Authentic inverter mode, as opposed to simple on/off control with a thermometer. Using a watt meter, I found that the maximum mode outputs 2100W if the actual temperature is far removed from the desired one, 1250W if the actual temperature is extremely close to the desired one but does not rise much higher, and 400-800W if the desired temperature is reached but does not decrease. And when the temperature reaches 400-800W, it shuts off entirely. The bottom-mounted temperature sensor measures incoming air temperature, so it can function reliably even if your floors are consistently cool. When the apartment floor drops to 14 degrees during a frost, it can keep running until it reaches 16 degrees, which is its maximum operating temperature. Increasing the temperature somewhat improves the process.