This Halacha is an excerpt from our Sefer
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From the letter of the law, an oven requires Libun Chamur. If one’s oven does not have a self clean cycle, it is very difficult to accomplish this. One cannot do Libun Chamur through using a blow torch, as the oven can break in the process. One is thus to buy a Pesach oven or alternatively Kasher it in the following way:
- Clean the oven well using a Chametz killing agent such as bleach or oven stain remover.
- Wait 24 hours prior to Kashering.
- Turn the oven on for a period of at least one hour to its highest temperature or blow torch the oven from the inside.
- After the Kashering process is complete, one should cover the walls and floors with aluminum foil.
Self cleaning oven:
An oven with self cleaning mode reaches a temperature of 900° F and is equivalent to Libun Chamur. An oven with a “Continuous cleaning” cycle is not equivalent to Libun Chamur, and hence the above-mentioned method must be used.
 Admur 461:1; Piskeiy Teshuvos 551:10
 The reason: As the Chametz at times falls onto the floor of the oven and the oven walls receive Chametz taste directly without liquid [Admur ibid] and we are initially stringent to follow minority usage. [Admur 451:27] Now, although we rule that two pots which touch each other do not transfer taste without liquid [Admur 451:67] perhaps we suspect that liquid may spill onto while cooking and make everything prohibited according to our custom to prohibit the food even if the pot is not be Ben Yomo.
 The heating elements are very delicate and can burn due to the heat of the blow torch. [Piskeiy Teshuvos ibid footnote 39]