Zeiya - Ovens

QUESTION: Is there a concern of zeiya (steam) in our ovens? Can I cook dairy in an oven and meat in the oven right afterwards?

ANSWER: Igros Moshe (YD i:40) writes that our ovens are considered closed boxes. Even though they have a small vent on the top to let out excess steam, this is not significant, and they should be viewed as though they were closed. Therefore, if one cooks dairy in the oven, the dairy steam will spread throughout the box, and the oven and walls become dairy. If afterwards one cooks meat in the oven, the steam from the meat will spread throughout the box, and the oven will become non-kosher. If some of the steam that touched the walls returns to the food, it can make the food non-kosher. The Chelkas Yaakov (YD 23) too is strict regarding using an oven for both meat and milk. He writes that if one did, it is possible that the food would be forbidden. Sefer Badei Hashulchan (Hilchos Basar B’chalav pg. 211) discusses reasons why one might be able to be lenient bedi’eved (after the fact). If one finds that they cooked dairy in a fleishig oven, a rabbi should be consulted. The proper procedure for one who must use his oven for both milk and meat is either to kasher the oven in between or to wrap the pans with foil, so that they do not emit any steam.

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The Gerald & Karin Feldhamer OU Kosher Halacha Yomis is dedicated to the memory of Rav Yisroel Belsky, zt"l, who served as halachic consultant for OU Kosher for more than 28 years; many of the responses in Halacha Yomis are based on the rulings of Rabbi Belsky. Subscribe to the Halacha Yomis daily email here.