1.Core Working Principle Built with single-ended glass-sealed NTC negative temperature coefficient thermistor: Low water temperature → High resistance Hot brewing water → Resistance drops rapidly The MCU outputs 5V reference voltage to the sensor, converts resistance variation into real temperature data, and automatically turns on/off the heating element to avoid temperature surges during continuous brewing. Standard Electrical Parameters (Industry Common) Nominal resistance: R25 = 100KΩ ±2% B-value: B25/50 = 3990K ±1% Accuracy: ±0.3℃ ~ ±1℃ Response time: ≤10s (fast thermal conduction brass/stainless steel probe) Operating temp range: -40℃ ~ +260℃ (covers brewing, steam & dry-heat protection) Withstand voltage: 1650V AC / Insulation ≥100MΩ @500VDC 2. Structure & Material (Food-Grade Standard) Sensing core: Glass encapsulated NTC chip (anti-moisture, long-term stability, no resistance drift) Probe housing: Brass screw / 304/316 food-grade stainless steel, corrosion-resistant against coffee acid & cleaning detergent Mounting thread: M10, M12, 1/8NPT, G1/4 customizable screw fitting Sealing: High-temperature food-grade silicone gasket, leak-proof against hot water & steam Lead wire: High-temperature braided silicone wire (200℃ resistance), customizable length + terminal plug (JST/AMP) Outer insulation: Heat-resistant woven tube for anti-scald & abrasion 3. Installation Position Primary: Espresso group head (brew surge outlet) Secondary: Thermoblock heating core, boiler water outlet, hot water flow pipeline Function distinction: Separate from boiler static temperature sensor; this one focuses on dynamic surge water temp during extraction 4. Core Functions ① Precise brewing temperature stabilization Controls surge water locked at 92–96℃: Too low (<90℃): Under-extraction, coffee tastes sour Too high (>98℃): Over-extraction, heavy bitter flavor Eliminates temperature fluctuation when brewing multiple cups continuously. ② Dynamic surge temperature compensation Captures instant temperature drop/rise when the pump pushes hot water through grounds; MCU instantly adjusts heating power to offset thermal surge. ③ Overheat safety protection Detects abnormal high temperature from dry burning or steam surge; triggers power cut & machine fault alarm to prevent component damage. ④ Steam milk temperature auxiliary monitoring For dual-boiler machines, monitors steam surge temperature to control milk foaming temp (optimal 60–65℃, no burnt milk taste). 5. Common Failure Symptoms Coffee taste unstable: alternating sour & bitter with every cup Machine shows temperature error code, auto-stop heating Brewing water always too cold or overheated Slow temperature recovery after continuous brewing Steam output temperature out of control for milk frothing Failure causes: Mineral scale covering probe surface, wire aging, internal thermistor drift, seal failure & steam corrosion. 6. Main Application Scenarios Semi-automatic / fully automatic espresso machines Capsule coffee makers, commercial coffee shop equipment Household multi-function coffee machines with hot water & steam functions Professional E61 group head commercial coffee machines