A. O. Smith ProLine XE ATO-140H Outdoor Natural Gas Tankless Water Heater User Manual

Introduction and Overview

The A. O. Smith ProLine® XE Ultra-Low NOx Outdoor 120,000 BTU Condensing Natural Gas Tankless Water Heater (Model ATO-140H) provides on-demand hot water with a flow rate up to 6.6 GPM. This unit features high-efficiency Ultra-Low NOx condensing technology, allowing for 3-inch PVC venting and 0-inch clearance to combustibles. It is designed for outdoor installation and complies with Ultra-Low NOx regulations, meeting ASHRAE 90.1b-1992 energy efficiency requirements. The unit utilizes a commercial-grade copper heat exchanger for efficient heat transfer and includes integrated temperature controls and advanced diagnostics.

Key features include:

• Continuous hot water flow rate up to 6.6 GPM.
• Wall-mount design for space-saving installation.
• Primary commercial-grade copper heat exchanger for rapid heat transfer.
• Vents with 3-inch PVC up to 70 feet or 4-inch PVC up to 100 feet.
• Integrated temperature controls and advanced diagnostics for simplified troubleshooting.

Image: A. O. Smith ProLine XE ATO-140H Outdoor Natural Gas Tankless Water Heater, showing its compact, wall-mounted design.

Setup and Installation

This tankless water heater is designed for outdoor installation. Proper installation is critical for safe and efficient operation. It is strongly recommended that installation be performed by a qualified professional. Key considerations include:

• Location: Ensure the unit is installed outdoors in a location with proper clearances as specified in the full installation manual.
• Venting: The unit can be vented with 3-inch PVC up to 70 feet or 4-inch PVC up to 100 feet.
• Gas Supply: Connect to a natural gas supply with appropriate sizing for 120,000 BTU.
• Water Connections: Connect cold water inlet and hot water outlet lines.
• Electrical Connection: A standard electrical outlet is required for operation.

Always consult the complete installation manual provided with the product for detailed instructions and safety warnings.

Operating Instructions

The A. O. Smith ATO-140H tankless water heater provides continuous hot water on demand. Follow these general operating guidelines:

• Power On/Off: Ensure the unit is connected to power and the gas supply is open. The unit will typically enter a standby mode.
• Temperature Adjustment: Use the integrated temperature controls to set the desired hot water temperature. The maximum temperature is 140 degrees Fahrenheit. Refer to the full user manual for detailed instructions on temperature setting and safety guidelines.
• Hot Water Delivery: When a hot water faucet is opened, the unit will sense the flow and begin heating water instantly.

For optimal performance and safety, do not block the unit's air intake or exhaust vents.

Maintenance

Regular maintenance ensures optimal performance and longevity of your tankless water heater. It is recommended to have maintenance performed by a qualified technician.

• Annual Flushing: It is recommended to flush the heat exchanger annually to remove mineral buildup, especially in areas with hard water. This process typically involves isolating the unit, connecting flushing hoses, and circulating a descaling solution. Consult a qualified technician or the detailed service manual for specific instructions.
• Exterior Cleaning: Keep the exterior of the unit clean and free from obstructions.
• Ventilation Check: Periodically inspect the venting system for any blockages or damage.

Troubleshooting

If you experience issues with your tankless water heater, consider the following basic troubleshooting steps. For complex problems, contact a qualified service technician.

• No Hot Water:
  • Check if the gas supply is open.
  • Verify the unit is powered on.
  • Ensure the temperature setting is appropriate.
  • Check for error codes on the unit's display.
• Insufficient Hot Water:
  • Confirm the temperature setting.
  • Check for multiple hot water demands exceeding the unit's flow rate capacity (6.6 GPM).
  • Consider if flushing is needed due to mineral buildup.
• Error Codes: Refer to the full user manual for a list of specific error codes and their meanings and recommended actions.

Specifications

Warranty Information

This A. O. Smith tankless water heater comes with a 15-year limited warranty. For full details regarding coverage, terms, and conditions, please refer to the warranty document included with your product or visit the official A. O. Smith website.

Support and Contact

For technical assistance, service, or to obtain a complete copy of the installation and user manual, please contact A. O. Smith customer support or visit their official website.

• A. O. Smith Official Website: Visit A. O. Smith Store on Amazon