1. Introduction
The Honeywell R8845U-1003 Relay Switch is a genuine OEM replacement part designed to facilitate the integration of various heating and cooling systems, particularly useful for adapting millivolt systems to modern 24V thermostats. This device provides the necessary interface and power conversion to enable compatibility between older heating units and contemporary smart thermostat technologies.
2. Setup and Installation
Installation of the Honeywell R8845U-1003 Relay Switch requires basic electrical knowledge. If you are unsure about any steps, it is recommended to consult a qualified electrician or HVAC professional. Always ensure power is disconnected before beginning any installation work.
2.1 Wiring Overview
The relay switch typically requires a 120V AC power input and provides a 24V AC output for the thermostat, along with relay contacts for controlling the heating system. Common wiring terminals include:
- L1 and L2: For 120V AC power input. L1 is typically the hot wire, and L2 is the neutral.
- X1 and X2: Connect to the millivolt system (e.g., gas valve on a fireplace or furnace).
- R, W, C: Connect to the 24V thermostat. R (Red) is typically 24V power, W (White) is for heat call, and C (Common) provides continuous 24V power to the thermostat.
Refer to the specific wiring diagram provided with your heating system and thermostat for detailed connection instructions. Ensure all connections are secure and properly insulated.
Figure 1: Front view of the Honeywell R8845U-1003 Relay Switch, illustrating the compact design and terminal block for wiring connections.
3. Operating Instructions
Once properly installed and powered, the Honeywell R8845U-1003 Relay Switch operates automatically in response to commands from the connected 24V thermostat. It acts as an intermediary, converting the thermostat's 24V signals into appropriate control signals for the millivolt heating system.
3.1 Push-To-Test Button
The unit features a 'Push-To-Test' button. This button allows for manual verification of the relay's function. Pressing this button should activate the relay, simulating a call for heat from the thermostat, and can be used to confirm basic operational integrity after installation.
3.2 Troubleshooting LEDs
Two troubleshooting LEDs are integrated into the device. These LEDs provide visual feedback on the unit's status and can assist in diagnosing potential issues. Refer to the specific product documentation or Honeywell support for detailed interpretations of the LED indicators.
4. Maintenance
The Honeywell R8845U-1003 Relay Switch is designed for reliable, long-term operation with minimal maintenance. Regular inspection is recommended to ensure optimal performance.
- Periodic Inspection: Annually, visually inspect the unit and its wiring connections for any signs of wear, damage, or loose terminals.
- Cleaning: Keep the unit free from dust and debris. Use a soft, dry cloth for cleaning. Do not use liquid cleaners or solvents.
- Environmental Conditions: Ensure the unit is installed in an environment within its specified operating temperature and humidity ranges to prevent premature failure.
5. Troubleshooting
If the relay switch is not functioning as expected, consider the following troubleshooting steps:
- No Power/LEDs Off:
- Verify that the 120V AC power supply to the L1 and L2 terminals is active. Check circuit breakers or fuses.
- Ensure all power connections are secure.
- If power is present but LEDs remain off, the internal transformer or unit may be defective.
- System Not Responding to Thermostat:
- Check the wiring between the thermostat (R, W, C terminals) and the relay switch.
- Verify the thermostat is calling for heat (or cool, if applicable) and is receiving 24V power.
- Use the 'Push-To-Test' button on the relay. If the heating system responds, the issue may lie with the thermostat or its wiring.
- Check the wiring between the relay's X1/X2 terminals and the millivolt heating system.
- Intermittent Operation:
- Inspect all wiring connections for looseness or corrosion.
- Ensure the unit is not exposed to excessive heat or moisture.
If troubleshooting steps do not resolve the issue, contact Honeywell customer support or a qualified technician.
6. Specifications
| Feature | Detail |
|---|---|
| Manufacturer | Honeywell |
| Part Number | R8845U1003 |
| Item Weight | 2 pounds |
| Product Dimensions | 6 x 4.5 x 3.5 inches |
| Material | Metal, Plastic |
| Voltage (Output/Control) | 24 Volts |
| Item Package Quantity | 1 |
| Date First Available | February 17, 2007 |
7. Warranty Information
The Honeywell R8845U-1003 Relay Switch is a genuine OEM replacement part. For specific warranty terms and conditions, please refer to the documentation included with your purchase or contact Honeywell customer service directly. Warranty coverage typically applies to defects in materials and workmanship under normal use.
8. Customer Support
For further assistance, technical support, or inquiries regarding the Honeywell R8845U-1003 Relay Switch, please contact Honeywell customer support through their official website or the contact information provided in your product packaging. When contacting support, please have your model number (R8845U1003) and any relevant purchase details available.