We use as many as eight units at a time units in our laboratory as low cost heater/circulators in constant temperature baths at up to 90 F. No food preparation is involved.
Our problem is apparent corrosion or fouling of the water level sensors resulting in faulting out of the affected unit and a failed experiment. I suspect the problem is fouling as a good scrubbing of the electrodes normally returns a faulting-out unit to good operation, for a while.
We do not need the water level sensors and, frankly, they are far more trouble than they are worth having in our application.
I think the mode of operation is that a low voltage is applied across two electrodes and the very low current that flows through the water is detected and this allows the unit to operate. If the electrodes are fouled, the resistance goes to infinity, no current flows, the circuit detects this and the unit shuts down “thinking” not enough water is present…
I am tempted to simply wire a 10K-ohm resistor across the two water level measuring electrodes so the resistance can never go to infinity and finesse the corrosion/fouling problem.
The units will NEVER be operated out of water, so no issue of over-heating.