Rheem vs AO Smith Water Heaters – Pros, Cons, Comparisons

Hi! There are a lot of questions about water heaters on forums and reviews and I’ve read a lot of those to solve my Rheem vs AO Smith problem when my almost twenty year old heater leaked from the hot water outlet.

rheem vs ao smith

Important! Installation and Labor

Think about installation costs and contractors BEFORE purchasing a heater!

Make sure the price the subcontractor quote is firm. Many of them, especially when working for big box stores charge more for upgrades once they get to your house. I had some experience with Lowes’s contractor.

Both plumbers and stores can charge you with $1000 for the labor part. Some companies install ONLY parts which you bought from them. And they are often much more expensive than Amazon.

Don’t need to agree right away. Ask about local plumbers, HVAC contractors and handyman who could do this job? They tend to do water heaters and are usually much cheaper.

Can you do some parts of the task yourself? For example, purchase and bring home (often free-of-charge) the heater? Usually home owner can turn off the gas and easily drain the water heater yourself. Getting the device and draining it are about 2 -3 hours of “work” that you are paying the contractor for.

Rheem vs AO Smith Natural Gas 50-gallon Water Heaters

ao smith water heater vs rheem
Check the price – Rheem PROG50-40N 50 Gallon Professional Classic Tall Natural Gas Water Heater

I called a HVAC & Plumbing guy to get an in-house estimate and I also made some research Home Depot, Amazon and Lowes to get an estimate. Here are my options.

1) Local Plumber $1875: AO Smith, drip pan, expansion tank, cold water inlet ball valve.

2) HD’s contractor gave me two Rheem options:

  • about $1500 for Rheem PROG50-38N RH60
  • about $ 1600 for Rheem XG50T12HE40U0 12 yr parts &3 yr labor

3) Amazon:

  • A.O. Smith XCR-50 ProMax Plus (10-yr, about $1,021 & free shipping)
  • A.O. Smith GCRL-50 ProMax Short Heater (6-yr, about $900)

Anode rod replacing

The way to replace the sacrificial anode rod can be difficult and require a specialist. So you need to buy the heater that you are confident you are able to do it yourself. Anode in standalone port is easier and cheaper to replace.

AO Smiths rods tend to be harder to replace. Rheem is easier, you can check the video on how to replace the rode.

Sediment flush is very simple on any heater.


ao smith vs rheem gas water heater
A.O. Smith XCR-50 ProMax Plus 50 gal Gas Water Heater

In my opinion, there is no significant difference between the guarantees of Rheem vs. AO Smith. When you buy a heater from a reputable brand (and they both are), the difference in prices for similar models is mostly due to the extended warranty.

For example, the Rheem heaters are all pretty identical and the price difference is just the warranty. Upper models have a slightly better control valve. Any model will likely work for 15-25 years and then will need replacement.

Of course, you can pay more for the unit with 12 year guarantee. And sometimes (rarely) you even will have additional anode in the unit. But my advice is to save the money and buy the six year product. 12-year one has the same tank, so if you replace the anode rod and flush the sediment regularly it’s going to live a long time.

AO Smith has also great customer support. One phone call from your plumber to the company will get you a brand new device in few days with no charge.

Energy efficiency

Energy efficiency of a water heaters is measured in UEF. It is Unified Energy Factor, the method of Department of Energy. The higher the UEF, the higher the efficiency.

For example, AO Smith Professional Classic Plus 48-Gallon Water Heater has UEF 0.80 and Rheem ProLine XE 50-Gallon Gas Water Heater – 0.72UEF, so the AO Smith is slightly better. But both heaters are Energy Star certified, which can lead you to tax breaks in the right state.

Conclusions: Rheem vs AO Smith tank water heaters

Both Rheem and AO Smith are good products and you can’t go wrong with either.

The difference is in personal preferences and the need to save money. Personally, I want to change the anodes myself and see no point in a 12-year or even a “lifetime” tank warranty. So I bought 6-year Rheem heater.

If you don’t want to bother with replacing anodes and and monitoring the technical condition of the heater – just call specialist every few years. And buy Smith with a 12-year warranty. They have great customer service and you will be more confident about that.

Read also our Rheem vs Ecosmart heaters comparison.

Rheem vs AO Smith Tankless Gas Water Heaters

Tankless water heaters are source of “endless” hot water, but they are more sensitive to water quality. Hard water, lack of maintenance (no descaling, no flush and drain), improper installation/venting etc. could significantly shorten the life of the heater. So every model of every brand needs some maintenance on it.

