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: In previous weeks, we noted that it’s a mitzvah to eat hot foods on Shabbat (Orach Chayim 257:8). We also noted that poskim disagree whether partially covering hot food is considered hatmanah and forbidden. The Rashba and Mechaber are strict while Rabbeinu Tam and the Rema are not.
According to Rabbeinu Tam, however, covering most of the pot is considered hatmanah and forbidden; the Chayei Adam maintains that it’s only hatmanah if the wrapper touches the pot on all sides.
But what’s wrong with hatmana in general? Isn’t the food already cooked? If so, why can’t one wrap it?
The Gemara (Shabbos 34b) discusses this question. Rava said, “For what reason did the sages rule that we shouldn’t insulate foods with materials that may increase their heat on the eve of Shabbat? It’s a decree lest one insulate food with ash that has a live [burning] coal mixed in it.” Rava said, “Our fear is that he will rake the coals” in the ash and violate the prohibition against cooking on Shabbat. He may also violate another prohibition by causing a flame to ignite from the live coal.
Today, we don’t store food in ashes. We store it in a towel or some other material, and there is no fear of moving the material such that a fire will be ignited. Nevertheless, the prohibition of hatmanah still applies if the following conditions are present:
1) The food is completely wrapped, which can lead to the food being cooked further.
2) The food is in its original pot. If one transfers the food from the pot in which it was cooked to a new pot, that pot is a klei sheni to which the rules of hatmanah don’t apply.
3) There must be the intent to wrap the food for the purposes of hatmanah. Thus, placing a lid on a pot isn’t hatmanah since one’s intention is merely to protect the food inside. (see Mechaber Orach Chayim 257:2).
4) The wrapping material is in direct contact with the pot (or food).
Based on these conditions, Rabbi Yosef Shalom Elyashiv suggested a unique and creative solution to using Crock-Pots: Place pebbles on the bottom of the outer pot. That way, the inner pot won’t be touching the outer pot directly and the very top of the inner pot will no longer be surrounded by the outer pot (as it will be forced higher than the outer pot by the pebbles). Thus, for two reasons, using a Crock-Pot won’t be problematic from a hatmanah perspective (Sefer Otzrot Shabbat 517-518; see Rema, Orach Chayim 253:1).
Another matter to consider is that inner pots of Crock-Pots don’t fit snugly into the outer pots (their heat source); they don’t touch the outer pots’ walls. Thus, according to the Chayei Adam, (topic 2:5) who rules that the wrapping substance must actually touch the wrapped object on all sides, there is no problem of hatmanah.
This author examined models of slow cookers at an appliance store, and noticed that the inner pots only minimally touch the bottom of the outer pots. In most of the models examined, the bottom of the inner pot has a thin ridge that rests on the outer pot. Furthermore, the walls of the inner pot do not actually touch the outer pot.
A lip at the top perimeter of the inner pot seemingly sits above the perimeter of the outer pot, but it does not completely form a seal against the outer pot, leaving plenty of wiggle room (probably to prevent overheating and a fire hazard).
Thus, using these slow-cookers doesn’t seem to present a problem of hatmanah and Ashkenazim may use them. It’s even possible, in light of our investigation, that Sefardim may use them too. (Of course, all are wise to consult with their rabbanim.)
In any case, if possible, it may be best to place a “blech” of thin aluminum foil between the inner and outer pots or all around the outer pot or at least on the lower portion of its exterior to serve as a heker (sign) that one isn’t cooking. However, more important is to cover the controls, perhaps with a piece of aluminum foil, or turn the pot around so that the controls face the wall. Without access to the controls, one cannot adjust the temperature and actual cooking is avoided.