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.
(https://forestryforum.com/gallery/albums/userpics/30769/036.JPG)
The temperature cord, I really need to get a one that is longer.
(https://forestryforum.com/gallery/albums/userpics/30769/037.JPG)
(https://forestryforum.com/gallery/albums/userpics/30769/038.JPG)
Back view, only one lower vent right now....trying to decide if I need more.
(https://forestryforum.com/gallery/albums/userpics/30769/039.JPG)
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
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?
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.
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 %??
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
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
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.
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 :)
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.
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
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.
I see on the spec sheet that the outdoor transmitter is good for 149'F. http://www.ambientweather.com/amws1170.html That's good.
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
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
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
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
just my thoughts. i would never let my lumber reach 147. bad things will happen.
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
Quote from: red oaks lumber on August 26, 2013, 06:20:15 PM
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...
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
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.
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
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.
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
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'.
Wouldn't high temps like 150 - 180 degrees be too high for oak, cause it to dry too fast, and ruin it? I can see how pine can take it, but how would you control the temperature on hardwood like oak?
Kingcha,get yourself a notebook to keep track of all this great info,closing vents,how much the sun is out,temps,ect. I kinda would be interested to know the temp inside your kiln in the morning. I would think it would get below freezing in the winter time. You need to add solar kiln to the things you have. ;D
WDH,I THINK a greenhouse exhaust fan would work. Set it too a certain temp and the exhaust fan would come on. But saying that you probably would have to buy a kiln exhaust fan due to the high temps. Seem like even the greenhouse one was $200 many years ago.
WDH: I don't think it's a problem in a solar kiln. The high temps will be during the day with ambient temps in the morning. This actually is better than a constant oven temperature in a conventional kiln. I dried beech in it once and the load did great. It had air dried for a few months, and the solar kiln took it down to 6% in a few days.
Well raining all morning, monsoon like at times. So I did not head outback at all. Though now that I write this maybe I should go and discount my power cord to be safe, really don't need the fans today.
Good idea Thecfarm, I actually just started a log sheet with temps, RH & vent info but outside air temp and amount of sun makes sense to add.
As I did not go outback no morning temp but I will get it the morning after the next time the kiln gets up to temp.
I picked up 3 fans for $78 from northern, so far so good. I have them set on a timer that turns on just before Noon and shuts them off at about 11pm.
I jumped head first into this solar kiln with not much understanding, knowing it was going to be a learn as I go project.
Yes farm it will get cold in the winter but then I will be all done Outback by November
matt
Just a note Kingja: I run the fans at night with the dehumidifier ON. This is actually when I catch the most water from the drying process. Ask pineywoods why that is the case..not me! :) He's the brains behind the system.
Quote from: Planman1954 on August 27, 2013, 04:56:50 PM
Just a note Kingja: I run the fans at night with the dehumidifier ON. This is actually when I catch the most water from the drying process. Ask pineywoods why that is the case..not me! :) He's the brains behind the system.
Not the brains, just the experience. The dinky little dh units don't work too well when the temp gets much over 100 degrees. Think about it, when the temp is 140, it takes a lot more cooling capacity to cool the air down to the dew point than when it's 75. Most of them have a high temp shutoff adjustment. Mine does, so I just turn on the fans and dh and leave them on.
Yes I can understand why you'd leave the fans on when running a Dehumidifier.
matt
Sun finally came back yesterday so I checked the temp in the kiln this morning. It was only 2-3 degrees warm at the back of the stack then the outside air and slightly warmer at the top of the kiln. My fans are timed to turn off at about 11pm nightly and don't turn back on until just before noon.
So after checking the temp I checked my lumber. I did not have any test pieces and I only tested ends and the sides. I'd say its close if not there. Most was readying between 6-8%. Had trouble reading some board that near the front of the kiln as they where around 5% on the ends. Even my thick stuff was around 8%. The only stuff that was high was the misc. stuff at the back of the kiln that my wife wants for birdhouses. Right in front of the lower vent was my highest reading at 14%. I did not have one solid stack as I had a mismatch of wood from thick live edge to to 1" cherry and some pine too.
