Caleffi 521509A 3/4” Sweat 3-Way Thermostatic Mixing Valve – 80°–150°F
🔥 Product Overview
The Caleffi 521509A is a high-quality 3/4” sweat three-way thermostatic mixing valve designed for precise temperature control in domestic hot water systems and radiant hydronic heating systems. This valve ensures consistent output temperature, compensating for variations in both hot and cold water supply pressure and temperature.
Built with low-lead brass and anti-scale materials, it is compliant with the latest safety and lead-reduction standards, making it ideal for residential, commercial, and hydronic applications.
⚠️ Note: ❗ Always ensure proper installation and system compatibility for optimal performance.
⚙️ Key Features
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✅ 3/4” sweat connection for easy installation
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✅ Maintains precise mixed water temperature (80°–150°F)
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✅ Low-lead brass construction for safe drinking water
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✅ Internal anti-scale components for long-lasting performance
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✅ Locking setpoint knob prevents accidental changes
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✅ Compensates for temperature and pressure fluctuations
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✅ Certified to cUPC, ASSE 1017, CSA B125.3, ANSI/NSF 372-2011
📊 Specifications
| Specification | Details |
|---|
| Part Number |
521509A |
| Brand |
Caleffi |
| Connection Type |
3/4” Sweat |
| Valve Type |
3-Way Thermostatic Mixing Valve |
| Temperature Range |
80°–150°F (adjustable 85°–150°F) |
| Max Inlet Temperature |
200°F |
| Max Working Pressure |
200 psi |
| Max Differential Pressure |
75 psi |
| Sensor Element |
N/A (internal thermostatic mechanism) |
| Material |
Low-lead brass, internal anti-scale materials |
| Certifications |
cUPC listed, ASSE 1017, CSA B125.3, ANSI/NSF 372-2011 |
⚠️ Common Symptoms Indicating Replacement
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Inconsistent domestic hot water temperature
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Reduced flow or uneven heating in radiant systems
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Valve leakage or malfunction
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Inability to maintain set temperature under varying pressure
❓ Frequently Asked Questions (FAQ)
Q: What is the maximum working pressure of this valve?
A: 200 psi
Q: What temperature range does this valve maintain?
A: Settable from 80°–150°F (adjustable 85°–150°F)
Q: Is it safe for drinking water?
A: Yes — low-lead brass construction complies with ANSI/NSF 372-2011 and the Reduction of Lead in Drinking Water Act
Q: Can this valve be used in radiant heating systems?
A: Yes — it is designed for both domestic water distribution and hydronic/radiant heating systems
Q: How does it maintain constant temperature?
A: The valve compensates automatically for variations in hot and cold water pressure and temperature
🛒 Shopping Tips
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Verify the system type (domestic hot water or hydronic heating)
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Inspect for scaling or mineral buildup regularly
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Adjust and lock setpoint according to desired output temperature
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Ensure compatibility with your plumbing system and pressure range
