Rheem vs. AO Smith Water Heaters

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Rheem and AO Smith are two leading brands with a full line of water heater products. But given they’re pretty much neck and neck competitors, it’s hard to decide which one is the best for your needs.

To know which one is the winner, take a look at the following article. It compares Rheem vs AO Smith water heaters and discusses the unique features of each brand and its products.

A Brief Review of AO Smith

Known for its reliability, high efficiency and innovative efforts, A.O. Smith is one of the biggest providers of water heaters in the world. It was founded in 1874, and produced its first water heater in 1939.

From water heaters to water treatment solutions, A.O. Smith produces a range of different items. Also, to meet the latest needs of its customers, this company continuously upgrades its products.

Whether you need an electric, gas, tank-based or tankless water heater, you can surely find your best fit from their precious collections.


  • Well-known and reliable brand.
  • Consecutive innovations.
  • Low running costs.
  • Sustainable approach.


  • No warranties for minor problems.
  • Installation costs are not covered in the warranty. 
A.O.Smith Brand Overview

A Brief Review of Rheem

Rheem is a one-stop source for all heating, ventilating and air conditioning (HVAC) systems. This company produces every type of HVAC equipment from refrigeration and ventilation products to water, pool and spa heating—but it’s mostly known for its earth-friendly water heaters.

The company was founded in 1925, and since then, it has committed to producing sustainable water heaters for commercial and residential purposes.

Regardless of your needs, Rheem is sure to provide a cost-effective and, at the same time, a quality option for you.


  • Eco-friendly.
  • High efficiency.
  • Inexpensive products.
  • Provider of both commercial and residential HVAC systems.


  • Poor customer service.
  • Not very durable.
Rheem Water Heater Introduction

A Full Comparison Between AO Smith and Rheem Water Heaters

Range of Products


First and foremost, the company’s line of products is not limited to water heaters. Rheem has been manufacturing various HVAC systems for about a century.

It sells gas, electric, solar and hybrid water heaters in both tankless and tanked versions. And they’re available for industry and residential applications.

AO Smith

AO Smith also manufactures tanked/tankless gas heaters, tanked/tankless electric water heaters, pump water heaters, and combi boilers. Their products are accessible for both commercial and residential users.


There’s equal competition between AO Smith and Rheem in terms of the product lineup, which means they’re as versatile as each other. But one brand might have a better performance in some models.

Here’s a short comparison:

  • Conventional/tankless gas water heaters: A look at customer reviews suggests that buyers prefer AO Smith’s gas water heaters. 
  • Tanked/tankless electric water heaters: Although AO Smith boasts numerous electric heaters, Rheem is the clear winner because its electrical products are easier to use, more efficient and durable.
  • Hybrid/heat-pump water heaters: Both AO smith and Rheem offer superior models of hybrid heaters.

Water Heaters Energy-Efficiency


Rheem is an ENERGY STAR certified brand that uses UEF ratings to measure the energy-efficiency of their products.

In general, the UEF ratings of electric and gas water heaters should be somewhere between 0.65 and 0.95. And luckily, most water heater series manufactured by Rheem have about 0.80 UEF rating.

AO Smith

AO Smith earns the most energy-efficient title among its rivals. By following EPA standards, it uses either Low NOx or Ultra-Low NOx burners to design low-energy water heaters.

Besides, although we still don’t have a LEED-certified product (Leadership in Energy and Environmental Design) in the industry, AO Smith has tried its best to meet the requirements. Therefore, it’s been a gold standard for energy-efficiency.


While both brands have an ENERGY STAR certification, AO Smith is more effective in terms of power efficiency.



On average, the duration of Rheem warranties ranges between six and 10 years. Also, when registering your purchase on their website, you can opt for another four years of coverage. In other words, your warranty can be extendable for up to 12 years.

These warranties include repair and replacement options for all heater components. But if you’re not a part of the Protection Plus program (the four-year extension plan), you should pay the labor costs on your own.

Some Rheem water heaters come with a lifetime warranty. Therefore, users will enjoy their replacement/repair options as long as they own the system. It means, once they move out of their house, the lifetime warranty will end.

Don’t be frustrated by that because there’s also a possibility to transfer ownership of the warranty. But you need to do it within a month of moving out, and the company will charge you about $25 for the operation.

AO Smith

Similarly, AO Smith offers a standard warranty of six–10 years for its water heaters. Some tankless water heaters come with more than 15 years of coverage. For commercial use, the durations can be just one to three years.

These warranties exclude labor costs. And they’re not transferable under any circumstances.


While AO Smith boasts the most extended warranties in the sector, Rheem is the winner in this area because it offers more flexible plans.



As mentioned before, Rheem is well-known for its consistent innovation efforts. It’s constantly pushing the boundaries of new design. And as a result, it’s gained remarkable attention from its customers.

Rheem provides a wide selection of models, especially with electric water heaters. For example, the Rheem Chamber RTEX-13 is a signature product that comes in a unique design.

Moreover, Rheem is very rich in terms of accessories. These include thermostats, burners, pilot generators and assemblies, immersion rods and valves.

AO Smith

AO Smith water heaters come in various sizes, fuel types, capacities and usage. As for the tank sizing, AO Smith water heaters range from 30 to 50 gallons, and heating power ranges from 30,000 up to 100,000 BTUs. They come in two-element and single-element models and have 750 to over 6000 wattages.


Both brands are versatile in terms of design. If you’re looking for more innovative models or extras, Rheem is a better choice. But if you want a more comprehensive selection, we recommend AO Smith.



All Rheem products come with comprehensive manuals that include all necessary instructions, warnings and precautions for installing their systems.

