A dualing switch is used to _____.

A dualing switch is employed in HVAC systems primarily to convert a proportional control action into a two-position control system. In a typical application, proportional control refers to a system where the output (like valve position or fan speed) is continuously adjusted based on the demand (like temperature or pressure), allowing for smooth changes. However, there are situations when a simpler two-position control is more appropriate or necessary.

Using a dualing switch allows an HVAC system to switch between two states—on and off—based on certain thresholds. This adjustment can simplify control mechanisms and reduce manufacturing costs. For instance, if an HVAC system typically regulates heating or cooling through a varying output, a dualing switch can make it toggle fully on or off based on the pre-set conditions, rather than modulating power.

This ability to alter the control method facilitates easier maintenance and offers more straightforward operational insights. The other choices, while related to HVAC functions, do not accurately represent the specific role of a dualing switch in controlling proportional actions to a two-position mechanism.