Rheem vs. AO Smith Water Heater: Difference and Comparison (A Complete Guide)

Last Updated on October 22, 2021 by Kimberly Crawford

When it comes to the water heating industry, Rheem and AO Smith are consistently at the top tier. Each with hundreds of years of reputable service and products under their belts, they are two of the best brands to look out for in terms of impressive product lines. 

In this review, we compare and contrast these two top water heating brands to see the major upsides and probable downsides of each. While they are at the frontier, it is still imperative to know which of them can fit our water heating needs and preferences. 

Related: 4 Worst Water Heater Brands and 7 Most Reliable Brands (Buying Guide)

Who makes Rheem water heaters?

Rheem has been around for 125 years, owned by Paloma Industries. Their main headquarter is in Nagoya, Japan but they also have a manufacturing subsidiary based in Atlanta, Georgia.

As an established water heater company, they have also extended their manufacturing and distribution in Australia and Mexico. 

Where are Rheem water heaters made?

rheem water heater company

Rheem water heaters are made in different states in the US. The manufacturing sites of Rheem water heaters are in Atlanta, Georgia, Eagan, Minnesota, and Oxnard, California. As for parts production and replacement parts manufacturing, you can find their headquarters in Randleman, North Carolina. 

Who makes A.O. Smith water heaters?

This family company started in 1821 in Wisconsin. Their water heaters are made by the AO Smith Water Products Company. Other water heater brands made by this company would be Aquasana and American Water Heaters. 

Where are A.O. Smith water heaters made?

a. o. smith

Through the years, AO Smith has been manufacturing water heaters in Milwaukee, Wisconsin. It is also considered as one of the first water heater companies to expand to Canada, Europe, and Asia.

Now, it has 24 manufacturing sites around the world. Some of its notable manufacturing sites would be in India, China, and the Netherlands. 

Rheem vs AO Smith water heater comparison

ao smith vs rheem

The easiest way to compare Rheem and AO Smith water heaters would be to look at each in a comparative view. This comparison here is based on reviews, customer satisfaction reports, and information from the respective companies’ sites. 

From a general perspective, here are some stark comparisons for Rheem and AO Smith. 

RheemAO Smith 
Better at producing a high performing tank/tankless electric water heater. Better at producing gas powered water heaters. 
Offer a wide range of products, not just water heaters. Offer a diversity of water heater models with high rated efficiency.
Provides a wide range of accessories as well as replacement parts. Professional repair service. 

For a head-to-head look at the comparison between these two companies, here are some specific aspects to consider: 

RheemAO Smith
Length of reputation80+ years90+ years
CategoryResidential, industrialResidential, industrial
Best productsWater heater, AC, Furnace, CoilsWater heaters, Tanks, Boilers
Available power options Gas and electricGas and electric
Number of featured modelsTanked water heater: 58Tankless water heater: 37Tanked water heater: 268Tankless water heater: 51
WarrantyLimited lifetime warranty6–10-year warranty
Geo-based service finder25-mile radius100-mile radius

In terms of product lineup, here is another comparison table for Rheem and AO Smith. This is important to note because there are specific water heater types/models for every residential and industrial use. 

RheemAO Smith
Residential water heater (with tank)Gas and electricGas and electric
Water heater (tankless)Condensing and electricGas and electric
Commercial tank water heaterGas and electricGas and electric
Offer combination boilers YESYES
Tank accessoriesYESYES
Heater accessoriesNOYES
Pool and spa heatersYESNO
Hybrid water heatersYESNO
Residential solar water heaterYES NO
Commercial boilerYESYES
Commercial storage tanksYES YES
Package systemOnly comes with AC and pumpComplete

In terms of buying factors and overall build and performance. This is based on customer satisfaction reviews and consumer reports. 

