AO Smith vs Rheem Water Heater

So you need a new water heater. You’ve probably already heard of two big names — AO Smith and Rheem. Both brands show up at every hardware store. Both have tons of reviews online. And both promise hot water whenever you need it.

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But which one is actually better for your home?

That’s the real question. And we’re going to answer it in plain, simple terms. No confusing jargon. No fluff. Just the facts you need to make a smart buy.

Let’s get into it.

A Quick Look at Both Brands

Before we compare them side by side, it helps to know a little background on each brand.

AO Smith has been around for a very long time. It started as a company that made steel frames for cars. Over time, it shifted focus to water heating. Today, it’s one of the biggest water heater brands in North America. They make gas water heaters, electric water heaters, tankless units, and hybrid heat pump water heaters.

Rheem is also a massive name in the water heating world. Rheem makes both residential and commercial water heaters. Like AO Smith, they sell gas, electric, tankless, and hybrid models. They also own the Ruud brand, which is basically the same product line sold through a different channel.

Both companies are well-established. Both build solid products. But they do have real differences — and those differences matter when you’re spending a few hundred dollars (or more) on a water heater.

AO Smith vs Rheem: Side-by-Side Comparison

Let’s break down the key areas where these two brands differ.

1. Product Lineup

Both brands cover all the major categories:

Tank water heaters (gas and electric)
Tankless water heaters (gas and electric)
Hybrid heat pump water heaters
Commercial units

AO Smith’s lineup tends to feel a little more premium. Their Signature and Signature Premier lines are popular for home use. Their ProLine and Voltex series also get strong reviews.

Rheem leans toward a wide range across price points. They have budget-friendly options that work well for tight budgets, and they have higher-end Performance Platinum models for people who want more efficiency.

Winner here: It’s a tie. Both brands give you plenty of options no matter your budget or fuel type.

2. Energy Efficiency

This is a big one. A water heater runs almost every day. Over time, the energy costs add up fast.

AO Smith is well-known for pushing energy efficiency. Their Voltex hybrid heat pump water heater has a very high Uniform Energy Factor (UEF) rating — often above 3.5. That means it produces more than three times the heat energy it consumes. For a water heater, that’s impressive.

Their ProLine XE electric models and high-efficiency gas units also beat the standard efficiency marks by a good margin.

Rheem is not far behind. Their Performance Platinum hybrid heat pump water heater also hits a high UEF, often above 3.7 in some models. They even introduced a smart hybrid model that connects to Wi-Fi and allows you to set modes remotely.

On the gas side, Rheem’s high-efficiency condensing tankless units are very competitive. The Rheem RTGH series, for example, can hit 94% or higher thermal efficiency.

Winner here: Slight edge to Rheem for the higher UEF ratings in their hybrid line. But AO Smith is very close.

3. Tankless Water Heaters

Tankless water heaters heat water on demand. There’s no storage tank. Cold water comes in, gets heated as it flows through, and comes out hot at your tap.

AO Smith Tankless: Their ProLine Whole Home gas tankless units are popular for families. Models like the ATNG-199-N handle high demand well. They also make condensing units that capture exhaust heat and use it for efficiency gains.

Rheem Tankless: Rheem’s RTGH and RTG series have a solid reputation. Many plumbers prefer Rheem tankless units for the ease of installation. Parts are also easy to find at most supply houses.

Both brands make indoor and outdoor versions. Both have strong warranty coverage on their tankless line.

One place AO Smith pulls ahead is with their advanced diagnostics display. Some AO Smith tankless units show error codes and system status right on the unit. That makes troubleshooting faster.

Winner here: Very close, but AO Smith gets a slight edge for the diagnostics display and build quality on their top-tier tankless units.

4. Traditional Tank Water Heaters

Tank water heaters are still the most common type in American homes. They store hot water in a tank, ready to go when you turn on the tap.

AO Smith Signature Series: This is their bread-and-butter residential line. It comes in multiple capacities (40-gallon, 50-gallon, 75-gallon, and more). The glass-lined tank is designed to resist corrosion. It also has a self-cleaning dip tube that stirs up sediment and keeps it from settling.

Rheem Performance and Performance Platinum: Rheem’s residential tank line is very solid. Their Platinum series is Energy Star certified. The EverKleen self-cleaning system is similar to AO Smith’s self-cleaning feature. Some Rheem units also have a built-in anode rod system that helps fight corrosion for longer.

