Watts 0382821 Relief Valve

The Watts 0382821 Relief Valve is a critical safety component for high-output hydronic systems, cross-referenced as the 740-1-75. Engineered for hot water space heating boiler applications, this ASME Section IV certified valve is designed to mitigate overpressure conditions in commercial and residential settings. It features a rugged iron body construction and expanded 1-1/4 inch NPT female outlets to ensure a large discharge capacity of 2,649,000 BTU/hr. The 1-inch NPT female inlet provides a secure connection for 75 PSI pressure relief setpoints. To prevent common failure points, the non-metallic disc-to-metal seating and non-mechanical alignment resist sticking and freezing, even in systems with corrosive water conditions. The raised seat design ensures that sediment and water cannot be trapped, protecting the stainless steel spring and internal working parts from fouling. This valve functions strictly as emergency safety relief, not as an operating control, maintaining system integrity under thermal expansion or runaway firing conditions up to 250°F.

• High Discharge Capacity: Rated at 2,649,000 BTU/hr to handle high-output boiler discharge requirements.
• Foul-Resistant Design: The raised seat above the drain prevents sediment accumulation and water trapping.
• Durable Construction: Features an iron body and stainless steel spring for long-term performance in hydronic environments.
• Reliable Seating: Utilizes a non-metallic disc-to-metal interface to prevent the valve from sticking or freezing.
• Standardized Compatibility: Direct replacement for 740-1-75 with 1" x 1-1/4" NPT connections.

Common Questions

What is the difference between the 174A and 740 series?
The Series 740 features iron body construction and expanded outlets specifically for high-capacity hot water space heating, whereas the 174A typically uses bronze bodies for lower capacity or domestic supply applications.

How do I size this for my boiler?
Always ensure the BTU rating of the Watts 0382821 (2,649,000 BTU/hr) exceeds the maximum heating output of your boiler as per ASME Section IV requirements.

Can this be used for steam boilers?
No, this model is specifically engineered for hot water boilers. Steam applications require valves rated under different ASME code sections with specific steam-discharge characteristics.

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.