. A fluid sensor system for a heating system, the sensor system comprising a probe and a control system , wherein: the probe having a finite length, a portion of which is to be immersed in a fluid , the probe comprising a resistive heating element and a fluid temperature sensor for measuring one or more performance characteristics of the heating system, wherein the fluid temperature sensor is configured to measure a fluid temperature, and the resistive heating element is operable as a heater to create a temperature differential along the length of the probe to detect a presence of the fluid , and as a sensor to measure a fluid level, and the control system is configured to operate the probe (102 202, 230, 250) and determine the one or more performance characteristics based on an electrical response of the resistive heating element operating as the sensor to measure the fluid level, an electrical response of the fluid temperature sensor , or a combination thereof; characterized in that the control system is configured to: obtain an ambient temperature, apply a first power amount to the resistive heating element to detect the presence of the fluid when the fluid temperature is substantially the same as the ambient temperature, wherein the first power amount causes the temperature differential to be generated along the length of the probe if the fluid is present, and after the presence of the fluid is detected, apply a second power amount less than the first power amount to the resistive heating element to measure resistance of the resistive heating element to determine the fluid level when the fluid temperature is different from the ambient temperature. the probe having a finite length, a portion of which is to be immersed in a fluid , the probe comprising a resistive heating element and a fluid temperature sensor for measuring one or more performance characteristics of the heating system, wherein the fluid temperature sensor is configured to measure a fluid temperature, and the resistive heating element is operable as a heater to create a temperature differential along the length of the probe to detect a presence of the fluid , and as a sensor to measure a fluid level, and the control system is configured to operate the probe (102 202, 230, 250) and determine the one or more performance characteristics based on an electrical response of the resistive heating element operating as the sensor to measure the fluid level, an electrical response of the fluid temperature sensor , or a combination thereof; characterized in that the control system is configured to: obtain an ambient temperature, apply a first power amount to the resistive heating element to detect the presence of the fluid when the fluid temperature is substantially the same as the ambient temperature, wherein the first power amount causes the temperature differential to be generated along the length of the probe if the fluid is present, and after the presence of the fluid is detected, apply a second power amount less than the first power amount to the resistive heating element to measure resistance of the resistive heating element to determine the fluid level when the fluid temperature is different from the ambient temperature. obtain an ambient temperature, apply a first power amount to the resistive heating element to detect the presence of the fluid when the fluid temperature is substantially the same as the ambient temperature, wherein the first power amount causes the temperature differential to be generated along the length of the probe if the fluid is present, and after the presence of the fluid is detected, apply a second power amount less than the first power amount to the resistive heating element to measure resistance of the resistive heating element to determine the fluid level when the fluid temperature is different from the ambient temperature. <EOS>