So after closing it up, I closed all vents for the big high heat test. I put one of my new temp/rh monitors on the back of the stack so it won't be in the hottest spot. I still have my other temps leads in place that can handle the higher heat and will check the temps at 2pm, 3pm & 4pm
matt
Its been a week since I started the kiln and most of the wood has been air drying all summer.
well planman we did not have full sun all day and for some reason I left the middle vent cracked about 2" , oops.
So party cloudy/still lots of sun. Outside temps got up to 90 degrees.
***It was a slow start today****
2pm temps front 125 top 127 back(exit) 107 50% rh
3pm temps front 129 top 129 back 117 44% rh
4pm temps front 145 top 147 back 127 42% rh
5pm temps front 147 top 147 back 133 40% rh
Just before I headed home about 5:20 the RH dropped to 38%
***monday when I hit 147 degrees I had 127 by Noon and today I did not hit that until 2pm***
I opened the bottom vent for the night but left all 3 top vents closed well actually had to close the middle one :-[
matt
Sounds like you almost have it down.
With top vents closed and bottom vent open and fans running the kiln was 6 degrees hotter then the outside air this morning. I almost wish I had left the bottom vent closed.
matt
Thanks for going to so much trouble! It will help you though in the future to understand the effectiveness of your kiln. What insulation did you use? Was it sheet foam? I don't recall seeing fiberglass batt. I used 15# felt on the outside behind my siding and 3 1/2" fiberglass in the walls. I also insulated the small attic created above my fans. I think in my kiln, the attic heats up really high, and the fans then blow that superheated air into the wood area. Maybe that mini attic is what gets my temps up so high...180.
Anyway, thanks for being so vigilant in checking the temps. Good luck to you.
I used sheet foam, though more expensive I do not have to worry about moisture. I also insulated my small top roof above my fans too. I truly believe mine will get hotter then the 147. I do actually have a little more sealing of air gapes which I will do before nailing up my siding. I might use housewrap before siding to cut down on air loss. Because I used roof coating on my interior walls I did not use a plastic barrier which would have helped with hot air escaping.
I am going to try closing all the vents again at some point to see.
matt
Sounds good! Time to dry some boards. Over 147 will do great, I'm sure. Today I began to surface one side of the last load of pine I dried for a week to use on the inside of my barn/rec. room project. It feels GREAT to make nice, finished boards from logs...
Planman you was saying the inside temp gets to 150-180 degree,Seems like that would play heck on the controls of the dehumidifier.I do remember in an older post you & pineywood was saying it opened the thermo-cut outs on some of the outside fans you had,So that is why I was wondering about controls. Mark,,,
What happened is a fuse blew on both fans (not the dehumidifier.) They were rated at 75 d. centigrade. That is around 170 d. Fahrenheit. I think the temperature was near 180 d. (I'm guessing.) The dehumidifier chugged away with no problems, drawing out moisture when the temps dipped down (mainly at night.) I'm not worried, since I found 3 dehumidifiers cheap at flea markets!
We had a hot sunny day today so. The kiln was heating up nicely so I thought what the heck, lets close it up completely. I closed it up tight at 3:45 and by 4:45 I got a front reading of 152(off my back up probe as the new sensor shut down at 149). The back reading was 140 32% RH and the top reading was at 154.
I cracked the vents at that point, hoping I did not fry the front meter.
I have know doubt now that my kiln can get to 160 in full sun all closed up. I probably will not move it the 20%+ degrees to line it up with the Noon sun as it seems to be doing a fine job drying the wood. I hit my daily High temps at between 4pm and 5pm. I lose the sun completely at 6pm.
I have a load coming out tomorrow morning that's been in there for about 10 days. It's my siding for the solar kiln. The next load has not air dried long but I got some bugs in some of it. Hoping the kiln will cook them good.
Matt
That sounds like it's working good. I do wonder about the sun's angle in June and July.The temp might really go up than.
