So I’m a couple days past the 2 week mark. We finally started getting some warm weather and sun the last few days so I didn’t want to open them. I will dig into the kiln tonight to pull some samples.
My Solar Kilns.
- Thread starter KJamesJR
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Update:
16 days in the kiln thus far. Here’s a belated two week update.
Average high since 6/12 : 80 degrees f
Average low since 6/12: 60 degrees f
Days of direct sunlight since 6/12: 5
Days of partly cloudy since 6/12: 3
Days of cloudy/rain/no sun: 8
Moisture reading done on a fresh split face. Results so far have been interesting. I pulled three splits from the uncovered stack and they seemed to trend lower in moisture when compared to the kiln stack. The splits from the kiln stack were noticeably lighter in color and felt drier (internally) than those in the uncovered stack. If I had to make a visual comparison, I’d guess the kiln wood was drier but the meter read otherwise.
I’m not sure if temperature is playing a roll here as the kiln wood was noticeably hotter.
First pic is the uncovered wood, second pic is the kiln wood. Currently I’m going to say the results thus far are inconclusive. Only two weeks into the project with less than ideal sunlight. I may modify the ventilation, or not. I’ll give it two more weeks before tampering with the experiment.
16 days in the kiln thus far. Here’s a belated two week update.
Average high since 6/12 : 80 degrees f
Average low since 6/12: 60 degrees f
Days of direct sunlight since 6/12: 5
Days of partly cloudy since 6/12: 3
Days of cloudy/rain/no sun: 8
Moisture reading done on a fresh split face. Results so far have been interesting. I pulled three splits from the uncovered stack and they seemed to trend lower in moisture when compared to the kiln stack. The splits from the kiln stack were noticeably lighter in color and felt drier (internally) than those in the uncovered stack. If I had to make a visual comparison, I’d guess the kiln wood was drier but the meter read otherwise.
I’m not sure if temperature is playing a roll here as the kiln wood was noticeably hotter.
First pic is the uncovered wood, second pic is the kiln wood. Currently I’m going to say the results thus far are inconclusive. Only two weeks into the project with less than ideal sunlight. I may modify the ventilation, or not. I’ll give it two more weeks before tampering with the experiment.
Attachments
weatherguy
Minister of Fire
I'm going to build one this July 4th weekend I have two cords of oak I'd like to use this year, keep us updated, I'll try to do the same, sun would be nice, seems like it's been raining more than sun.
Yes. Even though the weather has been warmer, there hasn’t been enough sunlight. The solar energy is what heats the internals of the kiln, not ambient temps.
I’m sure with a good two weeks worth of sunlight, I’d see a noticeable difference. The outlook over the next two weeks looks grim however.
Woodsplitter67
Minister of Fire
On a sunny 80 degree day what is the temperature in the kiln.
Your results may be less than optimal due to it not being hot enough on the good days. Your kiln should out perform the top covered stacks. There may be somthing wrong
No idea. I don’t have a prob thermometer. They’re quite a bit hotter than ambient. I can feel the hot air coming out of the vents but I couldn’t tell you how hot it is.
spudman99
Feeling the Heat
Not enough sunlight to heat the kiln for its desired result. Five days of sunlight is about 60 hours, not all of that at the high temperature. Also the humidity levels can affect the drying process since the sun has to dry out the moisture in the ambient air before affecting the wood.
Likely that the wind on the uncovered stacks had a drying impact, wind will work on cloudy days whereas it does not work in the kiln. Your first real measure might not come till about 30 days in the kiln with perhaps 14-16 days of sunlight. It has been noted that wind is a better moisture removal agent then sun (excluding a kiln of course)
Likely that the wind on the uncovered stacks had a drying impact, wind will work on cloudy days whereas it does not work in the kiln. Your first real measure might not come till about 30 days in the kiln with perhaps 14-16 days of sunlight. It has been noted that wind is a better moisture removal agent then sun (excluding a kiln of course)
I opened the side vents a little bit more this morning. There’s been a lot of wet weather and the condensation on the inside was a little more than I’d like.
After a day at work I check the kilns and they’re once again bone dry. Seems given the wet weather it’s a juggling act between too humid, need open vents. Too cool, close vents. Would be nice to try this in an actual drying shed.
After a day at work I check the kilns and they’re once again bone dry. Seems given the wet weather it’s a juggling act between too humid, need open vents. Too cool, close vents. Would be nice to try this in an actual drying shed.
barnaclebob
Feeling the Heat
I wouldn't worry about playing with the vents too much. It will get condensation on cool days and that will drip off or evaporate on dry hot days.