One thing Rheem does very well here is first-hour delivery rating (FHR). This is how much hot water a unit can pump out in the first hour of use. Some Rheem 50-gallon models have a higher FHR than comparable AO Smith models — which matters for busy households.

Winner here: Slight edge to Rheem for higher FHR on some comparable tank models.

5. Hybrid Heat Pump Water Heaters

Hybrid heat pump water heaters are the most efficient electric water heaters you can buy. They pull heat from the surrounding air instead of generating heat from scratch.

AO Smith Voltex: The Voltex is a well-respected hybrid unit. It has multiple operating modes — heat pump only, high demand, and electric-only modes. The control panel is user-friendly. The UEF is high, and it’s Energy Star certified.

Rheem ProTerra (Performance Platinum Hybrid): Rheem’s ProTerra is arguably the most talked-about hybrid water heater on the market right now. It has Wi-Fi connectivity, real-time energy monitoring, and a very high UEF. You can control it from your phone and track your energy usage. The LeakSense technology alerts you when it detects a water leak near the unit.

The Rheem ProTerra also integrates with smart home systems like Amazon Alexa. That’s a feature most people don’t expect from a water heater — but it’s genuinely useful.

Winner here: Rheem ProTerra wins this category. The smart features and higher UEF give it the edge.

6. Warranty Coverage

Warranty matters a lot with water heaters. These are not cheap appliances, and repairs can be expensive.

AO Smith Warranty:

Tank water heaters: 6-year or 12-year limited warranty (depending on model)
Tankless: 12-year heat exchanger warranty, 5-year parts
Labor: 1 year on most models

Rheem Warranty:

Tank water heaters: 6-year or 12-year limited warranty (depending on model)
Tankless: 12-year heat exchanger warranty, 5-year parts
Labor: 1 year on most models

Honestly, the warranties are almost identical between the two brands. For both, the higher-end models come with longer tank warranties. The 12-year warranty models cost more upfront, but they give you better peace of mind.

Winner here: Tie. Nearly identical warranty structures.

7. Price and Value

Let’s talk money.

AO Smith tends to sit in the mid-to-high price range. Their entry-level tank units are competitive, but their mid-range and premium lines cost more than the Rheem equivalents in many cases.

Rheem covers a wider range. They have true budget options (basic Performance series) that won’t break the bank. They also go high with the Performance Platinum and ProTerra models.

If you’re on a tight budget, Rheem likely gives you more choices at lower price points. If you’re willing to spend more for a quality build, both brands are comparable.

For tankless units, AO Smith and Rheem are similarly priced at the comparable tier.

Winner here: Rheem, for better budget options and wider price range.

8. Availability of Parts and Service

This one matters a lot in the long run. If something breaks, can you find parts? Can a local plumber fix it?

Both AO Smith and Rheem are widely stocked across the United States. You can find parts at major home improvement stores and plumbing supply houses.

However, many plumbers report that Rheem parts are slightly easier to find at local supply houses. This can cut repair wait times.

AO Smith parts are also easy to find, but there are occasional reports of longer wait times for specific components, especially for newer tankless models.

Winner here: Slight edge to Rheem for parts availability.

9. Installation

Neither brand is hard to install if you’re working with a qualified plumber. Both brands provide clear manuals and have support lines.

For DIY folks: AO Smith has a strong reputation for clear, beginner-friendly installation instructions. Their customer support is also well-reviewed for walking homeowners through troubleshooting.

Rheem’s installation process is also well-documented. Many contractors who work with both brands say they’re about equal in terms of ease of install.

Winner here: Tie.

10. Customer Reviews and Reliability

Let’s look at what actual users say.

AO Smith gets consistent praise for:

Long lifespan
Solid build quality
Good first-party customer support

Common complaints:

Some users report issues with the plastic parts on certain models
Occasionally higher upfront cost

Rheem gets consistent praise for:

Wide selection at different price points
Smart features on higher-end units
Good energy efficiency ratings

Common complaints:

Some reports of thermostat issues on certain electric models
A few users mention longer hold times for customer support

Overall, both brands get solid reliability marks. Consumer reports and plumber surveys consistently rank both brands among the top residential water heater brands in the country.

Winner here: Very close. AO Smith gets a slight edge for long-term reliability reputation.

