Chazara: The halachos of returning food to the fire on shabbos: -- A Kirah that is Gerufa or Ketuma, if one removes a pot from it even on Shabbos, he may return it as long as it is boiling hot RAMA: and it is still in his hand (Tur) and he has not placed it on the floor RAMA: and his intention is to return it (Tur). This is specifically to the top [of the stove] but to the inside it is forbidden. It is forbidden to return [a pot] to a Tanur even if it is raked and covered up. Similarly, a Kupach when fired with Gefes [olive waste] and wood. RAMA: This is specifically when the food is fully cooked (Beis Yosef). It is then permitted to return it, even to another Kirah. But if it is not fully cooked it is forbidden even to return it to the same Kirah. There are those who say that all is forbidden only where one removes it from the Kirah while it is still day and wishes to return it after dark. However, if he removes it after dark it is permitted [to return] even if in the meantime he places it on the floor. (R"an Perek Kirah). This is our custom to be lenient for our [type of] ovens, that have the status of a Kirah, because the lenient opinion is relied upon. And it is better to be more stringent. But in all opinions where it has cooled off it is forbidden [to return it] [Beis Yosef]. There are those who say that if one removes the food from the Tanur on Shabbos it is forbidden to wrap it up in pillows or blankets. There are those who say that close to dark or close to Barchu which for us constitutes an acceptance of Shabbos (Ha'agahot Mordechai), where it is so close to Shabbos that if the pot would be cool it would be impossible to boil it up while still day, the same law (of Chazora) applies as to Shabbos itself. Some are lenient in this, and such is the accepted practice. Nevertheless it would be preferable to be stringent where there is no real need. But this refers only (to returning) directly onto a Kirah, however placing it next to it (the stove) or even next to a fire where the heat is Yad soledes bo is permitted even close to dusk. For a Tanur there is no difference between returning a pot onto it or next to it when that area is at a temperature of Yad soledes bo, but if that area is not Yad soledes it is permitted even on Shabbos, as will be stated below in Siman 318.