Question: Is one allowed to use an electric slow cooker (such as a Crock-Pot) that fits into another pot for the purpose of maintaining hot food on Shabbos?
Answer: Your question alludes to the forbidden activity of hatmana, storing food on Erev Shabbos in a manner that adds heat. (The word literally means hiding, concealing – in this case, to insulate within another vessel or substance.) Therefore placing a pot of food that fits snugly into an outer heating pot would seem to be a classic instance of hatmana. Yet, we see that slow cookers are widely used today for chulents and stews. What leniency might be found to permit their use?
I remember discussing this general matter with my uncle, HaRav Sholom Klass, zt”l. He was clear that it’s important to eat hot foods on Shabbat and was very critical of the idea of only eating cold foods as doing so would detract from oneg Shabbos (the pleasure one must enjoy on Shabbat).
He directed me to the comment of the Rema on Orach Chayim 257:8. The Rema states clearly that eating hot foods on Shabbat is a mitzvah. Exodus 35:3 states: “Lo teva’aru eish b’chol moshvoteichem beyom ha’Shabbat – You shall not kindle a flame on the Sabbath in all your encampments.” The Sadducees interpreted this verse literally to mean that one should not have any flame, whether for light, heat, or heating food, on Shabbat. Thus, the Rema, with very sharp words, writes that anyone who doesn’t wish to eat hot foods on Shabbat is suspected of being an apikoret – one who, Heaven forbid, denies the very existence of G-d.
But to fulfill the mitzvah of eating hot foods on Shabbat, we have to ensure that we do so within the confines of halacha. There are, of course, many ways of keeping food warm on Shabbat. One of the most widespread is using a tin blech placed on the cook-top (usually of gas burners). However, doing so presents certain problems. In addition to halachic problems of chazara (returning a pot to a fire), a blech can be a source of sweltering heat in the kitchen or even a safety hazard.
An alternative is the slow cooker, which has become a staple in many modern kitchens. Some slow cookers consist of a metal pot that sits on a small flat heating pan. While the pan doesn’t present any Shabbat problems, it’s advisable to place an aluminum foil sheet on the heating surface and to cover the control knobs, if there is any, as a heker, a symbolic act that one isn’t cooking on Shabbat. Most authorities consider adjusting the temperature fundamental to cooking (see Iggrot Moshe, Orach Chayim, vol. 1:93); therefore, when a control knob is covered (or removed), bishul in the true sense cannot take place.
More common in stores is the Crock-Pot – an earthenware pot that sits within a metal pot, which contains an electric heating element. Many gourmands maintain that an earthenware pot yields a far superior and more delectable product.
When Crock-Pots first appeared on the market, many contemporary poskim were asked whether one could use them. There are a number of issues they had to resolve, including shehiyah (leaving food on a fire from before Shabbat), chazarah (returning food to a fire on Shabbat), and lastly, as we noted at the outset, hatmana.
(To be continued)