Rheem RTGH 8.4 GPM 157,000 BTU Natural Gas Indoor Condensing Tankless Water Heater (.93 UEF)

High-Efficiency Super Condensing Indoor Natural Gas Tankless Water Heater Delivering 8.4 GPM

The Rheem RTGH Series RTGH-84DVLN-3 is a super high-efficiency, condensing indoor natural gas tankless water heater designed to deliver continuous on-demand hot water with a maximum gas input of 157,000 BTU/h, a maximum flow rate of 8.4 GPM at a 35°F temperature rise, and a 0.93 Uniform Energy Factor (UEF).

Engineered for high performance and flexible installation, this unit features a super condensing design incorporating primary copper and secondary stainless steel heat exchangers. It supports Schedule 40 PVC, CPVC, or polypropylene vent runs up to 60 feet with 2-inch venting or 150 feet with 3-inch venting, and offers a compact cabinet profile that is up to 20% smaller and lighter than previous models to make one-person installs easier.

Key Benefits

• High Heating Capacity: Provides up to 157,000 BTU/h maximum gas input to support on-demand residential hot water needs.
• On-Demand Hot Water: Delivers up to 8.4 GPM at a 35°F temperature rise. Actual flow rate varies with incoming water temperature and selected output temperature.
• Super High-Efficiency Performance: An impressive 0.93 Uniform Energy Factor (UEF) supports efficient water heating and energy savings.
• Dual Heat Exchanger Design: Primary copper and secondary stainless steel heat exchangers are engineered to capture extra latent heat for maximum efficiency and durability.
• Hot-Start Programming™: Helps keep the unit ready between back-to-back hot water uses to help reduce cold water bursts.
• Flexible Venting Options: Supports Schedule 40 PVC, CPVC, and polypropylene venting materials up to 60 feet with 2-inch pipe or 150 feet with 3-inch pipe.
• Compact & Lightweight Profile: Enhanced design is up to 20% smaller and lighter to simplify single-person handling and mounting.
• Retrofit-Friendly Clearances: Industry-best 1/2-inch side-to-side clearance allows for safe placement in tight indoor utility spaces.
• 1/2-Inch Gas-Line Compatibility: Accommodates 1/2-inch gas lines up to 24 feet where permitted by local code, making tankless upgrades easier.
• Low NOx Emissions: Meets strict 14 ng/J NOx requirements and is SCAQMD Rule 1146.2 compliant.

Understanding Tankless Water Heater Sizing

The RTGH-84DVLN-3 provides a maximum flow rate of 8.4 GPM at a 35°F temperature rise. At a 45°F temperature rise, the maximum flow rate is 6.7 GPM, while a 67°F temperature rise provides a maximum flow rate of 4.6 GPM.

Flow capacity varies based on incoming groundwater temperature and the desired water temperature. The unit's flow-rate capacity by zone ranges from 3.6 to 7.0 GPM based on groundwater temperatures from 37°F to 77°F.

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

Refer to the Water Flow (GPM) chart below to compare estimated flow rates at different temperature rises and determine whether the Rheem RTGH-84DVLN-3 model can meet your household's hot water demand. Actual flow rates vary depending on incoming water temperature and the selected water heater temperature.

Energy Efficiency & Performance

• Uniform Energy Factor (UEF): 0.93
• Maximum Flow Rate: 8.4 GPM at a 35°F temperature rise
• Gas Input: 11,000 up to 157,000 BTU/h
• Activation Flow Rate: 0.4 GPM (0.26 GPM minimum continuous flow)

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 RTGH-84DVLN-3 Condensing Indoor Tankless Water Heater
• Mounting and Spare Parts Kit
• Vent Screens
• 6-Foot, 120V, 3-Prong Power Cord
• Use and Care Manual

Requirements & Considerations

• Fuel Type: Configured for Natural Gas. (Liquid Propane RTGH-84DVLP-3 model available separately).
• Installation Type: Indoor installation. (Outdoor conversion kit RTGH-X sold separately if exterior installation is required).
• Venting: Uses 2-inch or 3-inch Schedule 40 PVC, CPVC, or polypropylene pipe. Supports up to 60 feet of 2-inch pipe or 150 feet of 3-inch pipe.
• Gas, Water & Condensate Connections: 3/4-inch NPT gas, hot water, and cold water connections, plus a 1/2-inch NPT condensate drain connection.
• Clearances: Maintain 12 inches top/bottom, 1/2 inch sides, 1/2 inch front, and 0 inches back clearance for safe operation and service access.
• Electrical Requirements: 120V, 60Hz power supply (85W normal operation, 132W anti-freeze protection draw).