Watts 0383942 Relief Valve

The Watts 0383942 (Model 740-1 1/2-75) is a high-capacity ASME Section IV safety relief valve engineered specifically for liquid-filled hot water heating boilers and storage tanks. Featuring a 1-1/2 inch NPT threaded inlet and outlet, this valve is factory-set to discharge at 75 PSI with a massive steam-equivalent relief capacity of 5,909,000 BTU/hr. The Watts 740 series utilizes a large orifice design and a silicon-coated EPDM disc to ensure positive shut-off and prevent seat leakage during normal thermal expansion cycles. The non-mechanical pop-action mechanism provides immediate overpressure protection, while the stainless steel spring maintains calibration under high-temperature conditions. This boiler pressure relief valve is essential for large-scale hydronic systems where maintaining consistent BTU relief capacity is critical for equipment safety and code compliance. Contractors frequently specify the Watts 0383942 for commercial boiler retrofits requiring high-flow safety valves and rigorous pressure management.

• High BTU Capacity: Rated at 5,909,000 BTU/hr to handle high-demand commercial hydronic heating systems.
• Durable Construction: Features a bronze body and stainless steel spring for resistance to corrosion and scaling.
• Precision Seating: Silicone-coated EPDM rubber disc ensures a tight seal and prevents "simmering" near set pressure.
• ASME Certified: Fully compliant with ASME Section IV requirements for HVAC pressure vessels.
• Direct Replacement: The 0383942 is functionally identical to the 740-1 1/2-75 model for seamless installation.

Common Questions

What is the discharge capacity for the Watts 740-1 1/2-75?
This valve provides a 75 PSI relief setting with a verified capacity of 5,909,000 BTU/hr, making it suitable for large commercial boilers.

Can this valve be mounted horizontally?
Standard HVAC code and manufacturer specifications require safety relief valves to be installed in a vertical position with the drain line pitched for gravity drainage to prevent sediment buildup on the seat.

Is the Watts 0383942 compatible with steam boilers?
No, the 740 series is specifically designed for hot water heating boilers. Steam applications require valves rated under ASME Section I or VIII with specific steam-trim components.

This item is not eligible for free shipping.

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.