The Forestry Forum

General Forestry => Drying and Processing => Topic started by: luke on December 06, 2003, 07:51:04 PM

Title: Nyle L200 DH Kiln?
Post by: luke on December 06, 2003, 07:51:04 PM
Hi everyone,

Is the Nyle L200 DH Kiln, the same Dry Kiln, as woodmizer's DH4000 Dry Kiln?
Title: Re: Nyle L200 DH Kiln?
Post by: Paul_H on December 06, 2003, 09:41:59 PM
Pretty much the same unit,with some minor differences in the controls.The DH4000 is made by Nyle for WM and are the same sized unit.

What I know about kilns,wouldn't write a very big book,so I'm going to step aside and hopefully some other members will hop in and answer. :P
Title: Re: Nyle L200 DH Kiln?
Post by: Den Socling on December 07, 2003, 05:53:42 AM
From what I've heard, Paul is correct. The L200 and the DH4000 are both dehumidification units built by Nyle.

They're marketed differently. WoodMizer says it can dry oak in 4-5 weeks. Nyle says it can condense about 250 lbs of water per day from 2000 to 4000 BF. If you calculate the weight of water that needs to be removed from 4000 BF of Red Oak (4000 x .00449 x 62 x 8.34), you get 9291 lbs of water. If you remove 250 gallons per day (9291 / 250) you get 37 days (a little more than 5 weeks).

Neither has much for control. Nyle supplies a cycle timer for the compressor. WoodMizer suppliers a humidistat from Honeywell.
Title: Re: Nyle L200 DH Kiln?
Post by: Brian_Bailey on December 07, 2003, 07:39:17 AM
The nice feature about these units is their simplicity in taking wood down to the 6 - 8 % mc level consistently.

I have a NYLE L-150 which has a 1 3/4 hp compressor.  The L-200 has a 2 hp compressor.

Mine has basically 2 controls. One to adjust the chamber temp. and one to control the amount of compressor run time. By following Nyle's drying instructions / schedules it is pretty darn hard to ruin any lumber your drying. Once you have gained some experience running the kiln you can push the envelope so to speak and dry a lot faster but at the risk of some degrade.

IMHO, don't see the need for humidistat controls in this size kiln. Why complicate things?

Automatic over temp. vents would be nice but not necessary.

I would be hesitant in drying 4000 bf of green hardwoods in this size kiln, esp. maple as the compressor is too small to pull the water out fast enough to maintain a proper rate of drying. But, then again, that's MO for what it's worth  :D.
Title: Re: Nyle L200 DH Kiln?
Post by: oakiemac on December 07, 2003, 03:45:51 PM

I've read some of your posts and you seem to be real big on tight control for kilns and you seem to have the knowledge/experience. My question is, what kiln do you recommend that is in the price range of a Nyle L200 (approx.$4200)? Is tight control really needed for small kiln operations? Is the added cost made up for in shorter cycles. less loss of product, or better quality?
I'm asking these questions not to be a smart a**, but because I am a beginner and want to make informed decisions. I too have been eye balling the L200, but I'd like to know if there is anything better out there for the money.
Title: Re: Nyle L200 DH Kiln?
Post by: Den Socling on December 07, 2003, 05:01:22 PM

I'm into tight kiln control because the companies that I work with want to make the most money possible from their kilns. They want the shortest drying time possible. They want minimal degrade and they want predictable results. That means they need tight control.

The L200 "out of the box" might be just fine for many people. If you are in no hurry, lack of control can be offset by taking it real slow. But the same kiln could do much more with a decent controller.

Title: Re: Nyle L200 DH Kiln?
Post by: SawInIt CA on December 08, 2003, 07:58:26 AM
So are you saying that the nyle would benifet from better controls or that another entire controler with more flexibility might be better. ??? I am in the market for a kiln to dry mostly softwoods but some hardwoods.
Title: Re: Nyle L200 DH Kiln?
Post by: Brian_Bailey on December 08, 2003, 10:14:48 AM
I think we should be making sure that we are comparing apples with apples here. The kilns that your customers are using are probably not small volume, low temperature ( 120 degree max.) DH kilns but rather large volume, high temperature ones. There's no question that tight control of the drying process is required in the higher temp. units using steam, DH, Vac, or what ever to dry the wood.

