7 Best Rheem Tankless Water Heater In 2021 – Review & Buyer’s Guide

Water heating systems are an integral part of our day-to-day life. They deliver limitless warm water for cooking, showering, cleaning, and many other purposes.

Considering how much we are dependent on them, it is worth it to invest some time to ensure we select the best Rheem tankless water heater for our residence.

Finding the right device for your house or office can be a complex task. Numerous manufacturers are working in the industry, and they are vying for your attention. All of them claim that their appliances outperform their opponents, and Rheem is one of them.

Introduction Of Rheem

It is one of the biggest and most reliable companies when it comes to Rheem tankless water heater with recirculating pump.

By integrating revolutionary technology and cutting-edge features, they have been making award-winning HVAC systems and water heating equipment for more than 90 years.

Initially, they started working as a petroleum packaging company. It is now a universal brand producing products in several countries, including America, Canada, Mexico, New Zealand, and many others.

If you are thinking about deploying or replacing a water heater, you should consider buying a Rheem water heater 40 gallon gas.

Furthermore, their units provide endless warm water and never run out of water even for bigger households. They distribute both gas and electric heaters so that you can pick any one of them based on your needs.

In this guide, we will take a look at some of the best water heaters that Rheem has to offer to you and break down their advantages and disadvantages. Our Rheem electric tankless water heater reviews can help you make a knowledgeable decision.

7 Best Rheem Tankless Water Heater

Rheem RTGH 95DVLN 2 Tankless Water Heater9.8

Rheem RTGH-95DVLN-2 Tankless Water HeaterFeature:

  • Water-saving technology saves up to 1,100 gallons annually
Rheem RTEX 24 24kW 240V Electric Tankless Water Heater9.5

Rheem RTEX-24 24kW 240V Electric Tankless Water HeaterFeature:

  • Generates up to 5.9 GPM in one minute
Rheem RTEX 13 Residential Tankless Water Heater9.5

Rheem RTEX-13 Residential Tankless Water HeaterFeature:

  • Compact heater saves a lot of storage space
Rheem RTEX 18 18kW 240V Electric Tankless Water Heater9.5

Rheem RTEX-18 18kW 240V Electric Tankless Water HeaterFeature:

  • An energy-efficient heater can help you save a considerable amount
Rheem RTGH 84DVLN 2 Natural Gas Condensing Tankless Water Heater9.4

Rheem RTGH-84DVLN-2 Natural Gas Condensing Tankless Water HeaterFeature:

  • Designed for outdoor deployment
Rheem RTG 70DVLN 1 Tankless Water Heater9.5

Rheem RTG-70DVLN-1 Tankless Water HeaterFeature:

  • Never runs out of water
Rheem RTEX 27 Residential Tankless Water Heater9.5

Rheem RTEX-27 Residential Tankless Water HeaterFeature:

  • Supports multiple applications at once

1. Rheem RTGH-95DVLN-2 Tankless Water Heater

Natural gas heaters have a negative reputation in the market. People think that their dependence on fastly-depleting fossil fuels makes them injurious to the environment. Rheem RTGH-95DVLN-2 proves this claim wrong.

Best Overall
Rheem RTGH 95DVLN 2 Tankless Water Heater

Rheem RTGH-95DVLN-2 Tankless Water Heater


  • Designed for indoor installation
  • Water-saving technology saves up to 1,100 gallons annually
  • Hot start programming decreases cold water burst and stays in a ready-fire state
  • Comes with a recirculation pump

It does not release bucket loads of harmful gases into the atmosphere. In fact, it emits only fewer numbers of gases than a tank-style natural gas heater.

This Rheem tankless water heater with recirculating pump equips EcoNet smart home technology that comes with a smartphone application for both android and apple phones. After installing it on your device, you will be able to obtain timely care and maintenance alerts.

Furthermore, it allows you to operate it from a remote distance. You can conveniently set heating schedules, get weather forecasts, and plan for the weather head.

Its active monitoring system works 24/7 so that if your unit will require urgent care, it will notify you immediately. The automatic water-saving settings help you stop water wastage.

