A system corresponds to the outdoor/indoor unit combo. Let's say that you have two outdoor units, this means you have two systems. If you don't have Lennox Smart Zoning System to control the temperature in every room of the house, then the two systems will appear as two zones on your thermostat's display, and the system name will appear above the temperature setpoint control (a.k.a., horseshoe) on the home screen.
For more information or a visual representation of steps please reference our user guide here
