A.O. Smith Water Heaters Review

You can’t talk water heaters without mentioning A.O. Smith. This company is responsible for a large percentage of the innovations that have made modern water heaters so efficient. In addition, they have expanded to become leaders in electric, gas, tankless, and even solar water heaters.

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It would take a small book to review all of A.O. Smith’s top quality models, so instead, we’ll give you a good overview of the product lines and a comparison between some of the best from each type of water heater.

About A.O. Smith

As with some of the most famous success stories, the company that’s now synonymous with water heaters had very humble beginnings. Founded by Charles Jeremiah Smith in 1874 as a single-person hardware solutions shop, this small business quickly expanded to include three sons and was best known for manufacturing metal components for baby carriages.

The third son to join was Arthur Oliver Smith. He took the company to new heights when he developed a lightweight steel car frame that drew the attention (and business) of major car companies such as Ford and Cadillac. These innovations led to the unveiling of the Mechanical Marvel, the first automated frame production line in 1921 by Arthur’s son Lloyd Raymond.

In 1936, the engineers of A.O. Smith developed a method for adding glass linings to residential water heaters. Numerous further advances in water heater design followed, and the company began to expand to Canada, Europe, and China.

The company sold its automotive branch in 1997 and electric motor branch in 2011, replacing them with mergers of major water heater and treatment companies, making them a global leader in both industries – without ever throwing away the integrity and innovation that began nearly 150 years prior.

Gas and Propane

AO Smith gas water heaterGas heaters make up the largest group of heaters, and there are several quality lines to choose from. A.O. Smith divides their gas (and propane) heaters into three ProLine tiers. The third tier, ProLine XE, contains several product lines, while the other tiers contain only one line each.


A.O. Smith strives to maximise efficiency and quality. As a result, all of their gas heaters have LEED ratings, and many are ENERGY STAR certified. All have either low NOx or ultra-low NOx emissions and four different venting options are available.


When you need a seemingly endless supply of hot water, it doesn’t get much better than the Polaris line. The entire line is high efficiency with a high recovery rate, plus an ultra-quiet design that might make you forget it’s running.

ProLine and ProLine Master

These lines feature models designed for both home and mobile home use. They are all high recovery, with efficiency ratings of 80 percent or higher on some models. Many are also ENERGY STAR-certified. Several other lines fall under a third ProLine tier, the ProLine XE.


Sold exclusively at Lowes, the A.O. Smith Signature series consist of various Signature Select and Signature Premier water heaters for residential use. While not as energy efficient as some of the manufacturer’s other series, the Signature line is one of the best values in home water heaters sold by a big box store.


The pinnacle of gas heaters, the entire Vertex line is ENERGY STAR rated and feature high thermal efficiency and recovery rates.

Best A.O. Smith Gas Water Heaters

ModelCapacityRecoveryEnergy FactorWarranty
Signature Premier G6-PVS5040NV50-gallon45 GPH0.726-year
ProLine GCR-5050-gallon43 GPH0.626-year
Signature G6-S4040NV40-gallon41 GPH0.626-year


AO Smith electric water heaterAs with the gas models, electric water heaters are available in three tiers, with the ProLine XE being subdivided into two lines.


Using environmentally friendly materials, A.O. Smith’s electric water heaters are all LEED certified and offer superior efficiency to older models. Their ability to draw power from outlets allows for tiny point-of-use models that can fit into tight spaces.

ProLine and ProLine Master

The lowest tiers of electric water heater are essentially the same as their gas counterparts. All models have above-average or better efficiency. Sizes range greatly, with the smallest tanks only holding a few gallons.

ProLine XE

The main XE line features digital displays and ultra high efficiency. The mid-sized tanks make them great for apartment use and single-family homes.


As with the gas versions, the Signature series is sold exclusively at Lowes as of 2017. If you’re on a budget yet still want the high efficiency and durability that A.O. Smith is known for, be sure to consider this line.


