Shutting Off

Regarding an open vessel, your answer is going to be “it depends”. Temperature of the water, total surface area of the open vessel, temperature and humidity of the room that it’s in as well as air circulation are all going to contribute to the rate of evaporation.

And, some things that you’re cooking, you may only have an inch of “buffer” before what you’re cooking is exposed (thinking of pork back or side ribs). They tend to be cooked for 36 or 48 hours - that would be a lot of evaporation if in an open vessel. You don’t want your meat getting exposed as, now, you would have uneven cooking.

Open vessels can be fine for short cooks, but for anything longer, it could be pretty inconvenient. We’ve seen lots of “horror stories” posted by people here where the APC shut off due to low water while they were away and their meat had to be thrown away.