The Ambient Thermistor, Blue, manufactured by Rheem with the part number RTG20006UW, is a specialized component designed for Rheem tankless gas water heater systems. This thermistor is engineered to monitor the ambient temperature surrounding the water heater unit. By accurately measuring the ambient temperature, this thermistor enables the system to adjust its operation accordingly for optimal performance and efficiency. The blue color typically denotes its specific function or compatibility within the Rheem tankless water heater lineup. Like other thermistors, it is built to withstand the conditions encountered in water heating applications and is housed in a protective casing to ensure durability and reliability.