While starting up the machine, you can turn on the “setting” to save water by lowering its flow through the pipes in the activation stage. It intentionally puts a lid on the water entering and exiting until its internal temperature reaches the appliance’s set point.

It can help you save up to 1,100 gallons every year. On the other hand, this high-efficiency condensing indoor unit provides you limitless warm water.

It needs a minimum flow rate of 0.40 GPM to activate its built-in heating element and 0.26 GPM to keep it on. Its ultra-low NOx burner complies with the safety rules of SCAQMD with low emissions.


  • Material: Stainless Steel
  • Voltage: 120v
  • Installation Method: Wall Mount
  • Weight: 77 Pounds


  • Produces 9.9 GPM of water
  • Automatic water-saving setting
  • Integrates the latest technology


  • Pricey

Note: This water heating system provides you the best of both worlds. It delivers a maximum flow rate of 9.9 GPM in 60 seconds and needs a meager flow rate of 0.40 GPM for activation.
It utilizes natural gas to save money and features an ultra-low NOx burner that makes it an environment-friendly device.

2. Rheem RTEX-24 24kW 240V Electric Tankless Water Heater

This Rheem water heater 40 gallon gas is manufactured to deliver power of up to 24 kW and a water flow rate of 5.9 GPM. It uses larger ¾ connections that can be found on the appliance’s bottom.

Great Value
Rheem RTEX 24 24kW 240V Electric Tankless Water Heater

Rheem RTEX-24 24kW 240V Electric Tankless Water Heater


  • Self-modulating system
  • Generates up to 5.9 GPM in one minute
  • ON and OFF dial knob with adjustable digital temperature display
  • On-demand, constant hot water

You can fine-tune the hot water’s temperature between 80 to 140 degrees F using the integrated knob. The knob is present on the small screen.

It can supply endless water with an increment of 1 degree to the input, thanks to its advanced self-modulating system that works automatically. It ensures the appropriate temperature to the output, but you can change the temperature whenever you want.

Moreover, this residential machine is suitable for both small and bigger families. Its biggest advantage is that it is compact and has a modern design, allowing deployment at your desired location.

Best of all, the installation procedure of this affordable unit is straightforward and quick. Only a couple of tools and materials are required to install it.


  • Weight: 17.8 Pounds
  • Volts: 240 Volts


  • Sleek and modern design
  • Easy to install and operate
  • High-quality materials
  • 99.8% energy-efficient


  • Socket breakers and wiring are required
  • You will need to install a water softener to increase its lifespan

Note: You don’t have to be a technical expert to know that Rheem electric tankless water heater reviews are always a smart investment to make for your residence.
This unit is a sleek, reliable, sturdy, and easy to install model that will offer great value for money in the long run. So, why not take the dive?

3. Rheem RTEX-13 Residential Tankless Water Heater

Are you looking for a practical Rheem tankless water heater price? Then, the Rheem RTEX 13 can fit the mold. It is a tiny and energy-efficient device that offers top-notch results.

Premium Choice
Rheem RTEX 13 Residential Tankless Water Heater

Rheem RTEX-13 Residential Tankless Water Heater


  • Compact heater saves a lot of storage space
  • The thermostat dial lets you alter water temperature
  • Rugged brass and copper immersion heat exchangers
  • Self-modulating technology

For installation, it needs small space, but it is powerful enough to deliver warm water to several water sources. It is 8.25 inches wide and 12.625 inches tall, and its weight is only 8.5 pounds.

You can deploy this compact machine under the sink, in the bathroom or kitchen, or anywhere you want. It lets you regulate the temperature using the panel present on the front side of the heater.

Besides, it also features a thermostat dial that allows you to change the temperature over nine settings. The best Rheem tankless water heater needs only 0.3 gallons per minute for the startup of its heating elements.

It produces up to 3.17 GPM and distributes infinite hot water for two fixtures and a shower. Remember, in winters, RTEX 13 may not function as efficiently as in summers.

