Taco's SR502-4 is a two zone pump switching relay. With universal thermostat compatibility, it is designed to integrate quickly and effortlessly into any hydronic system, bringing Taco reliability to your zoned operations. The SR502-4's enclosure is unobtrusive and easy to mount in tight spaces, and the PC board was designed for quick maintenance and clean, simple wiring.
Easy-to-interpret external diagnostic lights and "ice cube" style replaceable relays mean that servicing a Taco switching relay is always easy.
Protected Priority Switching
With the SR502-4, a single zone may be designated as a priority zone whose heating demands are given precedence over other zones. Other demands will be met when the priority zone is satisfied or after sixty minutes of priority operation.