title: Thermostat
context: Warren S. Johnson (1847–1911) of Wisconsin patented a bi-metal room thermostat in 1883, and two years later filed a patent for the first multi-zone thermostatic control system.[5][6] Albert Butz (1849–1905) invented the electric thermostat and patented it in 1886.
question: Who invented the thermostat?
answers: Warren S. Johnson