small-scale wood kiln

I am trying to build my own small-scale kiln and have looked around at the options. The Virginia Tech seems too large a scale and cost-prohibitive. I was planning on a 12' L x 4' H x 2' D kiln. I was going to heat it using 3 100W light bulbs, a 535 CFM vent fan to circulate air on one end, and a passive flap on the other end (think dryer vent) to open on the opposite side when the fan kicks on. I am going to attach a Ronco temperature cut-of switch to regulate the light if the temps get too hot. I am trying to keep costs down under $400 and my 2 questions are:

1) I see radiant barrier foil and was considering lining my interior with that (R rating is crap but wondered about the heating value
2) does this kiln make sense

I am trying keep the drying time down to about a month and avoid the huge electricity draw of a dehumidifier.


Any help would be appreciated

You can size the VT solar kiln just about any way you want, including the size you listed. There are a couple of guidelines to follow: You need 1 sq ft of solar collector for every 10 bf of lumber capacity. You also need 150 fpm of air flow through the stack. To calculate the size fan needed in cfm, multiply the number of sticker layers by the length in feet of the wood stack times the thickness in feet of the stickers. Hint: 3/4" thick stickers = 1/16 ft.

You will also need some space in front of and behind the lumber stack for air circulation. With the two feet of kiln depth you stated, you will be limited to a very narrow stack...probably only one board deep. Also, the "passive" dryer vent-type flap you mentioned willneed to be adjustable to regulate moisture removal vs heat retention. That's always a trade-off as wider vents remove more moisture but also remove more heat from inside the kiln. I'm also not sure that the three 100w bulbs alone will provide enough heat for effective drying. The radiant barrier foil won't do anything for you as the heat comes from the energy input. You would be better off with batt insulation covered with flat-black plywood.

Would your kiln idea work? Probably, although it may not be very efficient and it might not take the lumber to 7% or 8% MC in anything close to amonth. (I'm just guessing here)

So, I'd recommend just re-sizing the VT kiln to suit your needs. I sized mine for ~300 bf and put the door on the front. It's hinged at the bottom and lays down when open. I have props to hold the top open when loading/unloading the kiln. You can build the kiln to fit the 535 cfm fan if you already have it.

Thanks, Cody. I appreciate the input. Sounds like I am trying to be too frugal for my own good. I'll look into the VT version on a smaller scale.