It relies on a rugged brass and copper immersion heat exchanger. This energy-efficient appliance modulates power consumption and delivers nonstop water.

Also, it requires 240v, 54 amps, and 13 kW of electricity. Along with that, you will also need to deploy a 6-amp breaker box.  


  • Weight: 0.01 Ounces
  • Voltage: 240 Volts
  • Watts: 13 kW


  • Max flow rate of 3.17 GPM
  • Supplies hot water to several fixtures
  • Easier to install
  • Durable and long-lasting


  • The temperature fluctuates between 109 and 135 degrees F

Note: This space-saving electric unit can replace your inefficient and large tank-style heater. Although it is energy-smart, you may have to upgrade your house’s electricity system. It does not work well in colder climates, but you can hang it in the RV, cabin, boat, and any other place.

4. Rheem RTEX-18 18kW 240V Electric Tankless Water Heater

This affordable and energy-efficient tankless machine provides endless warm water on-demand for single fixtures such as shower, sink, bathroom, and kitchen. It can deliver endless hot water in one or two bathrooms.

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater

Rheem RTEX 18 18kW 240V Electric Tankless Water Heater


  • An energy-efficient heater can help you save a considerable amount
  • The compact design makes installation easy
  • Offers limitless warm water
  • Replacement and maintenance are also easy
  • External digital thermostat control has an LED display

You can install it in the RV, camper, mobile house, and travel trailers. This residential Rheem water heater reviews device is easier to install. It has a compact design, so you won’t have to make extra space for it.

The whole appliance is solely 4″x15″x19″ so that it can fit easily into small spaces. This sleek and good-looking unit claims that it won’t ruin the beauty of your house’s interior design.

Additionally, Rheem RTEX-18 features digital temperature controls, so you can effortlessly set the desired temperature in 1-degree increments. Best of all, it is 99.8% energy-smart and creates up to 4.4 GPM, depending on the incoming water temp.

The downside of this Rheem water heater 40 gallon gas is that LED dimmable light bulbs flicker when the unit connects. You can easily resolve this issue by installing glowing bulbs.

The draw on the electric power can also become a cause of issues with other appliances. If your household’s electrical system is less than 200 AMP, you might have to upgrade it to supply sufficient power to the unit.  


  • Weight: 14.8 Pounds
  • Size: Small
  • Material: Steel
  • Volts: 240v
  • Watts: 18000 Watts


  • Powerful and sturdy
  • Easy deployment
  • Amazing warranties
  • Easy replacement


  • Large size compared to competitors
  • Noticeable sound

Note: Overall, this electric tankless water heater can fulfill the average hot water needs of the majority of houses. Whether deployed as a point of use or a complete device, it delivers never-ending hot water and is almost 100% energy smart. Additionally, it is backed by a warranty, so in case of any issue, the brand will repair or replace it.

5. Rheem RTGH-84DVLN-2 Natural Gas Condensing Tankless Water Heater

Rheem RTGH-84DVLN-2 is a high-performance condensing natural gas water heater that is designed for outdoor installation. It supplies endless warm water for up to two bathrooms in winters and three bathrooms in summers.

Rheem RTGH-84DVLN-2 Natural Gas Condensing Tankless Water Heater

Rheem RTGH 84DVLN 2 Natural Gas Condensing Tankless Water Heater


  • Recirculation pump kit-ready
  • Designed for outdoor deployment
  • 0.93 uniform energy factor
  • 0.96 energy factor

This energy-efficient device never runs out of water, so you can not only save money but can enjoy a continuous flow of perfectly hot water. Its uniform energy factor is 0.93, and its energy factor is 0.96.

Moreover, it arms stainless steel condensing heat exchanger. If we talk about its performance, it produces 8.4 GPM at 35 degrees F temperature rise and 6.6 GPM at 45 degrees F temperature rise.

This Rheem tankless water heater with recirculating pump has water-saving settings. Upon startup, this setting can help you save approximately 1,100 gallons annually.