RheemAO Smith
Design qualityExcellentSatisfactory
Design diversityGoodCommendable
Customer serviceGoodExcellent

Beyond these, here is a five-point comparison of Rheem and AO Smith’s water heaters. This would give you a better idea of what to go for depending on what water heater category you are looking for: 

Gas and fuel

Gas heaters are still a popular choice because of their service efficiency and their low fuel consumption. When it comes to gas and fuel choices, AO Smith is a top choice.

They have mastered the low gas emission technology, making them a finer option for overall performance with lesser environmental impact. 

Electric heaters

For instant and continuous water heating, electric heaters, be they tank or tankless are a good choice for those who rate in terms of performance rather than overall efficiency.

When it comes to electric heaters, Rheem is a better choice. The main selling point of Rheem’s electric heaters would be their quick startup. They also come with double copper features making them built to last and greater reliability. 

Tankless water heaters

Consumer reports reveal that there are more tankless water heaters in homes now than tank models. The reason for this is that they emit lower gas emission and promise instantaneous water heating performance like electric heaters.

For this, you must be aware that AO Smith is more environment friendly in build and technology. But when it comes to overall efficiency, more people are rooting for Rheem. 

Spare parts

Not all water tank models and types are built the same. Some have parts that are easily replaceable while others require more challenging replacements.

For this matter, you need to know that most AO Smith models have spare parts that are easy to replace. Such is the case with Rheem too but they have more interior parts than AO Smith so it might be more challenging to replace them. 

Manual guide

If you are a neophyte at anything water tanks, you would want a product manual guide that would cover everything.

To this end, Rheem has a very complete manual guide for their product lines while AO Smith has a very thin manual. Hence, for DIY assembly, repair and replacement, know that Rheem is more convenient. 

Related: 4 Tips For Cutting The Cost Of Your Water Heater

Who offers the best gas heater?

To give a solid basis as to who offers the best gas heater, we shall look at two gas heater products of Rheem and AO. We have here the Professional Classic Plus of Rheem and AO’s Proline series.

The main contention from customer reviews and consumer reports is that AO’s Proline is the winner in the category of the best gas heater. This is based on this comparison: 

Professional Classic PlusProline
48-gallon capacity50-gallon capacity
6-year warranty6-year warranty
Energy efficiency is .80 UEFEnergy efficiency is .72 UEF
Energy Star certifiedEnergy Star certified
4 out of 5 customer rating4.6 out of 5 customer rating

There is not much difference between the two when it comes to best gas heater so the main basis of holding AO Proline’s as the winner would be its near perfect customer rating. Customers indicate that Proline can accommodate more back-to-back showers compared to Rheem’s gas heaters. 

Which company is best for electric water heaters?

In terms of electric water heaters, we look at Professional 50-GAL Electric Water Heater by Rheem and AO Smith’s Voltex Hybrid Electric Heat Pump. For this category, Voltex Hybrid is the clear winner. Here is a comparative breakdown for these two electric water heaters: 

Professional 50-GVoltex Hybrid 
50-gallon capacity50-gallon capacity
0.93 UEF3.42 UEF
8-year warranty6-year warranty
Not Energy Star certifiedEnergy Star certified

The main reason as to why Voltex Hybrid is chosen is very clear: its energy efficiency. With an energy certification and its large UEF margin compared to Professional 50-G, there is no doubt about its performance.

As far as customer reviews are concerned, both are rated high when it comes to durability, and overall customer experience. The only downside to Voltex Hybrid is its slightly shorter warranty period.  

Related: 5 Worst Heat Pump Brands and 7 Most Reliable Brands (Buying Guide)

Which brand of electric tankless water heaters is best?

For this category, we shall look at the Electric Tankless 24kW 4-Chamber Water Heater of AO Smith and the 24kW Tankless Electric Water Heater of Rheem. To be honest, there is a slight margin to who is the winner in this category, but we give it to Rheem. 

