Single-Zone Switching Relay with Internal Transformer, 1 SPST Line Relay, 120VAC

Honeywell RA89A1074/U Single-Zone Switching Relay – SPST Line Voltage Control with 24V Coil

The Honeywell RA89A1074/U is a single-zone switching relay designed to control line-voltage loads through a 24 VAC low-voltage input. Commonly used in hydronic heating and HVAC systems, this SPST relay provides reliable switching of circulators, fans, or other 120/240 VAC components using thermostat signals or other control circuits.

This relay includes an integral transformer, eliminating the need for external power sources for the control circuit. Its compact steel enclosure allows for panel or surface mounting and is designed for use in indoor applications with moderate temperature ranges.

Functional Features

• Contact Type: SPST (Single Pole, Single Throw) for on/off switching of line-voltage loads
• Integral Transformer: Supplies 24 VAC control voltage to simplify wiring and circuit design
• Control Input: Accepts low-voltage signal to energize line-voltage contacts
• Application Use: Designed for single-zone hydronic systems or fan operation where isolated control is required
• Enclosure: Indoor-rated metal housing for mounting in mechanical rooms or control panels

Technical Specifications

• Model: RA89A1074/U
• Coil Voltage: 24 VAC
• Switching Action: SPST
• Electrical Rating: 10.2 A @ 120 VAC, 5.1 A @ 240 VAC (AFL)
• Frequency: 50/60 Hz
• Operating Temperature Range: 105°F to 115°F (ambient)
• Dimensions: 5-1/4 in H × 4-1/4 in W × 2-5/16 in D

Installation Information

The RA89A1074/U is intended for use in HVAC control systems requiring relay switching between thermostat circuits and high-voltage loads. The unit mounts securely in standard junction boxes or equipment enclosures. Installation should be performed by licensed HVAC technicians to ensure proper circuit loading, code compliance, and operational reliability.

System Integration Notes

• Low-Voltage Control: Suitable for 24V thermostats and zoning systems
• Relay Replacement: Field-replaceable relay component reduces maintenance time
• Wiring Terminals: Accessible for simplified connection of line and low-voltage circuits

Application Use

Commonly installed in zone heating systems, fan coil units, and packaged HVAC systems, the RA89A1074/U supports isolated switching and compact system design. It is appropriate for both new installations and retrofit work where control isolation and internal power conversion are required.