- It is ossur to warm up (to just remove the chill, there is room to be lenient) a container of liquid by completely submerging into hot water on Shabbos – it is considered hatmanna even if it cannot reach yad soleddes. (MB2 ShaH7)
- If the liquid in the container can possibly reach yad soleddes, it is forbidden to put it into the hot water even if it’s not totally sunken in. You may forget to take it out before it becomes hot – that’s bishul. (MB2)