Nyle has been making these low temp kilns for quite awhile.  I believe that if they felt tighter ( read this as more expensive )controls would result in a better finished product, they would have incorporated it into their controller.

Again, just MO ;).

Title: Re: Nyle L200 DH Kiln?
Post by: Tom on December 08, 2003, 12:07:48 PM
I think what you are hearing from Den is a perpetuation of his involvement in the design of kilns which places him on the road of always discovering a better mouse trap.  He's not saying that a less sophisticated kiln won't work but rather that a modification would make it more efficient.  Having heard his defense of vacuum kilns elsewhere, I savor his opinions of what will work, what won't and what will work best.  Not that he needs any defense nor that I consider your post an attack, it's just that I personally respect his opinions and feel good about touting them. :)
Title: Re: Nyle L200 DH Kiln?
Post by: Den Socling on December 08, 2003, 01:31:56 PM
Thank you, Tom.


When you're drying hardwood, regardless of the size or type of kiln you are using, you must be careful to keep the difference in moisture content between the center and the outside minimal. The outside has to be dryer to get the water out but not too much dryer or you create stresses in the wood.

In a DH kiln, just like any other, you are drying water off the surface. You keep water moving by condensing some of the water vapor. This lowers the RH and allows the air to pick up more water. If you lower the RH too much, you will overdry the surface and cause yourself a lot of problems.

Through calculations and experience, DH manufacturers know what percentage of the time the compressor needs to run to keep the RH low enough to keep the wood drying. Suppose that 50% RH would be ideal. But, because of factors they can't control they run the compressor a little less and leave the RH a little higher. Maybe the RH is now 60% and drying is a little slower. Then, for a safety factor, maybe you end up with a schedule that keeps 70% much of the time. Your wood still dries. You always have good results. You don't pay for any expensive controller. Why rock the boat? Imagine that you set your RH controller to 50% and it decides how much your compressor will run. maybe you would get quicker results and better color.

Title: Re: Nyle L200 DH Kiln?
Post by: DanG on December 08, 2003, 03:06:24 PM
Any of youse guys that ain't seen it oughta check out Den's website. It is most excellent, and there is a world of info on there. Most of it is oriented toward vac drying, but much of it is generic info that applies to any kind of drying. I've answered a lot of my own questions by lurking around over there.
Just click on the little house on one of his postings. :)
Title: Re: Nyle L200 DH Kiln?
Post by: Brian_Bailey on December 08, 2003, 06:14:46 PM
Den, Tom -  

My above posts were not intended to be an attack on you or any one else. I thought one of the purposes of this forum was to share ideas and experiences. With that said, let me state that I have been operating a low temp DH kiln since the mid 80s. I am quite familiar with their operation and the fundamentals of drying lumber. I use a lot of what I dry in my woodworking business.

These low temp. DH kilns are designed to be simple to operate so the average guy/gal can consistently dry small quanities of lumber to add value to their operation without having to become a scientist to do so.

Now getting to your statement of a tighter control.

I can precisely control the temperature in the drying chamber and also, precisely regulate the amount of water removed from that chamber with the standard controller. I fail to see the need for tighter controls on this type of kiln. I don't see the need for a better mouse trap as Nyle's design is a pretty darn good one.

Again for what its worth, that's MO  ;).

Title: Re: Nyle L200 DH Kiln?
Post by: Norm on December 09, 2003, 06:53:37 AM
I guess my thought on why Nyle uses the one they do is it's easy for beginners to use so they get good results without having to be experts in kiln drying. It is a pretty simple system and their pricing shows it. Yes better controls would do a better job but they may be too complicated and expensive for their target market.

Den when you say it could benefit having a better controller what ball park cost whould it be. I'm not asking for a concrete price just your best guess. Would this be a lot easier to use than the present one Nyle supplies? Do you have a rough idea of the time savings in doing a load through the kiln?

