Rheem vs. AO Smith: Which One Is The Better Water Heater?

Aug 31, 2021 | Home Improvement Reviews, What To Buy

When it’s time to pick a new water heater, you don’t want to select any old model without doing your research to ensure you get the right one that will meet your household’s needs.

Two of the top brands for water heaters are Rheem and AO Smith. This review will compare an AO Smith water heater vs. Rheem to determine which brand has better products. Both brands offer a wide selection of heaters from gas, electric, or solar to a tank or tankless, small tank capacity, or large size. 

We’ll also answer some frequently asked questions readers generally have about AO Smith and Rheem water heaters.

AO Smith Overview

AO Smith produced its first water heater in 1939 and is still going strong here in 2021. But the company has been in operation in other fields since its foundation in 1874. 

As a company proud to call themselves innovators, they have a range of creative inventions, such as a glass-lined water tank produced in the 1950s and going solar by 2010.

You can find water heaters made by AO Smith using electric, tankless, and gas power sources. There are also commercial boilers and heaters, combi boilers, and pump water heaters. 

As far as manufacturing facilities go, there are numerous plants spread throughout the US, Europe, China, and India. 


AO offers a robust line of water heaters, including the Proline XE – a high energy-efficient heater that allows for continuous heating, so you never run out of hot water.

Other benefits include: 

  • High energy efficient pieces
  • Eco-friendly
  • Affordable
  • Residential and Commercial products


  • Untrustworthy durability
  • Bad customer service

Rheem Overview

Rheem is one of the biggest producers of water heaters in North America, with facilities in New Zealand, Australia, and Mexico. With nearly 100 years of service, Rheem’s reputation for being one of the best reigns supreme.

Rheem offers heating and cooling products (HVAC), but they’re also known for manufacturing water heaters from tankless to standard tanked and powered by solar, electric, gas, or hybrid.

This company offers a long-standing commitment to excellence, and you frequently see them on “best of” review lists. 


  • Reliable, well-known brand
  • Constantly innovating
  • Low costs of operation
  • Sustainable


  • Warranty doesn’t cover installation costs
  • Warranties don’t cover minor problems

AO Smith Water Heater Vs. Rheem: What’s The Difference?

In the battle of Rheem vs. AO Smith, both companies have a similar product lineup. But there are some differences between the two. Here’s a comparison of different features in the AO Smith vs. Rheem showdown. 


Rheem’s obsession with innovation means they are constantly coming up with new designs. As a result, they have the widest variety of electric water heaters, including the unique-looking Rheem Chamber RTEX-13. Rheem also has many accessories – burners, thermostats, pilot generators (and assemblies), valves, and immersion rods. 

AO Smith has many heaters in different fuel types, sizes, usages, and capacities. For example, you can get tanks between 30 and 50 gallons, with heating power from 30,000 to 100,000 BTUs. In addition, there are wattage choices from 750 to over 6,000 and with a single or two elements.

Rheem is the better choice if you care about innovation, but AO Smith offers a broader selection. 


Rheem warranties have an average duration of six to ten years. But while registering your product online, there is the option to purchase four more years of protection to get warranty coverage for up to twelve years. 

This warranty covers all the repair or replacement of all heating components, but you’ll be responsible for labor costs if you don’t belong to the Protection Plug program. 

Some products have a lifetime warranty covering repairs or replacements during the lifetime of the original owners. You’ll have to pay $25 within one month of moving out to transfer the contract to the home’s new owners. 

AO Smith also has a warranty term of six to ten years for water heaters. But you can get some tankless heaters with coverage terms of 15 years or more. Commercial warranties are shorter – one to three years. 

A difference between AO and Rheem is that AO warranties do not cover labor costs. And they are not transferable to a new owner, regardless of circumstances. 

Rheem becomes the clear winner of the competition between these two water heater brands in terms of warranties.


AO Smith and Rheem are pretty equal in terms of reliability. Both brands are high quality, and all the products have similar lifespans, so there’s no advantage for either company. How you maintain your water heater will play a more significant role in the heater’s performance and lifespan than the brand name.

Fiberglass tanks last longer than regular tanks.

Customer Service

When choosing a company, customer service is a factor that many people forget to weigh. But you want to pick a brand that gives you access to helpful representatives if you ever need it. 

It can be tricky to determine Rheem’s customer service performance as many customers do not mention experiences in their reviews. But it does seem that most people find Rheem’s team to be helpful when needed. But it may take longer to get a response after reaching out via emails and phone calls multiple times.

On the other hand, AO Smith has reports of excellent customer service with a very high customer satisfaction rate. 

Energy Efficiency

Rheem certifies as an Energy Star brand with water heater UEF ratings around 0.80, falling in the optimal range of 0.65 and 0.95 UEF for electric and gas heaters. 

But AO Smith has the highest energy efficiency, known for low-energy water heaters due to Low NOx or Ultra-Low NOx burners that meet EPA standards. 


Both brands offer gas-powered water heaters. But AO Smith offers nearly 60 models of liquid propane and natural gas tank water heaters. That’s compared to the lower number of 43 types offered by Rheem. 

Based on numerous customer reviews, more people prefer the performance of AO Smith heaters, with a particular preference for the ProLine XE (50-gallon gas) compared to Rheem’s equivalent bestseller Professional Classic Plus (48-gallon natural gas). 

