FeelSTAT^TM is the first patented HVAC thermostat control algorithm that AUTOMATICALLY switches the HVAC unit between its heating, cooling, and idling modes based on the conditioned space apparent temperature.  Apparent temperature is a measure of feels-like human comfort and is calculated using the Steadman equation utilizing the conditioned space dry bulb temperature (temperature) and relative humidity (humidity).

The first practical application is that the User only needs to set the HVAC’s heating limit once and its cooling limit once.  Since FeelSTAT^TM operates up to these comfort lines, and is idle in between, the HVAC is always correctly operating by providing the proper User set comfort level regardless of varying conditioned space temperature and humidity. This is the concept of “Set it Once and Forget it Forever.”

The second practical application is that the User can now experiment by pushing the set heating and cooling limits to the “Edge of User Comfort”. The more the User expands the heating and cooling limits, the more the User approaches the energy savings shown in the Table .

HVAC engineers commonly use the Psychrometric Chart to calculate the HVAC unit’s behavior.  We superimposed FeelSTAT^TM ’s operation over the Psychrometric Chart to illustrate how effective FeelSTAT^TM is at saving HVAC energy:

Note that FeelSTAT^TM ’s heating and cooling limits shown on the Psychrometric Chart are the same limits that were superimposed on ASHRAE’s acceptable range of temperature and relative humidity chart.