Rheem Tankless Water Heaters Review and Buying Tips

A review of Rheem tankless water heaters for efficient domestic water heating. Explore the features, benefits, and find out how Rheem with the smart features, on-demand technology, and eco-friendly gas burner can lower your energy bills and help you protect the environment.

Moreover, 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 well-known Rheem manufacturer.

Best selling Rheem tankless models

(sold on Amazon.com)

Rheem tankless water heaters are designed as gas- and electric-powered devices for continuous water heating and an endless supply of hot water. This article is about natural gas and propane-powered models that provide the most cost-effective solution. Found only in gas tankless models, 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 – you won't run out of hot water because Rheem tankless water heaters ensure infinite and constant delivery.

The newest advanced models come with a built-in recirculation system and smart technology integration, so hot water is ready instantly at the set temperature.

You just have to buy the right – advanced model, such as Rheem RTGH-RH11DVL.

And, you can even connect tankless water heaters to the EcoNet WiFi system 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:

  • Rheem Prestige High-Efficiency models with built-in recirculation
  • Rheem Prestige High-Efficiency models with no recirculation
  • Rheem Classic Mid-Efficient models

High Efficiency with the built-in recirculation

Prestige High-Efficiency models with built-in recirculation are the most advanced models from all Rheem tankless water heaters. They use condensing technology and an integrated pump to maximize efficiency and savings and provide an accurate and stable output temperature, so showers are more comfortable for all 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 simple to repair.

There are two models with 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, making the installation costs lower. And if using the outdoor conversion kit, you can install a unit outdoors.

The largest model is RTGH-RH11DVL (sold on amazon.com), comes with a high power of 199,000 BTU and a flow rate of up to 11 GPM, making it ideal for large homes with up to 4 bathrooms, even if the house is located up to 10,000 feet above sea level.

If your home is smaller, buy a model - RTGH-RH10DVL (sold on homedepot.com), which comes with a lower gas input of up to 180,000 BTU and flow rate of 10 GPM. Both models have superior energy factors of 0.94.

The built-in recirculation system delivers hot water without waiting at the tap, resulting in reduced water and energy waste. It saves homeowners up to 12,000 gallons of water annually. 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
  • Ultra-Low NOx gas emission to reduce pollution
  • Preheat mode and recirculation eliminates "cold water sandwich"
  • 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 several sizes; 120,000, 157,000, 180,000, and 199,000 BTU, using natural gas or propane and installed indoors or outdoors. The largest model can also deliver enough hot water in 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, vent lengths of up to 150 feet, 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 needed power is used, even for small water flow such as Rheem's minimum of 0.26 GPM.


Mid-efficient heaters come from the Classic Plus (RTG) series and are equipped with only one heat exchanger, providing an energy efficiency of around 84% (UEF is 0.81-0.82). These tankless devices are not considered condensing, but due to their 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 PVC venting, RTG models use stainless steel and concentric vents instead. Other features such as Hot Start Programming, Overheat Film Wrap, and others, 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 indoor and outdoor models and provide enough hot water from smaller to larger homes, with up to 3 bathrooms, but in warmer regions.

Rheem Mid-Efficient tankless water heaters are designed with advanced electronics for better control, monitoring, and diagnostics. With the EcoNet WiFi feature, you can remotely check out the status and parameters (some models).


Max. Power (BTU) 160,000 180,000 199,900 120,000 157,000 180,000 199,900 199,000 180,000 199,000
Energy Factor (UEF) 0.82 0.82 0.82 0.91 0.93 0.93 0.93 0.93 0.94 0.94
Ultra-Low NOX No No No Yes Yes Yes Yes Yes Yes Yes
Energy savings (up to) 800 800 800 1100 1100 1100 1100 1100 1100 1100
Max water flow (GPM) 7 8.4 9.5 6.8 8.4 9 9.5 9.5 10 11
# of baths 2-3 3 3-4 2.5 3 3-4 4 4 4 4
Weight (lbs) 54 54 54 82 82 82 82 82 85 85

Features to look for


The recirculation pump installed inside the best of Rheem tankless water heaters – Rheem condensing circulates hot water through your home plumbing and is always ready at the fixture. No more waiting for hot water to come, no more wasted water and energy. The circulation pump activates either on-demand or when the timer engages.


The EcoNet allows homeowners to take advantage of the smart integrated features so you can use your smartphone to check the status or even protect your home from water damages. These include water leak detection, system shut off, NEST and WINK smart home integration system, maintenance reminders, gas, and water usage reports.

Auto-Learn programming

This feature allows a water heater to track your water usage so it can provide the best experience when you need it the most.


Modulation with the high turn-down ratio allows a gas burner to change its power depending on the demand. It provides better control, accuracy, and savings. The water temperature is stable, so there are less fluctuation or "cold water sandwich" effects.

Features that save on installation

Look for a water heater with flexible venting so it can provide more options during installation. For example, condensing and tankless water heaters use PVC vents with up to 150 ft. in length for 3" tube size and lengths up to 50 ft. for 2" tube size. Such models are compatible with the room air intake.

Tankless models are usually designed to use ¾ water and gas piping, but if they are compatible with the ½" gas line, that will bring more flexibility and increase savings.


If you are not on a budget, have a large family, and would like to enjoy the most advanced features one tankless water heater offers, select a Rheem RTGH-RH11DVL

Rheem RTGH-RH11DVL is the tankless water heater with the highest water flow and power, comes with the reduced gas emission, and utilizes condensing technology and a recirculation pump.

Also, if the above model is too powerful for your needs, or is too expensive, choose the condensing RTGH-95 model, it includes the most innovative features and specs but without the recirculation system.


Before you buy any of the great Rheem tankless hot water heaters, keep in mind to select the right size or unit with the proper water flow (in GPM), so it can satisfy your family's needs at peak times. These appliances do not have a storage tank, but they heat water on demand, only when the hot water tap is open.

Rheem tankless is the right solution for efficient domestic water heating, not only at the point of service but also for the whole house, saving you valuable floor space, time, and energy. And for the greatest experience, maximized efficiency and savings, choose one of the condensing models.


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