I’ll stick my arm in there when I get home and see if I’m losing too much heat for having bigger vents. We’re only forecasted two storms over the next 2 weeks. Mostly sunny or partly cloudy. Mid to high 80’s and two days hitting 90. I’m expecting good results on the next moisture reading.
barnaclebob
Feeling the Heat
I wonder if you should take a few readings at various "depths" in the wood? It might not dry evenly, kind of like how a roast doesn't cook evenly throughout its thickness. Even after a few weeks of good drying conditions the middle might only fall a few % while the outer part has gone down more.
Woodsplitter67
Minister of Fire
Or you can put an air prob in it and know exactly how low the temperature is and make the proper adjustments to the vents. Take the guess work out of it. Your arm cant tell you the actual temperature in the kiln. Air probes are relatively cheep and easy to fined.. you went through all the trouble to build the kiln. Why not take the one step you need and make sure you achieve the results your looking for.. i really dont get your thought process....
That didn’t really occur to me. I was just checking the dead center of the spilt. The splits lower in the stack may also be drier as the top splits are basking in hot humid air. I only pulled splits 2 or 3 rows deep...
I’m typically not home during peek hours throughout the week so I can’t really justify buying a thermometer that will never get used. Sticking my arm in there right around dusk is a good enough indication that the kiln was at least running hot during the day. I will look around amazon for an inexpensive thermometer. I do have an infrared thermometer... maybe that will suffice?
When the suns gone down the stack continues to vent off hot steamy air. So the hand is more or less a feeler gauge. Mind you... none of this is entirely scientific. I’m just a dude.
maple1
Minister of Fire
Any thermometer should do. They're pretty cheap. Just set it in there somewhere that you can read it through the plastic?
Montanalocal
Minister of Fire
They make many maximum/minimum thermometers.
https://www.amazon.com/dp/B006OP2O3Q/?tag=hearthamazon-20
https://www.amazon.com/dp/B006OP2O3Q/?tag=hearthamazon-20
Woodsplitter67
Minister of Fire
The one im useing is for cooking. Its an air probe that i use for my smoker .. i can also use it for the grill and in the oven.. so it has a purpose..
Alright I got some temp numbers for y’all...
Current temp 84f
Humidity 40%
Sun was hiding behind some clouds when I got home, around 4:30pm, not sure for how long but today was mostly sunny.
Temp inside first kiln was 114f temp inside second kiln was 118f
For some odd reason there was a portion of the second kiln reading 128f so maybe the sun had just disappeared.
Vents were mostly closed on the first kiln. Open on the second. Lots of condensation on the plastic inside which I’m not too worried about.
Current temp 84f
Humidity 40%
Sun was hiding behind some clouds when I got home, around 4:30pm, not sure for how long but today was mostly sunny.
Temp inside first kiln was 114f temp inside second kiln was 118f
For some odd reason there was a portion of the second kiln reading 128f so maybe the sun had just disappeared.
Vents were mostly closed on the first kiln. Open on the second. Lots of condensation on the plastic inside which I’m not too worried about.
maple1
Minister of Fire
Wonder if it's possible you're wrapped too close to the wood & bottom? So moisture laden air can't get out & drier stuff can't get in? (Not enough air movement through?) I haven't tried this myself but kind of thinking there shouldn't be a lot of condensation showing when it is up to temp? Then also if that condensation can't run down the plastic and get away from the stack it will likely just keep coming back.
I think I would likely do heavy black plastic on the ground vs. fabric.
Interesting stuff!
I think I would likely do heavy black plastic on the ground vs. fabric.
Interesting stuff!
Thanks for sharing. Have wrapped a face cord and a holzhausen recently and seeing similar results on temp and condensation. Thanks for updates
The plastic is offset an 1 1/2” away from the ends of the splits top to bottom and the entire length on both sides. The stacks are also 4” off the ground... There should be air coming up from under the kiln and the sides over the split ends. the only thing stopping the natural convection I would think is keeping the vents closed.
I’m going to open the vents up and just leave them open. There’s a lot of condensation on the top inside the stack. When the vents are open it stays dry inside. I might lose some heat but I’ll open them and check again in an hour or so.
83f outside, mostly sunny, 130f in the stacks. Supposed to hit 87 before the days over and 90 tomorrow. We haven’t had rain an a couple days so I’m inclined to think all this condensation is from moisture leaving the wood, which would be awesome.
maple1
Minister of Fire
Two week update since June 28th
Days of full sun: 8
Days of partial sun: 6
Days of clouds/rain: 2
Average high: 89
Avaerage low: 59
I did a redesign on the kilns on the 6th of this month. I was getting some substantial temp swings between the bottom of the stack, pallet wrapped and the top of stack, mil plastic. The bottom of the stack was reading in the low 90s and the top of the stack was in the 130’s. I since finished the entire stacks in mil plastic. Using a staple gun I buttoned it up real tight and cut two vents in the top on either side.
