When adding central air to an existing furnace with an electronic air cleaner, which device should be used at the fan centers?

When integrating central air conditioning into an existing furnace that has an electronic air cleaner, it is crucial to manage the operation and control of multiple devices efficiently. A Double Pole Double Throw (DPDT) switch is utilized in this scenario because it allows for the switching of the fan motor and the electronic air cleaner between heating and cooling modes.

This switch can manage two circuits simultaneously and allows for both the reversing of the current direction and the controlling of the respective loads, which is essential when the system transitions between heating and cooling. It ensures that the electronic air cleaner operates correctly in both modes, enhancing the overall air quality and efficiency of the system.

Utilizing a simpler switch, like a single-pole switch, would not provide the needed control for both functions effectively. A relay switch, while useful in various electrical applications, does not offer the maneuverability needed for separate modes of operation. A capacitor would not be appropriate either since it primarily serves to store and release electrical energy rather than facilitate control between different circuits in this context. Thus, the DPDT switch is the optimal choice when modifying the setup of an existing furnace with added air conditioning components.