Conbraco 18C-521-3-125 Valve

The Conbraco 18C-521-3-125 is a professional-grade, high-capacity Temperature and Pressure Relief Valve engineered for the protection of commercial-scale hot water heaters and storage tanks. This ASME Section IV certified valve features a 1" Male NPT inlet and 1" Female NPT outlet, specifically calibrated for a 125 PSI set pressure and a 210°F temperature limit. With a substantial 1,825,000 BTU capacity, it is designed to meet the rigorous safety demands of high-output systems where rapid thermal and pressure discharge is non-negotiable.

Constructed with a heavy-duty bronze body and a 3" coated element probe, this T&P valve provides superior resistance to corrosion and mineral buildup, ensuring the thermal relief mechanism remains responsive over time. The silicone seat disc ensures a tight seal and reliable resets after operation. For a proper HVAC high-capacity installation, ensure the probe is fully immersed in the top six inches of the tank where the water is hottest. This commercial water heater safety valve is an essential component for contractors maintaining code compliance and preventing catastrophic over-pressurization in industrial hydronic applications.

• High Discharge Capacity: Rated at 1,825,000 BTU/HR to handle large-scale commercial heating loads safely.
• Code Compliance: ASME Section IV Certified and CSA listed to ANSI Z21.22 for professional-grade reliability.
• Durable Construction: Heavy ASTM B584 bronze body and stainless steel springs provide longevity in harsh water conditions.
• Enhanced Protection: The 3-inch coated probe prevents galvanic corrosion and lime scale from interfering with temperature sensing.
• Standardized Fit: 1" MNPT x 1" FNPT configuration allows for straightforward replacement on most high-capacity storage tanks.

How do I choose between a 125 PSI and 150 PSI setting for my tank?
The valve's set pressure must never exceed the Maximum Allowable Working Pressure (MAWP) of the storage tank. Check the tank's nameplate; if the tank is rated for 125 PSI, you must use the 18C-521-3-125 to ensure the system relieves pressure before the vessel’s limit is reached.

What is the purpose of the 3-inch probe length on this relief valve?
The 3-inch probe is designed to penetrate deep enough into the tank to sense the actual water temperature. For technical compliance, the sensing element must be located within the top 6 inches of the tank water to accurately trip at 210°F and prevent steam flashing.

Can I use a smaller discharge line than the 1" outlet?
No. The discharge piping must match the 1" outlet size of the valve. Reducing the pipe size creates backpressure and restricts flow, which can effectively lower the 1,825,000 BTU capacity and void the safety rating of the installation.

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.