4-Zone Switching Relay w/ Priority, Expandable


Brand: Taco

Mfr Part#: SR504-EXP-4

UPC#: 687752198881

Availability: In Stock
Usually ships: within 1 business day
Qty Price
$176.95 / each & Free Shipping
x2 $331.90 & Free Shipping
(2 x $165.95 / each)
  • Description
  • Literature
  • Reviews (1)
  • FAQs

Taco SR504-EXP is a 4-Zone Expandable Switching Relay. Combines clearly labeled PC board layout with advanced features that allow for total system customization. Taco expandable switching relays allow to expand up to 20 zones, while built-in PowerPort slots allow to utilize the advanced features of the PowerPort Cards and Add-on Power Controls. External indicator lights provide instant diagnostic feedback, making a snap of service calls or new installation start-ups. Taco SR504-EXP expandable switching relay is UL and CSA listed, uses standard “ice cube” replaceable relay and is 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;
  • (3) Plug-in PowerPort Card Slots;
  • Add-on Power Control Plug;
  • Expandable to 20 Zones;
  • Interface with Expandable (-EXP) Taco Zone Valve Controls;
  • Made in the USA.

Technical Specifications:

  • Zones: 4;
  • Power: 120VAC;
  • Max combined load: 20.0 AMPs;
  • Dimensions: 10.25" wide x 6.75" high x 2.75" deep.


Extended 3 Year Warranty;
4-Zone Switching Relay w/ Priority, Expandable has an average 5.0 out of 5 rating based on 1 user review.
Taco circulator zone controls are proven to work well
By Geo Man (from New Hampshire) on 3/2/2015
The local suppliers of this Taco board was considerably more even to a tradesman like me who buys many of these. Pex universe had a great price for this product and we got it next day. That service from out of state is just as good as we would have recieved from our local suppliers.
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