In HVAC terminology, what is the function of the "ON" position in a fan switch?

In HVAC systems, the "ON" position of a fan switch is designed to bypass the thermostat control, allowing the fan to run continuously regardless of the heating or cooling demands determined by the thermostat. This means that when the fan switch is set to "ON," the blower fan operates non-stop, providing constant air circulation throughout the space.

By allowing continuous operation of the fan, this setting can improve air distribution, help maintain a more even temperature throughout a building, and enhance air filtration since the air is continually being drawn through the HVAC system's filters. This function is particularly useful in applications where consistent air flow is desired, rather than cycling the fan based on the thermostat's temperature setting, which would only activate the fan when the heating or cooling equipment is running.

Understanding this function helps HVAC professionals effectively communicate the benefits and applications for using the "ON" position in various scenarios.