10 days was just a little optimistic in my solar kiln

Kingcha · August 01, 2014, 10:33:38 PM

To be fair its been a bit colder then normal with some cloudy days to boot. We did have a couple days that got into the 80's but most days barely got over 70 degrees.

It is the biggest load I have had in the kiln so I knew 10 days was wishful thinking. Just glad that I'm not in a hurry.

almost 1000 board feet of 1" pine flooring

After finishing my door system I only have the 3 upper vents, is that enough??? I am still learning the vents and really do not have the hang of it yet. Should I close them In the morning and open them before the night??? Early on I had them about 1/4 open and have since opened them to about 1/2 way open.

Matt

glassman_48 · August 02, 2014, 07:25:08 PM

matt,
I am interested in what others will be saying about this, I went to the pigroast today, bunch of really good people there. If your cutting on your mill some weekend I would not mind a drive over to watch. kalglass@charter.net is my e mail. thanks, ed

Kingcha · August 02, 2014, 11:06:52 PM

Ed, next time I have some logs for a weekend saw I will give you a call.

I was suppose to be out of town this weekend and my plans got changes, I should have gone to the pig roast but did not get motivated this A.M.

I need to stop starting new projects and finish up all that I have started :D :D :D

My next tree will be a white pine or 2. I think I will pick them out for cutting tomorrow. I guess I had better look up what white pine is best for.

My kiln hit its highest temp for the year today. The air coming off the roof was at 128 degrees . My readings are showing that the RH is coming down. Thinking maybe now its time to close up the vents some as to help retain the heat more. The temp on the outflow side is usually about 12-16 degrees cooler and the Rh is always higher then the Inflow side.

I open up the doors the other day and with my inexpensive meter I had a few boards reading around 12% but most where in the 7-9 range. Next time I open up the kiln I will have to cut a board or 2 in half and get a better reading.

GeneWengert-WoodDoc · August 03, 2014, 08:16:04 AM

The three upper vents are enough IF YOU ALSO HAVE SOME LOWER VENTS. For some woods, you will have the vents open just a tiny bit, while for others, like pine that dries fast, you will have th dents open almost all the way. That is, the vents control, somewhat, how fast the lumber will be drying. For oak, we want slower drying than we do for pine. By keeping the vents closed most of the way, you assure a high RH in the kiln which means slower drying. But for pine, we want to dry as fast as possible o keep the color good and avoid staining.

The more wood in the kiln, the more venting we need.

Generally, the vents are adjusted every 5 days or so, rather than hourly. once set for the day, that should work for the next few days without further work, unless you just fine tune the settings because the initial setting is not perfect. Venting brings in drier outside air, but also exhaust the kiln heat, so the best setting allows for more heat and a reasonable kiln humidity (50% RH for pine and 85% RH for oak, for example, during the middle of the day).

As discussed in other threads, do not runt he kiln fans 24/7. Rather run them only when the kiln is warmer than outside by 10 to 20 F. Also, run them for pine every day even when could. When cloudy, consider running the fans with the vents wide open to get virtually 100% air drying, especially when the wood is still quite wet. It is at the end of the cycle when we think about closing the vents more to achieve the hottest and driest conditions so we get the low MCs that we need.

Pine also needs good air flow, compared to oak. So, I would be tempted to block off the 4x4s to make sure that nearly 100% of the air goes through the pile itself and not through the 4x4 space.

Kingcha · August 03, 2014, 09:57:29 AM

Thanks Gene that helps a lot. I always air dry at least a month before loading the kiln. So I guess I go with leaving the vents wide open the first 5-10day's then I will experiment on how much go close them.

My fans are on a inexpensive light timer, turning on at about 11:30am and turning off at about 10:30 pm daily.

Thank yo for the 4x4 blocking idea.

I do a daily log of temps & RH when I am out back so I can see the daily changes. It's one of those things that will be more help as time goes on.

So it sounds like I need to put in some lower vents. So would it make more sense to have the lower vent open more then the upper vents, I would think I would have less heat loss that way?

Thanks again
Matt

glassman_48 · August 04, 2014, 08:33:49 PM

Matt,
I just had a great idea

when I was down at the pigroast, there were some very MISCHEVIOUS people there. They said I should go over to your place and process firewood for you, and you could bring your sawmill to my new site and build me a solar kiln :laugh: :laugh: Then I thought about it and if I had a kiln then I would have to buy a sawmill. Dang those guys were sneaky tryin to get me to buy a mill. We had a blast down there, hope you make it next year. Next time I am over that way I will give you a call.