Watts 0556016 Valve

The Watts 0556016 (model LF40XL-150-3/4) is a heavy-duty, automatic reseating temperature and pressure relief valve engineered for critical protection in commercial hot water supply systems. Designed for large-scale storage tanks and water heaters, this 3/4-inch NPT valve features a 5-inch thermo-bonded coated thermostat probe. This specialized coating is essential for service longevity, as it effectively retards mineral accumulation and scale buildup in harsh water conditions. With a pressure relief setting of 150 psi and a temperature relief point of 210°F, it delivers a massive ASME steam discharge capacity of up to 1,437,600 BTU/hr, ensuring safety during extreme over-pressure or runaway heating cycles.

Constructed from lead-free copper silicon alloy, the Watts 40XL-5-150 utilizes a non-mechanical seat-to-disc alignment for consistent, leak-free operation. The professional-grade design includes tamper-resistant bonnet screws and a reinforced test lever for manual maintenance protocols. This valve is the industrial standard for contractors requiring ASME Section IV and CSA listed components that meet ANSI Z21.22 requirements. For optimal performance, the extended 5-inch probe must be positioned within the top six inches of the tank where the hottest water resides, mitigating the risk of thermal lag and ensuring instantaneous response to temperature spikes.

• High-Capacity Steam Discharge: Rated at 1,437,600 BTU/hr to handle high-output commercial water heating applications.
• Advanced Corrosion Resistance: The thermo-bonded probe prevents calcification, maintaining sensing accuracy over time.
• Durable Lead-Free Build: Complies with all safe water regulations without sacrificing the structural integrity provided by the copper silicon alloy body.
• Precision Safety: Features automatic reseating and a non-mechanical alignment system to ensure the valve closes tight after a relief event.

Is the 0556016 a direct replacement for non-lead-free models?
Yes, the 0556016 is the lead-free identical match for the legacy LF40XL-150-3/4, specifically the 40XL-5 series with a 150# pressure rating. It maintains the same dimensions and thread patterns for seamless retrofitting.

Can this valve be installed on the cold water inlet?
No. For the thermostat to function correctly, the probe must be immersed in the hottest water. It should be installed directly into the tank tapping or in the hot water outlet piping within the allowable distance from the tank top.

What is the difference between the 40L and 40XL series?
The Watts 40XL series features the extra-length extension thermostat, whereas the standard 40L has a shorter probe. The 5-inch length on this specific model is required for tanks with thicker insulation or deeper tapping ports.

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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.