The kiln is operational

[Kingcha]

I figured I would start this on a new thread here....a link to the old thread in case your interested is down below.

I finally got my baffle up and my back opening all closed in today. Then I made a temporary power cord.  I need to either make a proper ext. cord 120' or bury some cable.

about 15 minutes after closing it up I got a reading of 111 degrees, but that is near the top.   I need to add a timer, but for now its just running until I unplug it.

Most of my baffle will not be in the sun do to the metal sheets but I do need to paint about the first foot black after this load of nearly dry wood get done.

 

The temperature cord, I really need to get a one that is longer.


  

  
Back view, only one lower vent right now....trying to decide if I need more.


  

Some of this is just temporary.  Once my siding is dried and installed I my actually build doors for the back.
matt

Link from solar kiln begins below
https://forestryforum.com/board/index.php/topic,67821.0.html

[thecfarm]

That's what I've been waiting for!!! Now I want to see some lumber in there. Then I will want to see what the lumber is used for. Expect alot don't I ??  ;D  I wonder if one of those thometers that gives you the low and high would work for you? I have one,but wonder about the high temps. I don't know how high those read. Good luck. Would you imagined that you would have a mill and a kiln a few years back?

[Kingcha]

I had checked back at 3 pm and it had gotten up to 123 degrees.

I really think I have to much top venting, but I can always close some off.  I also think I will need 2 more small bottom vents but will wait and see.

It  is hard to see the wood in there Cfarm but its in there.   I do want to get something that will track temps at least some and I also need to get something to read the humidity as well.   I really do not have much for plans on the lumber that's in the kiln right now.   It really is a mixed bag.  I got some 1"cherry board, some thick cherry slabs with live edge.  Some slabs of pine and some 1" pine for bird houses.   

The next load of lumber is the siding for the kiln.

A few year back I was thinking of getting a boat.........I would never have guessed 2 years ago I would own a sawmill.
matt
Oh yeah, tomorrow I plan on blocking off 2 off the upper vents.

[Kingcha]

My biggest mistake on this project was believing I knew which direction south was.   I was a little off meaning I do not get the best angle from the sun until around 1:30ish.   I think am going to sister a couple of beams onto the sides so I can move it off the cement blocks.

So that leads me to a Question about temps in the solar kiln.   I know air drying you cannot get down to 6-8 % moisture, What is to lowest avg. air temp in the kiln i need to be able to get my wood to 6-8 %??

[beenthere]

You can find the temps and relative humidity levels to seek in the Dry Kiln Operators Manuals. Several sources,

one being this link, and leads to the different chapters available.

http://www.fpl.fs.fed.us/products/publications/pubs_specified_topic.php?groupings_id=113&sort_criteria=title

[Kingcha]

Thanks beenthere, I have not found the right answer yet but I will do some more reading later.

Today was sorta overcast so it did not get that hot.   It is suppose to be sunny tomorrow so I will experiment with my vents.

Matt

[beenthere]

There should be a table that shows the MC (%) of wood in equilibrium with a temperature and a relative humidity. i.e temp of 70 F will have emc of 6.9% at 35% RH

The RH is a key to the question.

[red oaks lumber]

i know nothing about solar drying. heat is what releases water in the lumber.in a d.h.kiln as the m.c goes down the temp needs to increase, also your humitity in the chamber will also go down.so in the latter stages of a kiln cycle with the temp rising the need to vent would be less thus holding more heat, which inturn helps the temp climb.
my best guess would be if your m.c. is under 20% you could safley have your vent set at 130 deg. and not have any problems. doing any damage to the suface of the lumber at this stage i wouldn't worry to much.
the way i dry lumber may not be suitable for everyone but,it works for me.

knock on wood i havent wrecked a load yet. over 25 million b.f. and counting

[Kingcha]

Thanks again beenthere, I saw the table I just have to read and get my thinking straight.   Its my understanding as the wood dries you need more heat.   I am really just wondering if lets say my kill only manages to get to 120 degrees will I still be able to get the wood to 6% or does the kiln need to get to 130 to achieve that.     Yes I have still have more reading which I have not done yet.   Going to some right after this.

The good news today is the kiln temp at the top was 131 at 2:30 and 112 degrees near the bottom.   I made adjustable vents today and closed them some.   I will check the kiln at about 5:30 today.

Thanks again
matt
I was just thinking about the where to temp....would it be a good spot to take the temp in front of the stack where the air enters the pile.   I can drill a hole and get a thermo lead there easy.

[Ianab]

Main thing that determines how dry you can get the wood is the relative humidity, not the temperature. You could dry wood to 6% in a refrigerator if you could keep the humidity low enough.

What the heat does in a solar kiln is lower the humidity inside, because heated air has a lower RH. The heat also speeds the drying by providing more energy to evaporate the water.

Don't know if you will get to 6%, that depends on what the average humidity you end up with in the kiln, but it's unlikely you actually need 6%, unless you live in a desert (In which case you will probably get there) 6 - 8% is the normal range, so you can happily call 8% "kiln dried" and carry on.

Ian

[Kingcha]

Thanks all, after a morning of reading I have a little more understanding.   

I am also happy to report my 5:30 temperature was at 144 degrees up high and I had a temperature of 124 about a foot of the floor.   Today I will put a temperature lead in the front of the kiln.