The ProLine is a larger tank with a lower Uniform Energy Factor (UEF) of .72 compared to Rheem’s .80 UEF. Both heaters come with a six-year warranty and are energy-star qualified. AO’s tank has dimensions of 51” H x 24” W x 24” D, while the Professional is 60” H x 22” W x 22” D.


Rheem also produces over twenty electric water heaters, with some bestsellers featuring 13 KW wattage and 240 voltage. These heaters come with warranties for around five years. 

While AO Smith has over 30 different models of electric water heaters, the majority come with a six-year warranty, with the best lines coming in 1600 watts with 120 voltage.

But Rheem’s water heaters use less GPM (gallon per minute), saving you money on your water bills while reducing the amount of water your house wastes.


Rheem’s bread and butter – and the reason for their popularity and fame – is its large selection of tankless heaters. There are more than 35 options for tankless heaters, with a 0.96 average energy factor. And the majority have a 12-year warranty. 

AO Smith offers more than twenty choices for tankless water heaters. Top models feature an energy factor of 0.93 with a 12-year warranty. 

Tankless heaters warm the water instantly while it flows through the heater. No water stays stored internally but goes through the heat exchange coil to warm up before rushing out the faucet. For this reason, they use less than 35% of energy. 


Rheem water heaters are more affordable ($400 to $2,300) than AO Smith heaters, ranging from $400 to $3,500. 

If you have your water heater professionally installed, you might spend $400 to $900 for a tank heater (40 to 50 gallons) or $1,470 to $2,510 for tankless water heaters. You may also see $250 to $500 extra for a plumber. If they have to remove the old heater, it could take $450 to $1,200.


While the expected lifespan of gas heaters is 9 to 12 years, Rheem and AO Smith only provide warranties for five to six years. 

And although you should expect to get 10 to 15 years out of an electric heater, AO only warranties your heater for five to six years – the same amount of warranty time as Rheem.

Finally, tankless water heaters will usually last twenty years. Both Rheem and AO Smith have twelve-year warranties on their tankless heaters.

Factors that can affect your water heater’s lifespan include:

  • The installation process (DIY vs. professional and incorrect vs. correct)
  • Usage (the more you use it, the faster it wears out)
  • Maintenance schedule (you should do yearly maintenance)
  • Quality of the tank


Rheem makes it easy to install your water heater DIY (if you have the proper experience) with comprehensive manuals with detailed instructions, precautions, and warnings for installation. 

Rheem also offers access to plumbing experts that have minimal fees and get your heater installed ASAP. There’s also a “Find a Pro by City” tool that lets you search near your location to find nearby professionals – not employed by Rheem, so do your research to pick the right contractor. 

AO Smith also offers access to a large selection of contractors to back up by taking responsibility for any issues. If the contractor turns out to be unqualified for installing your system, AO Smith takes the brunt of the costs because they recommended the dud. 

If you’re going to DIY install your AO Smith water heater, you will receive instructions. But these are not as detailed and explanatory as those that come with Rheem heaters. In addition, there will be minimal directional information on how to install, maintain, or remove the heater.

Rheem wins when it comes to which brand offers better instructional materials for a simple and successful DIY installation. But AO is more willing to step up to the plate and comp you if there’s a problem with the installation by a company AO recommended.

Considerations Before You Buy


Your first concern should be budget. While the cost of the heater is a primary consideration, you’ll also want to consider the type of energy source and how much it will cost for operation. 

Gas Vs. Electric

You’ll also want to consider whether you want a water heater powered by electricity or by gas. Gas heaters are excellent for locations that experience unreliable power, allowing you to have hot water still even if the electricity is off. But if your current water heater is already on one power supply, you could face additional costs if you decide to swap to another type.


Gas water heaters must have some venting so that you can remove harmful gases. Water heaters can have power venting or direct venting

Power vents use a blower fan (electric) that pulls the exhaust through the vent pipes. While this can help prevent carbon monoxide from blowing into the house, it makes the heater more energy efficient. 

With direct venting, air from outside your home helps vent exhaust gases and excess heat from the heater and pushes it back outdoors.


You’ll also want to consider what size and capacity heater you need. Large families will usually require a bigger heater, so you’re not constantly running out of hot water and having to wait for the tank to refill.


Both brands offer access to professionals that can install your Rheem or AO Smith heater. However, although Rheem gives you a list of installers, these contractors are not affiliated with Rheem. Therefore the company doesn’t cover any installation errors.

AO Smith also gives you a list of contractors to install your heater. But these installers are backed by AO Smith, which means if the installer does something wrong, AO Smith takes responsibility and covers any lost costs.

AO Smith Water Heater Vs Rheem FAQ

Check out these frequently asked questions before you go if you still have things you want to know about AO Smith vs. Rheem water heater.

Is Rheem Or Ao Smith A Better Water Heater?

When you take in all the factors, it becomes pretty challenging to decide the winner. Both brands have advantages and disadvantages. The best heater brand will depend on your needs more than your reputation.

What Brand Of Water Heater Is The Most Reliable?

To be a reliable brand, you have to count on your water heater to function as expected without breaking the bank. AO Smith and Rheem are two of the most reliable water heaters on the market.

Are AO Smith Water Heaters Any Good?

AO Smith has an excellent reputation that they’ve earned over the years due to the quality of its products, including water heaters. 


While picking a water heater manufacturer requires much thought and research, narrowing your choice down to AO Smith vs. Rheem makes the decision process easier. Both brands are superior choices, so you really can’t go wrong with either one. However, your needs will influence which heater is right for your home. 


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