AO SmithRheem
24 kW operation24 kW operation
Unlimited shower minutesUnlimited shower minutes
5-gallons per minute6-gallons per minute
5-year warranty5-year warranty

The significant feature of electric tankless water heaters would be their ability to dispense water continuously. While these two products work similarly, the win is given to Rheem because of its GPM.

It might just be a point higher but it reveals that it can accommodate more than one device at a time. If you are living in a large household, this is a big plus. 

Related: 4 Benefits Of Hiring Home Heating System Installers in Winchester VA

Which offers the best condensing gas tankless water heater? 

For larger households maintaining three and more bathrooms, condensing gas tankless water heaters are the best choice. For this category, we shall look at AO Smith’s NOx Tankless Water Heater and Rheem’s High-Efficiency Pump.

It is another slightly margined verdict but we give it to AO Smith on the basis of warranty. 

AO SmithRheem
.93 UEF.94 UEF
Energy Star certifiedEnergy Star certified
15-year warranty10-year warranty
Unlimited back-to-back showersUnlimited back-to-back showers

For one, the energy efficiency rating of these two products is very impressive. But the 5-year gap in the warranty is hard to miss. Since condensing gas tankless water heaters are for larger households, you will benefit from all the warranty coverage that you could get. 

Final verdict

As we could infer, there are no significant differences between Rheem and AO Smith’s water tanks. Notwithstanding the minute details where they are different, you should have an in-depth review of your preferred water tank. As such, our verdict of which is better depends on certain aspects: 

When it comes to gas water heaters, condensing gas tankless water heaters, and electric water heaters, AO Smith can offer a more upscale choice. As for electric tankless water heaters, we give it to Rheem. There are other products offered by Rheem. Most have high UFEs and the warranty coverage, service and repair are also more commendable. 


Aside from this comparison, there is also other important information that you should be aware of in terms of Rheem and AO Smith water heaters. Hence, here are some of the FAQs that you should know of.

What is the best AO Smith water heater?

AO Smith offers a range of water heater products but the following are considered to be the best water heaters along their product lines. 

  • Proline/Proline Master: This gas and electric water heater selection is tagged as commendable for both mobile and home use. They are 80% higher in ratings compared to other models. They also have a higher recovery rate and higher efficiency ratings. Although not all, most of the water heaters under the ProLine series are Energy Star certified. 
  • Polaris: This is another gas water heater model from AO Smith. It is well-rated for its efficiency, fast heating capacity, high recovery rate, and its very quiet running performance. 
  • Vortex: It has easily become one of the gold standards of gas water heaters, its high thermal efficiency, sleek features, and Energy Star certification make it one of the most in-demand gas water heaters from AO Smith. 

How long does A.O. Smith water heater last?

Depending on the model of the water heater, expect an AO Smith to last for 6-10-years. Its tank models could last for 10-16 years as long as it is well-maintained.

This longevity range is typical among water heaters so one can say that for this account, AO Smith is a durable water heater. 

Is Rheem a good brand?

Yes. This is not just because the brand has been around for more than a hundred years but also because their water heaters are rated high across various features.

The main selling point of Rheem is their endless product options for different water heater types. Other upsides of the Rheem brand would be: 

  • Differently powered water heaters 
  • Reputation for longevity and reliability
  • Market availability, good repair and service 
  • Convenient features 
    • Wireless connectivity: to control the functions of your water heater, Rheem offers models with built-in WiFi connectivity through an application.
    • Away mode: You can program your water heater to turn off for extended periods when you are not at home and then program it to automatically switch on so that you have instant hot water when you come home. 
    • Leak detection: This smart feature is very convenient because it will automatically notify you of leakage and then immediately shuts off the valves so that no water damage is induced. 
    • Scheduled water heating: When it comes to energy efficiency, this is a very inventive smart feature. With this feature, you can control the water heater to produce more hot water during seasons and temperatures where it is most needed and to produce less hot water when it is not that needed. 

Is AO Smith a good brand?

