Fan center with Double-Pole, Single-Throw (DPST) switch, 50-volt (AC), provides low-voltage control of line voltage fan motors and auxiliary circuits in heating, cooling, or air conditioning systems. Transformer powers low-voltage control systems and provides overload protection. Low-voltage terminal board provides convenient connections for thermostat and heating/cooling equipment wiring. Mounts on standard 4 X 4-inch junction box. Relay is easily replaced without disturbing wiring. For hydronic applications; use with SV9600 SmartValve™ system and other systems that require 50-volt capacity.