It will be interesting next year since I did not get it up and running util August on how it does in early summer.
matt
In a solar kiln with lumber in it and the fans blowing, the heat that is used to heat the air is used to evaporate water, as well as heat the lumber and the kiln, and is used to heat losses through the walls, floor and roof. These losses will use up the heat, so a kiln should not get very hot--typically with dry wood you might get 30 F above outside and this is with two layers for the clear collector roof. In your case, about 60 degrees F hotter than outside seems too hot; maybe the sensors were heated by the sun or too close to the hot wall? The question is "Why wasn't this heat used to dry the wood, heat the wood, and to cover the heat losses?" When you heat outside air this hot, the humidity drops well under 20% RH. SO, how could 150 F and 20% RH not cause a lot of drying? Assuming that the fans are running, if the kiln does get hot, the wood temperature inside the wood is much cooler, that 150 F, so you cannot be certain about killing insects and their eggs.
Gene I have multiple sensors and I do have double layer of clear. My fans I leave on medium from 11:30am to about 11pm. My front one is on the front wall out of the sun but in the path of the hot air blowing down from the collector. The back sensor sits on the back of the wood stack. My average readings have always indicated hotter and dryer in the front and cooler and more RH in the back. Tuesday was 90 with high humidity. I do still have to make side baffles to extend down to the floor for shorter loads, so I do have a some heat going around this batch. That being said I can still feel air moving through the stack.
On sunday I had an afternoon reading of 123 20% up front and 116 27% in the back with the top vents mostly open and the bottom vent half open.
For today's load I will add side baffles in hopes to get the wood hot enough to kill bugs.
matt
Well I only got outback for a little while today. We had a cool high 50's and windy most of the day. It did manage to get up to 60 at 4:45 in the shade. I was happy to see that the kiln on a cooler windy day is getting right up there. Front reading of air going into stack was 117 and RH of 20 the back side got to 104 or 107 RH of 40 that was at 4:45. This is a new load of wood that went in on Wednesday that did not air dry long.
matt
As the old instrument mechanic once said: "Test your instruments using ice water and boiling water, that's if they are rated for these tempetures". They should be with 5%.......... if you are lucky. It is not uncommon to find temperutre sensors out by as much as 25%. Back when we were calibrated tempeture sensors, we used instruments that were +/- .25%. But boy did they cost a bunch and HAD to be sent to a NIST tracable lab about once per year for their calibration. Anyways, one of the things I would do is check your trmp sensors. They may be out.....by a bunch.
Bruce
I actually have 4 sensora. 2 newer ones that remote the temp & RH and I also have 2 wire temp leads that go into the kiln that I can hook up to a separate unit that I use for smoking meats. The leads read within 2 degrees of the remote units.
Matt
I am just amazed on how well the kiln is heating up. Much better then I would have thought. Tuesday this week the outside temp only got up to 69° but the front sensor got up to 136 by 4:30. That is the heat blowing into the stack. The sensor on the back of the stack was at 128° with a RH of 23.
I checked the wood yesterday and with my inexpensive moisture reading. In many spot it would not register but a few spots where 7-8%. From what I could see the wood looked good. The wood was from a dying red pine that much of it was blue stained. I did get a little mold growth while air drying though.
matt
I snow shoe'd out back last week. I forgot to walk over and check everything at the Solar Kiln but it looked fine.
(https://forestryforum.com/gallery/albums/userpics/30769/winterobck16.JPG)
(https://forestryforum.com/gallery/albums/userpics/30769/winterobck20.JPG)
We had a 2 day warm up with the sun out yesterday, so I am assuming the snow fell off. I hope to take another trip Outback tomorrow.
Matt
I finally got started on my back doors for the kiln. I had been just using foam boards to seal up the back.
(https://forestryforum.com/gallery/albums/userpics/30769/kilnback2.JPG)
(https://forestryforum.com/gallery/albums/userpics/30769/kilnback3.JPG)
I still have to make the adjustable doors for the vents and possible cut a few lower vents into the door panels. The back is made up of 3 door panels that just lift into place.
The photo below is my start of hopefully flooring boards for my next house. I hope to get them into the kiln in about 10 days.
(https://forestryforum.com/gallery/albums/userpics/30769/kilnback5.JPG)
Matt
Matt,
That is a nice stack of lumber.
Thanks WDH I think I need about 30 more 1x8x12' boards and I will have enough. Of course to get that many 8" boards out of my small trees I end up with a whole lot of smaller stuff as well. I have been only getting the 8" boards out of the first 2-12' sections then I get 3-4 8' logs.
