Rheem RTE 9 Electric Tankless Water Heater, 3 GPM Review



Rheem are known as the pioneers in the water heater market as they have consistently produced well received and high end water heaters over the year. The Rheem RTE 9 electric tankless water heater is another example of a great water heater provided by the manufacturers who always keep performance and quality in the picture.

The Rheem RTE 9 water heater can deliver 3 gallons of hot water per minute and is viewed as an ideal point-of-use model. The RTE 9 is an Energy Star Certified water heater, which means it is designed to provide energy efficiency in long term use. The RTE 9 features a standard body with a mounted on-unit temperature control. The RTE 9 has been well received by users so far, so let’s take a look at what its features before deciding whether it is suitable for your needs or not.

Important Specs and Features

The Rheem RTE 9 electric tankless water heater features a rugged brass/copper heat exchanger that accounts for high energy efficiency. The heat exchange is built for durability in the long term, and will be the last element in the water heater that gets worn out. Its compact design and relatively lightweight body makes it easy to install just about anywhere. Rated by Energy Star, the RTE 9 allows the user to save on their monthly energy bills. The body is designed to maintain consistent water temperature, which eventually helps cut down on water heating bills.

The Rheem RTE 9 features an LED that indicates when the water heater is active or in standby mode. The water heater is fairly simple to install and use. All you need is a standard 1/2 inch water connection and a power supply cord to use the RTE 9. It only consumes 240 volts of electricity to provide continuous supply of hot water, and is ideally used for showers and sinks.

The RTE 9 electric tankless water heater features an on-unit temperature control knob that easily allows the user to adjust temperature levels based on their needs. The self modulating control automatically adjusts the power consumption that is required to meet the pre-set temperature by the user. In other words, the self modulating control will account for minimum heat loss, ensuring energy efficiency in the long run.

The Rheem RTE 9 comes with a 10 year limited warranty on the heat exchanger, and a one year warranty on other parts. It’s one of the fastest electric tankless water heaters as it can provide hot water
within 15 to 20 seconds of turning the tap or shower on. The RTE 9 only requires yearly maintenance which in all fairness is quite easy. The Rheem RTE 9 is designed for flexibility, as it can be used as a standalone alone, as an add-on unit for your existing water heating system, or as a point-of-use tankless water heater.


  • Compact design and lightweight – highly portable and convenient.
  • Energy Star rated – highly energy efficient.
  • Fairly simple to install, use, and maintain.
  • Durable heat exchanger – accounts for more energy efficiency.
  • Ideal as a standalone, complimentary, and point of use unit.


  • Only practical for small homes or places where hot water usage is low.
  • Hot water flow tends to get low in colder areas.

Who Should Buy

The Rheem RTE 9 electric tankless water heater is ideal for homes, apartments, condos, offices, restaurants, and even boats. It’s basically a water heater that is ideal for all applications where hot water is needed. It can be used as a standalone unit for small homes and apartments with not more than three people. This will ensure continuous hot water supply at constant flow rates.

For bigger homes and apartments, we recommend that the RTE 9 be used as a complimentary unit and not as a standalone unit. For example, the RTE 9 can be used on a shower and sink of a particular room in a home or apartment. As for point of use, the RTE 9 can be installed on independently on showers, sinks, and any water outlet that meet the requirements.


The Rheem RTE 9 electric tankless water heater has quite a reputation to live up to, and so far it has been successful. It can be installed quickly and easily without having to buy additional materials. The users have found it as quite useful and have praised the RTE 9 for its energy efficiency both in the short and long term.

The Rheem RTE 9 is yet another amazing water heater from Rheem that delivers consistent and continuous hot water. While it may not be as compact as other tankless water heaters today, it definitely is one of the most cost effective ones. Overall, the RTE 9 is a great buy that will prove to be a worthwhile investment in the long run.