It took several incarnations to come up with a satisfactory design for the bottom heated greenhouse bench. In the final version we used two 55 gallon drums welded end-to-end for the firebox and a salvaged piece of 12” stainless steel chimney for the horizontal flue. We learned the hard way that a large firebox and flue are necessary to dissipate the intense heat into the surrounding air chamber and to minimize heat stress on these components.
The SFJ library owns a lovely old leather volume, “How the Farm Pays” which features a curious and thought-provoking treatise on farming 100 years ago. We offer the introductory remarks, originally presented as an interview of the authors, here for your review. Hope you find this as interesting and useful as we have. SFJ