Experimental passive solar wood kilns

[Firefighter938]

I've enjoyed watching your progress.

 

[Coalescent]

I am in awe, Poindexter. I'm finding myself wishing there were blueprints I could follow to construct these myself to get a jump start on drying out the wood I'll need starting next winter. Very impressive, sir. Thank you for taking the time to detail the steps you've taken and the iterations you've made to your concept.

 

[Poindexter]

I am in awe, Poindexter. I'm finding myself wishing there were blueprints I could follow to construct these myself to get a jump start on drying out the wood I'll need starting next winter. Very impressive, sir. Thank you for taking the time to detail the steps you've taken and the iterations you've made to your concept.

Briefly the four verticals for the lower level at each end are 68". The two verticals at each end for the upper level are 24".

The header and footer for the upper level are 14" each. You'll need one piece of 2x4 11" long at each end for the ends of the upper shelf. The footer for the lower level is 42", the header for the lower level is 35". Floor is still 42" wide by whatever for length, I haven't gone greater than 8 feet long per module myself.

Whatever your length is you'll need seven pieces of 2x4 that long, you can see six of them in post #123 above. The seventh is the ridge pole, not yet installed in post 123. Those tiny short pieces between the top box and not yet installed ridgepole, 6".

On the ridge pole I am using 1" PVC fittings, a piece of straight pipe 3 7/8" long, with a 45 elbow cemented on to each end. Copper pipe hanger to fasten those to the top of the ridgepole on 24" centers.

Each 10' long 1/2" diameter PVC pole fits into the open end of a 45 degree elbow, one drywall screw in the 2x4 68" up, and then into a galvanized 1" pipe hanger screwed into the floor joist. I have been drilling through the pole 45" from the top to make install easier. I am using galvanized screws and pipe straps BELOW the level of the plastic between the flooring and joists, but not above that level.

I am putting in diagonal braces - Spanish windlasses - every second or third unit. I think 550/paracord is adequate, but if you have heavier scrap taking up space use it.

If money is no object you can get SS screws, but they are twice the price of regular painted DWS.

Best of luck, I have two cords of green spruce splits getting dropped tomorrow and 8# of beef committed to becoming pastrami after a six hour smoke on Saturday that I'll need to deal with daily for the rest of the week. So maybe more detailed instructions next week sometime...

 

[Coalescent]

Best of luck, I have two cords of green spruce splits getting dropped tomorrow and 8# of beef committed to becoming pastrami after a six hour smoke on Saturday that I'll need to deal with daily for the rest of the week. So maybe more detailed instructions next week sometime...

Thank you! I look forward to making my own attempt soon. Many things coming together to bring wood heat back to this old house...

I look forward to the possibility of more detailed instructions after the delicious transformation that beef is undergoing. Great shots you've included in this thread; that helps, too.

 

[Poindexter]

Is that hooped-over 3/4" PVC going to be able to stand up under the weight of any snow you're going to get over it? Or are you moving it someplace else during snowfall season?

Apparently yes. Finally got one measurable snow fall since November. About two inches in 36 hours. I let all the side curtains down to keep blowing snow out of my stacks, my roof is steep enough that the plastic and hoops held up just fine. No experience with freezing rain yet...

So looking again at your description ... I assume by "passive" you mean no sort of mechanical ventilation? I can't quite envision how your condensate removal actually functions. Is the idea that the condensation on the inside of the plastic will run down and drain at the bottom on the sides? If so, my experience with greenhouses tells me that may not work, since condensate on the inside of the roof (if vents weren't used) just tended to drip right back down when things cooled off at night.

I hope it works though - would probably keep things simpler.

I have observed interior condensation running down the inside of the plastic from ridgepole all the way to the ground now. The plastic does need to be fairly taut. If the plastic membrane has sags in it the condensate will get soaked up by whatever horizontal 2x4 the membrane is sagged against.

The cheap plastic membrane I am using does expand or stretch in warmer temps. Likewise, it contracts in colder temps. So far I am having to re-tension all the membrane when the temp changes about 40dF or so. Hoping to get it taut at +70dF later this spring, maybe May or so, and not have to fool with it again until temps drop below freezing in September.

 

[Poindexter]

I do have some sagging going on. When these are next empty I am going to have to put in some plywood scraps to hold the uprights square.