Rheem RTG-84XLN-3 Tankless Natural Gas Water Heater - Continuous Hot

In this review of the Rheem RTG-84XLN-3 the bottom line is clear: this compact outdoor tankless natural gas water heater is for homeowners who need reliable, continuous hot water with lower running waste. The reviewer found it especially useful for medium to large households where simultaneous uses like showers and dishwashers are common, because the unit delivers up to 8.4 GPM and uses Hot Start Programming to avoid cold-water bursts. Installation is simplified by the smaller size and wall-mount design, and customers report the heater warms quickly and consistently.

Key Features

• Continuous Hot Water: Delivers enough hot water for whole-house use, supporting simultaneous applications such as a shower and dishwasher without noticeable drop in temperature.
• High Efficiency: Operates only when hot water is needed so it reduces standby energy use compared with tank heaters and can lower utility costs.
• Water Saving Setting: Includes a setting that can save up to 1,100 gallons of water per year by reducing wait time for hot water at fixtures.
• Hot Start Programming: Keeps the heater in a ready state to prevent cold-water bursts between back-to-back uses, improving comfort during consecutive showers.
• Compact Design: The newer model is about 19% smaller and 22% lighter than the prior version, making it easier to fit into tight outdoor mounting locations.
• Safety Overheat Protection: Rheem's Overheat Film Wrap on the heat exchanger offers protection against overheating for added peace of mind.

Who It's For

The RTG-84XLN-3 suits homeowners with moderate to high hot water demand who prefer an outdoor, wall-mounted solution to save indoor space and avoid a storage tank. It is a strong choice for families running multiple appliances and showers at the same time because of its 8.4 GPM capacity and quick recovery.

It is less suitable for very small properties where minimal hot water flow is required or for installations that require a condensing unit for higher thermal efficiency. Also, those who need indoor installation or are limited by strict venting rules should verify local codes before purchase.

Pros & Cons

Pros

• Provides reliable, fast hot water recovery for whole-house use, with customers noting quick heat-up times.
• Energy efficient operation since it only runs when hot water is needed, helping reduce energy waste.
• Built-in features like Hot Start Programming and Overheat Film Wrap improve comfort and safety.
• Smaller and lighter than the prior model, simplifying handling and installation in tight outdoor spaces.

Cons

• As a non-condensing outdoor unit, it may not reach the highest possible thermal efficiency compared with condensing models in very cold climates.
• Outdoor mounting requires appropriate clearances and weather protection, which can limit placement options on some properties.

Specifications

Brand	Rheem
Model	RTG-84XLN-3
Fuel Type	Natural Gas
Flow Rate	8.4 GPM
Configuration	Outdoor non-condensing tankless
Size / Weight	Approximately 19% smaller and 22% lighter than previous model
Special Features	Hot Start Programming, Water Saving Setting, Overheat Film Wrap

Our Verdict

For homeowners who need dependable, on-demand hot water and want to save space and operating energy, the RTG-84XLN-3 is a practical, value-oriented choice. Its combination of continuous hot water, water-saving features and safety protections makes it a smart upgrade from tank systems, particularly for those able to mount the unit outdoors and who prioritize quick recovery over the absolute highest condensation efficiency.

Frequently Asked Questions

Can this unit supply multiple showers at once?
Yes, the RTG-84XLN-3 delivers up to 8.4 GPM, which is sufficient for simultaneous shower and appliance use in most family homes.

Is the heater suitable for indoor installation?
This model is an outdoor non-condensing unit and is designed for outdoor wall-mount installation; indoor installation is not implied by the product description.

How does the water saving setting help?
The Water Saving Setting reduces wait time for hot water and is reported to save up to 1,100 gallons of water per year by minimizing cold water draw before hot arrives.