Watts 0556015 Valve

The Watts 0556015 is a professional-grade automatic reseating temperature and pressure relief valve designed specifically for commercial hot water heaters and supply tanks. This 3/4-inch lead-free valve, model LF40XL-5-125, provides essential protection against catastrophic failure by monitoring both thermal and pressure conditions. With a pressure relief setting of 125 psi and a temperature relief threshold of 210°F, this unit features a 5-inch extension thermostat with a unique thermo-bonded coating to resist mineral accumulation. As the direct updated replacement for the 40XL-5-125 and LF40XL-125-210-3/4, it meets the rigorous demands of modern plumbing codes while offering a steam discharge capacity of up to 1,218,000 BTU/hr. The bronze body construction and tamper-resistant bonnet screws ensure reliable performance in high-demand environments. Contractors should note the NPT male inlet and NPT female outlet configuration for standard integration into commercial water heating systems.

Key Benefits

• High Capacity Protection: Provides an ASME steam pressure rating of 1,218,000 BTU/hr, suitable for large-scale commercial boilers and tanks.
• Advanced Thermostat Coating: The 5-inch probe features a thermo-bonded coating that prevents calcification and mineral buildup in hard water conditions.
• Lead-Free Compliance: Constructed from lead-free brass to meet federal and state potable water requirements.
• Automatic Reseating: Engineered for automatic reseating after a relief event, minimizing system downtime and water loss compared to manual safety valves.
• Simplified Replacement: Directly replaces the legacy LF40XL-125-210 series with updated metallurgical standards and improved seat-to-disc alignment.

Common Questions

Is the 0556015 compatible with older 40XL-5-125 installations?
Yes, the Watts 0556015 is the official updated version of the 40XL-5-125 and LF40XL-125-210-3/4. It maintains the same 3/4" NPT threads and 5-inch probe length for a drop-in T&P valve replacement.

Why is the 125 psi setting used instead of 150 psi?
System engineers specify the 125 psi relief valve for tanks with a maximum working pressure (MWP) rating of 125 psi. Installing a higher-rated valve on a 125 psi tank would violate safety protocols and local plumbing codes.

Can the extension thermostat be shortened?
The 5-inch coated thermostat is fixed to the valve body. For installations requiring a shorter probe directly into a tank tapping, a Series 40L (short thermostat) model should be utilized instead.

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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.