Switching Relay with Internal Transformer DPST Line Voltage Relays

Honeywell R845A1030/U Switching Relay – DPST 24V Coil for Line Voltage Control

The Honeywell R845A1030/U is a switching relay designed for low-voltage (24 VAC) control of line-voltage loads in hydronic heating and HVAC applications. It features a DPST (double-pole single-throw) switching configuration and includes an internal transformer to supply control circuit voltage. This relay is suitable for circulator pumps, fan centers, or auxiliary load switching where isolated 24V control is required.

Built with a compact steel enclosure, this relay mounts easily in standard electrical cabinets or equipment panels. Its terminals are clearly marked for simplified wiring during installation or service.

Product Features

• Relay Type: DPST for two-line load switching
• Control Voltage: 24 VAC coil input via internal transformer
• Mounting: Designed for indoor surface mounting
• Switching Load: Supports common HVAC and pump control loads with reliable contact ratings
• Compact Form: Space-efficient housing for use in tight mechanical spaces

Technical Specifications

• Model: R845A1030/U
• Coil Voltage: 24 VAC
• Contact Form: DPST (Double Pole, Single Throw)
• Frequency: 50/60 Hz
• Contact Ratings: 7.4 A at 120 VAC, 3.7 A at 240 VAC (resistive load)
• Dimensions: 5-1/4 in H × 4-1/4 in W × 2-5/16 in D

Installation Considerations

The R845A1030 is typically mounted in proximity to the appliance or control panel and wired to thermostats or low-voltage controllers. It requires line voltage wiring for load connections and 24V input from a compatible thermostat. Installation should be performed by qualified personnel familiar with HVAC wiring practices and local code requirements.

Typical Applications

• Circulator pump switching in hydronic heating systems
• Fan or motor control in air handlers or terminal units
• Low-voltage to line-voltage interface for auxiliary HVAC loads

Usage Notes

This relay provides isolation between low-voltage control circuits and high-voltage loads. It is not designed for switching high inrush inductive loads without contact protection. For optimal service life, ensure the connected load is within specified current ratings.