Solar Kiln Fans Question

An airflow management problem in a solar kiln. April 15, 2012

Question
We built a solar kiln last year from plans in the Wood Magazine. We have two fans installed. Recently we were loading the kiln and it was hot so we turned the fans on. The plastic that hangs from the fan panel was blowing to the front of the kiln. I thought it would be sucked up to the back of the fans. Is this how the fans should work? The fans do blow to the front of the kiln for sure.

Forum Responses
(Sawing and Drying Forum)
From Gene Wengert, forum technical advisor:
I am not certain how you have done this. Do you have a vertical solid wall (fan baffle wall) with two holes for the fans? Is this located about 18" from the rear wall? Is there a piece of plastic or fabric that hangs down from the fan baffle to the top of the lumber bundle? Is this the plastic you were talking about? If the fans are going to the front, I do not understand how this plastic would also be going frontwards.

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From the original questioner:
Gene we have a vertical wall with two fans mounted in it. We have a third hole for a fan but have it coverd. We have a plastic baffle hanging from the fan wall. I’m not sure how far the wall is to the back, but will check. Here are two photos of our kiln.

Click here for higher quality, full size image

Click here for higher quality, full size image

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From Gene Wengert, forum technical advisor:
Try wrapping the edge of the fam shrouds with duct tape as it couldbe that you are getting flow or suction off the sides.

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From the original questioner:
We covered the fans with tape and added some wood from the fan board to the top of the kiln between the 2x4. That helped a lot. We also put plywood across the ends of the stack to help direct the flow.