The best replacement for thermostat is thermometer.

The best alternatives to thermostat are rated as following:
★★★★★  thermometer
★★★  water pump
★★★  no thermostat
★★★  heater core
★★  head gasket
★  furnace
★  element water heater
★  thermistor
★  radiator
★  honeywell
★  rheostat
★  coolant temperature sensor
★  analog thermostat
★  element
  temperature sensor
  timer
  trv
  thermocouple
  mercury thermostat
  non programmable
  heating element
  nest
  double pole
  conventional thermostat
  mugen thermostat
  195
  wifi thermostat
  ecobee
  180
  two wire
  restrictor
  restrictor plate
  radiator cap

Your alternative for thermostat is not listed? Suggest!
Speaking about thermostat, one probably shouldn't forget about humidity control.

Other search terms related to thermostat and their ratings are:
★★★★★ humidity control
★★★ humidistat
outside temperature
heat pump
You have in mind a companion for thermostat and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of thermostat in all years. Click on graph for more.
thermostat
thermometer
water pump