Turning On a Hot‑Water Urn by Bein Hashmashos of Yom Tov and Shabbos

Question:
I am not sure how this happened, but my hot‑water urn, which I had prepared hours before Yom Tov, was somehow switched out of Shabbos/Yom‑Tov mode. As a result, the water will cool off. By the time we realized this, it was already after sunset, or very close to sunset. May I turn the urn back on in order to have hot water on Yom Tov? This is particularly important for us, as having hot water for tea or coffee on a cold and rainy day is a significant need. May this be permitted taking into account that Yom Tov prohibitions are rabbinic, and that turning on electricity is likewise rabbinic? Would there be any difference between Yom Tov and Shabbos?

Answer:
With regard to Yom Tov, it would be permitted to turn the urn back on during Bein Hashmashos, and certainly by Safek Bein Hashmashos, by activating its Shabbos/Yom‑Tov mode, provided that there is no other way to obtain hot water, such as if no flame was left on and placing a pot of water on a blech or plata would not result in the water becoming hot. However, on Shabbos it is forbidden to do so, even through the agency of a non‑Jew.

Explanation

There is a general rule regarding bein hashmashot, which is that a Shvus may be performed in a time of need. This means that a rabbinic prohibition may be performed if it is for the sake of a mitzvah, for the sake of a great need, or for the sake of an essential Shabbos necessity. This is in addition to the general allowance that applies throughout Shabbos itself, whereby a Shvus Deshvus Bemakom Mitzvah is permitted, which means that a rabbinical prohibition may be performed through a non‑Jew in a case of great need or for the sake of a mitzvah. The novelty of bein hashmashot is that under these circumstances, the Rabbinical act may be performed even directly by a Jew, provided the prohibition involved is only rabbinic. Accordingly, in order to answer the above question—whether turning on hot water is permitted during bein hashmashot—we must first determine whether electricity and cooking constitute biblical or rabbinic prohibitions on Shabbos and Yom Tov.

On Shabbos, cooking is a biblical prohibition. Furthermore, even in a case where the water is already fully heated—such as in the above case where the water was hot before Shabbos—activating electricity may still involve the biblical prohibition of hav’arah (kindling), if doing so causes a flame or filament to ignite.

If, however, no flame or filament is ignited as a result of turning on the electricity, one could argue that according to the primary opinion, activating electricity on Shabbos is only a rabbinic prohibition, and would therefore potentially be permitted during bein hashmashot of Shabbos. Nevertheless, an additional concern arises in a case where the water is not yet fully heated, namely the prohibition of shehiyah. The Sages prohibited leaving food or water on an exposed heat source going into Shabbos unless it was at least partially cooked beforehand, and prohibited doing so even through a gentile. For all of these reasons, practically speaking, there is generally no permissible scenario in which one may turn on a water heater during bein hashmashot on Shabbos.

On Yom Tov, however, the halachic framework changes entirely. Making a fire and cooking are biblically permitted on Yom Tov. The primary restriction is the creation of a new flame, which is prohibited on a rabbinic level, including through electricity. In addition, the prohibition of shehiyah does not apply on Yom Tov. Therefore, in the scenario discussed above—where a hot‑water urn was accidentally turned off—we concluded that it is permitted for a Jew to turn it back on during bein hashmashot of Yom Tov. This is because electricity on Yom Tov constitutes only a rabbinic prohibition, no cooking prohibition is involved, there is no concern of shehiyah, and having hot water is considered a great need.

Nevertheless, an argument could be raised to be stringent. Since on Yom Tov one is allowed to cook water using an existing flame, one could question the necessity of turning on the urn via electricity. Why permit even a rabbinic violation if hot water could theoretically be obtained in a permitted manner? For this reason, our allowance was limited to cases where no alternative method of obtaining hot water is available—for example, when no flame was left on from before Yom Tov, or where placing water on a heat source would not result in the water becoming hot in time. In such circumstances, since hot water on Yom Tov is considered a great need, we permitted turning on the urn during bein hashmashot in this specific scenario.

Addressing the Final Objection: What Constitutes a “Need” During Bein Hashmashot? One final argument must be addressed, as it has the potential to undermine the entire heter we presented. This argument centers on the definition of a need (tzorech). Perhaps having hot water on Shabbos or Yom Tov does not qualify as a sufficient need to permit even a rabbinic prohibition during bein hashmashot. After all, one may still have food and beverages available, and hot water could be viewed as merely an added convenience rather than a necessity.

Support for this concern can be drawn from the ruling of the Alter Rebbe, who explicitly writes that although me’aser of fruits is only rabbinically prohibited, it may nevertheless be performed during bein hashmashot only if one has no other food available to eat. If other food is available, the act remains prohibited. Seemingly, the same logic could apply here: who says that specifically hot water constitutes a need great enough to justify performing a melachah—even a rabbinic one—during bein hashmashot, if one has other food and drink available?

The response to this question is found in the Kuntres Acharon of the Alter Rebbe. There, he explains that it is permitted to insulate food (hatmanah) during bein hashmashot, despite the fact that insulation is generally prohibited on Shabbos. This permission applies even if one already has other food available that is insulated. The reason is that this is considered a tzorech Shabbos.

The Alter Rebbe clarifies an important distinction: there are two different categories of need. One is a “great need”, which is powerful enough to permit even actions that have no direct connection to Shabbos itself. The other is a Shabbos need, which does not have to rise to the level of a great need. Any matter that is considered a normal and complete necessity for Shabbos—such that a person would experience real discomfort or distress without it—is sufficient to permit a rabbinic prohibition during bein hashmashot.

This explains why tithing fruits is not permitted when other food is available: it is entirely possible to get through Shabbos without fruits, and their absence does not place a person in a state of distress. Therefore, it is not considered a Shabbos need.

Hot water, however, is different. As is well known, the lack of hot water can cause genuine discomfort and distress, particularly in contexts of having a hot tea in a cold winter night or afternoon, and a hot coffee on Shabbos day. As such, it qualifies as a true Shabbos or Yom Tov need, even if it is not technically a “great need.”

Accordingly, even though turning on the hot water involves only a rabbinic prohibition, it may be permitted on Yom Tov during bein hashmashot, since a Shabbos or Yom Tov need does not have to reach the level of a great need—so long as its absence would cause real discomfort.

Sources

See regarding Performing Melacha During Bein Hashmashos: Admur 261:1-2; 342:1; 372:18; 455:12; Siddur Admur in Seder Hachnasas Shabbos; Michaber 261:1; Tur 342; Rambam Shabbos 24:10; Eruvin 6:9; Ketzos Hashulchan 75:2; Piskeiy Teshuvos 261:1

See regarding Prohibition to Tithe fruits if has food available: Admur 261:2; M”B 261:4

See Regarding the allowance to insulate food, and the definition of a Shabbos need that justifies Rabbinical Melacha by Bein Hashmashos: Admur 261 Kuntres Achron 1; Biur Halacha 342; Piskeiy Teshuvos ibid footnote 7