{"product_id":"taco-sr506-exp","title":"Taco SR506-EXP 6-Zone Switching Relay with Expandability","description":"\u003cp\u003eThe \u003cstrong\u003eTaco SR506-EXP\u003c\/strong\u003e is a high-performance, contractor-grade 6-zone switching relay engineered to seamlessly interface conventional, programmable, or Wi-Fi thermostats with circulator pumps in commercial and large-scale hydronic multi-zone heating loops. Equipped with a premium multi-layered printed circuit board, this universal control integrates advanced multi-zone distribution pipelines into an efficient, central boiler management hub.\u003c\/p\u003e\n\n\u003ch3\u003eAdvanced System Integration\u003c\/h3\u003e\n\u003cp\u003eFeaturing specialized -EXP PowerPort control slots, the SR506-EXP expands easily up to 20 zoning panels (managing up to 120 individual zones simultaneously). Built-in smart features include selectable post-purge timers, automated pump exercise cycles to prevent offseason scaling, and dual boiler contacts designed to leverage the modular modulation profiles of modern condensing or high-efficiency boilers.\u003c\/p\u003e\n\n\u003ch3\u003eKey Commercial Operational Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eExternal Diagnostic LED Arrays:\u003c\/strong\u003e Troubleshoot system operations instantly without opening the enclosure door via externally visible indicators showing active power, thermostat connection status, and individual zone call indicators.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIntelligent Priority Protection:\u003c\/strong\u003e Prevents freeze-ups by automatically resetting system functions if an indirect domestic hot water tank demands priority heating continuously for more than 60 minutes.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eContractor-Friendly Main Board Architecture:\u003c\/strong\u003e Spacious box casing features deep rear knockouts, a removable hinged enclosure cover, and highly isolated terminal connections to streamline rapid field swap-outs.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cem\u003eLooking for exact electrical blueprints or system staging submittals? \u003ca href=\"\/pages\/contact-us\" title=\"Request Official Taco Technical Manual\"\u003eClick here to request the official factory engineering documentation sheets.\u003c\/a\u003e\u003c\/em\u003e\u003c\/p\u003e","brand":"Taco","offers":[{"title":"Default Title","offer_id":42913134313566,"sku":"1050","price":349.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0663\/7151\/8558\/files\/Taco_SR504-EXP_4-Zone_Expandable_Switching_Relay_steel_enclosure_box_in_signature_slate_green_featuring_the_black_faceplate_diagnostic_window..jpg?v=1782046328","url":"https:\/\/nationalboilersupply.com\/products\/taco-sr506-exp","provider":"National Boiler Supply","version":"1.0","type":"link"}