Kiln Controller

shopteacher · February 08, 2004, 06:30:47 AM

   Can anybody give me information as to what functions the controller preforms on a dehumification kiln, like an ebac or nyles?
   Whats the difference of a kiln unit and a common central air conditioning unit. I know the kiln has both the evaporator and condensor inside the kiln and the unit just recirculated air between the two extracting water as it condenses on the evaporator.

   What is the btu rating on a small unit that would be used in a 1 0r 2000 bd/ft kiln?

Frank_Pender · February 08, 2004, 06:41:53 AM

Well, from one x teacher to a present teacher, I believe it controls the temp as well as the rate at which you want the moisture to be removed. I have one setting for the temp and one for the % of the time to have the moisture to be removed. Since my unit is much smaller than the space and amount of material to be dried it was designed for, I have it set at 90% all of the time. I do this on purpose for the remainer of the system I have set into motion.

shopteacher · February 08, 2004, 07:35:18 AM

Frank: Does it use a sensor inside the kiln to determine the humidity of the area or is it attached to the wood itself? Like a pin moisture meter?
Could you use a pin sensor in the center of the stack to send back moisture readings and control the dehumification from those readings?
Is there heat being added to the kiln over what the compressor add to the space during daily operation?

Den Socling · February 08, 2004, 09:09:34 AM

You have to use an auxiliary heat source to get a DH kiln started. After drying starts, all of the heat should be provided by the compressor.

You never control any kiln by reading the MC of one sample. You control all kilns by setting drying conditions.

Controlling RH by controlling the duty cycle (% of time 'on') of the compressor gives you rough but often adequate control. It's better (but more expensive) to use an RH sensor and controller to turn on/off the compressor.

shopteacher · February 08, 2004, 09:17:07 AM

Den: A RH sensor is that what a home dehumidifer uses or something like it?
What about the difference between the works in one of these small kiln units and a central air cond. unit, is there any?
Hope you get a smaller vac kiln perfected, I really like the idea of being able to dry a load in that time frame?

Den Socling · February 08, 2004, 09:24:29 AM

shopteacher,

Basically the same thing. You don't let your home dehumidifier running all the time (except maybe the people in Florida :D) and the dehumidification in a kiln does the same thing.

Den

Frank_Pender · February 08, 2004, 05:35:42 PM

Shopteacher, I have developed and system with the Ebac and the auxilary heat system ( Taylor hotwater furnace) that has been very successful. I do not understand all the lingo of relative humidity and the cone issues. The system just works well.

Yes you can place pins at different sites in a stack and use that as a method of controling the dehumidifier, I suppose. but I do not. The Ebac runs on a continuem.

I gues I am too far to the West to figure there is a right or wrong way of doing things. The methodology seems to wokr for me on the site I have chosen. It must be my GIS of some thing like that, that helps out. I can however, stand in the area of the kiln and the my blasted cell phone does not work. Must be the polar pull from the South of Oregon for the phone not to work. :D

shopteacher · February 08, 2004, 06:12:24 PM

Is there a brand name on the controller or or RH control?

Frank_Pender · February 09, 2004, 07:08:12 AM

For my controller it is the one that came with the Ebac

Den Socling · February 09, 2004, 07:36:57 AM

Any cycle timer would work. You just set 'time on' and 'time off' to get a percentage of time on.

shopteacher · February 09, 2004, 08:01:03 AM

Den: Is there an optimum % of RH that the kiln chamber should maintain throughout the drying process?

Last night I was looking on ebay and found all type of RH measuring and controling devices. Controling in that the device would operate a set of contacts from a humidity sensor. I was wondering if I could set the compressor to come o and off according to RH in the kiln rather than on a time cycle. Would that be better, worse, or about the same as a timer?

Frank: Does your ebac system have a btu capacity listed for its compressor?

Den Socling · February 09, 2004, 08:42:47 AM

In my opinion, it is much, much better to control RH.

Yes, there are optimal settings for RH. They range from high for thick Red Oak to low for easy stuff like poplar or soft maple. If you are to make optimum use of kiln time, you would develop, through history, settings that give the best drying time with minimal degrade.

Our controllers are too expensive for small kilns that are run part time but you can see how we have our control system set-up at our website.
http://www.pcspecialties.com/dh11602x.html

SawDust_Studios · May 13, 2004, 08:08:29 PM

Den,

What is the difference between the controller you linked to and the others you have listed on your site?

I thought I saw one or two in<$500 range.

Den Socling · May 14, 2004, 05:44:27 AM

Hello SawDust_Studios,

How is it in Breezewood? I used to go through Breezewood on the way to the shore when I was a kid. A long, long time ago. :D

The term 'controller' is about as descriptive as the term 'day'. There's all kinds of controllers just like there's all kinds of days. You can kinda-control a DH kiln with a cycle timer for less than $100. If you can figure out how to use a PLC, you can get more control for a couple hundred. If you want something more idiot-proof and easier to use, you can put in a loop controller and a wet bulb for less than $500. If you want to add control of auxiliary heat and vents to the dehumidification control, now you're up around $1300. If you want it all plus a chart recorder recording temperature and humidity, the cost goes up about another $1000.

As far as the controllers that we build are concerned, they all use similar components but they vary greatly in programming.

Den

SawDust_Studios · May 14, 2004, 08:40:29 AM

Den,

Thanks. Breezewood is still a traffic nightmare :(

Luckily, we are out far enough for it not to affect us too much.

As for the controller question, thanks. I am currently in the thinking, pondering, and wondering phase of planning to put in a kiln. I have been reading through all of the posts.

So far, all of the posts have done is made me think, ponder, and wonder some more. Solar, DH, Vac :-/ :-/ :-/

I like the degrade and quality of the lumber from a solar kiln, but I don't like the idea of 3-6 loads per year.

I like the speed of a vac kiln, but not the complexity or the idea of building my own personal black hole ;)

So, I am leaning toward a DH, but don't know if I should build from scratch as some others have done and add a decent controller or go with a Nyle or Ebac.

Maybe I'll read a few more hundred post till I decide!