Rheem RTG 8.4 GPM 157,000 BTU Natural Gas Outdoor Non-Condensing Tankless Water Heater (.82 UEF)

High-Efficiency Tankless Water Heater Delivering 8.4 GPM

The Rheem RTG-84XLN-3 is a non-condensing tankless water heater designed for outdoor installation and natural gas operation. It delivers a maximum flow rate of 8.4 GPM at a 35°F temperature rise, with a maximum input of 180,000 BTU/h and a Uniform Energy Factor (UEF) of 0.82. Its tankless design heats water on demand. Installation and operation must follow Rheem’s requirements for this specific model.

Key Benefits

• Enjoy Hot Water on Demand: Provides hot water as needed without the storage limitations of a traditional tank water heater, making it suitable for everyday residential use.
• Save Space in Your Home: The compact, wall-mounted design helps free up valuable floor space compared with conventional storage-tank water heaters.
• Support Efficient Water Heating: The tankless design heats water as needed rather than maintaining a stored volume of hot water.
• Experience More Consistent Hot Water: Rheem's Hot-Start Programming™ helps minimize cold-water bursts during back-to-back hot-water use.
• Meet Household Hot-Water Needs: The 180,000 BTU/h maximum gas input and rated flow of up to 8.4 GPM at a 35°F temperature rise provide an option for residential hot-water demands, depending on operating conditions.
• Use Natural Gas Fuel: The natural gas configuration is designed for homes with a compatible natural gas supply and properly sized gas connections.

Understanding Tankless Water Heater Sizing

Tankless water heaters are sized by flow rate (GPM) and temperature rise. Flow rate refers to the amount of hot water the unit can deliver per minute, while temperature rise is the difference between the incoming cold-water temperature and the desired hot-water temperature.

For the Rheem RTG-84XLN-3, the rated maximum flow rate is 8.4 GPM at a 35°F temperature rise and 6.7 GPM at a 45°F temperature rise. Available flow rate decreases as the required temperature rise increases. Actual performance depends on incoming water temperature and operating conditions.

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 water temperature is 120°F:

120°F - 55°F = 65°F Temperature Rise

Use the flow-rate information for the specific RTG model to compare its available hot water flow with your home's expected demand. Actual flow rate may vary depending on the required temperature rise and other operating conditions.

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Advanced On-Demand Tankless Water Heating

The Rheem RTG Series is a non-condensing tankless gas water heater designed to provide hot water on demand without the need for a traditional storage tank. Available in natural gas and liquid propane models with multiple capacity options, the series offers residential hot water solutions for different household needs.

Designed for outdoor installation, the RTG Series features a compact design and Hot-Start Programming, which helps minimize cold-water bursts during consecutive hot water demands. Model capacities vary, allowing homeowners to select a unit suited to their household's hot water requirements.

Energy Efficiency & Performance

• Uniform Energy Factor (UEF): 0.82
• Maximum Flow Rate: 8.4 GPM at a 35°F temperature rise
• Gas Input: Up to 180,000 BTU/h

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 RTG-84XLN-3 outdoor natural gas tankless water heater
• Hanging bracket

Requirements & Considerations

• Fuel Type: Designed for natural gas (NG).
• Installation Type: Outdoor installation.
• Venting: Designed for outdoor installation. Follow Rheem's installation instructions for placement and applicable requirements.
• Gas & Water Connections: Follow Rheem's model-specific installation manual for gas supply sizing, inlet pressure, water connections, and pressure-relief valve requirements. Compatibility with a 1/2-inch gas line is subject to local code and installation conditions.
• Clearances: Follow the model-specific installation manual and applicable local codes for required clearances and service access.
• Electrical Requirements: Follow Rheem's model-specific installation manual for electrical supply, grounding, and freeze-protection requirements.