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Buderus GA124 with Taco SR503

CGeorge Member Posts: 4
I'm in the process of installing a Buderus GA124 in our old system that has seem several boilers. I'd really like to utilize our Taco SR503 relay box but cant figure out how to get them to communicate. Any Help on this greatly appreciated.


    HVACNUT Member Posts: 5,448
    Assuming you're not using the Logamatic, you'd connect R-W on the aquastat (note 2 on the diagram) to X-X on the SR503.
  • Joe Mattiello
    Joe Mattiello Member Posts: 689
    HVACNUT is correct, pretty straight forward. thermostat is a simple normally open switch to control a 24v relay, in this case, it’s your great boiler control RW for red, and white coded wire. (Doesn’t need to be Red and white color)
    SR503 is a facilitator for your three thermostats wired into top of control, snd your corresponding circulators wired to bottom 120 volt output terminals.
    only interface with boiler is the isolated end switch that emulates the thermostats XX terminal to RW on boiler control using low voltage 18gauge wires.
    hopefully this was helpful. For additional questions, if any, reach out to Taco directly at 401-942-8000, and ask for tech support. Great bunch of technicians eager to help.
    have a blessed day
    Joe Mattiello
    N. E. Regional Manger, Commercial Products
    Taco Comfort Solutions