Permissible ways to heat up food on Shabbat: Difference between revisions

# There’s a rabbinic prohibition in returning cooked foods to a fire on Shabbat because it looks like cooking. <Ref> Baal HaMoar 16b, Rashba (38b D”H MeKlal) in name of some geonim, Ritva (40b D”H VeAskina), and Ran (17b D”H Bei Rav Ashi) write that the prohibition of Chazara is a gezerah of Chazal because it looks like cooking when one heats up cold food on Shabbat. </ref>

# On Shabbat some posikim permit one to cover the fire with a metal tray if the flame isn’t strong enough to make the tray red-hot. <Ref> Sh”t Zera Emet 3:26 permits one to put a metal tray (with small holes) on a fire on Shabbat and then do Chazara based on S”A 318:8 where he brings the dispute whether one can do Chazara on an empty over the fire and rules like the lenient opinion. Chazon Ish 37:11 argues that actually placing the metal sheet on the fire is the forbidden act of [[Mavir]] based on Rambam (Shabbat 12:1, 9:6) who says that one who heats metal to mold it violates [[Mavir]]. Even though S”A 253:3 writes that on Shabbat day one can put a empty pot on a fire (and then return a pot that was on the fire right before), Chazon Ish explains that S”A is talking about a earthenware pot and not metal. However Nishmat Adam 20:1, Kesot HaShulchan (134 pg 42), Sh”t Shevet Halevi 1:91, Sh”t She’ilat Shaul 29, Chazon Ovadyah (Shabbat 1 pg 55), and Sh”t Tefilah LeMoshe 1:59 (pg 647) argue that in our case the tray won’t become hot as a coal or hot enough to be reshaped and so it should be permitted. So rules Shemirat Shabbat KeHilchata 1:38 to permit covering the fire as long as the fire isn’t strong enough to make the tray red-hot. </ref>

# One may not return food to the oven on Shabbat even if the food is fully cooked and is very hot since an oven is considered an uncovered flame, chazara is forbidden. <Ref>Shemirat Shabbat KeHilchata 1:17 </ref>