A. O. Smith ProLine XE ATI-310CX3 Indoor Tankless Gas Water Heater User Manual

1. Introduction

This manual provides comprehensive instructions for the safe and efficient installation, operation, and maintenance of your A. O. Smith ProLine XE ATI-310CX3 Indoor Tankless Gas Water Heater. This unit is designed to provide continuous hot water for residential applications, featuring X3 Scale Prevention Technology and a high-efficiency design.

Please read this manual thoroughly before installation or operation and retain it for future reference. Professional installation is strongly recommended to ensure proper function and safety.

2. Safety Information

Important Safety Instructions:

• This appliance must be installed by a qualified professional in accordance with all local codes and regulations.
• Ensure proper ventilation as specified in the installation guide. This is a non-condensing unit designed for indoor use with a concentric vent system.
• Do not store flammable materials near the water heater.
• The unit is equipped with exhaust and water temperature safety control, an overheat cut-off fuse, and an air-fuel ratio (AFR) sensor for safe operation. Do not bypass or tamper with these safety features.
• Always turn off the gas supply and electrical power before performing any service or maintenance.

3. Product Overview

The A. O. Smith ProLine XE ATI-310CX3 is an indoor, non-condensing tankless gas water heater designed for efficiency and longevity. Key features include:

• X3 Scale Prevention Technology: Prevents scale buildup, eliminating the need for annual descaling and isolation valves.
• High Flow Rate: Delivers up to 8.0 Gallons Per Minute (GPM) of hot water.
• Energy Efficiency: Achieves up to a 0.81 Uniform Energy Factor (UEF).
• Compact Design: Wall-mount installation saves space.
• Fuel Versatility: Convertible from natural gas to propane with the included kit.
• Advanced Controls: Integrated temperature controls and diagnostic features.

Figure 3.1: Front view of the A. O. Smith ProLine XE ATI-310CX3 Tankless Gas Water Heater, showing the control panel and water connections.

Figure 3.2: Illustration highlighting the energy and cost-saving benefits of the tankless water heater, indicating potential reductions in water heating costs.

4. Setup and Installation

Installation of this tankless water heater requires adherence to all local and national plumbing and electrical codes. It is highly recommended that installation be performed by a licensed professional.

4.1 Mounting

The unit features a wall-mount design, allowing for flexible placement and space saving. Ensure the mounting surface is capable of supporting the unit's weight (approximately 51 pounds) when filled with water.

Figure 4.1: Rear view of the water heater, illustrating the integrated mounting brackets for wall installation.

4.2 Venting

This model utilizes a direct vent APNC35 concentric vent system. Vent termination can be installed vertically or horizontally. Refer to the detailed installation manual for specific venting requirements and clearances.

Figure 4.2: Top view of the water heater, highlighting the concentric vent connection point.

Figure 4.3: Side view of the water heater, displaying the exhaust vents and various utility connections.

4.3 Gas Type Conversion

The unit is factory-set for natural gas but can be converted to propane using the included conversion kit. This procedure must be performed by a qualified technician.

4.4 Sizing and Application

The appropriate sizing for your tankless water heater depends on your geographical location and hot water demand. Refer to the sizing map below to match the unit to your needs.

Figure 4.4: Sizing map illustrating recommended usage (sinks and showers) for the tankless water heater based on Northern, Central, and Southern geographical zones in the United States.

Note: Calculations are based on simultaneous use of 0.5 GPM faucet and 1.5 GPM showerhead.

5. Operating Instructions

The A. O. Smith ProLine XE ATI-310CX3 features an intuitive control panel for easy operation.

5.1 Control Panel

The control panel, located on the front of the unit, allows you to power the unit on/off, adjust temperature, and view operational status.

Figure 5.1: Detailed view of the control panel, showing ON/OFF button, temperature adjustment buttons (HOT/COLD), and status indicators (IN USE, STAND BY, INFO).

• ON/OFF Button: Press to power the unit on or off.
• HOT/COLD Buttons: Use these buttons to adjust the desired water temperature. The integrated display will show the set temperature.
• IN USE Indicator: Illuminates when the unit is actively heating water.
• STAND BY Indicator: Illuminates when the unit is powered on but not actively heating.
• INFO Button: Provides access to diagnostic information or error codes. Refer to the troubleshooting section for interpreting codes.

5.2 Initial Startup

1. Ensure all gas and water connections are secure and leak-free.
2. Open the cold water supply valve to the unit.
3. Open a hot water faucet in your home to purge air from the system. Close the faucet once water flows steadily.
4. Turn on the gas supply.
5. Connect the unit to a 120 Volt power supply.
6. Press the ON/OFF button on the control panel to power on the unit.
7. Set your desired temperature using the HOT/COLD buttons.

6. Maintenance

Regular maintenance ensures optimal performance and longevity of your tankless water heater.

• X3 Scale Prevention Technology: This unit features X3 Scale Prevention Technology, which significantly reduces scale buildup. This technology eliminates the need for traditional annual descaling procedures and the installation of isolation valves.
• Self-Cleaning: The unit incorporates self-cleaning features to maintain efficiency.
• Vent Inspection: Periodically inspect the vent system for any obstructions or damage.
• Water Filter (if applicable): If an external water filter is installed, follow its manufacturer's recommendations for replacement.
• Professional Inspection: It is recommended to have a qualified technician inspect the unit annually to ensure all components are functioning correctly.

7. Troubleshooting

The A. O. Smith ProLine XE ATI-310CX3 includes advanced diagnostics to assist in identifying operational issues. If the unit displays an error code or exhibits unusual behavior, refer to the following general steps:

1. Check Display: Note any error codes displayed on the control panel. Consult the full installation and service manual for a complete list of error codes and their corresponding solutions.
2. Power Cycle: Turn off the unit using the ON/OFF button, wait 30 seconds, then turn it back on. This can resolve minor electronic glitches.
3. Check Gas and Water Supply: Ensure both the gas and water supplies to the unit are fully open.
4. Ventilation: Verify that the vent system is clear of obstructions.
5. Professional Assistance: For persistent issues or complex error codes, contact a qualified service technician or A. O. Smith customer support. Do not attempt repairs beyond your technical expertise.

8. Specifications

Technical specifications for the A. O. Smith ProLine XE ATI-310CX3 Tankless Gas Water Heater:

Figure 8.1: Dimensional drawing of the tankless water heater, indicating its height (20.50 in), width (13.75 in), and depth (11.50 in).

9. Warranty Information

The A. O. Smith ProLine XE ATI-310CX3 Tankless Gas Water Heater comes with a 15-year limited warranty on the heat exchanger for residential applications. Please refer to the warranty card included with your product for full terms and conditions.

10. Customer Support

For technical assistance, troubleshooting, or warranty inquiries, please contact A. O. Smith customer support:

Phone: (800) 527-1953

For additional resources, visit the official A. O. Smith website.