The electric equivalent of the Vertex line, these models are all ENERGY STAR compliant. What makes them especially appealing is the hybrid design. This allows the Voltex to double as a dehumidifier, pulling excess moisture from the air to reduce water requirements and  running costs.

Best A.O. Smith Electric Water Heaters

ModelCapacityRecoveryEnergy FactorElements
Signature Premier ES12-50R55DV50-gallon25.3 GPH0.952 x 5,500W
ProLine XE PXNS-5050-gallon25.0 GPH0.952 x 5,500W
Signature E6-50H45DV50-gallon20.7 GPH0.932 x 4,500W


AO Smith tankless water heaterSeveral tankless models are available for gas and propane usage. As with all A.O. Smith gas models, these are low NOx or ultra-low NOx for improved environmental safety.


Tankless systems fit into much smaller spaces and can provide hot water on-demand. Most models offer remote control, and some of the newest models have digital displays.

Gas and Propane

Many of the models which are non-hybrid feature both ENERGY STAR and LEED certifications. Those models are all rated as ultra-low NOx, while the remaining models are rated as low NOx. In all cases, these tankless models are highly efficient.

Hybrid Gas/Propane

Designed to be fueled by either gas or propane, these models can be used with a wide range of domestic systems. They are generally non-condensing and have a high efficiency level.

Best A.O. Smith Tankless Water Heaters

ModelGallons/MinuteMax BTUsEnergy FactorWarranty
ATI-540H-N9.0 GPM199,0000.9315-year
ATI-340H-N8.0 GPM180,0000.9515-year
ATI-310-N8.0 GPM190,0000.8015-year


The list of water heaters could not be called complete without mentioning the Cirrex solar system. Not only are these heaters extremely efficient and great for the environment, but they come with OG-300 certification, meaning they’re eligible federal tax breaks and rebates in several states.

Owning this system may reduce heating costs by as much as 70 percent, meaning they’re a great choice for those on tighter budgets.

A.O. Smith Water Heater Parts

As with all water heaters, those by A.O. Smith will require maintenance and may need to have parts replaced over time. Some of the most commonly replaced parts are screw-in elements, gas thermostats, pilot assemblies, thermocouples, burners, valves, and anode rods.

A few parts may need replaced less often, such as flu dampers, heat exchangers, and temperature controls. Note that gas water heaters will generally have more parts to maintain than electric. If you need specific part numbers, your A.O. Smith user manual will have that information.

A.O. Smith Contact Info

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  1. **Stay away from AO Smith water heaters!*
    – Purchased Model #GCNH40 200 in November 2014. I had to replace the pilot assembly three years later – a $200 repair.
    – Today – December 17, 2018 – the burner assembly burst. AO Smith cannot get one of their contracted service providers out to fix my water heater for over a week.
    – Every plumber I’ve talked with has mentioned the problems and issues AO Smith is having with their water heaters, a recall, and that they’re overwhelmed.
    – I have talked with the AO Smith recall department 8x this evening. Long story short: they can’t do anything. They can’t get a part to me for over a day; their only service provider in my area doesn’t know when he can schedule a visit – he says for at leat 6-7 days. Other service providers will charge me an out-of-area charge to travel out of their local area.
    – One service provider has the needed part but will charge $395 because I am slightly out of his service area. First, AO Smith said they would cover this charge. When I pressed for confirmation, they said they would not. AO Smith should just agree to pay this extra charge
    and the problem would then be resolved tomorrow.
    – As I cannot get an answer, I have no choice but to hire a reliable local plumber to install an entirely new water heater. $1300-$1500 out of pocket.
    DO NOT BUY AO SMITH WATER HEATERS – they are having recall issues, technical issues, and the people in their service departments have no ability to make decisions that can help and resolve.

    • Wow, I’m sorry for the ordeal you’ve been through. That’s definitely not my experience with AO Smith in the past but it does bring up the point that no brand is without their problems. Hopefully they’ll end up getting you taken care of.

  2. Our AO Smith is 27 years old & it’s finally reached its end of life. Occasional moisture can be seen around the bottom & there’s slight rust. It’s a 40 gallon natural gas from 1992. We’re interested in replacing with the same brand but we’ll look into recalls involving Jessica’s issues before buying another AO Smith.

