COOKING WATER ON SHABBOS [Shabbos: cooking: water]
41a (Mishnah): If one cleared a kettle, one may not put water in it to get hot, but one may put water in it or in a cup to become lukewarm.
Question: What does this mean?
Answer #1 (Rav Ada bar Masnah): If one emptied the water out of a kettle, one may not put a small amount of water in it to get hot, but one may put much water in it to become lukewarm.
Putting cold water in hot metal is Metzaref. The Mishnah is like R. Shimon, who permits Davar she'Eino Miskaven (something he does not intend for).
Objection (Abaye): The Mishnah does not say that he cleared out of a kettle, rather, he cleared a kettle!
Answer #2 (Abaye): If one cleared a kettle [off a fire], one may not put a small amount of water in it to get hot, but one may put much water in it to become lukewarm. If one emptied the water out of a kettle, one may not put water in it at all, for it is Metzaref. The Mishnah is like R. Yehudah, who forbids Davar she'Eino Miskaven.
Rav: One may put water in it to become lukewarm, but not to be Metzaref.
Shmuel: It is permitted even to be Metzaref.
Rav permits only a Shi'ur of water that will become lukewarm, but not a Shi'ur to be Metzaref. Shmuel permits even a Shi'ur to be Metzaref.
(Beraisa - Beis Shamai): One may pour hot water into cold water, but not vice-versa;
Beis Hillel permit both of these.
This refers to a cup. In a bath, one may put only hot into cold.
R. Shimon ben Menasiyah forbids.
(Rav Yosef): A bucket (used for bathing) is like a bath.
Rejection (Abaye - R. Chiya's Beraisa): A bucket is not like a bath.
Question: How could Rav Yosef have thought that a bucket is like a bath? Rav Nachman taught that the Halachah follows R. Shimon [ben Menasiyah]. Is there no way to bathe in hot water on Shabbos?!
Answer: Do you think that R. Shimon discusses the Seifa (a bath)? No, he discusses the Reisha, in which Beis Hillel permit hot into cold and cold into hot;
R. Shimon forbids [cold into hot].
(Rav Huna brei d'Rav Yehoshua): I saw that Rava was not particular about the Kli (Rishon or Sheni). He relied on R. Chiya's Beraisa:
(R. Chiya - Beraisa): One may put a flask of water into a bucket, whether hot into cold or vice-versa.
Question (Rav Huna): Perhaps this is permitted only because [he put the flask itself in the bucket, so] a Kli separates the hot and cold water!
Answer (Rav Ashi): The Beraisa permits pouring a flask of water into a bucket, whether hot into cold or vice-versa.
Rif (Shabbos 20a): We conclude like Beis Hillel, for Amora'im saw that Rava was not particular about pouring hot into cold or vice-versa.
Rosh (3:15): The Rif holds that also in the conclusion, R. Shimon argues about the Reisha. Based on Rava, he rules like Beis Hillel, unlike Rav Nachman, who rules like R. Shimon. We could have said that Rava was not particular about a bucket, and poured hot into cold into a bucket, like R. Chiya's Beraisa, unlike Rav Yosef, and say that R. Shimon argues with the Seifa, like the simple reading of the Beraisa. Rav Yosef holds that a bucket is like a bath. This forced him to say that R. Shimon discusses the Reisha. However, the Sugya concludes that he discusses the Seifa, and the Halachah follows R. Shimon, who forbids hot into cold in a bath.
Rosh (ibid.): It seems that the Rif rules leniently, unlike I explained, for presumably we do not need Amora'im to say that they saw that Rava was not particular about a bucket, to oppose Rav Yosef, for Rav Yosef himself never [definitively] said so. He merely thought to say so, until Abaye told him R. Chiya's Beraisa. Rav Yosef then retracted. Also, 'do you think that R. Shimon discusses the Seifa? No, he discusses the Reisha' connotes that there was a tradition for this. If it was merely an answer, he would have said [just] 'R. Shimon refers to the Reisha.'
Rambam (Hilchos Shabbos 22:5): One may not put cold water into a hot bath of a bathhouse, for it will get very hot. However, one may put hot water into a cold bath.
Tosfos (42a DH Nosen): The Beraisa permits hot into cold even in a Kli Rishon, for this does not cook. One may not put cold into hot even in a Kli Sheni. Beis Shamai decrees a Kli Sheni lest one do so in a Kli Rishon. Beis Hillel permit cold into hot only in a Kli Sheni, like it says 'this refers to a cup.' This implies that Beis Hillel agree about a Kli Rishon. Rashi says that this is because Tatah Gavar (it depends on the food on bottom. Cooking occurs only if it is hot.) This is wrong. If so, this would be difficult for the opinion that Ila'ah Gavar (it depends on the top food). Also, the one who says Tatah Gavar holds that (when the bottom is cold) a layer (peel) gets cooked. Rather, R. Tam says that 'hot into cold' connotes that the majority is cold. One normally pours the minority into the majority. The minority of hot water cannot cook the majority of hot water. Cold into hot is forbidden, for the majority of hot water cooks the cold water.
Shulchan Aruch (OC 318:12): If one removed hot water from a kettle he may put in (much) cold water to warm the water.
Gra (DH Meicham): The Shulchan Aruch explains like Rav Ada because Rav and Shmuel hold like him.
