Schottky diodes question for circuit

Recently, I’ve been experimenting with my circuit, as shown in the attached image. The resistance values presented correspond accurately to actual resistor readings in my setup. However, I’ve encountered an issue where the section showing 3.17 volts in a perfect scenario reflects only 1.688 volts in reality. While I understand that the ideal simulation differs from the real world, this deviation seems too significant. Removing the zener diode allows it to reach 3 volts, suggesting that the diode is limiting the voltage—yet I’m puzzled why it’s resulting in such a low value instead of hovering around the expected 3.17 volts. Admittedly, I’m not an expert; I’m just a hobbyist engaged in an enjoyable project.

The 9.78k resistor in my circuit functions as a water temperature thermistor (as I believe it is called), intended to vary from 115 Ohms to a higher value. Given my use case, I am solely concerned with lower Ohm readings, specifically in the range from 110 Ohms up to a bit higher (which is why I’ve selected the 9.7k resistor for testing my protection circuit). However, in an event of an unusually cold winter, the thermistor could go below the critical voltage of 3.3 volts, potentially damaging the ESP32 chip.

I want to extend my gratitude to everyone for their invaluable assistance. I am gaining so much knowledge from this experience!

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As a newcomer in electrical engineering, I would greatly appreciate it if someone could review my schematic to identify any flaws or suggest improvements. In my schematic, I have integrated an XT60-M ...

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