For sure, this is what happened with my ranco. The probe let water in and it was reading extremely high temps. So heaters remained off for a number of days. Didn't drop below 70, expected it to drop lower being in my basement, but I guess 300+ gallons of water holds heat pretty okay. Redundancy is a really great thing, and clearly something we both take seriously.
Yes, I learned the hard way that relying on the heater without a backup method of turning it off is a bad idea...was not a fun experience.
