Resideo L8148J1009 Aquastat Relay

The Resideo L8148J1009 Aquastat Relay is a specialized immersion-type hydronic controller designed for contractors managing forced hydronic heating systems. Engineered for high-limit protection, this unit integrates a switching relay to provide simultaneous control of both burner and circulator motors. It features a broad high-limit operating range of 120-240°F with an 8°F fixed differential, ensuring precise temperature regulation and thermal safety. The SPST switching action is optimized for low-voltage or millivoltage burner circuits, while maintaining line-voltage control for the circulator. This model is a direct Honeywell L8148J1009 replacement for legacy units including 8J48A-209 and 415-510-000, offering field-proven reliability in a rugged gray enamel case. Designed for installation flexibility, the internal components support both horizontal and vertical mounting configurations, accommodating varied boiler tapping setups. Technical requirements include a 24 Vac boiler thermostat with a heat anticipator setting of 0.2A for stable operational performance.

Key Benefits

• Universal Mounting Flexibility: Field-adjustable case allows for vertical or horizontal orientation to fit restricted boiler spaces.
• Enhanced Circuit Control: Built-in transformer and accessory terminals allow for the seamless addition of a remote low-limit controller.
• High-Limit Precision: The 8°F fixed differential maintains tight control over high-limit setpoints, increasing system safety and efficiency.
• Legacy Compatibility: Serves as a direct technical update for older aquastat relay models, minimizing rewiring time during replacement.
• Versatile Electrical Ratings: Supports dual-burner circuits, compatible with both standard 24V gas valves and millivolt systems.

Common Questions

Can the L8148J1009 power zone valves?
Yes, this model is designed to power up to two V8043 zone valves. If your application requires more than two hydronic zone valves, an additional external transformer must be integrated into the system.

What is the proper way to set the heat anticipator for this relay?
For optimal cycle timing and to prevent premature burner shutdown, ensure the 24 Vac thermostat's heat anticipator is set exactly to 0.2A as per the manufacturer's technical specifications.

Does this unit include the immersion well?
The L8148J1009/U is typically provided less well. It includes a well adapter and a tube of heat conductive compound to ensure high-sensitivity bulb response when installed in an existing immersion well.

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.