Taco SR502-4, 2 Zone Switching Relay with switchable priority.
The Taco SR502-4 Switching Relay is the best choice for all your zoning needs, with advanced PowerPort Cards, external diagnostic lights, switchable priority and contractor friendly PC board layouts. Combined with the time proven reliability of the 00 family of circulators and thermostats, total system integrating is achieved. External indicator lights provide instant diagnostic feedback, making a snap of service calls or new installation start-ups.
