ao smith proline vs signature

ao smith proline vs signature

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

Gas 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

Signature Premier G6-PVS5040NV


As 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

Signature Premier ES12-50R55DV


Several 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 WaterHeaters


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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BY M. Kogan

Hello, I am Marcio. I am an architect and designer, alma mater is Mackenzie. Retired in theory, but an architect never retires completely. Along with architectural projects, I am a filmmaker and have completed some short documentaries. Filmmaking and design are my passions. In HomeQN I write about home decoration and foundations. The goal is to teach homeowners to DYI as much as possible, and when this is not possible, enable them through knowledge, to evaluate service quotations and choose the best service technicians.

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