If you’re not a DIY person, you can ask for their plumbing experts. These servicemen require minimum fees and undertake your installation as fast as possible.

To further assist you with the installation process, Rheem has a “Find a Pro by City tool on its website, which connects you to the nearest professionals. But it would be best if you remembered that these service providers are not Rheem employees. So, the company won’t guarantee their performance.

AO Smith

This company also has a wide array of handymen to suggest to its clients. But unlike Rheem, AO Smith takes the responsibility of these contractors. So, in case they were not qualified or capable of installing your unit, the company will make up the losses.

Just like Rheem products, these units feature instruction guidelines. But compared to the Rheem manual, they’re less explanatory. They include minor directions about installing, maintaining and removing the water heater.


Thanks to its informative and detailed handbooks, Rheem products are more straightforward to set up. But AO Smith is more responsible for its customer experience. Based on reviews, it has excellent customer service, and installation is a great part of it.



Most of Rheem’s gas heaters and storage heaters come with replaceable components. However, tankless versions usually don’t have spare parts. So, in case you need to change a component, you have no choice but to call a plumber.

AO Smith

Whether you buy an electric, gas, storage or tankless model, all AO Smith products have completely removable components. This means you can remove the aging parts with ease and replace them with new ones.


AO Smith has more replaceable options, so you have more freedom when it comes to repairing your water heater and extending its life. 

Return and Exchange Policies


If you order the wrong unit from Rheem, you can return and refund it only in the following circumstances:

  • Make sure your Rheem water heater is returnable (some products are not).
  • Notify the company within 30 days from the date of purchase.
  • The unit should remain untouched, uninstalled and in its original packaging.
  • You should accept the responsibility of all return charges, including the shipment costs and potential damages during the delivery.
  • The company will also subtract the initial shipping costs and 10 percent of the total money for restocking purposes. (Normally, the company doesn’t charge you for shipping the products, but in case of returns, you should make up for the loss.)

Note: If the problem was the company’s fault—if they shipped a different item from what you ordered—Rheem will bear the costs and exchange the unit for free.

AO Smith

AO Smith’s refund policies are similar to Rheem’s. Once they receive the product undamaged, they’ll refund your money minus some amounts for service tax and bank charges.


AO Smith and Rheem have nearly identical procedures when it comes to returning products.



Based on the model, efficiency and size of tanks, the up-front costs for Rheem water heaters may vary. But typically, Rheem water heaters cost you less money in comparison to its competitors. On average, a standard Rheem water heater ranges between $400 and $2300.

AO Smith

Depending on the model, AO Smith water heaters are available from $400 up to $3500.


Compared to AO Smith products, Rheem water heaters are more cost-effective. 

Signature Features

Rheem Has the Most High-Tech Options

Rheem boasts more than 300 patents in its collections. Some of the water heater models, such as the Rheem ProTerra Hybrid Electric Water Heater feature an EcoNet Wi-Fi Kit that allows you to control temperature settings using your smartphone.

You can also find systems with Water Leak Sensors. These sensors detect the leaking valves and alarm you instantly. What’s more, they have a shut-off feature that won’t allow more than 24 ounces of water leakage.

AO Smith Has a Special Coating Process

With its PermaGlas ultra-coat lining, AO Smith provides superior protection for both the inner and outer shells of the water heaters, which guard them against corrosion.

Rather than spraying the coat on the surface, AO Smith uses the slush molding process to coat their water heaters. Therefore, it ensures their maximum durability.

This type of thermal bonding is exclusive to AO Smith, so you can’t find it in any other brand’s products.

Frequently Asked Questions

What Brand of Water Heater Is the Most Reliable?

AO Smith and Rheem are some of the most reliable brands fighting head-to-head for the first place in the market. Yet, here’s a short list of other dependable manufacturers:

  • Bosch.
  • Rinnai.
  • Stiebel Eltron.
  • Kenmore.
  • Noritz.
  • EcoSmart.

How Long Do AO Smith Water Heaters Last?

AO Smith water heaters last at least a decade, though many customers and plumbers say this can be extended to three decades if you take good care of it. They boast warranties of up to 15 years, which means the manufacturer has predicted at least a 15-year service life for its products. 

How Long Does a Rheem Water Heater Last?

A Rheem water heater usually lasts about 12 years but it can vary based on its model, energy supply and level of usage. For example, tankless units can endure more than two decades, while tank-based water heaters last roughly 10 to 15 years.

Are Rheem Water Heaters Good?

Rheem water heaters are excellent in terms of variety, eco-friendliness, durability and design. The brand offers innovative yet affordable water heaters, with low running costs. With its excellent reports of customer care, this brand goes on and on in competition with the AO Smith company.

What Is the Best Rheem Electric Water Heater?

In our opinion, the best Rheem electric water heater is the Rheem RTEX-18 Electric Tankless Water Heater.

As an Amazon Associate I earn from qualifying purchases. Last update on 2024-06-24 at 01:19


Buy Rheem water heaters if:

  • You’re in the market for electric water heaters.
  • You need more affordable options.
  • You look for more accessories.
  • You’re into high-tech systems.
  • You want a more informative handbook.
  • You want to protect the environment.

Buy AO Smith water heaters if:

  • You’re in the market for gas water heaters.
  • You need a more durable option.
  • You want the most energy-efficient system.
  • You seek readily assembled and replaceable components.
  • You expect better customer service.
  • You want to protect the environment.
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Welcome to Air Wisely! I am Darren. I worked as a plumber for years and found that my clients were interested in learning basic HVAC knowledge. That's why I build this site.