{"product_id":"mcdonnell-miller-181525-250-3-4-50-relief-valve-3-4-npt","title":"McDonnell \u0026 Miller 181525 250-3\/4-50 Relief Valve, 3\/4\" NPT","description":"\u003cp\u003eSafeguard your hydronic heating system against dangerous over-pressurization with the \u003cstrong\u003eMcDonnell \u0026amp; Miller 181525\u003c\/strong\u003e relief valve. Engineered for precise calibration, this model \u003cstrong\u003e250-3\/4-50\u003c\/strong\u003e unit serves as a critical safety component, automatically discharging fluid to maintain internal system integrity when pressure limits are exceeded.\u003c\/p\u003e\u003cp\u003eThis valve utilizes a high-tension spring mechanism to keep the seat tightly sealed during normal operation. If the system pressure hits the relief set point, the valve lift action facilitates rapid venting, preventing potential damage to boilers, piping, and connected equipment before resetting once pressure returns to safe levels.\u003c\/p\u003e\u003ch4\u003eKey System Performance Baselines:\u003c\/h4\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePressure Calibration:\u003c\/strong\u003e Factory set to ensure accurate response to system over-pressure events.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConnection Standard:\u003c\/strong\u003e Features a standard 3\/4\" NPT threaded inlet for easy installation into existing hydronic piping.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDurability Rating:\u003c\/strong\u003e Constructed with robust materials to withstand high-temperature hydronic environments.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e⚠️ \u003cstrong\u003eApplication Profile:\u003c\/strong\u003e Suitable for residential and commercial hot water boilers, hydronic space heating loops, and industrial fluid pressure relief applications requiring a 3\/4\" connection.\u003c\/p\u003e","brand":"McDonnell \u0026 Miller","offers":[{"title":"Default Title","offer_id":43127326670942,"sku":"181525","price":184.95,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0663\/7151\/8558\/files\/181525_image_241635bc-83df-42b7-8c3a-511c8021a3d7.png?v=1786050407","url":"https:\/\/nationalboilersupply.com\/products\/mcdonnell-miller-181525-250-3-4-50-relief-valve-3-4-npt","provider":"National Boiler Supply","version":"1.0","type":"link"}