Yes. As a matter of fact, it is arguably considered as the most popular water heater company worldwide. Its presence in over 60 countries in terms of distribution and manufacturing vouch for its quality.

Its models, from gas, electric and hybrid have sleek designs, high UFEs, all Energy Star certified and good warranty coverage all affect its performance. So yes, overall, as a leading water heating brand, AO is a top-notch choice. 

Where to buy Rheem water heaters?

Rheem is a highly accessible brand and it is sold in major stores as well as online sites worldwide. There are more than 40 Rheem stores across North America, Asia, and Canada. Rheem water heaters are sold at: 

  • Sears
  • Home Depot 
  • Amazon
  • Walmart
  • Ace Hardware
  • Grangier
  • Ferguson
  • Warner’s Stellian

How long do Rheem water heaters last?

According to water heater reviews and consumer reports, Rheem water heaters last at an average of 14 years. This is true for all of their water heater products from gas, propane, electric, solar, and hybrid water heaters.

What affects the longevity of water heaters? 

Beyond brand names such as Rheem and AO Smith, there are also general questions that must be answered. One of the more pressing concerns would the factors affecting the longevity of water heaters: 

  • Bad installation: The wiring and the overall installation have a lot of bearing when it comes to the lifespan of water heaters. If you do not know how to install them yourself, better ask a professional. Relative to this would be choosing the best location for the water heater so that it would not be susceptible to flooding and other risks. 
  • Maintenance: This is perhaps the most significant thing to consider when it comes to water heaters. If you are in a location where water is considered hard water, more frequent maintenance is needed. By hard water we mean water that is composed with higher mineral content, reducing the life expectancy of water heaters. To prevent mineral buildup, frequent maintenance must be employed to the water heater.  
  • Usage: Of course, as with anything else, frequent use of water heaters add to its wear and tear. Using more hot water on an everyday basis has an effect on the longevity of the water heater so even if Rheem, for instance, has an average lifespan of 14 years, you cannot entirely take it on with the brand if it does not meet this range especially if the usage is high. 
  • Quality: There is a reason why Rheem and AO are on top of the water heater tier. In a word, that would be because of their unmatched quality when it comes to producing water heaters. You can always purchase a cheaper water heater but not all of them prove to be durable and reliable. In this sense, look for reputable brands like the two in this case here. 

Why is UEF an important factor to consider? 

UEF stands for Uniform Energy Factor. It is an important factor in buying water heaters because it stands for the general energy consumption of a water heater. If you are wondering about the energy bill dent water heaters have per month, here is a breakdown for your reference: 

  • Gas tank: $100-350
  • Gas tankless: $150-200
  • Electric tank: $250-400
  • Electric tankless: $100-190

What is the most common problem with water heaters?

The most common problem among water heaters would be producing too little water. The default response to this would be turning the temperature up at a maximum in the water heater’s thermostat.

This can become a health hazard, however, since it can be scalding hot. You need to take all the precautions you must employ if you have problems like this. At the first sight of this problem, you have to call a professional. 

How much do Rheem and AO Smith water heaters cost on an average? 

The price range for Rheem water heaters would be $600-1400 while AO Smith range from $300-1500. This range still varies depending on the model and features of the water heater to be bought from any of these brands. 

How much is the installation cost for Rheem and AO Smith water heaters?

As has been said, there is no significant difference between Rheem and AO Smith when it comes to build and form. As such, you can calculate a general range of installation cost for these two brands. Here is a breakdown of their installation cost: 

  • 40-50-G tanks: $400-1000
  • Tankless water heaters: $1400-2500

These ranges do not include labor costs and for that, you have to add $200-500 to compute the overall installation cost. 


Ultimately, we have established here that both Rheem and AO Smith are reliable brands in the water heating industry not only because of their sustained years of service but also because of their innovativeness when it comes to their product lines.

When it comes to water heaters, they do not have a lot of difference but the small details where they are different are important factors to consider.