The seriously ill patient
101. It is permitted to heat water for a seriously ill patient if a hot bath or wash would revive and strengthen him and thus increase his well-being, if no hot water is available or there is no non-Jew available to do so. This is so even if not having the bath would not cause a deterioration in his medical condition. If possible, one should heat the water to the required temperature so that the patient may wash or bathe without having to add cold water, even though this will mean that a larger quantity of water has to be heated.
102. If no hot water is available, it is also permissible to put on the electric boiler even though much more water is heated than necessary for the patient's needs.
103. If no hot water is available, it is permissible to draw water from an electric boiler for a seriously ill patient, even though cold water will inevitably enter the tank in its place. If the patient is to have a bath the hot water faucet of the bathtub may be closed. However, if he will be washed in bed, the hot water faucet may not be closed since, as a result, the cold water in the tank will now be heated. If there is a possibility that the patient will require more hot water later that Sabbath, the hot water faucet may be closed.
104. If a non-Jew was asked to boil water for a drink for a seriously ill patient, and a full kettle is on the stove, there is no need to first pour out the water that is in excess of the patient's needs before the non-Jew lights the flame. However a healthy person may not drink or make use of the excess water on the Sabbath.
The non-seriously ill patient
105. One may ask a non-Jew to turn on an electric boiler, draw water from it or to boil water for a non-seriously ill patient who requires a hot drink or bath.
 Written communicaiton from R. Y.Y. Neuwirth, who added that even R. Yosef Karo (see sect. 5 above) agreed that, if possible, a non-Jew should heat the water.
 Shemirat Shabbat Kehilchata 32:81.
 Shemirat Shabbat Kehilchata 32:82.
 If a non-Jew fills an empty water kettle, he should be told not to fill it with more water than the patient needs; oral communication from R. Y.Y. Neuwirth.
 Rema in Orach Chayyim 328:17.