Mishnah Berurah (80): One may not add a small amount of cold water that could become Yad Soledes Bo.
Shulchan Aruch (ibid.): One may pour hot water into cold water, or cold into hot, as long as it is not in a Kli Rishon, for then the water gets very hot.
Beis Yosef (DH Kos): Rashi explains that the first Tana permits hot into cold because he holds that Tatah Gavar. Therefore the hot water does not cook the cold water. It only warms it. One may not pour cold into hot, for the hot water would cook the cold. The first Tana permits a cup, for it is for drinking, so he does not want the water to be so hot. Also, it is a Kli Sheni. R. Shimon ben Menasiyah forbids even hot into cold. Rav Yosef says that a bucket is like a bath. Even though it is a Kli Sheni, since he wants it for bathing, and not for drinking, he wants it to get very hot. Therefore, we decree to forbid it. We answer that R. Shimon does not discuss the Seifa [and forbid hot into cold], rather, the Reisha (he forbids cold into hot for drinking.) The Rif says that we conclude like Beis Hillel. Some disagree and rule like R. Shimon, because Rav Nachman rules like him. They hold that in the Hava Amina R. Shimon refers to the Reisha, but really, he discusses the Seifa, i.e. a bucket [for bathing] and forbids even hot into cold. The Ran (DH v'Havi) and R. Yerucham mention such opinions. However, the Rosh explained the Rif's reasoning. R. Yerucham agreed to it, and the Rambam rules like it.
Beis Yosef (DH v'Kasvu): It seems that Rashi agrees with Tosfos, and permits hot into cold even in a Kli Rishon. This is why the Tur wrote that if a Kli Rishon is for drinking, one may pour from it into cold water, but one may not pour hot water into it. He also permits [into] a large amount of cold water that cannot get cooked, just the chill will be blunted. We learn from the Heter to put much cold water into a kettle.
Gra (DH v'Hu): The Mechaber allows both hot into cold and vice-versa, since only Abaye distinguishes, and the Mechaber rules like Rav Ada. This is why he did not bring the Heter of much water.
Mishnah Berurah (81): In a Kli Sheni we permit even a small amount that will become Yad Soledes Bo, for we hold that it does not cook.
Mishnah Berurah (82): One may not pour from a Kli Rishon onto a small amount of cold water that could get cooked.
Kaf ha'Chayim (127): We permit putting cold water into a kettle to become warm. One may not do so into a bath.
Rema: If there is so much [cold] water that it cannot get cooked, just the chill will be blunted, it is permitted even in a Kli Rishon as long as it is not on the fire.
Gra (DH v'Im): This is like the Tur, who rules like Abaye. The Rema did not write that hot into cold is permitted, for he relies on his comment in Sa'if 11. (The Mechaber forbids cold into hot into a bath, and) the Rema says 'even though it is a Kli Sheni.' This implies that the same applies to a Kli Rishon. (Damesek Eliezer - i.e. even in a Kli Rishon, we forbid only cold into hot.) This is like Tosfos (DH Nosen). However, even according to the answer that Abaye agrees with Rav Ada's answer, and Abaye merely explains [how] the Mishnah [could be] like R. Yehudah [we hold like R. Shimon, so one may put in much water, like Rav Ada]. Therefore, both of them (the Mechaber and Rema) wrote [the Heter of much water into an empty kettle, and the Rema permits much water into a Kli Rishon - Damesek Eliezer.]
Kaf ha'Chayim (130): Hot into cold is permitted even in a Kli Rishon, because Tatah Gavar. This is if there is enough cold water so the mixture will not be Yad Soledes Bo.
Mishnah Berurah (83): The Chayei Adam permits a majority of cold into hot only if he pours at once. If he pours slowly, it gets cooked immediately. It does not help if it cools off later.
Bi'ur Halachah (DH v'Hu): Tosfos explicitly requires a majority of cold water also for hot into cold. The Magen Avraham connotes that the Tur agrees. The Taz says that the Tur is lenient, but the Rambam is stringent. Beis Meir says that the Tur, Rashba and Ran are lenient. It is not considered Iruy, since the water mixes, so it is like a Kli Sheni, which cannot cook. Even so, l'Chatchilah one should not be lenient against Tosfos for a Torah Isur. B'Di'eved, one may rely on the Rashba and Ran who explicitly permit, and it seems that the Rambam and Tur permit even a majority of hot into cold, although I cannot understand why. If tea essence was cooked and cooled off, we do not protest against one who pours hot water onto it, for the Rashba and his followers say that Bishul does not apply. A pious person should not do so. Also the Gra connotes that he is concerned for Tosfos' opinion.
Yechaveh Da'as (6:21, b'Sof): If a hot water urn has a glass tube outside with water to show how much water remains in the urn, when one takes water, some of the water in the tube enters the urn and gets boiled. Shalmei Yehudah measured and found that the water in the glass is about 50 degrees (Celsius). Surely this is Yad Soledes Bo. Therefore, there is no concern at all. Also R. Y. S. Elyashiv and R. Binyamin Zilber permit.
Note: If boiling water is mixed with a slight majority of cold water at 20 degrees, the mixture will be almost 60 degrees. Tosfos says that the cold water will not get cooked. It seems that he holds that the mixture is not Yad Soledes Bo.