Description
The Weil McLain 510-312-021 is a high limit temperature control designed for reliable overheat protection in hydronic boiler and heating systems. Featuring SPST (Single-Pole, Single-Throw) switching action with automatic recycle, this control continuously monitors system water temperature and automatically resets once safe operating conditions are restored — minimizing downtime and manual intervention.
Temperature & Control Specifications
- Temperature Range: 140°F – 220°F
- Fixed Differential: 30°F
- Switch Type: SPST (Single-Pole, Single-Throw)
- Reset Type: Automatic Recycle
Mounting & Connection
- Control Well: 1/2″ NPT Brass
- Remote Capillary: None — mounts directly on well
- Direct-mount design simplifies installation and eliminates capillary tube routing
Key Features & Benefits
- Automatic recycle operation restores system function without manual reset
- 30°F fixed differential provides consistent, predictable switching performance
- Brass 1/2″ NPT control well ensures durable, corrosion-resistant immersion
- Direct-mount configuration reduces installation complexity and potential leak points
- Wide 140–220°F sensing range suits a broad range of hydronic heating applications
- OEM Weil McLain replacement part ensures compatibility and system integrity
Application
The 510-312-021 is an OEM Weil McLain replacement high limit control, engineered for use with Weil McLain boilers and compatible hydronic heating systems. The direct-mount, no-capillary design makes it ideal for installations where a compact, reliable high limit solution is required. Its automatic recycle function makes it well-suited for systems that benefit from self-restoring overheat protection.







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