The Mysa thermostat is designed around a solid state switching device called a TRIAC. The TRIAC is the component in the thermostat that regulates the amount of current flowing to the heater(s). The TRIAC enables Mysa thermostats to take advantage of proportional control algorithms to better heat your space. Mysa's proportional control algorithm can adjust the output of the heater to match the power that is required to maintain the setpoint. This is something a relay cannot achieve.
The graph on the left represents heating a room with a relay based thermostat that implements an on/off control strategy. As the measured temperature swings above and below the temperature frequently, you may feel too warm and too cold at times. There are also significant energy losses as a result of using a relay. The graph on the right represents heating a room with a TRIAC-based thermostat implementing a well tuned proportional control algorithm. The room temperature will be maintained at the setpoint temperature, usually within ±0.1° C.