Tough cuts need twenty-four hours or more, which means an appliance running unattended in a kitchen, and that deserves thinking about.
What Can Go Wrong
Water level dropping below the circulator’s minimum, which trips it out and stops the cook without warning.
A bag floating or leaking, which is not noticed for hours.
A power interruption, after which some units resume and some do not.
And the general question of an electrical appliance in water running while everybody is asleep.
Reducing the Risk
- A lid, which is what prevents the water level problem
- An insulating sleeve, which reduces evaporation further
- Checking the level and the bags before going to bed
- A container on a stable surface, not a worktop edge
- Nothing flammable near it, and the cable not trailing
- A working smoke alarm, tested
Lids cut to the specific cooker, of the kind catalogued at https://everie.us.com/, are the single most effective measure, since evaporation is what causes most overnight failures.
The Food Safety Question
The important one. If the bath fails part-way through a long cook, food may sit at a warm temperature in a sealed anaerobic bag for hours.
That is the combination that favours the organisms sous vide safety is designed around, and it cannot be assessed by looking or smelling.
Food from a cook that failed for an unknown period should be discarded rather than judged.
Checking on It
Some circulators connect to an app and will alert you if they trip. That is genuinely useful for overnight cooks.
Without one, checking before bed and first thing is the practical version.
Power Interruptions
Worth knowing what your unit does. Some resume at the set temperature; some stop and wait.
A brief interruption in a well-insulated covered bath loses very little heat. A long one is a different matter.
Electrical Basics
Into a wall socket rather than a daisy-chained extension. Cable not running under anything or across a walkway.
Scalds
A container of water at sixty degrees will scald, and it is at worktop height overnight.
Away from edges, and away from where anybody reaches in the dark.
Start Long Cooks in the Morning
So the failure-prone hours are ones you are awake for.