McDonnell & Miller 250-3/4-60 Valve

The McDonnell & Miller 250-3/4-60 is a high-capacity 3/4" NPT pressure relief valve engineered specifically for hydronic heating systems and large storage tanks. Designed to provide critical over-pressure protection, this ASME Section IV certified valve is factory-set at 60 PSI and features an impressive thermal discharge capacity of 1,252,000 BTU/hr. As a veteran-grade boiler safety relief valve, it utilizes a durable bronze body and seat combined with an EPDM rubber diaphragm to ensure a positive seal and consistent performance in demanding environments. The unit is specifically built to minimize water hammer and the destructive effects of flash steam, maintaining a tight 3 PSI differential between opening and closing cycles. For contractors managing hydronic boiler maintenance, part number 181905 offers the reliability needed to protect pressure vessels while meeting strict professional mechanical codes. Whether you are performing a new installation or a critical HVAC part replacement, this valve ensures system integrity at operating temperatures up to 250°F.

• ASME Section IV Certified: Verified performance for pressure vessels and heating boilers, ensuring compliance with local mechanical codes.
• High BTU Capacity: Rated for 1,252,000 BTU, making it suitable for large-scale residential and light commercial hydronic applications.
• Anti-Hammer Design: Specifically engineered to reduce noise and system stress caused by flash steam during discharge.
• Corrosion Resistant: Features a robust bronze body and seat with a high-temperature EPDM diaphragm for extended service life in harsh water conditions.
• NPT Compatibility: Standard 3/4 inch NPT inlet and outlet connections allow for straightforward integration into existing piping manifolds.

• What is the relief setting for the 181905 model? This specific model is factory-set and sealed at 60 PSI; it is not field-adjustable.
• Is this valve suitable for potable water systems? No, the Series 250 is designed for non-potable hydronic heating and storage tank applications. Use the LF (Lead-Free) series for potable requirements.
• What causes this valve to drip or leak? Common causes include system pressure exceeding 57 PSI (close to the 60 PSI set point) or sediment buildup on the EPDM seat; regular flushing via the lift lever is recommended.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.