Are you allowed to adjust the oven temperature on Yom Tov? Well, according to some Poskim, oven temperatures can be adjusted depending on the type of oven. The Star-K has approved a series of ovens in which the temperature may be adjusted on Yom Tov. For those who hold that oven temperature can be adjusted, here is an alternative method that you can install on your oven that mechanically adjusts your oven temperature.
If your manual control oven were to break, it is extremely hard these days to replace it with a similar model. Most ovens today are electronically controlled and come with a "Shabbos mode". A "Shabbos mode" oven enables the oven to continuously stay on for 3 days to enable the observant Jew to cook or warm up food during a 3-day Yom Tov and Shabbos.
The Star-K Kashrus Organization approved "Shabbos mode" ovens allows for the pressing of an up/down control switch on the front panel to manage the temperature of the oven.
Many observant Jews are not comfortable utilizing this leniency and would much prefer to not adjust the oven temperature on Yom Tov. Other observant Jews whose Posek permits them to make adjustments to the oven temperature will only utilize a mechanical interface and not an electronic interface. See Rav Avraham Blumenkrantz's, zt'l, description in his Laws of Pesach - a Digest. (Click on a thumbnail below to start a slideshow.)
Reb Chaim has invented a gadget, called, "The Tweaker", that mechanically interfaces with an electronically-controlled Shabbos mode oven.
Rabbinic Approvals
The Tweaker was initially approved by Rav Zushe Blech of Monsey, NY, now has the written approval by
Dayan Shmuel Fuerst,shlita and Rav Gedalia Dov Schwartz,shlita of the Chicago Rabbinical Council,
Rav Yisroel Belsky, zt"l, of the Orthodox Union, and
To purchase a solution for a reduced-range Tweaker approved by the CRC, please visit my shop.
CRC Endorsement of TweakerOrthodox Union Endorsement of Tweaker by Rabbi Belsky, zt"l
Rabbi Peretz Moncharsh, of Revach.net was asked to review the design and this is his endorsement.
Dear Chaim,
Congratulations on the zechus of developing a method for adjusting ovens on Yom Tov that should be acceptable to all Poskim. Have a Kesiva VaChasima Tova.
Rabbi Peretz Moncharsh
How the Tweaker Works
Tweaker Wiring Diagram
This is how it works:
Just like the bi-metalic strip in the old manual oven could be rotated for an offset to the rotation of the valve that calls for heat, the modification adds a sparkless variable resistor in line with the oven temperature sensor of the new stove.
We dial in 500 degrees before setting Shabbos mode, and with a half turn we keep the oven equivalent to 180 degrees, and with a quarter turn we keep the oven equivalent to 350 degrees, and we do this without sending in any new programming to the computer controller, and without opening or closing any electrical switches to make new connections.
Tweaker Control Knobs
Reb Chaim proposes a list of 10 questions to ask your LOR (Local Orthodox Rabbi) should you be interested in using his device.
Reb Chaim, makes the invention design freely available to all yidden (to build and use at their own risk) and would also make it available to any appliance manufacturer or kashrus agency that might want to incorporate it, with the only request that it be used in the merit of his father, Avraham ben Betzalel z"l, and his maternal grandfather Nussin ben Shimon HaKohen z"l.
This invention is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.