Hi, I am learning shehiya now and have a question about our ovens. If someone wants to follow the Biur Halacha’s opinion is there any heterim to leave food that is mitzamak ve’yafe lo like cholent or overnight potato kugel in our ovens?
There is a machlokes whether removing the knobs is considered טוח בטיט. Minchas Shlomo chelek beis 34:21 leaves this as a safek, and Rav Vosner (letter in Orchos Shabbos page 516) is lenient. It would seem that in the case of your question one may be lenient, since the Biur Halacha that you quoted (253:1 ד”ה ונהגו) is only “machmir” (“לכתחילה בודאי טוב לזהר”) like the first opinion of the Shulchan Aruch and does not argue on the Rema that the halacha follows the second opinion of the Shulchan Aruch which is lenient.
Covering the knobs, as opposed to removing them, is more stringent. Rav Moshe holds that it is not considered גרוף וקטום (Igros Moshe O:C 1:93 ד”ה ולפ”ז), and this seems to be the opinion of the majority of poskim. However, Rav Aaron Kotler (as brought in Rav Eider’s sefer on Shabbos, page 338- see footnote below) held that covering the buttons is considered גרוף וקטום. Although the minhag is to be stringent regarding this matter and to not consider covering the buttons to be גרוף וקטום, in the case of your question there is room to be lenient, at least in a situation of necessity. As written above, the reason for this is that the Biur Halacha that you quoted does not write that the halacha follows the first opinion of the Shulchan Aruch, rather he writes that although the Rema is lenient, it is good to be careful (לכתחילה בודאי טוב לזהר). I.e. according to the strict letter of the law, there is no issur at all. Therefore one can be lenient regarding the above machlokes, at least in a case of need.
I hope this clarifies things.
All the best
Since you may not have access to Rav Eiders book, here is a copy of his words:
שמעתי בשם מו”ר ר’ אהרן קוטלר דבתנורים דידן אף דטוב שגם האש יהיה מכוסה בבלעך, העיקר הוא בכיסוי הכפתורים, ובדיעבד או במקום שקשה לכסות האש כגון באיזה תנורי חשמל, בכיסוי הכפתורים לבד מהני