Rheem IKONIC S 10.1 GPM 180,000 BTU Natural Gas Indoor Condensing Tankless Water Heater (.96 UEF)

High-Efficiency Tankless Water Heater Delivering 10.1 GPM

The Rheem IKONIC S Series Tankless Water Heater provides high-efficiency on-demand hot water with a maximum gas input of 180,000 BTU/h, a maximum flow rate of 10.1 GPM at a 35°F temperature rise, and a 0.96 Uniform Energy Factor (UEF).

Designed for easy installation and retrofit applications, the unit supports PVC vent runs up to 70 feet with 2-inch venting or 150 feet with 3-inch venting. It also allows flex venting through existing B-vent up to 50 feet and features a full-text digital display for simplified setup without dip-switches.

Key Benefits

• High Heating Capacity: Provides up to 180,000 BTU/h maximum gas input to support residential hot water demands.
• On-Demand Hot Water: Delivers up to 10.1 GPM at a 35°F temperature rise. Actual flow rate varies with incoming water temperature and selected output temperature.
• High-Efficiency Performance: A 0.96 Uniform Energy Factor (UEF) supports efficient water heating.
• Stainless Steel Heat Exchangers: Primary and secondary stainless steel heat exchangers are designed to provide increased efficiency and durability.
• Hot-Start Programming™: Helps keep the unit ready between back-to-back hot water uses to help avoid cold water bursts.
• Simplified Setup: The full-text digital display supports setup and operation without dip-switch settings.
• Flexible Venting Options: Supports approved venting configurations, including 2-inch flexible venting up to 50 feet. Follow Rheem’s installation instructions for approved materials and maximum vent lengths.
• 1/2-Inch Gas-Line Compatibility: Supports 1/2-inch gas-line installations where permitted by local code. Verify gas-line sizing and supply capacity against installation requirements.
• Manufactured Home Applications: Rheem lists the IKONIC series as approved for manufactured or mobile home environments, subject to applicable installation requirements and local codes.

Understanding Tankless Water Heater Sizing

The RECTGH-S10iN provides a maximum flow rate of 10.1 GPM at a 35°F temperature rise. At a 45°F temperature rise, the maximum flow rate is 7.9 GPM, while a 67°F temperature rise provides a maximum flow rate of 5.3 GPM.

Flow rates vary depending on the temperature of incoming cold water and the water heater set temperature. The capacity information provides flow-rate guidance based on different groundwater temperature zones.

How to Calculate Temperature Rise

To determine temperature rise, subtract the incoming water temperature from your desired hot water temperature. For example, if the incoming water temperature is 55°F and the desired hot water temperature is 120°F:

120°F - 55°F = 65°F Temperature Rise

Refer to the Water Flow (GPM) chart below to compare estimated flow rates at different temperature rises and help determine whether the Rheem S10i model can meet your household's hot water demand. Actual flow rates vary depending on incoming water temperature and the water heater's set temperature.

Energy Efficiency & Performance

• Uniform Energy Factor (UEF): 0.96
• Maximum Flow Rate: 10.1 GPM at a 35°F temperature rise
• Gas Input: Up to 180,000 BTU/h

Actual hot water flow depends on the incoming water temperature and the required temperature rise.

Warranty

Rheem provides a 15-year heat exchanger warranty, 5-year parts warranty, and 1-year labor warranty for single-family residential installations.

Important Warranty Conditions:

• Residential Use: Standard residential installations qualify for full coverage. Commercial installations receive 5-year heat exchanger and parts coverage.
• Recirculation Systems: Controlled recirculation qualifies for full residential coverage. Uncontrolled, continuously operating recirculation reduces heat exchanger and parts coverage to 3 years.
• Operating Hours: All warranty coverage ends after 12,000 hours of operation.
• Installation & Maintenance: Damage from improper installation, mineral buildup, scale, or water quality outside Rheem's specified limits is excluded.
• Labor Coverage: Covers reasonable labor costs for covered repairs during the first year when performed by a licensed, qualified contractor trained on Rheem tankless water heaters.
• Ownership: Warranty applies only to the original owner at the original installation location and is nontransferable.

Warranty coverage begins on the documented installation date. Without documentation, coverage begins 90 days after manufacture. Product registration does not extend the warranty period.

Review Rheem's official Limited Warranty Certificate for complete terms, exclusions, and coverage details.

What's Included

• Rheem IKONIC S10i tankless water heater
• Brass service valves
• Pressure relief valve
• NG to LP gas conversion kit
• 5-foot, 120V, 3-prong power cord
• Mounting and spare-parts kit
• Vent screens
• Use and care manual

Requirements & Considerations

• Fuel Type: Factory-configured for natural gas (NG) and includes a liquid propane (LP) conversion kit for qualified field installation.
• Installation Type: Indoor installation. The outdoor conversion kit is sold separately.
• Venting: Use approved vent materials and configurations according to Rheem's installation instructions.
• Gas, Water & Condensate Connections: Follow the installation manual for connection sizes and requirements.
• Clearances: Maintain the clearances specified in the installation manual for safe operation and service access.
• Wi-Fi: Standard included feature for the S10i model.