The focus of this research is the manufacture of a temperature monitoring system in a FFB heating system based on the ATMega16A-PU microcontroller. This monitoring system consists of LM35 Waterproof sensor, Type-K Thermocouple sensor, MAX6675 module,  power supply circuit, 20x4 character LCD, voltage follower amplifier and ATMega16A-PU microcontroller module. Whereas the TBS heating system consists of steam, boiler, air control room and chamber. LM35 Waterproof sensors are used 3 pieces for monitor the temperature in the boiler, air control room and chamber. Thermocouple sensor Type-K is used to monitor temperature in steam. This monitoring system is also equipped with data acquisition using the Delphi 7.0 software to display data in real-time and save it to Microsoft Excel. Test carried out by turning on the steam and filling the boiler with water and flowing the wet steam from the boiler to the air control room and chamber. The temperature monitoring process was carried in for 3 hours for the 60°C set point in the chamber without using FFB loads. The average error value of reading a gauge that has been made with the standard gauge for the LM35 waterproof sensor in the chamber, air control room and boilerwith a measurement range of 20-80°C and 20-100°C is 0.03°C; 0.02°C and 0.02°C. Whereas for the Type-K Thermocouple sensor on steam, the average error value with a measurement range of 30-200°C is 1.94°C.

Keyword: Heating system, monitoring system, LM35 Waterproof sensor, Thermocouple sensor Type-K, temperature