Taco SR502-4, 2 Zone Switching Relay w/ Priority

Taco SR502-4 Switching Relay Module Side View
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Taco SR502-4 Switching Relay Module Top ViewTaco SR502-4 Switching Relay Module Bottom ViewTaco SR502-4 Switching Relay Module BackTaco SR502-4 Switching Relay Module Open SideTaco SR502-4 Switching Relay Module Open FrontTaco SR502-4 Switching Relay Module in Box







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Taco SR502 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 SR502 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
  • Extended 3 Year Warranty
  • Made in the USA



Zones: 2;

Power: 120VAC;

Max combined load: 15.0 AMPs;

Dimensions: 10.25" wide x 6.75" high x 2.75" deep.

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Is it possible to control a zone valve from a switching relay?
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Taco SR switching relays are for circulators only. If you need to control zone valves, use Taco ZVC (Zone Valve Controls).
Answered on 12/10/2013 by PexUniverse Customer Service
I have 4 zones of baseboard heat in my home. I installed a fifth zone which is radiant heat with its on pump, zone valve and mixing valve. I purchased a tacosr502 switching relay so that the pump can run for the radiant side when thermostat call for heat. My question is do I leave all the the existing thermostat wires connected to the TT ?
Read 1 answer
If radiant heating zone requires a separate temperature control, then a separate thermostat has to be installed and wired to the Taco SR502 panel.
Answered on 9/4/2012 by PexUniverse Customer Service
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