  3. Built a house and have been living in it for about 3 years now. We have an AO Smith water heater and noticed it was leaking. My wife has tried calling because it is under warranty but has yet to get someone on the phone to get the issue fixed. She finally filled out the information online and has a case number. Which does not do us any good because we still can’t get anyone on the phone. As of this morning, we have no water heater and I have been listening to music for 15 minutes waiting to speak to someone to get this resolved. I’m sure some of their products are great, but I would stay away because their customer service is horrible. Well, let me rephrase that, their customer service seems to be non-existent.

  4. I purchased a life time warranty A.O. Smith hot water heater in 1994. It started leaking in February 2018. 24 years aur our water system had already took 3 heaters out of service. I called the company and was able to get full price replacement refund. I still cannot believe I got 24 years service out of it and NO trouble with refund.

  5. This is by far the worst heater we have ever purchased! Stay away from AO Smith heaters at all costs. Our heater began giving us problems within six months of purchase. We did everything we could to fix the water heater andhad repairs of over $600. We get absolutely no support from the company they are the worst in customer service. Do not buy this heater at any cost!

  6. Bought a house with a one year old AO Smith water heater in 2015. Last night the tank blew out. No problem, still under the 6 year warranty, right? Wrong. The warranty only covers the original purchaser. Not cool. You either stand by your product or you don’t. Will be looking elsewhere for a replacement.

  7. Update to a comment left earlier week:

    AO Smith did eventually agree to cover my failed unit and gave me a redemption code. Props for that, at least. That said, the number for a local dealer they gave me was bad and Lowe’s could not order my particular model because it was part of the “Pro” line, so I was left calling around to plumbing supply houses looking for a replacement. The story ended well this time. The new unit is in and working, but I doubt I’ll consider AO Smith if and when I need another one.

  8. Model#GCVT50300 – Installed March 16, 2015.
    Unit making a high squeal noise during low pressure hot water usage from five different faucets. Noise coming from inside unit. Heater is under warranty but labor is $400.00 to fix. This doesn’t make sense only 4 years after insulation

  9. Steer clear of this brand and all other water heater brands they own.
    I purchased an electric water heater from Lowe’s eight years ago. It has a nine year warranty. There was a problem with the Smart panel. We checked the ohms on each of the elements. We are able to manually set the temperature if we by pass the smart panel. But the smart panel locks the temperature on 150 degrees. Enough to scald a person. They sent us a new smart panel. Same problem , BUT every time you call you get another person. Now, for some reason, they believe that the water heater was not installed up to the National Electric Code (after eight years). In order to get warranty, we have to PROVE is is installed up to code by taking photos or having someone inspect it. Because we said we would not do this, they said we no longer have a warranty on the water heater. So I can continue to use the panel and have scalding water which is dangerous especially for small children and the elderly, or I can by pass this feature because they won’t warranty their product.
    I will never own another A O Smith product if I have a choice for some other brand.
    Some of the other brands That they own are American, Whirlpool, State, John Wood, GSW,Hague Quality, Aquasana, Lochinvar, Reliant, US Craftmaster, Takigi and of course A O Smith.
    Their customer service will no longer talk with me about my product unless I can prove my unit was installed up to code ( which it is and has been for the last eight years). Don’t believe that that is true? Call the customer service at 1-877-817-6750 and ask about case 11682111.

    Just saw someone returning a unit to Lowe’s today because it didn’t work. I told him just get a full refund and shop another brand.

  10. I had an AO Smith water heater installed less than 2 years ago. It quit working yesterday so I had a plumber from the company who installed it come out today and discovered there was a manufacturing defect that had caused a wire to be burned through. The warranty only covers the part, not labor, so I’m stick shelling out $258 to fix a part that was defective in the first place….on a water heater I spent $1300 to have installed less than 2 years ago. I’m highly disappointed in the poor quality of this water heater and wouldn’t recommend it to anyone

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