Weil McLain, 381300000, Electric Aquastat

Weil-McLain 381-300-000 Electronic Aquastat with Integrated Low Water Cut-Off

The Weil-McLain 381-300-000 is an OEM electronic aquastat designed for use in hydronic heating systems requiring both temperature control and low water safety protection. This unit combines high and low temperature limit settings with an integrated low water cut-off (LWCO) circuit, providing both operational control and equipment protection in a single assembly.

This model is engineered for compatibility with select Weil-McLain boiler systems and is suitable for field replacement or OEM installation in systems utilizing immersion well-based temperature sensing.

Functional Capabilities

• High Limit Temperature Control: Adjustable from 100°F to 220°F for regulating boiler water temperature.
• Low Limit Temperature Control: Adjustable from 110°F to 200°F, commonly used for maintaining boiler standby temperature.
• Integrated LWCO: Shuts down burner operation when water level is insufficient, enhancing system safety.
• Anticipator Circuit: 0.2A for thermostat compatibility and response stability.
• Circulator Control: Rated for 5.8 FLA motor loads.

Technical Specifications

• Manufacturer Part Number: 381-300-000
• High Limit Range: 100°F–220°F
• Low Limit Range: 110°F–200°F
• Circulator Load: 5.8 FLA
• Thermostat Anticipator Load: 0.2A
• Mounting Type: Immersion well (well not included)

Installation Requirements

This electronic aquastat must be installed by qualified HVAC or plumbing professionals. Proper installation requires connection to a compatible immersion well and system wiring per boiler specifications and local code. Ensure that temperature limits and differential settings are calibrated based on system requirements. Post-installation checks should confirm proper high limit cutoff, circulator activation, and LWCO lockout operation.

Contractor Notes

This unit is designed to streamline boiler control by combining limit protection and low water sensing in a single control. It eliminates the need for separate LWCO wiring and simplifies control panel layout in replacement and new installations. Verify that the existing system supports integrated LWCO logic before installing.