Ravenheat Thermistors
The thermistor decreases the current resistance as it gets hotter. The PCB sends a current to the thermistor and can tell whether an increase or decrease in heat is needed by the relative resistance in the thermistor.
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RAVENHEAT 0012POT08005/0 DHW/CH POT SET-0204-82/84/100/85/SYS
Part No: 1841637 / MPN: 0012POT08005/0