It has the capability to lower the water flow rate through pipes until the temperature touches the unit’s preferred temperature. Besides, its minimum flow rate is 0.26 gallons per minute, and the minimum activation flow is 0.40 gallons per sixty seconds.

This flow rate guarantees that you will acquire warm water in the lowest demand conditions. On the other hand, the RTGH-84DVLN-2 features a recirculation pump kit-ready that offers quicker hot water at the fixture and saves up to 12,000 gallons per year.

Besides, the hot start programming mechanism remains in a ready-fire state to decreases cold water bursts and for frequent hot water needs. A great thing about it is that you can link it to EcoNet mobile app using the EcoNet accessory kit.

If your water demand is very high, you can connect it to multiple tankless appliances to work as one unit. To attach two units, you can utilize EZ Link Cable.

However, you will need to use the MIC-6 control board and MIC-185 plus MICS-180 manifold control assembly to join six and twenty units, respectively.  


  • Weight: 77.9 Pounds
  • Finish: Stainless Steel
  • Material: Stainless Steel


  • Can deliver hot water to multiple appliances at once
  • Work silently
  • Take up lesser space
  • Easy to understand installation instructions


  • Quite expensive
  • Plumbing and service valves do not come with it

Note: If you are on the outlook for a unit that is energy efficient, works on natural gas, and delivers endless hot water, the Rheem RTGH-84DVLN-2 has covered you. This technologically advanced heater can help you save money, water, and valuable storage space.

6. Rheem RTG-70DVLN-1 Tankless Water Heater

This mid-efficiency water heater is constructed for indoor installation. It runs on gas and provides infinite warm water instantly and on-demand.

Rheem RTG-70DVLN-1 Tankless Water Heater

Rheem RTG 70DVLN 1 Tankless Water Heater


  • Intended for indoor installation
  • Runs on natural gas
  • Never runs out of water
  • Guardian overheat film wrap prevent it from reaching risky temperatures

Just like many other Rheem gas water heaters, it also requires a minimum flow rate of 0.26 gallons per minute and a minimum activation flow rate of 0.40 gallons per minute.

With this flow rate, you can be certain of receiving water in low-demand situations. Its ultra-low NOx burner complies with the SCAQMD safety requirements with low discharges.

Besides, it has a guardian overheat film wrap that is liable for preventing it from touching hazardous temperatures. Along with that, the EcoNet smartphone app, maintenance notification setting, and self-diagnostic system make it a valuable purchase.

With this best Rheem tankless water heater, you get a digital remote control and 10 feet of thermostat wire. It can provide water for up to three bathrooms. Best of all, it flaunts a 12-year heat exchanger, 5-year components, and a 1-year labor warranty.


  • Weight: 62 Pounds
  • Material: Stainless Steel
  • Finish: Stainless Steel
  • Voltage: 120v


  • Work efficiently
  • Operates quietly
  • Water Savings technology
  • Hot Start Programming


  • Costly

Note: This indoor natural gas tankless water heater can efficiently meet the hot water needs of a big family. We loved it because of its quiet operation that does not disturb you when you are resting or sleeping. Its only downside is its high price.

7. Rheem RTEX-27 Residential Tankless Water Heater

The Rheem RTEX-27 comes with 3 heating elements, generates 27 kW, and creates 6.6 gallons per minute of hot water. Users confirm that it works perfectly well and does not produce any annoying noise.

Rheem RTEX-27 Residential Tankless Water Heater

Rheem RTEX 27 Residential Tankless Water Heater


  • External thermostat control lets you set your desired temperature in 1-degree increments.
  • Supports multiple applications at once
  • Copper immersion three heating elements
  • Easier installation

You can rely on it to get water for two tubs, dishwashers, kitchen sink, washing machines, and two toilet fixtures, all at once. To fulfill its electrical supply needs, you may have to deploy additional circuit breakers and wiring that may cost you a heavy amount.

By setting its temperature to 125 degrees F, you can get water for full bathrooms, a washing machine, a kitchen, and 3 showers simultaneously.

