This model outputs ON/OFF signal to control fan operation.
When the system is in mode like unoccupiedOff, safety, it outputs
false so that fan should be OFF and provide 0 pressure rise;
When the system is in mode like unoccupiedNightSetBack,occupied,unoccupiedWarmUp,
unoccupiedPreCool, it outputs true so that fan should be
ON and provide preRis pressure rise.