Now I have to break down and order me remote sensor, any thoughts of the one below.
http://www.amazon.com/Ambient-Weather-WS-1171-Temperature-Barometer/dp/B003OSSH9G/ref=wl_it_dp_o_pC_nS_nC?ie=UTF8&colid=PNN2FPDBR208&coliid=I12ZMUO1RTHHXV

Any thoughts, thanks again
matt

I also noted last night that I lose the sun at about 6 pm do to trees, one reason I think I need to move the kiln some.  I am guessing I am about 20 degrees west of do south.  It would be nice to get the sun a little earlier.

[Den Socling]

I see on the spec sheet that the outdoor transmitter is good for 149'F. http://www.ambientweather.com/amws1170.html That's good.

[pineywoods]

one of our local kilns is instrumented with a dual probe unit from radio shack. It tops out at 160 degrees and frequently goes over that. Try putting one probe in the air inlet side of the stack, the other on the exit side. The difference in the two temps is a good indicator of how much water is coming out of the lumber. Evaporating water cools the air

[Kingcha]

Thanks den, It guess I will have order that one then.

I moved one of my sensor leads to the front of the wood pile.   Before moving it this morning I check the temp at the back near the floor and it was at 80 degrees with no fans running.    Went up 10 degrees once the fans where on.

I guess I do not have to be worried about my kiln getting up to temp.   By 1pm after moving my temp sensor lead I was getting 124 degrees in front of the stack.      By 5 pm It was reading 142.  Since my wood went in air dried to 15-20% I have closed down my vents to just let in a little air.   I will have to make a chart tonight for recording temps & RH.
matt

[Kingcha]

Thanks pineywoods.   I have multiple leads for checking temps and will track upper near the fans, in front of the stack and in the back.   

Where would be the best place to track the RH, I am assuming on the outlet side maybe sitting on the stack??

matt

[Kingcha]

Well I guess my kiln is having no problems getting to temps.   We had a cloudy overcast start of the day but by noon the front temp was up to 127 as well as the top sensor.  I had turned my fans up from low to medium and my front and top temps are now always about equal.    Before leaving I check the temp at 4:30 and both where at 147 degrees.   To be fair it is a very hot day at about 88-90 plus humidity.

I finally got my compass out  yeah I'm a good 20 degrees east of do south, but at the temps I am getting I am not sure I need to move the kiln. 

Piney I order my monitor it has 2 remotes so I will be able to put one in front and one on the exit side, though it only goes up to 149 http://www.amazon.com/dp/B00DNI6KZA/ref=pe_385040_30332190_pe_175190_21431760_M3T1_ST1_dp_1

off to read more about RH
matt

[red oaks lumber]

just my thoughts. i would never let my lumber reach 147. bad things will happen.

[Kingcha]

Thanks Red, I was wondering if maybe I was getting hotter then needed.   I will open the vents some tomorrow.   Now that is the temp coming off the collector and not the actual wood pile.....just the air entering the stack.

matt

[pineywoods]

just my thoughts. i would never let my lumber reach 147. bad things will happen.

Good things happen too, kills bugs and cooks the eggs. Herein lies one of the big differences with a solar kiln. The temp will get to 147 deg or more, but it won't STAY that hot for more than a few hours. By the next morning it will be down close to ambient. I'll say again, temp and humidity charts for drying lumber, DO NOT NECESSARILY APPLY to solar kilns. your mileage may vary...

[Kingcha]

Thanks piney, so I guess leaving my vents alone would be ok.   From past readings I am guessing it held that temp until just after 6pm when I start losing the sun and it probably got there about 2-2:30.

I have not been checking it that early but I will tomorrow but it seems to hold some heat over night.   My plastic sheeting on the roof is a double layer which might help with heat retention some.

Started a chart for logging temps today.   Once my new temp/humidity monitors get here I will add RH to the charts.     I will check my wood moisture when I install those as well.

matt

[Planman1954]

I'd sure like you to do an experiment for me! (This is just a suggestion to prove something to myself.) In the morning, shut ALL the vents, and then at 3:00 pm, take a temperature reading inside the kiln. I'm just curious. Thanks.

[Kingcha]

Planman I would be glad to do that, though tomorrow might not be the best day do to the weather.   http://www.weather.com/weather/tomorrow/Maple+City+MI+49664:4:US

One question though, Why?

I will temp it in the morning when I close the vents too.

matt

[Planman1954]

Because the pineywoods design includes no vents. I was just extremely interested in the temperature your kiln will get with inside air circulation only...fans only w/dehumidifier working. Mine gets over 180 d. Fahrenheit. I just dried a load of pine in 6 days from over 20% mc to a common mc of around 5%. Since it cools down at night, there is less stress on the wood with the heat/cool cycle. I'm curious if yours can do the same thing. Thanks.

[Kingcha]

Thanks Planman, I can't wait to see what the temp gets up to.   I think I will try a couple of experiments.   First one I will close the top vents and the one bottom vent.  Then I will just try the top vents and leave the bottom open.    I am a little nervous about my fans though getting that hot.   

The present load has been in there since Wed afternoon.  Its a mixed bag of lumber that had air dried for about 3 months.

Oh by the way I am on the lookout for a cheap dehumidifier     I am still running my temporary power cord to the kiln for now.

Matt

[Planman1954]

Used dehumidifiers seem to hang around flea markets and swap meets. Keep your eye out, 'cause they like to hide underneath tables since they're a little heavy, and the vendors don't like to tote them very far! But they ARE there! I found 3 in the course of a few months when I was a lookin'.