AO Smith vs Rheem: Quick Summary Table

Category	AO Smith	Rheem
Product Variety	Wide	Wide
Energy Efficiency	High	Very High
Tankless Quality	Excellent	Excellent
Tank Water Heater	Great	Great
Hybrid (Heat Pump)	Very Good	Best in Class
Warranty	Strong (up to 12yr)	Strong (up to 12yr)
Price Range	Mid-High	Budget to High
Parts Availability	Good	Very Good
Smart Features	Limited	Strong
Overall Reliability	Excellent	Very Good

So Which One Should You Buy?

Here’s the honest answer: it depends on what matters most to you.

Go with AO Smith if:

You want a long-lasting, reliable tank or tankless water heater
Build quality and proven reliability are your top priorities
You like straightforward units without too many bells and whistles
You value clear diagnostic displays on tankless models

Go with Rheem if:

You want a hybrid heat pump water heater with smart features
Budget matters and you want solid options at a lower price
You prefer a unit with Wi-Fi control and app integration
You want easy access to parts through local plumbing supply stores

Who Wins for Specific Use Cases?

Best for Large Families

Rheem. Their first-hour delivery ratings on tank models tend to be higher. For big households that use a lot of hot water fast, that matters.

Best for Energy Savings

Rheem ProTerra Hybrid. The high UEF rating and smart modes make it the most efficient residential electric water heater you can buy right now.

Best Tankless Water Heater

AO Smith. Their top-tier condensing tankless units are well-built, efficient, and have excellent diagnostics. Great for whole-home use.

Best Budget Option

Rheem. Their base Performance series is affordable and reliable for basic residential use.

Best for Long-Term Reliability

AO Smith. Their units have a strong track record for going the full warranty period and beyond with minimal issues.

Common Questions About AO Smith and Rheem

Are AO Smith and Rheem made by the same company?

No. They are separate companies. AO Smith is based in Milwaukee, Wisconsin. Rheem is headquartered in Atlanta, Georgia. Both are independent brands.

Does Rheem own AO Smith?

No. Rheem owns the Ruud brand. AO Smith is its own independent company.

Which lasts longer — AO Smith or Rheem?

Both brands can last 10 to 15 years or more with proper maintenance. Tank flushing, anode rod replacement, and regular checks extend the life of either brand.

Is AO Smith made in the USA?

AO Smith manufactures many of its residential water heaters in the United States, particularly in Ashland City, Tennessee. Some of their commercial and specialized units are made in China.

Rheem also manufactures products in both the United States and internationally.

Which brand do plumbers prefer?

Surveys vary, but Rheem often comes up as a top choice among plumbers for ease of installation and parts access. AO Smith also gets high marks for build quality. It often comes down to regional availability and personal preference.

Tips for Getting the Most Out of Your Water Heater

No matter which brand you go with, these tips will help your unit last longer and work better.

Flush the tank once a year. Sediment builds up in the bottom of tank water heaters. It reduces efficiency and shortens the tank’s life. A quick annual flush removes the sediment.

Check the anode rod every 3-5 years. The anode rod is a metal rod inside the tank that sacrifices itself to prevent corrosion. When it’s used up, the tank starts to rust. Replacing it is cheap and extends tank life significantly.

Set the temperature to 120°F. This is the sweet spot — hot enough to kill bacteria, but not so hot that you’re burning energy or risking scalding.

Insulate the pipes. Insulating the first few feet of hot water pipe coming out of your heater reduces heat loss and gets hot water to your tap faster.

Install a drip pan. Put a drip pan under any tank water heater. If the tank ever leaks, it will catch the water before it damages your floor or the area around it.

Final Thoughts

Both AO Smith and Rheem are great brands. You’re not making a bad choice with either one. They both build water heaters that millions of people rely on every day.

The difference comes down to your priorities.

Rheem wins on smart technology, hybrid efficiency, and budget options. AO Smith wins on long-term reliability, build quality, and tankless diagnostics.

If you’re going hybrid and want the smartest, most efficient unit available right now, go with the Rheem ProTerra. It’s genuinely one of the best residential water heaters on the market.

If you want a rock-solid tankless or tank unit and you care most about durability, go with AO Smith. Their reputation for lasting the long haul is well-earned.

Either way, get the right size for your household, make sure it’s installed by a licensed plumber, and follow the basic maintenance steps above. Do that, and you’ll have hot water without any headaches for many years to come.