You say 24/7 so than set all (Morning, Day, afternoon, evening to 79 degrees). for weekdays as well as week ends. I believe the unit is set at 1 degree swing. So when the temperature reaches 80 the ac will turn on. You can change the swing degrees on this unit. You can download the manual from the Lux Web site. Don't forget this unit will only work with units that come on after power is turned off. So if you ac unit is on and you pull the plug and than when you plug it back inif the ac comes on without you having to press any buttons than this unit will work.
I use the LUX with an oil filled heater in two rooms and keep the temperature set at a medium level. The heater has to warm up, but I have found that this works really well to regulate the overall room temperature.