My results thus far remain inconclusive, to slightly underwhelming. Due to the stacks being kind of a “closed loop system” now I am only taking the temps from the air exiting the vents at the top. I DID however open them today to get some readings. I will most likely leave the new system closed until sometime in August.
Now the air temp exiting the vents is roughly 135f there’s still a temp difference at the bottom of the stack. It’s about 100f. This is where the air intake is from so I don’t think there’s a whole lot I can do about it. Fresh air in, hot wet air out. The only problem is the air in general here in the North East is WET. Average humidity has been about 70-80 percent. I think this may be why I’m seeing poor results but I digress... on to the moisture content.
All on fresh splits... red oak, uncovered stack averaged 30% moisture. Covered stack average... 30% moisture. It seems the oak in the uncovered stack dropped an average of 1% over the last two weeks. Whereas the kiln wood dropped 3% and has caught up. This might have been just recently due to the design of the new kilns. I’m almost positive the splits lower in the kiln may be wetter being cooler. However I’m not going to tear apart my stacks to find out. I could be seeing an issue with my moisture meter as well.
The beech did test 24% in the kiln stacks. I wasn’t tracking the beech but it seems like it’s getting dry. Overall it looks like the kiln stacks have settled quite a bit more than the uncovered stacks.
I was hoping to see a greater decrease in moisture than what the data is projecting. Given we’ve had good sun and hot weather. Reports of getting wood seasoned in three months seems a little unrealistic as I’ve only lost 3% from 33% in four weeks. I’m still optimistic however and will let the redesigned kilns do their thing. I will post a pic of the new kilns.
Some issues that might be hindering performance. Poor design for the first few weeks, too much airflow, too humid, too cloudy, living in the North East.
Days of full sun: 8
Days of partial sun: 6
Days of clouds/rain: 2
Average high: 89
Avaerage low: 59
I did a redesign on the kilns on the 6th of this month. I was getting some substantial temp swings between the bottom of the stack, pallet wrapped and the top of stack, mil plastic. The bottom of the stack was reading in the low 90s and the top of the stack was in the 130’s. I since finished the entire stacks in mil plastic. Using a staple gun I buttoned it up real tight and cut two vents in the top on either side.
My results thus far remain inconclusive, to slightly underwhelming. Due to the stacks being kind of a “closed loop system” now I am only taking the temps from the air exiting the vents at the top. I DID however open them today to get some readings. I will most likely leave the new system closed until sometime in August.
Now the air temp exiting the vents is roughly 135f there’s still a temp difference at the bottom of the stack. It’s about 100f. This is where the air intake is from so I don’t think there’s a whole lot I can do about it. Fresh air in, hot wet air out. The only problem is the air in general here in the North East is WET. Average humidity has been about 70-80 percent. I think this may be why I’m seeing poor results but I digress... on to the moisture content.
All on fresh splits... red oak, uncovered stack averaged 30% moisture. Covered stack average... 30% moisture. It seems the oak in the uncovered stack dropped an average of 1% over the last two weeks. Whereas the kiln wood dropped 3% and has caught up. This might have been just recently due to the design of the new kilns. I’m almost positive the splits lower in the kiln may be wetter being cooler. However I’m not going to tear apart my stacks to find out. I could be seeing an issue with my moisture meter as well.
The beech did test 24% in the kiln stacks. I wasn’t tracking the beech but it seems like it’s getting dry. Overall it looks like the kiln stacks have settled quite a bit more than the uncovered stacks.
I was hoping to see a greater decrease in moisture than what the data is projecting. Given we’ve had good sun and hot weather. Reports of getting wood seasoned in three months seems a little unrealistic as I’ve only lost 3% from 33% in four weeks. I’m still optimistic however and will let the redesigned kilns do their thing. I will post a pic of the new kilns.
Some issues that might be hindering performance. Poor design for the first few weeks, too much airflow, too humid, too cloudy, living in the North East.
Attachments
barnaclebob
Feeling the Heat
I don't think high humidity of the intake air is really a concern in solar kilns. If the temp is 85 degrees and 80 percent humidity, when its heated to 130 degrees it will only be at about 25% humidity. Hot air can hold a lot of moisture.
True. The exhaust air coming out always feels really sticky. I’m also still getting condensation inside the kiln... I guess I’ll wait and see where it’s at in a couple weeks. I think I’m going to give it three weeks this time before I check it again.
