Crunch Time!

[DanG]

OK, it's time to make a decision about what type of kiln to build. I can go with any type, but I want to get the most bang for my bucks.  I can air dry, then finish in a kiln, which seems to be the most practical method.  I'd like to know how much time I should expect to spend drying hardwoods from 20-25% down to 6-8%, for each type of kiln.  How much difference is there between, say, a good solar kiln, and a DH unit, for getting rid of those last drops of water?  Keep in mind that I live in the Sunshine State, where a solar rig is more practical than it is in Michigan.  Also, I can build a lot more capacity into a large solar kiln, or a series of smaller ones, for the price of a good DH unit with a controller.  That makes it sound like I'm leaning toward solar, but I don't know if it is fast enough. I'd like to be able to tell a customer, "I have some air dried stock in the barn that I can finish for you in ? weeks."
I can also try the air conditioner thing on the cheap, but I'm not sure it would be faster than solar.  The discontinous vacuum kiln idea sounds intriguing, but is limited in size. What do you do when a builder wants 2000 bf of flooring and 1500 bf of panelling at the same time?
I can imagine that, over the years, I will have more than one type of kiln, but I need to get started, and which one to build first is a tough call.  

[Brian_Bailey]

I'd put my money into a Nyle L-200, then as business expands I'd go for another one.
Solar is nice, but with a DH like Nyle's you have complete control over temp and water removal and it is simple to operate.
Plus you can depreciate the cost on your taxes.
Vacuum is great, but I don't think it's practical for a small operation.

My 2 cents  .

[Den Socling]

I agree with Brian. DH is the best way to go for smaller operations and Nyle has the experience needed to provide the best product at a reasonable price.

[Norm]

The dh kilns like Nyle sells work well Dan, I'm not sure about which model to use if setting pitch is necessary. We have the L-200 and like it fine.

[Ga_Boy]

Norm,

Once you mentioned that you use a type of heater to bring the interior of your kiln up temp.

I am not familiar with the type of heater you mentioned.  Is it electric, propane or some other type of fuel?

Sorry about hijacking your thread Dan. :



Mark

[DanG]

Thanks for the input, guys.  I'd been thinking that DH was the way to go, but recent comments about limitations and long drying times had given me second thoughts. What kind of drying times are y'all experiencing with your Nyle 200's?  Do most of you dry from green, or air-dry first?  Do you use an additional heat source?

Ga-boy, you didn't hijack. :D  Your question is just part of the discussion. As far as I know, heat is heat.  Any source should be ok, as long as it doesn't introduce more moisture into the chamber. Frank is using a wood-fired boiler and heat exchanger, which seems to work well for him. That seems ultimately practical for a sawmill operation. Most, if not all, big mills use waste to heat their kilns.

I don't see why you couldn't use solar as a heat source for a DH kiln.  Dr. Gene says not to do it, but doesn't give any reason, leaving the opinion a bit short on credibility. In our climate, solar will produce a LOT of heat. Any thoughts on this?

[Brian_Bailey]

DanG,  

I believe you'll find that the temp. varies to much in a solar collector to be of much use in a DH kiln.

Maybe at first you could use solar heat to help bring the chamber up to temp. but once you get the load drying you need to contol the temp. and water removal rate or risk some degrade.

On hot sunny days you'll be seeing temps of 150* plus in a solar kiln.
Some species drying in a DH kiln will most likely suffer some serious degrade if you allow the temp to rise to this level at this stage of drying.

Now if you could regulate the heat from the solar collector to augment the DH electric heat source that would be great.

But now we are getting into a controlly thingy thats going to make a simple system complex.
Which in MHO isn't good.

I'll bet if you do set up a DH, you'll find that you'll be more concerned about dumping excess heat rather than adding it.

[Larry]

Dr. Peter Chen built an experimental solar DH kiln in the early 80's.  Found a little information about it on the Forest Products site but nothing that told if it was a success.  Dr. Chen is listed as on the faculty at Carbondale but doesn't have an email or phone number so I suspect he is semi retired or something.  I heard of another one that is running in France but never have been able to get any information on that one either.

I suspect that if they were a success everybody would have heard of them.  I am guessing the problem is heat control just as Brian stated.

[ElectricAl]

DanG,

Build a tight DH chamber and use the Nyle heat or hot water and an exchanger. Then if you want to try a solar kiln keep it separate.

If you build a solar collector big enough to heat your DH chamber, what are you going to do with the heat it makes for  the 20 days when the DH make it's own heat :

Just a thought ;)

[Don_Lewis]

Dr. Chen's kiln did not work well. Used more electricity than a DH system.

DH can dry as fast as a conventional kiln if the high temp (160F) systems are used. Lower temp systems such as the L200's take longer when moisture contents are below 25% but they dry in about the same time from green to 25%, providing the loads are matched to the unit size properly.

Is this a serious hobby or a business?. If a business, solar is not really a consideration.

[DanG]

Don, this is a business, but a very small one, at this point.  One of the key points of my business plan is flexibility. I may get fairly large quantities of pecan, from time to time, but may have a need to dry 200bf of magnolia or sweet gum, too. Do you think it would be practical to consider the L200 for the bigger jobs, then several small solar kilns for the little jobs?  Any idea of drying times for 4/4 pecan?

[Frank_Pender]

With inflation and all, Dang I am going to install my tow bits worth.

  I woudl strongly suggest a hotwater system with a heat exchanger and a small DH  I use an Ebac 800 with a Taylor and a Refer trailer.  I run about a 30 day cycle for hardwoods that have bee air diried for at least 60 to 90 days.  For  soft woods like Firs, Pines, etc.  for construction purposes I run for about 10 or 12 days and only have to get to about 15% for them.   I am planning on a new building this late Spring, early Summer of which a portion will be a 16' x 32' room with my Taylor as the heat and a Ebac 3000 for the DH system.

[DanG]

Thanks, Frank. I assume those times are for 4/4 stock. ???  I'll probably build my own chamber. If I go DH, I'll definitely go with Nyle. I don't know how Ebac's various models compare, size-wise, with Nyle's various models. If all other things were equal, I'd choose Nyle because of Don Lewis' generosity with his knowledge on these forums. He's a class act, so I figure his company is, too.
I will also build my own boiler. I just can't justify the price of a commercially built furnace just to heat a pot of water. ??? : :D :D