HELP ! DH-4000 Questions

[DR Buck]

Help !    I'm confused.   ???    I've tried reading the book  :P   and it only makes my head hurt.  smiley_fused_bomb   Wood-Mizer has added pages to the manual specific to their custom controller but also left in the L-200 pages as well.  There is no way to tell which pages are specific to the WM DH-4000.  And, absolutely no "operating" instructions  or descriptions as to what does what for the control panel!

This is a DH-4000, not an L-200 controller.   They are different.[/size]

Background

I just got the DH-4000 up and running.   (Pictures will be in a separate post shortly)   I loaded it with about 1500 bf of red and white oak that has been air drying for about 4 months.   Going in MC of the wood was about 25% measured.  I started out per the "Drying Schedules" in the manual that say MC 35%-25%   Temp should be 100 deg and Rh 60%.    After 24 hours operation, the temp is at 100 deg, Rh is at 55% and NEVER got any higher.    I just measured the wood MC and it is averaging  (25 readings) 15% MC

So ......

Questions

1 -  What does the blinking "ALM" light on the temp control mean?

2 -  Do I drop to the next phase of drying and raise the temp to 120 deg and lower Rh to 40%?  This is the next line from the table in the manual.

3 -  How do I determine "wet bulb" temp with the WM controller?

4 -  What do I do when the Rh in the kiln reaches 40%?     Do I continue to raise the temp and lower MC until the wood reaches 6% MC?

5 -  Do I keep adjusting RH and Temp to try and maintain the recommended  Max MC% loss per day?  How do I do this?  Is there a "set" amount of MC that any given Temp/Rh setting on the controller will remove

[Don_Lewis]

The blinking ALM light means that the condition is outside the range. Call Nyle at 1800-777-NYLE for instructions on how to disable this.

The reason you are not reaching the humidity set point is that you have a small load that is giving water up faster than it is leaking from the kiln or that the lumber is dryer on the surface and the water is not evaporating as fast as it might.

If the lumber is all below 25% you cannot dry too fast so you can raise the temperature to the next level as long as you are not exceeding the drying rate in the manual.

There is a table in the manual that converts rh to wet bulb etc.

Don't let the humidity drop below 30% or you will over dry. That would only be a problem if the kiln is leaking air. If the heater is cycling on and off to maintain temperature, that is an indication there are air leaks or heat leaks.

There is a maximum moisture loss that should be your speed limit. If you  mix red and white oak, use the value for white oak as that is slower.

Call Nyle tomorrow for some help with this.

[scsmith42]

Dr.Buck.

Several comments, but first and foremost give Don Lewis at Nyle a call.  Nyle makes the kilns for Woodmizer, and he really helped me out when I first got started with this same kiln.  I too was very confused with the manual, but after a few calls to Nyle things started coming together.

My experience with Nyle is that all of their folks are great to deal with.  If you need to troubleshoot a technical problem with the kiln (such as the alarm light on the temp contoller), call Nyle and ask for Stan.  He's a real technical wizard and has pretty much seen it all with respect to what can go wrong with the DH4000.

Your question # 5 below is the most pertinent one.  YES - you should manage your temp and RH to keep the rate of drying within the recommended range.  If you dry too quickly, you'll damage the wood.  Consequently, it's best to dry a load of the same thickness and species, as 8/4 dry's at a different rate than 4/4, etc.   Different species have different max rates of drying that they can withstand w/o damaging the wood.  Oak is a "group 4" wood and it has to be dried relatively slowly.

A really great resource is a document called "Drying Hardwood Lumber" by Gene Wengert, et al.  This link will take you to a web page where you can download it from:  

http://www.woodweb.com/knowledge_base/Drying_hardwood_lumber.html

The "alm" light on the controller comes on when the temperature is too low or too high for the dehumidication elements to cycle.  If you're at 100 degrees, I don't think that it should be coming on.  You may have a wiring or other problem - give Stan a call and pick his brain.

When I run a load of oak through mine, if I start around 25 - 35% MC, typically my RH will go up to 80 -  90% or so and then drop based on how I set the controller.  One thing that throws me is that you stated that your MC dropped from 25% to 15% in a day or so.  This seems a little odd to me for Oak.  It's almost as if your vents are open or something is causing the kiln to lose humidity too rapidly.  I have found that when I check my loads, there will be a termperature and humidity difference in the sections closest to the kiln doors (I lose RH and temp when I enter / leave).  You may need to shut the doors behind you to keep the moisture inside the kiln when you're taking your measurements.  You also might need to add some pans of water inside the kiln to bring the RH up higher so that you can manage the daily MC reductioins.

One of the sections of your manual has a table which provides information on the equilibrium between temp, RH, and MC (I think that it's section 3 or 4).  

With respect to the rapid drying, another thing to check is the airflow between your layers.  How wide are your stacks and how thick are your stickers?

Gene Wengert is teaching an introductory kiln drying class in Memphis (I think next month).  You can find out about it on Woodweb.com under the sawing and drying forum.  Also, this link will take you to a list of reference documents and articles that can further assist.

http://www.woodweb.com/KnowledgeBase/WDKBPPKilnOperation.html

http://nhla.com

Good luck!

Scott

[DR Buck]

Don, Scott,

Thanks for the info .  It sure helps some and I'll call Nyle tomorrow.   I should have been a little clearer on some things.  First, the 'alm' light came on when I first fired up the kiln.   It wasn't on tonight when the kiln was at 100 deg.   As far as the wood dropping from 25 to 15% in 24 hours, it could have been because the wood had a lot of surface water on it from rain when I loaded it into the kiln.  That said, the inside Rh never got over 55%.   I even threw a bucket of water on the wood perr WM recommendation.

The kiln is pretty air tight and well insulated.   During a trial run, empty, I ran the inside temp up to 120 deg in about an hour.  Then after I shut down it stayed over 90 deg  inside for more than 3 hours.  The outside temp was about 30 deg.

Tonight I raised the tem to 120 and lowered the Rh to 40% per the drying schedule in the manual.  I could hear the compresor kick on and start working.

[scsmith42]

OK - this is starting to come together.  I don't think that you need to worry about the alarm light on the controller - it was probably on when the temperature was too low for the compressor.  Also, with the rain on the wood the MC reading were probably misleadingly high.  Your insulation and temp rise sounds really solid, too.  I would not be concerned with the low RH considering the low MC that was probably present in the wood when you started.

If you get a chance to review "Drying Hardwood Lumber" before you talk to the folks at Nyle you may better understand their feedback.  If not, it will come together afterward.

By the way, I looked at the pix of your kiln - NICE JOB!  I converted a 45' shipping container and I know firstand that a lot of work is involved with converting something. 

[DR Buck]

All is well 8) 8)    and.... I think I understand what I'm doing now.  : 


Called Nyle today and spoke with Don.   He was very helpful and steered me in the right direction.  Once I got on the right page in the manual things fell in place.   

With Don's help, I should be a pro  ;D   in no time at all!


                     Thanks Don !