I am getting some much lumber I know have to build a wood shed. :) I am guessing it never stops once bitten. :D :D
Matt
Nice Job ,
smiley_thumbsup
nice stickering :)
Now that is a nice compliment coming from the Sticker Master ;D.
Well thanks for the stickering compliment. Just glad it ain't a close up :D It might not be that neat of a job, but hey if it looks good to the pro's I am happythen. 8)
Matt
kingcha,
I live in kalkaska, and am pondering on purchasing a sawmill, I just purchased 6 acres of commercial property. If you are ever over this way I own kalkaska window and glass right on m-72 as your coming into kalkaska. My work number is on my profile, I would like to ask some questions about purchasing a sawmill, kilns etc. thanks, ed
kingcha,
I got your pm, left you my phone numbers, hoping I can talk to some of the guys at the pig roast, I have a lot to learn. thanks ed
Got the first load in for the year. 800 bf of 1x8's and another 25 smaller 1x's all 12 footers. All pine with some of it already air dried a little.
(https://forestryforum.com/gallery/albums/userpics/30769/002%7E0.JPG)
I am hoping to get down to 8-10% in about 10 days or so.
I forgot to check moister % before closing it all up but will do so first thing tomorrow.
These are the ones in that earlier photo that I plan to use for flooring if the turn out good.
Matt
Picture perfect!
Agree with Den, looks to be a picture perfect job of placing stickers for drying. smiley_thumbsup
Thanks for the pic.
Very nice.
You are brave to post a pic of a stickered stack :D.
You did good.
Well thanks........ You do know Brave and Stupid are real close together.
I actually was looking at the pic thinking......Oh @#%$ there are a few off the mark.
Matt
matt, the picture makes me understand what we talked about on the phone today. Thanks for your telephone time and great job on your kiln. ed
I got my first load of wood for the season in a few weeks ago. The weather hasn't cooperated very well. It is a small load as I did not wait for more boards. Works out good as the next load is all ready to go in. Sunday morning will be unload and reload day.
Today it got up to 133 with 1%RH on the front side of kiln, I measure the heat as it is blown down and into the wood. Very happy to see it that hot as It only got up to about 67 in the shade today. For some reason my temp gauge on the back of the stack was not working(thinking I need ne batteries) but it was looking good yesterday with only about a 15 degree drop and a low RH.
Matt
Indeed, nice stickering.
I am just a bit curious...will the vent openings have lids or covers so that you can open or close them as much as needed?
Let me assume that you have the fans blowing from top back toward the front. So, a little (the key is a little) cool air will enter through the vents on the back top. Then this air will mix with the rest of the air in the kiln as it travels down toward the front and will be heated by solar heat. Now, if you have vents in the front, some of this air that is ready to do some drying will exit the vents before it does any drying. It might be best to have the exit vents on the bottom rear, in which case the exit air will have just left the pile after doing a bit of drying. Make sense?
The more venting, the cooler the air and the more it will be like outdoors. Oftentimes, if the humidity does not get too high, we prefer to maximize heat, so venting is not a lot. However, a lot of heat at very high humidity is not the best drying situation for many white colored woods, but would work well for many oaks, if the temperature is jot too hot, and will work well to achieving the low final MC.
Gene I really do appreciate your comments as it helps me a ton.
Yes the vent openings do have covers and I can open them all the way or close them down tight.
You are correct about the fans. I have no front vents at this point. I was going to make vents in the doors near the bottom(as your just stated) but have not done that at this point.
When the wood goes in I keep the top vents about 3/4 open(most of the wood gets air dried some first) so I can get the humidity out. As my reading show that the humidity is going down I close the vents down some.
Today reading the vents where almost closed as I knew that the wood was becoming dryer and the humidity was low. I am sure that is why I was able to get such Hot temps on a cool day. I really try to know where my wood is at before I close up the vents. I often open the kiln in the morning and take check the wood with a moisture meter.
The one reason I have not bothered with additional vents is because I am drying almost only Red Pine and occasionally some white pine.
Thank you again...that last paragraph really helps me understand.
Matt