In addition to that, it features an external digital thermostat control with an LED display. You can change the temperature with 1-degree increments.

Rheem has integrated the most innovative self-modulating system in it that allows it to adjust power to meet your household water demands.

Robust copper immersion three heating elements make it a reliable heater for residential properties. Its installation process is simpler, and you can perform it yourself.

But, we would recommend you to rely on professional services. It is not only easy to install but easy to replace and maintain as well.   


  • Weight: 17.8 Pounds
  • Voltage: 240 Volts


  • Suitable for small and medium-sized families
  • Reliable brand
  • Saves money
  • Never runs out of water


  • May have to upgrade your house’s electricity system

Note: Rheem RTEX-27 is one of the most popular tankless water heaters that have three heating elements. Its maximum flow rate is 6.6 GPM so that you can run several applications at the same time. This device is ideal for small and medium-sized houses.

5 Things To Consider Before Buying The Best Rheem Tankless Water Heater – Buying Guide

As we mentioned earlier, Rheem is a prominent brand worldwide, and its products are of the greatest quality. However, before buying any of their heaters, make sure to consider these things.

Heater Type

Rheem offers three different types of tankless units such as gas, electric, and hybrid devices. Before choosing any type, check your house’s gas line or electrical system to determine if it can support the demands of the new machine.

Plumbing Cost

It is another significant factor that you should consider before replacing your existing unit with the new one. It is better to follow Rheem’s expert advice on the plumbing state because they will offer you a detailed plan.

You might need new pipes to connect the main boiler to the water heater. And then, you might need to connect the heater to many other outlets within the locality. If you want to change the water tank’s location, then you should install new plumbing pipes.

Type Of Efficiency

When it comes to water heaters, efficiency plays a vital role. Tankless units have two efficiency types: condensing and non-condensing heaters.

Rheem provides both types with superior quality checks so that you can choose any one of them according to your personal preferences.


The device’s size depends on various aspects. Primarily, you should calculate the heat amount that will be utilized and the temperature rise you will need.

Both of these factors have a huge impact on the heater’s reliability and efficiency. The small-sized appliances are budget-friendly and dependable to use.

Secondly, it is crucial to evaluate the total number of units that will be attached to the unit and the flow rate.

Calculate the total flow rate of all appliances to know about what size of the heater you should opt for. Besides, you can take guidance from Rheem’s experts on how to determine the tankless machine’s size.


Many best Rheem tankless water heater feature a 5-year, 10-year, or limited lifetime warranty.

If you can afford to spend more, we would advise you to grab a model with a longer warranty, preferably a limited lifetime guaranteed.

Heaters with lower warranties are affordable, but you get the same amenities and security of post-sale services.

What Are The Different Types Of Tankless Heaters That Rheem Offers?

They supply three different types of water heaters that are as follows:

Tankless Electric Water Heaters

Electric machines are designed to provide on-demand hot water, and they run on electricity. Just like other units, they don’t have a storage container.

It heats water as it flows from the source via the device to your tap. They are more energy-efficient than gas ones and don’t need a venting system as well.  

Hybrid Tankless Water Heaters

They are also called Rheem tankless water heater with recirculating pump. They rely on electricity to transfer warmth that has already been produced instead of producing additional heat.

This factor makes them more energy smart than other types of appliances. In case of higher water demand, they function like regular electric units and depend on electricity as a fuel to heat the water.

Gas Tankless Water Heaters

They produce warm water just like electric devices. The only difference is that they use natural gas or propane as fuel and need a venting system.

These units are difficult to install and have a bigger size. Furthermore, they are less energy-efficient and cheaper than electric machines.

Also, They Make Two Extensive Groups Of Rheem Water Heaters:

Performance Series

They sell performance-oriented heaters in home improvement and online stores. These units are identical to professional line models. They typically are started with “ECOH” and “RETEX”.

Professional Series

Only Rheem dealers sell these units as a package deal that includes installation. They generally are started with “RTGH” and “RTEX”.

