Hey Everyone, I’m in my first year of firewood production. We mainly focus on retail ¾ Cubic Feet Bundles for retail stores. I fell into this business and dove head first.....honestly we are much further along than we ever thought we would be at this point.....but still have LOTS AND LOTS to learn. I’ve got a 36 Cord Kiln that is direct fired with a 5,000,000 BTU burner (natural gas). I figured incorrectly that the kiln would come with a magic button to run the perfect cycle for me. Turns out there is a lot of trial n’ error and testing to be done to find the most efficient kiln cycle for my desired outcome. 1. Mix of red oak / white oak and poplar. 2. 5’ x 5’ x 5’ Kiln Baskets 3. I can heat (Dry Bulb) my kiln up to 300 Degrees “safely”. Currently using a Set Point of 275 Degrees 4. Desired moisture content of 15% to 18% or less (including core) 5. Using a Future Design Control Panel. It’s a pretty cool setup that allows you to build your own drying program with as many stages as you’d imagine. 6. I’d love to get my drying time down to 30-36 Hours. I’m at 54 Hours now….which is probably a little too long. I’ve talked to several experts and there has not been too many cut and dry answers to my questions, so I thought I might ask some of you that have more experience drying FIREWOOD (note not lumber!). 1. What is the desired temperature of the core of the wood for the best drying condition? 2. It is necessary to use a “rest cycle” to allow the moisture from the inside of the wood to equalize with the outside temp/humidity? 3. How often do you use a “dump cycle” to remove the moisture from inside the kiln? Should I be using EMC and Relative Humidity Levels to auto dump the kiln? 4. Is there a standard program that most operators use to dry firewood? 5. After the kiln cycle is completed do you continue to let the wood dry inside the kiln or do you open the kiln up to allow for a quicker cool down? I learned the hard way, you MUST run the fans if you elect to leave the kiln closed up! 6. How dry does the wood need to be to avoid mold issues for extended storage periods (3-4 months in a warehouse). Thanks for the help!
Welcome to the forum Southern Legacy Wood Great to have you here. I too sell the same sized bundles but use season dried wood. Wish i could answer your KD questions but have no experience with one.
Welcome aboard Southern Legacy Wood I think your going to have a captive audience here. Probably giving more than getting on how to run a Kiln. Keep it coming
Hi Southern Legacy Wood . No direct fired kiln experience. Couple of questions/ideas though. Since the drying rate varies by species, oak being one of the slower ones, poplar a bit quicker, would making separate allow you to maximize the drying process for each? Do you let your split wood dry on its own for a little while before putting it in the kiln? I've spent some time weighing splits as they dry to figure out what is going on, one thing I noted was that about 1/2 of the water will dry out within a month or so of the wood being split. (That is with sunny summer days, green wood that was cut within a few days). I would figure that you could save a bit on your kilning energy cost if you are taking advantage of natural drying first. As far as venting, getting the moisture out of the kiln will lower the RH (wet bulb) and make more 'space' in the air mass for it to hold moisture. So yes venting it at some point will probably help you. But the rule of thumb that I learned is that the RH is cut in half for every 20 degrees F that the temp goes up. So why not run your kiln at 300? And have that much more headroom to take up moisture? As far as your wood getting moldy when stored; Properly dried into the high teens I doubt that will be an issue. I don’t recall anybody ever complaining that the wood in their woodshed got moldy. There is at least one guy here who has a barn full of wood. Just keep a little air flow going the only thing that will get you is a leaky roof or other water infiltration. Show us some pictures of your operation!
My opinion, the key to reducing drying time all-else-being-equal would be air/heat flow into the "basket" center and so moisture out. The next big factor: the trade-off /optimum of temperature and humidity (the more fresh air the lower the humidity but at a lower the temperature given a constant burner heat output) should be available some where on the web which would require a good creative search.
I would have thought a constant turn over/release of moist air would be better. Maybe that would waste too much heat/gas
Welcome aboard Southern Legacy Wood Dang it if the wasn’t a video somewheres around here showing what looked like a trucking container kiln.... the guy said 240°F for 6 days... Anybody remember that vid?
I took a pic of one like this along the highway a while back. Not sure if this is it or not. kiln-direct.com
This link gives the equation relationship for temperature and humidity and firewood drying time about two thirds the way down: Wood drying - Wikipedia Baskets would create higher drying times than calculated by the equation. The example includes the equation constants for red oak which should be sufficient for your wood. The article says the drying time equation works for both firewood and lumber but to avoid higher temperatures for lumber to avoid cracking.
That’s the thread for sure. I think originally there was a video perhaps at the website that used to be good, in the first post. Click that link now and it says “parked for free” at go daddy.... I don’t know what that means. But yes Tim, nice job sniffing that old thread out.
