{"id":7274,"date":"2016-01-10T23:10:54","date_gmt":"2016-01-10T21:10:54","guid":{"rendered":"https:\/\/ph.yhb.org.il\/en\/?p=7274"},"modified":"2016-07-14T16:51:03","modified_gmt":"2016-07-14T13:51:03","slug":"01-10-24","status":"publish","type":"post","link":"https:\/\/ph.yhb.org.il\/en\/01-10-24\/","title":{"rendered":"24. Electric Boilers"},"content":{"rendered":"
One may not benefit from water that was heated in a forbidden fashion on Shabbat. But if the water was heated in a permissible fashion, one may benefit from it on Shabbat. Seemingly, then, if a boiler was on before Shabbat, one could use the hot water produced by it even on Shabbat. However, there is a problem. Today\u2019s electric boilers are built in such a way that whenever the hot water is turned on, cold water flows into the boiler tank to replace it. If the heating elements in the boiler are working and heating, then turning on the hot water tap on Shabbat causes cold water to enter the boiler and become cooked. Therefore one may not turn on the hot water on Shabbat when the boiler is on.<\/p>\n
If the electric boiler was turned off before Shabbat, then the question whether the hot water may be used depends on whether the cold water that will flow into the boiler will become cooked. If the hot water coming out is scalding, it would be forbidden to turn on the hot water tap, because the replacement cold water would become cooked. But if the hot water is cool enough to touch, even just barely, then even if it is yad soledet bo<\/em> it can be used on Shabbat, because the remaining water in the boiler cannot cook the incoming cold water (as explained in the note). When it is unclear whether the hot water is hot enough to cook the incoming water, one may turn on the faucet, as this is only forbidden if it is clear that the cold water entering the boiler will become cooked. If it is initially unclear how hot the water is, but when the faucet is turned on it becomes clear that it is extremely hot, cold water should be added to reduce the water\u2019s temperature to below yad soledet bo<\/em>.[28]<\/a><\/sup><\/p>\n One may also set the electric boiler on a timer that will turn it on for 15 minutes every few hours. This way, the water will heat somewhat, but will not reach yad soledet bo<\/em>. One can then use the lukewarm water on Shabbat without worrying.<\/p>\n