Rheem gas tankless Water Heater
Rheem Gas Tankless Water Heater

When it comes to capacitive heaters, both manufacturers go head to head, for example Tankless Water Heater Condensing Ultra-Low NOx by Rheem has almost absolutely similar specs with 10.0 GPM Indoor Natural Gas Tankless Water Heater by AO Smith.

The vast majority of the water heater components are universal. So, my answer to the Rheem vs AO Smith Tankless Gas Water Heaters question is to choose what’s cheaper and actually do the necessary maintenance on it.

Check the anode every year and replace it if required. Some handyman recommend to loosen and reinstall the anode after buying and before you turn on the water heater for the first time. It will help you to get the anode out later. Drain the sediment out of the water heater at least once a year once a year. Just do that and your heater should last a lifetime.

Rheem vs AO Smith Electric Water Heaters

AO Smith Electric Water Heater
AO Smith Electric Water Heater

Electric water heaters are much more simple than gas ones. They don’t need gas nozzles, ignition automation and are more safe. Tank models are more durable, require less power (due to water preheating), but they are much larger and limited in the amount of hot water.

The main difference between warranty is in anode rod diameter. For example, a 6-year typically has .75-inch anode and 12-year .90-inch rod. So you can easily convert 6 year tank into 12 year one by changing anode each 1-3 years or installing larger one.

So again, the advice is to buy what you like and don’t spend too much. Check the heater for leaks every six months. Check water pressure and ensure it doesn’t exceed 80 psi. These actions will prolong life of any heater.

But my choice is AO Smith heaters, they arrive with detailed manual, easier maintenance, and troubleshoot steps.

EcoSmart vs Rheem Water Heaters

Gas water heating is usually cheaper, but an electric tankless water heater is your choice if you don’t have proper gas supply lines or ventilation system, need a small, quick and durable unit in office suites and all other public buildings. In the United States, there are two leading electric water heater manufacturers: EcoSmart and Rheem and few less popular – Bosh, Stiebel (Germany), Camplux (China), and others.

Read also our Rheem vs AO Smith comparison.

EcoSmart ECO Electric Tankless Water Heaters

Lifetime Warranty, self-modulating technology – unit will adjust power to current water flow. Temperature control in digital 1-degree increments.
Stainless and copper components for high durability and efficiency, six models (8-36KW, 2-6 gallons per minute), 240 volts


EcoSmart gives the most extensive warranty on the market: Residential Heaters ECO8–36, lifetime warranty on electronics, Exchangers, and elements.

EcoSmart also offers SmartBoost unit – a 7.2 kW electric heater ECOTB240 to be connected to a tank gas or electric water heater to increase hot water delivery. SmartBoost will increase the efficiency by 45%, so you’ll get more hot water (like with much larger tank) for the lower price and installation costs. The Ecosmart will adjust pressure settings and power usage to keep a consistent output for you.


Warranty is eligible for tankless electric water heaters installed by licensed electrician/plumber within 30 days of purchase, warranty registration must be filled and post marked within 30 days of purchase. Be careful to register your unit properly.

Service wait times sometimes are long and warranty covers the parts only cost. Labor to repair might be expensive, and it is not a very complex device and you can often make simple repairs yourself if you are handy.


Buying EcoSmart  Electric Water Heater is a good decision. The Ecosmarts is well-reviewed, reliable and efficient units. It is a great choice for most people – has a power range of 5.5 to 36KW that is suitable for appliances from hand washing to large family home in cold climate regions.

Rheem Tankless Electric Water Heater Characteristics

Energy efficient – 99.8%, digital temperature display. Industry leading low flow activation – unit start heating when the tap is turned on low.


Rheem units are one of the most compact tankless water heaters, and it allows to install it right near the sink and minimize hot pipe losses. Besides, the Rheem units are cheap enough to allow energy savings pay off expenses in a reasonable time – in several years, one of the best turnover periods.


Hard water ruins these units fast, so you should put a softener in line ahead of it or clean it annually. It is an important thing you have to factor in the cost of going tankless when your water is hard (see our maintenance manual).

Similar to Ecosmart, if the unit is not installed by professionals, it could get you into an issue upon returning the item.


Rheem units have low flow activation, have nice displays, look great and are cheaper than Ecosmart. But warranty conditions are worse, reliability issues occur, and there are more assembly quality complaints. Nevertheless, Rheem is a great cost effective choice if you need a compact solution.