Question: What is the proper way to kosher a household gas stovetop? Similarly, is it permissible to place bread on the stove’s grates throughout the year?
Answer: We have explained previously that any vessel which one wishes to use for Pesach and has been used with Chametz foods throughout the year must be koshered. The koshering method for any given vessel depends on its method of absorption. For instance, a pot which had a Chametz soup cooked in it must be immersed into another larger pot with boiling water on the flame and in this way, the same way the pot absorbed Chametz flavor, it will now release this flavor into the boiling water.
Regarding the iron or stainless-steel grates surrounding the stove’s burners, the Rama (Chapter 451, Section 4) writes: “A grate requires Libun.” This means that the way to kosher a grate is by actually torching it with fire until it turns red-hot.
The Magen Avraham explains that since Chametz foods sometimes spill onto the grate, it has thus absorbed Chametz flavor and it cannot be used for Pesach until Libun has been performed to it.
Nevertheless, many great Acharonim question the Rama’s ruling since the grate is always very close to the fire and any time food spills on it, it will immediately be burned and the flavor will thus not have an opportunity to be absorbed in the grate. (See Ma’amar Mordechai Chapter 451, Subsection 11)
Similarly, the Acharonim ask that in general, food is not placed directly on the grate; rather, the grate is meant to place pots on top of it. It is well-known that the flavor absorbed inside one pot cannot transfer to another pot or vessel unless food or liquid serves as a conductor between both these vessels. For instance, if non-kosher meat was cooked in a pot and a pot with kosher meat was placed right next to it (and the vessels touched), the kosher meat remains kosher since the kosher pot has not absorbed any flavor from the non-kosher one since there was no food or liquid that could serve as a conductor to transfer the flavor from one pot to the other. (See Issur Ve’Heter, Chapter 31)
The same applies to our grates where pots and pans are placed on top of, in that even if we assume that the grates did absorb Chametz flavor throughout the year, nevertheless, this flavor cannot transfer to the Pesach pots since there is presently no food or liquid between the pot and the grate.
Thus, halachically speaking, Maran Rabbeinu Ovadia Yosef zt”l rules (in his Chazon Ovadia-Pesach, page 137) that according to the Sephardic custom, it is sufficient to clean the grates thoroughly and then pour boiling water on it from a Keli Rishon. This means that water should be boiled in a pot or electric kettle and when the water bubbles aggressively, it should be poured onto the clean grate (it is permissible to do so in the sink after it has been koshered).
Nevertheless, Ashkenazim customarily follow the ruling of the Rama and for Pesach, they actually torch the grates, purchase new grates for Pesach, or cover them with heavy-duty aluminum foil. However, this stringency applies only to Pesach because of the severity of the prohibition of Chametz; however, during the course of the year, even Ashkenazim act leniently and place both meat and dairy pots on the same grate (one after another). (See Mor U’ktzia, Chapter 491 and Igrot Moshe, Orach Chaim Volume 1, end of Chapter 124)
Based on the above, according to the letter of the law, it is permissible to place a pita or other Chametz on the stovetop throughout the year when the stovetop is clean, for we are not concerned that the stove absorbed any forbidden flavors since whatever spills on the grates is immediately burned and is not absorbed by them. There is room for leniency for Ashkenazim as well; however, one who acts stringently is certainly praiseworthy. (See Yabia Omer, Volume 10, Chapter 35, Section 10)
Summary: The grates on the stovetop should be cleaned thoroughly and afterwards, boiling water from a pot on the fire or from an electric kettle should be poured on them. During the rest of the year, it is permissible to use the grates for both meat and dairy pots without koshering them in between, for it is sufficient that they merely be clean. (It is likewise permissible to place bread on a clean stovetop throughout the year.) Ashkenazim customarily act stringently regarding Pesach and they either perform Libun to the grates, get new ones, or cover them in heavy-duty aluminum foil.