# Solar firewood kiln ??????



## giXXer (Jun 22, 2010)

Has anyone built one, used one, been successful, un-successful? Any input would be appreciated.

I am asking because I have a relatively large amount of oak in 8' logs that I have been working on bucking, splitting, and stacking. I already have enough wood for myself for this winter, but would like to sell some to help offset the cost of my CAD and procuring equipment in need of a good home. The wife says it's out of control and something needs to be done. I have successfully placated her by saying I will just sell more firewood this year. I have sold some in the past, just on a very small scale and always run out in December. I added firewood sales to my LLC's liability policy and already have two great retail locations (one is across from a huge campground that also rents cabins year around and the other has an awesome downtown location) that are already staffed so I won't have to sell it myself or pay any additional wages. My problem is the 12 full cords that I have split and drying will be ready, or very close to ready this late summer/early fall. The trees were dropped last summer, cut and split last fall, and have been drying in the sun since. All of the wood that I cut and split from here on will not be ready until next summer, unless I can come up with a way to dry it more quickly. I refuse to take peoples' hard earned money for wet wood...bad for them, bad for me, and bad for my other businesses' reputations that are the retail locations. I would rather just wait until next year to sell it, unless, this solar kiln idea will help.

I think it's cost prohibitive to build and heat a conventional kiln (for my uses), but I think a few solar kilns could be built pretty economically. I have a lot of really nice left over building and decking materials that could be used to help save money. I would have to purchase: a timer, a few crawl space vent fans with 12v motors, battery, RV type or larger solar panel to charge the battery, and corrugated plastic for the 45 degree roof slope. I'm sure it would only take a few beers (depending on how hot the day is) to build a 4' X 10' structure and maybe a couple more to install the electrical.

If you don't know what I am referring to with this idea a couple of examples can be found on Youtube and other sites on the web under solar kiln. I know that drying firewood takes time and patience and this brain fart is contrary to that. What do you think? Foolish idea? Think it might be beneficial? If it would work, why aren't more people doing it? Expense? Too much work? Drying in the sun works that well it's not worth it? Any input would be appreciated.


----------



## leon (Jun 22, 2010)

*solar wood kiln*

the simplest thing to do is build hot boxes and stack your firewood in a holzhuauzen.

You can buy a large roll of 4 inch solid drainage pipe and put a small fan in one end and then roll the pipe out to absorb the heat before it enters the hot box and then pipe it under the holzhuazen with perforated white PVC 
under the holzhuasen.

you can make a hot box out of a sheet of plywood and 2 by 4's and use wooden storm windows or an 1/8 inch sheet of plexiglass with countersunk holes for screws.

nail the 8 foot 2 by 4's the long way on the plywood or screw and glue them to the sheet. 6 inches apart with a solid exterior frame-but drill one one air passage hole in each 2 by 4 before you screw them into place-making sure each hole is opposite the other one to allow the air to pass from one space to the other.

paint the entire thing flat black let it dry and then secure the storm windows or plexiglass to the box.

set the box in full sun and unroll the solid PVC 
attach one end of the solid drainage pipe to the hot box and then run the soild PVC to where you want to stack the wood in the round house fashion and attach the perforated PVC to the solid PVC and feed it through 12 by 8 hollow core cinder blocks to protect it and also dry out the fire wood.

if you use a good tractor trailer tarp to cover the wood as it is heated it will dry easily. 


You only have to stack the wood in the round the width of the tarp and its done and a 48 foot tarp will cover a lot of wood in the round.


leon


----------



## kd460 (Jun 22, 2010)

For what it's worth:

http://www.builditsolar.com/Projects/WoodDrying/fputr7.pdf


----------



## giXXer (Jun 23, 2010)

leon said:


> the simplest thing to do is build hot boxes and stack your firewood in a holzhuauzen.
> 
> You can buy a large roll of 4 inch solid drainage pipe and put a small fan in one end and then roll the pipe out to absorb the heat before it enters the hot box and then pipe it under the holzhuazen with perforated white PVC
> under the holzhuasen.
> ...



Thanks for your input Leon. I have heard about the holzhauzens and have seen a couple of pictures of them, but not with fans or solar heaters. I would imagine it would work well. I have a similar set-up for my above ground ghetto pool. I used 200' of black irrigation pipe and T'd it into the pump with a valve to slow the rate of flow through the pipe. I shut the valve two days ago because the pool was 82 degrees.


----------



## giXXer (Jun 23, 2010)

kd460 said:


> For what it's worth:
> 
> http://www.builditsolar.com/Projects/WoodDrying/fputr7.pdf



I saw that study a few weeks ago. Man, that guy had some extra time on his hands to do that kind of research and data collection. Think of dedicating that kind of time and those many years to solar kilns! I'm glad he did it though, it proves they work. On the moisture chart you'll notice that after just 30 days all of the wood lost at least half of it's moisture and almost all of it was under 20% moisture content.

I like the holzhauzen idea because of the initial cost. But if I built them like (my design is very similar to the link) the one in the link, they will look nice, all of the wood would be out of site, and I can move the entire units including the wood with the end loader. I just don't know if its' practical???? With the cost of materials to build enough square footage of solar kilns to dry the amount of wood that I need to, I don't know if I would be further ahead just stacking it on pallets, letting mother nature do the work for free, and just wait a year to sell it. The old timer I know that sells 200+ cords per year says instead of wasting all that time and money, "get off your duff and cut enough wood so you are a year or two ahead...lazy kids!" He might be right, but the idea is still floating around in my head.


----------

