Question:
Can I plug my Shabbat urn into a timer so that it will go off late Friday night and come on again on Shabbat.
The water will be fully boiled before Shabbat
Answer:
From a technical halachic standpoint it would be permitted, with the buttons on the urn covered, however I would not advise that you do it, for a number of reasons. The reason why halachically it is permitted is because the water was boiled already, and when shabbos comes in, it is useable as hot water for tea, therefore there is no issue of shehiya, or bishul, because you are not cooking anything. Regarding chazora, you didn’t do any action of returning it to the fire on shabbos, therefore it is also not an issue. There is also no issue that maybe you will come to stir the water because there is no issue with stirring hot water, because there is nothing to mix. However I would not advise you to do it, because it is it is very easy for people, including yourself, to mistakenly mix things up and end up doing this when the food wasn’t cooked before shabbos, (which according to many poskim is not permitted). Secondly because it will turn shabbos into a day of “do what you want with a shabbos clock”, and it will detract from the ambiance and specialness of shabbos.
Sources:
מנחת יצחק ח”ד סי’ כ”ו סוף אות י”ב, וסוף אות כ,’ מתא דירושלים על הירושלמי שבת פרק א’ הל’ ה’ ד”ה וכן, אג”מ או”ח ח”ד סי’ ס’, מנחת יצחק ח”ד סי’ כ”ו, סי’ כ”ז, ח”ח סי’ כ”ט, מלמד להועיל ח”ג סימן נ”ח, ששכ”ה פרק א’ סעי’ כ”ו [דפו”ח, סעי’ ל”ב], באר משה ח”ו קו”ע סי’ א’, ציץ אליעזר ח”ב סי’ ו’, סי’ ז’, ח”ג סי’ י”ח, עי’ ח”ז סי’ ט”ז, חי”ב סי’ צ”א, הר צבי ט”ל הרים מבשל סי’ ג’, מנחת שלמה ח”ב סי’ ל”ד אות א’, משנה הלכות ח”ד סי’ ל”ד, שבט הלוי ח”ט סי’ נ”א אות ב, ארחות שבת פרק ב’ סעי’ ס”ח הע’ קט”ו, שבות יצחק ח”ב סוף עמ’ ק”י.
