5 Best Rheem Tankless Water Heaters Reviewed



Choosing a new tankless heater isn’t a decision that you should make quickly because selecting the wrong one can limit how long your showers are and how many people can shower in a single day. You also risk choosing one that causes your energy bills to skyrocket. A smart way to find one that fits the needs of your home is with a look at the products available from top manufacturers like Rheem.

We know that many people use these models in their homes today, but we wanted to find out which model does the best job. That is why we looked at customer reviews as well as information from the manufacturer and prices to find out which models are worth your investment.

Our ultimate choice was the RTE 13 (Check Price on Amazon.com), which is an electric model that is easy to use and highly affordable. Unlike other fancy tankless heaters that come with a lot of bells and whistles that you’ll never use, this one has three simple lights that tell you when it’s on and when it’s in standby mode and a knob to turn up the temperature. The 13 also has a four gallon per minute flow rating, which is suitable for smaller homes with one bathroom and one kitchen.


How to Choose the Model?

How Does the Flow Rate Compare to the Temperature Rise?

Whenever you shop for a tankless heater, you need to look at the flow rate, which is a measurement that determines the amount of H2o you can use at the temperature you selected in one minute. You also need to look at the temperature rise. This refers to the difference between the temperature of the groundwater as it reaches the unit and the heat that you chose.

The reason this comparison is so relevant is that it tells you how much H2o you can use based on the temperature outside. If the temperature needs to change by 30 degrees or more, you’ll usually enjoy less water than if it needs to change by 10 degrees. This also plays a crucial role in showing you which tankless heaters will work better based on your climate.

How Many Rooms Can it Accommodate?

Rheem makes products like the RTE 13 that is perfect for smaller homes. You can hook one up and get almost instant hot water in both your bathroom and your kitchen. Some larger tankless heaters have a higher flow rate and can accommodate more rooms with two or more bathrooms as well as your kitchen.

How Do You Change the Temperature?

Consider looking at how you will change the temperature too. The RTE 13 is an example of one of the older models that is still in production. It has a convenient knob on the front for adjusting the temperature, but instead of letting you pick an exact degree, it only enables you to choose a temperature range like medium or hot.

The RTEX-18 is a modern model that has a digital design that lets you make more accurate adjustments. You can turn the temperature up and down by one degree at a time to reach the perfect temperature for your home.

Where Will You Install It?

You also need to look at where you will install it. This tells you whether you need to hard wire it into your existing electrical system or if you can plug it into a nearby outlet. Rheem makes products designed for both indoor and outdoor use.

One significant benefit of an indoor system is that you don’t need to go outside when the tankless heater fails, or you want to make some setting changes. These systems are usually smaller in size. You’ll find some that are small enough for installing inside a cabinet or a sink too.

Outdoor tankless heaters will mount onto one of your exterior walls and will require that you head outside each time you need to access the menu. The manufacturer makes some models that come with a remote control and have a long range. This lets you make the adjustments that you need while standing on your front porch or across your yard.

When buying an outdoor model, always make sure that it comes with freeze protection. If the water coming from the ground is too cold, it can freeze inside the pipes and cause the pipes to burst while also preventing you from using hot water.


Top-Rated Picks on the Market


1. RTE 13 Electric (Check Price on Amazon.com)

RTE 13 Electric

For smaller homes and apartments, the 13 will do a fantastic job because you can hard wire it directly into your electrical system and start using it just minutes later. Though it does use some electricity, it uses a smaller amount to help you keep your energy bills at manageable levels.

The RTE 13 comes with a durable heat exchanger that uses both brass and copper to help it last longer rather than the plain copper exchanger that comes with other tankless heaters.

This model took our top spot because it is so easy to use. Markings on the front show you where the lowest temperature level is and the location of the highest temperature, and you can turn this knob in either direction to adjust the temperature almost instantly.

As it has a maximum flow rate of only four gallons though, the RTE 13 does a better job in smaller homes than larger ones and may not provide you with all the water that you need.


Easy to use because of a temperature knob on the front
Works with most homes because it needs just 240 volts
Includes a more durable heat exchanger made from brass and copper


Much more understandable and more fundamental than some modern models
Has a lower four gallon per minute flow rating that is best for small homes


2. RTG-84XLP (Check Price on Amazon.com)

RTG-84XLP 8.4 GPM Low

Our second choice is the RTG-84XLP, which came close to landing on our number one spot because it works in most climates, though you will need to install it outdoors.