Important Features Of The Best Rheem Tankless Water Heater

Tankless water heaters by Rheem are equipped with many essential features. Below are the notable characteristics that make Rheem tankless water heater price stand out from other heaters available in the market.

Condensing Technology

The manufacturer offers a wide variety of condensing machines to choose from. These devices have a higher upfront cost, but they are less costly to install as they don’t need a venting system to eliminate the harmful gases.

Instead, they utilize the hot exhaust to warm water, which means they are extra energy-efficient and usually have an energy star rating.

Flow Rate

All Rheem electric tankless water heater reviews have different GPM ratings, ranging from 0.9 to 8.8. GPM is the abbreviation of gallons per minute and refers to how many gallons it can produce in sixty seconds.

The heater that has a higher GPM will provide you more water so that you will be able to run multiple applications at once. The machines with high GPM are suitable for bigger houses.

Energy Efficient

All Rheem tankless water heater with recirculating pump are energy-efficient and have energy star certification. Most of their models are 99.8% energy smart.

It means they lose only 0.2% of the BTUs produced, and the rest of the BTUs are transmitted to the water to warm it up.


The units with integrated WIFI features EcoNet wireless technology that enables you to check and control the device using the smartphone application.

Gas Line Compatibility

Many of their gas appliances don’t need an upgrade from a ½ line to a ¾ line. The gas line compatibility helps you save money on installation.

Installation Expenditures

A professional plumber charges approximately $600 to $1500 for installing the Rheem water heater reviews. The final cost depends on multiple factors such as indoor or outdoor deployment, vent material, and whether or not the electrical system or gas line needs to be upgraded.  

Outdoor And Indoor Usage

Some of their heaters are intended for indoor usage, and some are designed for outdoor installation. A few of them can be installed both indoor and outdoor. Before buying a model, check the description to know if it is suitable for where you are planning to deploy it.

Heating Output

British Thermal Unit (BTU) inputs can be different in all appliances, ranging from 157,000 to 199,000 BTUs. BTU refers to the heat released from the burners.

Higher BTU means the unit will heat water quickly. Thus, you should buy the one with a higher BTU, so that you can get warm water without waiting for too long.

Linking Up Various Heaters

You can link the Rheem water heater 40 gallon gas with one or several other hot water or power supplies. They provide you cable connections or ports for connectivity purposes. If you have higher water demand, you can attach multiple gas units.

Recirculation Pumps

Many heaters by Rheem use recirculation pumps. They recirculate the already heated water that was not utilized by an open fixture. As a consequence, they become extremely energy-efficient and help you save a substantial amount.

These pumps are prevalent because they reduce or eliminate the waiting time. If you want warm water instantly, we would recommend buying a Rheem tankless water heater with recirculating pump.  

Frequently Asked Questions

Q. Can Rheem Tankless Heaters Resist Corrosion?

They use stainless steel heat exchangers for making their condensing heaters to increase their resilience and resist corrosion.

Q. Does Rheem Produce Low NOx Water Heaters?

Yes, all their machines comply with the SCAQMD and Low-NOx rules.

Q. What Is The Uniform Energy Factor Of The Best Rheem Tankless Water Heater?

Their models have a uniform energy factor of 0.82 to 0.94. The UEF provides information about the heater’s overall energy efficiency. A higher rating means the unit can increase liquid temperatures with less energy.

Q. Why Choose Rheem?

Rheem is one of the most popular and cherished water heater brands in the industry. They make a wide range of units, and most of their products are top-rated. Their models are:
Sturdy: They can resist rust, corrosion and have stainless steel heat exchangers.
Low emissions: All of their machines are designed to satisfy the Low-NOx requirements.
Energy-efficient: They have many heaters with energy star ratings.


We are optimistic that you will benefit immensely from our thorough guide and will be able to use this information to get a model that fits your needs and budget. Rheem is a dependable brand that is ruling the market with its pioneering technology.
Their products and services are of premium quality. They offer amazing warranties and groundbreaking features. You can order any of the above-mentioned best Rheem tankless water heater with confidence.

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