It maybe reach 1000* celsius then it measures the temperature on the pellet burner. But in the rest of time its just normal decimal around 0-100* celcius.
It is this system Pellmon, some monitoring software you can connect to your Pellet burner with a raspberry pi or other linux based system with a FTDI seriel rs232 link https://github.com/motoz/PellMon
Here are a little example : 