Rheem Tankless Hot
Water Heaters Review and Buying Tips

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Review of the Rheem tankless hot water heaters for home use. Explore the features, benefits and find out how Rheem with the on-demand technology can lower your energy bills on water heating. And with the endless supply of hot water and better than ever comfort and convenience, you will surely make the right decision – getting a tankless and condensing water heater from the Rheem manufacturer.

Rheem tankless water heaters are designed as gas- and electric-powered devices for the continuous water heating and an endless supply of hot water. The advanced engineering ensures accurate temperature control, stable and reliable operation, compact and space saving design, long life, better diagnostics, and safety.
So don’t worry if you have to run the dishwasher, washing machine and take a long bath at the same time – Rheem tankless ensures plenty of hot water. And with the built-in recirculation system, hot water is ready instantly. You just have to buy the right – advanced model.

And, you can even connect tankless water heaters to EcoNet WiFi feature and get the notification if there is a leak (with shut off option), about gas and water usage and allow integration with NEST & WINK smart home systems.

Rheem gas tankless water heaters

Rheem gas tankless water heaters for home use are designed as:

  • High Efficiency with Built-in Recirculation

  • High Efficiency
  • Mid-Efficient

High Efficiency with Built-in Recirculation

High-efficiency models with built-in recirculation are the most advanced. They use condensing technology and built-in pump to maximize the efficiency and savings and provide an accurate and stable output temperature, so the showers are more comfortable for all the users.

Condensing models preheat and heat water in two stainless steel heat exchangers, resulting in ultra-high efficiency and simultaneous supply of hot water to multiple fixtures. The advanced self-diagnostic system makes the units very safe and simpler to repair.

There are two models with the built-in recirculation, both coming from the Professional Prestige series. They are designed for indoor use only, utilizing direct venting systems with PVC pipes and up to 100 feet in length.

The largest model is RTGH-RH11DVL, which comes with the high power of 199,000 BTU and flow rate of up to 11 GPM, which is sufficient for homes with up to 4 bathrooms. If your home is smaller, buy a smaller model - RTGH-RH10DVL, which comes with the gas input of up to 180,000 BTU and flow rate of 10 GPM. Both models have the energy factor of 0.94.

The built-in recirculation system provides hot water without the wait at the tap and with no water and energy waste. This is done with the on-demand or timer based pump activation allowing hot water to be ready anytime.


  • Recirculation pump allows instant hot water and water savings

  • Preheat mode and recirculation eliminates “cold water sandwiching”

  • Auto-Learn programming keeps the record of water usage for enhanced comfort

  • More safety with the water and gas leak detection

  • 12-year warranty

High Efficiency

You can also buy tankless water heaters from Professional Prestige (or RTGH) series that are ultra-high efficient and condensing but without the recirculation system built-in. These High-Efficiency models are available in three sizes; 157,000, 180,000 and 199,000 BTU and can be installed either indoor or outdoor, using natural gas or propane. While the above values are the highest output, they can modulate the power 10 times less. The largest model can also provide enough hot water for homes with up to 4 baths.

Installation of the High-Efficiency models is fast and easy. You can use PVC venting with pipes in three different sizes, and take advantage of the built-in condensate neutralizer and ½” gas pipe.

Safety and comfort are superior over other types and brands; freeze protection protects the unit from lower temperatures (up to -30 F), Overheat Film Wrap from overheating, while Hot Start Programming reduces the temperature fluctuation and cold water bursts. The modulating power ensures that only the power that is needed is used, even for small water flow such as the Rheem’s minimum of 0.26 GPM.


rheem tankless hot water heater rtg74Mid-Efficient heaters, which are coming from the RTG series, are equipped with one heat exchanger only and are able to provide energy efficiency of around 84% (EF is 0.81-0.82). These tankless devices are not considered as condensing, but due to its ability to modulate the power, they are still efficient and able to deliver greater savings than the tank-type. As opposed to condensing models (RTGH series) and its PVC venting, RTG models use stainless steel and concentric vents instead. Other features such as Hot Start Programming, Overheat Film Wrap and other, including the warranty of 12 years are the same as found in the above High-Efficiency models.

Rheem RTG-95, RTG-84, and RTG-70 series are available as the indoor and outdoor models and are providing enough hot water from smaller to larger homes, with up to 3 bathrooms.

Rheem tankless water heaters are designed with the advanced electronic for better control, monitoring, and diagnostics, and with the use of EcoNet WiFi feature, you can check out the status and parameters remotely (some models).

Rheem tankless electric

Rheem tankless electric water heaters from RTEX series are designed for both point-of-use (POU models) and whole-house heating, for distant sinks or where it is not economical to use the central heating system.
These small electric and on-demand heaters can be installed under the sink in the bathrooms or kitchen, even in the garage, workshop or barn, cabin or cottage, and anywhere else where you need hot water fast and in an endless supply.

What makes them attractive to buy, is not only the sleek and modern look but also features such as adjustable digital temperature display, self-modulating power control, and standard size connections.

Based on the desired temperature settings, the temperature of the groundwater in your area and flow rate, you have an option to select one of several models, ranging from 12 to 36 kW, and for up to three fixtures.
They come with the 5-year warranty on the heat exchanger and one on other parts.

The most popular and sold unit is RTEX13.

Advantages of tankless type

  • Continuous and endless supply of hot water

  • High efficiency

  • Energy Star compliance

  • Fast water delivery with the recirculation

  • Advanced electronics with the self-diagnostic system

  • Low operating costs

  • Ultra-Low NOx emissions

  • Small and compact size

See the reviews and prices on Amazon.com.


Before you buy any of the great Rheem tankless hot water heaters, keep in mind to select the right size or unit with the right water flow (in GPM), so it can satisfy your home needs at the peak times. These appliances do not have a storage tank, but they heat water on demand when the hot water tap is open. Rheem tankless is the right solution for heating domestic water, not only at the point of service but the whole house also, saving the valuable floor space, time and energy. And for the greatest experience, maximized efficiency and savings, choose the High Efficient and condensing model RTGH-95.

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Picture is courtesy of Rheem company

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