What is the difference between a low voltage and a line voltage thermostat? Low voltage thermostats should be used when the heater load is greater than 3,800 watts such as commercial heater (ex. Cadet CEH unit heater), or central forced air systems. Line voltage thermostats should be used for zonal heat systems such as electric fan heaters, baseboard heaters and radiant heaters. Cadet has a variety of options to meet your specific needs. What should I do if my wall thermostat feels hot to the touch? Cadet recommends you replace the thermostat. A “hot” thermostat indicates that it is not working efficiently; decreasing its accuracy. NOTE: A normal operating thermostat will be slightly warmer than the room temperature by 3 to 5 degrees.