Taco's SR503-EXP-4 is a three zone 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. Post purge and pump exercise operation modes will run your pumps briefly after calls for heat or long periods of inactivity. These improve the efficiency and dependability of your system, respectively. The SR503-EXP-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 SR503-EXP-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.
Taco's -EXP switching relays may be combined with other relays or expandable Taco zone valve controls for large scale zoning applications. Up to 20 zoning panels may be connected together, providing you with complete zone control regardless of the scope of your system.
Add-On Power Controls
The SR503-EXP-4 is compatible with Taco's PC700 line of supplemental controls. It's easy to add outdoor temperature reset via variable speed pump mixing or boiler reset control.
Product Compatible with
- Taco -EXP Expandable Zone Controls