Yeah and that's what was wired to my floor heater, but I wanted it hot in the morning, warm during the day, and off at night. They wanted $200 for a smart programmable thermostat, so I made my own for $20. And I can chart the temperatures over time, or reprogram it over wifi.
And it's still wired in series with that old bimetallic thermostat just in case my thermomstat and its watchdog chip both fail on.