3-Zone Switching Relay w/ Priority


Brand: Taco

Mfr Part#: SR503-4

UPC#: 687752857566

Availability: In Stock
Usually ships: within 1 business day
Qty Price
$128.95 / each & Free Shipping
x3 $374.85 & Free Shipping
(3 x $124.95 / each)
  • Description
  • Literature
  • Reviews (2)
  • FAQs

Taco SR503 Switching Relay combines clearly labeled PC board layout with advanced features that allow for total system customization. External indicator lights provide instant diagnostic feedback, making a snap of service calls or new installation start-ups. Taco SR503 switching relays are UL and CSA listed, use standard “ice cube” replaceable relays and are compatible with conventional and programmable thermostats.


  • 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;
  • Made in the USA;

Technical Specifications:

  • Zones: 3;
  • Power: 120VAC;
  • Max combined load: 15.0 AMPs;
  • Dimensions: 10.25" wide x 6.75" high x 2.75" deep.


Extended 3 Year Warranty;
3-Zone Switching Relay w/ Priority has an average 4.5 out of 5 rating based on 2 user reviews.
Taco relay
By Jack (from Minnesota) on 3/31/2015
It's the right product for my application. One relay for multiple zones, works and looks good.
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One complaint
By Gary P. (from Barre, MA) on 2/26/2013
The SR503-4 3 zone switch appears to be a quality unit. No operational issues so far (
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