Taco SR503 Three Zone Pump Switching Relay with Priority (Replaces AR861-3)

Taco Switching Relays combine clearly-labeled PC board layouts with advanced features that allow you to completely customize your system. Whether youre using basic priority switching, Taco Plug-In PowerPort Cards or add-on power controls, tailoring the system has never been easier. External indicator lights give you instant diagnostic feedback, making service calls or new installation start-ups a snap. All switching relays are UL listed, use standard "ice cube" replaceable relays and are compatible with conventional and programmable thermostats. For larger jobs, switching relays can be expanded up to 20 zones with priority.

With the exclusive Taco PowerPort Plug-In Cards, you can easily add such features as post purge, priority protection and pump exercise. Any expandable switching relay can also interface with the Boiler Reset Control and Injection Mixing Add-On Power Controls.
Mix-and-match as needed to customize the system.

Features include:

• External Indicator Lights
  

• Switchable Priority
  
• Simplified Wiring
  
• Fully Enclosed Snap-Out Relays
  
• Compact Design
  
• Fuse Protected
  
• 100% Factory Tested
  
• Isolated End Switch
  
• Contractor Friendly PC Board Layout
  
• Universal Thermostat Compatibility
  
• UL and CSA Approved
  
• 24 Volt Power Input or Output Terminal
  
• Extended 3 Year Warranty
  
• Made in the USA