Rheem RTEX-24 Residential Tankless Water Heater Review


The Rheem RTEX-24 brings it all to the table when it comes to providing hot water throughout your home. This highly energy efficient model does an outstanding job at providing hot water services to one fixture, or your whole house. Like other tankless models, the RTEX-24 offers instant continuous hot water that won’t ever leave you in a cold shower. 

It is easily capable of heating the water for an entire house, or just a single appliance at a time. At 6 GPM, more than 3 devices at a time may start to push the limits of this heater. 

More on that later.

But for a two or three bath house, this heater does a quality job.

This model offers unlimited hot water in a small form factor that is easy to install nearly anywhere. It only weighs 17.8 pounds making it easy to mount on the wall in the most convenient location. Additionally, the heater has 3 durable copper immersion heating elements that are able to be serviced in the field.

One handy feature is the external digital thermometer display that you can control in 1 F increments, making setting your preferred water temperature as easy as possible. The heater is self-modulating, so it will only use the necessary power to heat your water, and nothing more.

This particular model is 99.8% energy efficient, making it one of the more efficient models on the market right now. After just a few years of using the RTEX-24, this heater will pay for itself in energy savings.


  • Instant, continuous hot water to your whole house
  • Small form factor, easy installation
  • Digital temperature display
  • Self-modulation that adjusts power to meet hot water demand
  • 99.8% energy efficient


  • Cost to operate increases during the winter
  • May not work as advertised if ground water is exceedingly cold
  • May require extra components to install

Let’s Dive More Into This Hot Water Heater

Are you tired of running out of hot water in your shower? Does unlimited hot water to all the devices in your home sound too good to be true? The Rheem RTEX-24 delivers all of this in one easy to install package. 

It can easily replace a 50 gallon hot water heater with its powerful 6 GPM output. While it can easily provide hot water to multiple fixtures, it can get a little stressed with over 3 fixtures at one time. 

This chart will help you to determine how many fixtures this Rheem heater can operate at one time (add up to 6 GPM)

  • Standard Hand Sink – 0.5 GPM
  • Washing Machine – 1 to 1.5 GPM
  • Kitchen Sink – 1 to 2 GPM
  • Dishwasher – 1 to 2 GPM
  • Water-Saver Shower Head – 1.5 GPM
  • Standard Shower Head – 2.0 GPM
  • Bath Tub – = 4 GPM
  • Whole-Home – up to 6 GPM

Installation is fairly straightforward and uses a bottom ¾” NPT connection to connect to the main line. The heater comes with an installation manual, but if you are unsure it is always wise to call a professional to ensure it is getting hooked up properly. Once installed, you can expect hot water that never ends!

Read Customer Reviews From Around The Net

Here’s what reviewers had to say about the RTEX-24:

“Replaced a 50 gallon hot water tank and have not noticed any difference in our hot water. Still waiting for an electric bill to compare costs; but as of now it was the right decision.”

Wow – the industrious heater was able to replace a 50 gallon hot water tank – now that’s powerful performance from the little guy!

“So far fantastic. Limitless hot water. Relatively easy installation. Wife thrilled with long showers. Needs a reduced inline from 3\4 to 1\2 inch so heater can keep up. Well worth the money.”

See – what we’ve been telling you is true! Fully enjoy your showers knowing that you will never run out of hot water – even the person after you will have no fear turning the shower knob! This reviewer also gives a handy tip that the heater needs a reduced inline to help the heater keep up with demand – if you are unsure about this, consult a professional before installing!

“I also had only two. I had to add the third one. My electrician was able to use the old connection for the old water tank for the 3rd connection. It cannot work without the 3rd connection. I am so glad I called the electrician and had it set up correctly. It is perfect.”

This reviewer is talking about making sure the third chamber in the hot water heater is on and running properly to maximize performance.

Wrapping It All Up

The Rheem RTEX 24 is one of the best hot water heaters you can but in 2020. Rheem is a well-known brand that has stood the test of time. They are constantly innovating in the tankless field and are always bringing new technologies to the table. Whether you are looking for a heater for an apartment or for your whole house, the RTEX-24 will deliver the goods. So if you are looking to replace your old bulky water heater, this model would be a perfect way to go.