Q.
I am planning to construct a solar kiln. I need the following clarifications:
1. Are glass panels better than plastic (transparent)?
2. For a kiln size of 18 by 14 feet, (with a maximum height of 12 feet), are two air outlets at the bottom and two air intakes at the top sufficient?
3. Should the fans be placed at the air outlet points?
4. Will the efficiency increase if the side walls also have glass or plastic panels? Otherwise, could it be a brick wall?
A.
1. Glass is better but breakable.
2. This should be plenty of venting.
3. Offset them a little, and keep them at least one foot from the rear wall. The fans blow away from the vents.
4. Brick is OK if insulated. Clear is usually a poor option due to increased heat losses, and just a little gain in solar. Rather, paint the walls a dark color (but keep them breathable).
Gene Wengert, forum moderator
The only change that I would make would be to construct the rear wall so that it could be opened completely for easier loading. We made the mistake of putting rectangular doors in the end walls, and have enjoyed numerous bumped noggins as a result.
Also, we were fortunate to find a greenhouse supply store which had some ribbed fiberglass glazing on hand that they had special ordered which was never picked up. We got an excellent price on it, and have had the same glazing in place for the life of the kiln. It is showing its age now, but it still keeps the rain out .