I appreciate the help guys I'm just learning. I haven't got tons of experience running my Nyle L200 so this thread has been a big help. It's not like I can go talk with my neighbor to see how he does it. :D
Title: Re: Nyle L200 DH Kiln?
Post by: Den Socling on December 09, 2003, 08:56:52 AM

I'm sure that Nyle supplies what they do because they want the small kilns to be affordable. With bigger kilns, they include control systems. It would be hard to justify a $2000 control system if you were drying only a couple/few mBF per year.

Guys like Brian, who know what they're doing from lots of experience, could check MC samples frequently and change settings to control RH daily. With electronic controllers, you might set a target RH and a ramp rate down to that target on day one. Then, everything is automatic. You would still check your samples once in awhile to make certain MC is where it's supposed to be. So, I would say an electronic controller should be easier to use. How much faster would depend on how much manual control you presently do.

Title: Re: Nyle L200 DH Kiln?
Post by: Norm on December 09, 2003, 10:24:14 AM
Thanks Den :)
Title: Re: Nyle L200 DH Kiln?
Post by: Brian_Bailey on December 09, 2003, 03:47:10 PM
I just want to go on record here and state that I'm not knocking Den's controller or his wanting tight control of the drying process.

I believe we are confusing two different types of DH systems.

One is a low temperature system that max's out at 120 degrees and uses a low hp compressor to remove water slowly from the chamber.

The other is a high temperature system that operates up to 160 degrees and is run much like a conventional dry kiln. This type of DH system needs to have an experienced operator and tight controls as Den has suggested or the results could drastically affect your bottom line. I fully support Den in this regards.

As I stated before, we must make sure we are comparing apples with apples when discussing DH kilns.

If your interested, here's a link to the Dry Kiln Operators Manual at the Forest Products Lab. site.  When the page opens up click on Chapter 7 - Kiln Schedules. It's a PDF file.

When it downloads read the first page or two about why the schedules were developed, then scroll down to the section on DH kilns.
Now check out the tables paying particular attention to the table that shows examples of general schedules. Here you'll find that most of the schedules except the ones for oak have a starting temperature greater than the max operating temp of a low temp. DH system. If you look a little farther you'll find a table that converts a steam kiln schedule to one for a low temp DH one. As you can see things get a little vague here and this is why I feel tight controls aren't necessary. The OEM controls are more than sufficent to acheive the end results.

Oh yeah, the link  :).  
Title: Re: Nyle L200 DH Kiln?
Post by: Tom on December 09, 2003, 04:36:58 PM
Hey! you guys put your expertise on the General Topic where impulse drying is raising its ugly head.  Perhaps you can enlighten some of the questioneers (is that a word?) on the validity of the equipment. :P :D

click for General topic thread (;action=display;num=1071000648)
Title: Re: Nyle L200 DH Kiln?
Post by: Brian_Bailey on December 09, 2003, 07:59:17 PM
Hey Tom,  

Does this impulse drying take place just before or just after you attain warp speed in hyperspace or is it just another one of those anomalies that occur in a continuum?

I can attest to impulse buying, as my wife frequently exhibits this trait  ;D  :D :D

Title: Re: Nyle L200 DH Kiln?
Post by: Tom on December 09, 2003, 08:21:26 PM
It's impulse eating that corners my market.

I think impulse drying must have something to do with the time continuem.  Didn't Einstein say that stuff slowed down as you approached the speed of light?  Well, things must speed up as you approach stagnation.  So, the water in wood must be stagnant cause those N. Koreans aren't too swift.

