Preparing a Microwave for Passover

Hello, It is necessary to distinguish between the two kinds of microwaves found today. There are some that also have heating elements for browning, and their law is like that of a regular oven. After waiting twenty-four hours without cooking or heating in it, one should clean the appliance thoroughly, and then turn on the browning elements at the highest heat for about an hour. In this way, the oven is kosher for Passover. There are others that do not have heating elements, but operate only by radiation. If these ovens are used mostly only for heating food, and not for cooking, some say that they do not need any koshering at all, since the walls usually do not reach the temperature at which the hand recoils. Even if, on some occasion, something was heated there for several minutes and the walls did reach that temperature, one follows the majority of uses. Others disagree. Therefore, regarding chametz on Passover, it is proper to kosher them by cleaning them thoroughly, placing a cup containing a little water and a little detergent, but not bleach, and boiling the water for several minutes until the walls of the oven absorb the steam. It is proper to add another stringency by using the microwave on Passover only with a cardboard or plastic container that is tightly closed. Some are satisfied with the first method, or with heating food inside a closed container. And if the microwave oven is also used for cooking, as well as microwave ovens in stores, where use is more frequent and it is likely that the heat of the walls reaches the point where the hand recoils in most instances, it is proper to be stringent and not use it at all on Passover (Kitzur Shulchan Aruch Yalkut Yosef, Siman 451, seif 10, and his father, Rabbi Ovadia Yosef, of blessed memory, agreed with him in practice). 

With blessings, Hillel Meirs