hello99- thanks for your note. Indeed, in siman Tzadik- bais (92), ‘zeiah” (sweat or more accurately, vapor) is mentioned but- if my memory serves me right- it is in the context of an actual pot and a boiling pot at that, where you obviously see the vapor rise and hence it is considered “mamashos” – something real and solid.
I was talking about R’Moshe’s teshuvos where he maintains that in a regualr oven, there is also ‘zeiah’ from the walls, and it traspires from the walls, thereby making it improper to use the same oven for milchig and fleishig, for example.
ovens are heated and produce dry heat- and if the actual pot is covered, i don’t see how you can say that there is “zeiah”. i juts never understood that teshuvo- especially if you contrast it to the shulchan aruch and the halochos of ovens.(see joreh deah 108)