Resideo RA89A1074 Relay

The Resideo RA89A1074 Relay is a reliable, industry-standard solution for technicians managing hydronic systems that require seamless interfacing between low-voltage controls and 120V line-voltage equipment. Built with a 120Vac primary voltage transformer and a 24Vac coil, this switching relay allows a standard 2-wire thermostat to drive heavy-duty components like circulator pumps, fans, or boiler ignition circuits. Its SPST switching action ensures precise, single-pole single-throw logic, providing a high-capacity contact rating of up to 10.2A AFL at 120V. Designed for a 1 zone switching relay setup, the unit is housed in a rugged enclosure that simplifies surface mounting in mechanical rooms. This switching relay with transformer is essential for zoning applications where isolation between control and load circuits is critical for system safety and performance. Use the RA89A1074 to maintain high electrical efficiency with its 5.0W maximum input rating while preventing common feedback issues in complex hydronic loops.

Key Benefits

• Integrated Transformer: Internal 24V power source simplifies wiring by eliminating the need for external control transformers.
• Versatile Compatibility: Seamlessly bridges low voltage controllers with 120Vac or 240Vac inductive loads like pump motors.
• Rugged Durability: The included enclosure protects internal components and features a standard 1/2-inch conduit knockout for professional wire management.
• Standardized Replacement: Matches the footprint of many legacy Honeywell switching relays, making it a preferred choice for service technicians.
• Reliable Logic: Provides dependable SPST switching for singular zone control or as an intermediate relay in larger sequencing panels.

Common Questions

How do I wire a 2-wire thermostat to this relay?
The thermostat connects directly to the T and T terminals on the low-voltage side. The internal transformer provides the 24V signal required to energize the coil when the thermostat calls for heat.

Can the RA89A1074 be used for cooling applications?
While primarily used for hydronic heating and circulators, this SPST relay can switch any line-voltage load within its electrical rating (up to 10.2A AFL) upon receiving a 24V signal.

Will this work with a 240V circulator pump?
Yes, the contacts are rated for 5.1A AFL at 240Vac, though the primary transformer power must still be supplied via the 120V input terminals.

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.