I have historically best luck with 2 percent, which gets me a load of good, not warped oak lumber, about every month or so. 

I'm am by no means an expert, this is just what works for me with the L53.  Hope this helps.

YH

[Dan_Shade]

That was a great post, YellowHammer, thanks.

[FeltzE]

You can increase your kiln capacity (throughput) and increase your cost efficency by air drying your oak to 20% then finishing in the kiln. The oak is more stable at that MC and you can push your temps higher in 4/4 stock to push the moisture from the heart of the lumber as the moisture transfer rate is lower below 20% mc

Good points Y.H. My N200 will run temps up in the summer but not in the winter, running r30+  on the walls and ceiling

[John C.]

thanks for the info on drying red oak

[jim blodgett]

Thanks, Yellow Hammer.  That was a lot to explain.  I'm going to have to reread several times and try to absorb as much as I can. 

I guess it's like most things in life though, at some point I just have to jump in and start experimenting, make my own mistakes, hopefully learn from enough of them to not get discouraged.

Thanks again.

[YellowHammer]

The theory can get real complicated, but in practice, its not that hard.  If you try to absorb too much info too fast you'll drown.  Kind of like my buddy said of skydiving, (I don't) "go to all the classes, learn all the technical stuff about rate of descent, form, wind, planes, etc, but it really boils down to jump from the plane and pull the string..."

I don't know if you've called Nyle, they are a great company to work with, talk to Hank, tell him you are interested, he'll email you plans and manuals and discuss them with you.  It also helps that Nyle builds a good unit, too.

And of course you've got a tremendous amount of really knowledgable people on this forum to help out.

YH

[John C.]

after reading of your success drying red oak i ordered one from hank yesterday.also door gasket kit you recommended.are you kiln drying green to avoid air drying defects?i ask because the 4/4 red oak i cut to air dry to 30%mc before kiln has some surface checking.i was air drying to cut cost.
thanks john

[YellowHammer]

Glad to hear you got the Nyle, its a good unit.  Congratulations.

I've done it both ways, air dry then kiln, or straight from the tree to the kiln.  I have less defects going straight to the kiln, so I prefer to do it that way. From my experience, oak is very touchy about air drying correctly to avoid defects.  Although using air dried wood will speed up the throughput of the kiln and basically cut the drying time in half, you will loose more wood to air drying defects, like you are seeing, and end up costing money and wood in the long run, in my experience.  The kiln costs me $30 per month in electricity so the electricity cost savings is only $15 dollars per load of air dried verses straight from the tree.  I can make the $15 dollars back easy if I save only a couple boards out of a load by going straight to the kiln instead of air drying first and getting air drying related defects.  I also dry a good bit of white oak and it is even more sensitive to air drying than red oak.  I have ruined a bunch of white oak air drying because Alabama summertime air will suck the moisture out of the wood way too fast.
Anther reason I like to kiln green wood is that the moisture will come out of the wood much more readily, at lower temps, and more predictably than if it is air dried first, even at the lower MC's.  There are folks here who can explain that phenomenon better than I can, but it is true.

Also don't let the wood get too dry.  There is a big temptation to just suck it flat, squeeze every last bit of moisture out of the wood, just because you can.  I did it once, had a beautiful load of wood, flat as pool table at about 8 percent MC, and just decided to keep going.  Then one day I went to check the wood and found many of the boards had curled and warped like long potato chips.  They were ruined. 

YH

[John C.]

thanks for the help yellowhammer.

[FeltzE]

I'm not so sure you can find somthing more difficult to dry than white oak! 

Although the Kiln manuals will have a gazilion tables and rate charts (which are all technically correct) you will find that after running a small DH kiln. Starting from green to your final MC that you can develop your own schedule which will be more of a calander of settings rather than a set of temperature/depression targets. But you will need to work a basic load of (x)number of BF of that species, Checking the temp and dewpoint for the first few loads check your daily MC and track your temperature and compressor cycle rates. Keep notes and you will find you have a pretty standard trend you can work with after a bit. Then you can set your temp and cycle rate by calander and skip all the other checks until your finishing.

That being said, I'm sure a professional kiln manager is about to explode with facts about defects and differences in starting MCs but I am generalizing and simplifying and it does work although maybe not perfectly for every stick in the load.