The most common causes are excessive heat from restricted venting

and advanced HVAC control systems

What is the difference between the 750 and the 750TO

It typically indicates a cracked heat exchanger

AERCO Boiler and Water Heater 123449 Temperature Sensor 318518-761 The most common causes areThe AERCO 123449 Temperature Sensor is a precision engineered exhaust temperature sensor specifically designed for high performance AERCO boiler and water heater systems. This critical HVAC replacement part is essential for real time monitoring of exhaust gases, ensuring your equipment operates within safe thermal parameters to prevent overheating and potential system hazards. By converting thermal data into accurate electrical signals, this Balco