Rheem Vs Ao Smith

According to the study made by Statista Research Department in 2021, Rheem and AO Smith combined accounted for more than 70% of residential heater sales. They are the two most popular water heater brands in the US. This makes a lot of customers wonder about the Rheem vs AO Smith company comparison – especially if they’re in the market for a new water heater. [1]

Both of these companies offer several types of water heaters, so no matter the size of your household, you’ll likely be able to find something for yourself.

They sell products that work on both electricity and gas and they sell both tankless water heaters, and water heaters with tanks. This makes them very versatile.

But, when it comes to Rheem vs AO Smith water heater, which one should you get? If you want to learn which of these two companies is the right for you – you’re in the right place.

Rheem vs AO Smith Comparison


It is really hard to determine if AO Smith better than Rheem or vice versa without making a thorough comparison – and this is exactly what we’re going to do! We’ve looked through dozens of reviews to find out the pros and cons of both brands and to make a conclusion.

Most notably, we’ve looked through their:

  • Gas water heaters
  • Electric water heaters
  • Tankless water heaters
  • Warranties

Rheem Hot Water Heaters


Rheem has been on the market for almost an entire century! Throughout the years, it produced ll sorts of high-quality water heaters.

However, it is mostly known for its amazing tankless water heaters that have made the company a major player in the industry.

Ever since 1925, the brand does its best to keep its high customer satisfaction rate with many new models and innovative features and technologies. This can be seen in one of their best-selling models, the Rheem RTEX-18 water heater.

Let’s look at the brand product’s features:

Gas Water Heaters

  • The brand offers 40+ gas water heater models.
  • Rheem’s gas water heaters are found in around 22% of households.
  • Most can hold around 40 gallons of water.
  • Most have a warranty of up to 6 years.

Electric Water Heaters

  • Rheem offers 20+ electric water heater models.
  • Some of their best models have a voltage of 240, with a 13 KW wattage.
  • Most have a warranty of around 5 years.

Tankless Water Heaters

  • The brand is famous for its tankless water heaters.
  • Rheem offers 35+ models of tankless water heaters.
  • They have an average energy factor of 0.96.
  • Most have a warranty of 12 years, making them very durable


  • The average lifetime of a gas water heater is 9-12 years. Rheem offers a 5-6 year warranty on most. [2]
  • The average lifetime of an electric water heater is 10-15 years. Rheem offers a 5-6 year warranty on most.
  • The average lifetime of a tankless water heater is 20 years. Rheem offers a 12-year warranty on most.


  • Rheem published that they had two recalls. The first one was in April 2016, when they recalled electric water heaters due to potential fire risk. Here you can find problematic serial numbers.
  • The recall was related to indoor power vent units.  This happened between May 2004 through December 2006. [3]

AO Smith Water Heaters


The AO Smith exists just a few years longer than Rheem, as it was founded in 1921. The brand is known for making some revolutionary changes in water heaters. AO Smith was among the first companies to produce tankless high-efficiency water heaters, as well as solar hybrids.

AO Smith holds the Energy star certificate for its amazing performance, which speaks volumes about the brand’s efficiency.

Gas Water Heaters

  • The AO Smith offers about 60 various models of natural gas and liquid propane tank water heaters.
  • The brand’s gas water heaters can be found in up to 37% of households in the US.
  • Most water heaters hold up to 40 gallons.
  • Most water heaters have a 6-year warranty.

Electric Water Heaters

  • AO Smith offers more than 30 models of electric water heaters.
  • Some of its best models have a voltage of 120, with 1600 watts.
  • Most have a warranty of up to 6 years.

Tankless Water Heaters

  • The brand offers over 20 tankless water heaters.
  • Some of the most popular tankless heaters have an energy factor of 0.93
  • Most have a warranty of 12 years.


  • The average lifetime of a gas water heater is 9-12 years. AO Smith offers a 5-6 year warranty on most.
  • The average lifetime of an electric water heater is 10-15 years. AO Smith offers a 5-6 year warranty on most.
  • The average lifetime of a tankless water heater is 20 years. AO Smith offers a 12-year warranty on most.


    • Here we found one recall from November 2018. They recalled Ultra-Low NOx water heaters because of potential fire risks. This water heater poses a fire hazard if it’s installed directly on a wood or other combustible floor. [4]

Read Also: Bradford White vs Ao Smith

Rheem Vs AO Smith – Reliability


When it comes to reliability, both of these brands are more or less equal. Both will offer you high-quality products, and all of their water heaters have the same lifespan.

In fact, the durability of the water heaters mostly depends on maintenance and how well you take care of them and it’s not up to any of these two manufacturers.

Overall, any product with a fiberglass water tank will last longer than a regular tank. Both brands have high-end products that provide a lifetime warranty on the tank.

This means that if the tank goes out, the entire water heater will be replaced. Yes, if something goes wrong with the tank, it cannot be repaired. Your only option is to replace it.

Some things can affect the lifespan of any water heater. These things are:

Five factors that affect water heater lifespan

  1. Improper installation – Don’t install a water heater on your own, unless you are a professional. If the installation isn’t good, you’re risking a leaky water heater or even floods.
  2. Poor water quality – Poor water quality can lead to sediment buildup and corrosion within gas water heaters, reducing efficiency, shortening the appliance’s lifespan, and potentially causing malfunctions.
  3. Lack of maintenance – Don’t skip flushing/draining, descaling, anode check and replacement once per year
  4. No thermal expansion tank – this element will prevent damage due to expansion of hot water
  5. Venting – If you are using gas water heater, you need to setup proper venting

When it comes to Rheem vs AO Smith, there are a few things worth noting.

Both brands offer many high-quality products and a few not-so-good ones. This is regular for any brand, and not just these two. You can find better and worse products no matter the manufacturer. Some series are simply better than the other ones.

Maintenance and usage are up to you, and the brands have little to nothing to do with them. The warranty can help you do some repairs free of charge, or even to replace some parts or even an entire tank!

Otherwise, the repairs can end up costing you thousands of dollars. Also, both brands offer installation for most of their models.

Overall, as you can see, they are more or less equal when it comes to how long their water heaters can last.

Rheem Vs AO Smith Final Choice

It’s time to draw some conclusions from what we’ve gathered so far.

When it comes to gas water heaters, AO Smith is the clear winner. More people prefer the brand over Rheem’s products, and this is something no one can argue about. They have a wider selection of gas water heaters, and it’s easier to find a product that works for you when you have such a big choice.

Both companies offer a good choice of electric water heaters, but it appears that Rheem has some more reliable models that tend to last a bit longer compared to AO Smith ones. This makes it the winner in this category.

When it comes to tankless water heaters, it’s a known fact that no one can be a match to Rheem and its products. This company is the ultimate leader in tankless water heaters, and there is no denying that.

However, when it comes to warranties, AO Smith does offer a bit longer guarantees on its products compared to Rheem, and it appears that the customer service is a bit more eager to help.

Read Also: Water Heater Vacation Mode vs Pilot Mode

The Verdict

As seen above, both brands have some good and some bad sides. While Rheem provides the best tankless and electric water heaters out there, AO Smith offers better warranties and a wider choice of gas water heaters.

In the end, it all comes down to your preferences and what type of water heater you’re looking for. You should always look at as many reviews as possible so you can be certain you’ve picked the right product for you.

Just because a company excels at, for example, gas water heaters, doesn’t mean it also has to produce amazing electric ones, and so on. Look at the individual product you’re interested in before making such a decision.

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