I've got to think on that logic.  Somehow it doesnt make sense. :D
Title: Re: Nyle L200 DH Kiln?
Post by: Don_Lewis on December 10, 2003, 04:32:55 AM
This was my first visit here because someone told me about this thread. I read it all and everyone seems to be pretty well informed and on the ball. The L200 is designed for reliability and simplicity. There are good reasons for the approach we use on the WoodMizer unit and the standard L200. The WoodMizer system is better for mixed loads because it pays attention to the conditions of the circulating air. Plenty of people accomplish this with a hygrometer and a little common sense. Nyle builds larger systems with more sophisticated controls, systems that weigh sample boards, systems that automatically adjust conditions based on drying rate etc. There is no way to justify this expense on a small
Title: Re: Nyle L200 DH Kiln?
Post by: Fla._Deadheader on December 10, 2003, 04:57:37 AM
Welcome to the forum, Don. Plant yerself a tree on the member map, and don't be afraid to join in.

  There are Many on here that want to set up a small kiln, and from reading your input on the "other" forum, you can be a very big help to those trying to get things right the first time.
  We have some long time operators of small kilns that hang out here and offer good advice. Glad to have another knowledgable person, to keep us all on the right track.
Title: Re: Nyle L200 DH Kiln?
Post by: Tom on December 10, 2003, 05:51:13 AM
Welcome to the forestry forum, Don.  I like to see you guys congregating here.  It always leads to an interesting thread to hear of the science, theories and disciplines of drying wood. :)
Title: Re: Nyle L200 DH Kiln?
Post by: DanG on December 10, 2003, 06:51:55 AM
Welcome, Don! 8)  I've been hoping you would show up here without me having to physically drag you over here. :D :D  I look forward to learning more from you. Who knows, I might even buy something from you someday. :)
Title: Re: Nyle L200 DH Kiln?
Post by: Norm on December 10, 2003, 08:48:51 AM
Welcome aboard Don, glad to have you here. Now plant ya a banner over there on the left,  ;) lots of interest about DH kilns here.
Title: Re: Nyle L200 DH Kiln?
Post by: Rod on December 12, 2003, 04:00:35 PM
Can you use a 45'x 8' refrigerated trailer as a kiln building?
Title: Re: Nyle L200 DH Kiln?
Post by: DanG on December 12, 2003, 07:15:07 PM
Yes, I can use it. When can you bring it? ;D

:D :D Just pullin' yer leg.

Old reefer trailers make great kilns, as I understand it. I take it you got a shot at one?
Title: Re: Nyle L200 DH Kiln?
Post by: SawInIt CA on December 12, 2003, 08:32:55 PM
I have a friend that has one in a reefer trailer....Works Great
The refrigerated shipping containers have better insulation though.
Title: Re: Nyle L200 DH Kiln?
Post by: Don_Lewis on December 22, 2003, 05:56:16 PM
Thanks for the welcome all.....I didn't check the posts on the second page until now.  

A refer container works great. There are some larger sized ones available in Montreal. We had one delivered today and will convert it to a pallet sterilizer and send it on to Mexico.
Title: Re: Nyle L200 DH Kiln?
Post by: Norm on February 28, 2004, 11:58:23 AM
Thanks Don, I don't want to waste time trying something that others have learned by trial and error.

Appreciate the help. :)
Title: Re: Nyle L200 DH Kiln?
Post by: Den Socling on March 08, 2004, 04:42:30 PM
I asked Tom to move this thread over here because I thought it was being lost.
Title: Re: Nyle L200 DH Kiln?
Post by: Norm on March 09, 2004, 04:51:23 AM
Good idea Den, thanks.

I have a question, Don mentioned in another thread to not buy a trailer and insulate it. Why not? I don't see any difference in doing that from building my own chamber from scratch. My thoughts are to buy a cheap dry van trailer and insulate it with the foil insulation. Use two layers with a vapor barrier in between the two. Seal the gaps with a good silicone. I would glue these on using the new high temp construction adhesive. For heat I want to use an exchanger kind of like what Al is using. Then use my L200 to remove water. Whatchya think?
Title: Re: Nyle L200 DH Kiln?
Post by: Don_Lewis on March 10, 2004, 04:43:27 AM
It is very difficult to insulate the floor properly and board insulation on the wall should be put on in multiple layers because it expands and contracts. Even so, this causes cracks to open and condensation to form on the steel. The steel quickly corrodes and in a few months you have a lousy kiln. Also it costs more to try to insulate a trailer than to buy the right thing in the first place.