We at the STAR-K have worked with numerous appliance companies to make modern appliances more kosher consumer friendly for Shabbos and Yom Tov. During this process we have, in many cases, eliminated lights, icons, tones, and digital displays, provided for timed bake without tones and icons, and temperature adjustment on Yom Tov. However, these companies have chosen to name this feature the Sabbath Mode, and we are concerned from a halachic point of view that there may be some misunderstanding as to the proper use of these ovens on Shabbos. We would therefore like to make some clarifications.
1. No adjustment to the temperature is permitted on Shabbos even in the Sabbath Mode.
2. All food must be fully cooked and placed in the oven before Shabbos. No food (cooked or non-cooked) may be placed in the oven on Shabbos to re-warm or cook. This is true regarding ovens, as well as warming drawers.
3. It is the opinion of Rabbi Heinemann that on Shabbos, for a thermostatically controlled oven that is running (as opposed to one shut off by timed bake), the door may be opened once at any time and all the food removed at that time. The oven may not be used any further for that Shabbos.
4. The controls of an oven that is left on for Shabbos (or part of a Shabbos with a timed bake) should be covered with something like a piece of aluminum foil. Caution: Please be careful not to cover the vents.
5. Please see the appliance section of our web site for further information.
We would greatly appreciate help from Rabbonim in publicizing this information to their congregants.