It has built-in protection against freezing temperatures to stop from freezing inside the lines and to keep the water that reaches you at a higher temperature. You even get a remote control that lets you change your maximum temperature rating when you’re further away from the tankless heater.

We like the high flow rating on this tankless heater, which hits a maximum of 8.4 gallons every minute.

The exact rating depends on the temperature of the ground H2o and how high the temperature needs to rise, but you’ll get more than eight gallons of H2o per minute when the temperature needs to raise by 30 degrees.

On the downside, that means the flow rating can drop significantly when the groundwater is much colder.


Hits a maximum flow rating of more than eight gallons per minute at a rise of more than 30 degrees
Comes with a remote control for fast setting changes
Suitable for use in both warmer and colder climates


Only works when installed in an outdoor spot
Flow rate can drop significantly when used with colder groundwater


3. RTG-64XLN (Check Price on Amazon.com)

RTG-64XLN 6.4 GPM Low NOx

When searching for a model that works with your natural gas and will keep water from freezing when installing outside, the RTG-64XLN is one of your top choices. This tankless heater comes with 10-feet of wire for fast connecting to your thermostat, which lets you adjust the temperature in seconds.

You’ll also get a remote control that lets you change the temperature while several feet or more away from the unit.

This model is perfect for use in colder climates too and any region where the groundwater is chilly because it works with a temperature rise of up to 35 degrees and lets you get more than six gallons of H2o out of your faucet per minute at the temperature you set.

It’s also a low emissions tankless heater that produces less noise as it starts up and runs.


Comes with a spool of wire for connecting to your thermostat and a remote control
One of the top low emissions models that is safe for use in all regions
Produces more than six gallons of H2o when the temperature needs to change by up to 35 degrees


Only works outside because it provides some fumes as it runs
Regular power outages can void your warranty


4. RTGH-95DVLN (Check Price on Amazon.com)

RTGH-95DVLN 9.5 GPM Indoor Direct

Many homeowners searching for the best tankless heater want one that will help them lower energy costs, and if you’re one of those shoppers, you’ll like the RTGH-95DVLN.

This mode comes with a high rating from Energy Star and has a 94% energy efficiency rating because it uses significantly less energy than comparable tankless heaters from other manufacturers do.

It comes with both electronic and intelligent controls too that each person in your household can use to adjust the temperature.

Designed for use with most PVC pipes, this model will work with two-inch tubes of up to 38-feet long and three-inch pipes of up to five-feet long, which gives you more freedom as to where you install it.

You’ll want to pick a safe location outside because high winds can loosen connections and wires inside. This model comes with a newer and more modern heat exchanger made from durable stainless steel too.


Has a 94% energy efficiency rating from Energy Star
Compatible with both two-inch and three-inch PVC pipes
Electronic controls are comfortable for all family members to use


Takes some time for the H2o to heat up, especially when the ground temperature is low
High winds can loosen connections and keep the unit from working


5. RTEX-18 (Check Price on Amazon.com)

RTEX-18 240V 2 Heating Chambers

When creating a list of the top tankless heaters from Rheem, we added the RTEX-18 because it’s an example of the newer designs the company makes as it moves forward.

This has a state of the art design that includes two heating elements inside that both use copper and help the water come up to the maximum temperature you selected faster. It does tend to adjust that temperature though because of the temperature of the water as it comes out of the ground.

One of its top features is a digital display located on the outside of the case that lets you see the temperature, and you can use this show to adjust the temperature by one degree at a time.

It also has a self-modulating design that we like because this design lets it adjust the flow rating and H2o pressure based on the needs of your home.


Digital external display lets you make temperature changes by one degree at a time
Self-modulating design allows it to change pressure and its flow rating based on household need
Two heating elements made from copper inside provide more hot water with less wait time


Manufacturer requires a lot of steps to replace parts or make repairs
Temperature settings can fluctuate without your permission


Best Model from Rheem

RTE 13 Electric

Check Price on Amazon.com

Out of all the options available from Rheem, it wasn’t hard to pick the 13 as the top model after looking at customer reviews and factors like the cost to run and ease of use.

Changing your water temperature with this tankless heater is as comfortable as turning the knob, and you can set the knob all the way in one direction to turn it down to the lowest level or all the way in the opposite direction to enjoy steaming hot H2o. It comes with a heat exchanger that uses both brass and copper to cut down on the maintenance needed and to extend the life of that piece.

Another feature that we like about the 13 is the three lights located on the front and just above the temperature knob. Two of the views come on and glow bright red to let you know that the tankless heater is on. Those lights switch off as a green light comes on when the product enters standby mode.