AO Smith

A. O. Smith is a manufacturer of residential and commercial water heaters, headquartered in Milwaukee, Wisconsin, and founded in 1874. A. O. Smith produces a full range of water heating equipment for residential and light commercial applications: natural gas and propane storage water heaters, electric storage water heaters, gas tankless water heaters, electric tankless water heaters, hybrid electric heat pump water heaters, condensing gas water heaters, combi-boiler systems, and solar water heating systems. The A. O. Smith Voltex hybrid electric heat pump line includes units certified to ENERGY STAR. The A. O. Smith X3 Scale Prevention Technology is engineered to extend anode rod life and reduce scale buildup, with the manufacturer citing a claim of 300% longer service life compared to standard units under qualifying conditions. For plumbers and mechanical contractors specifying residential and light commercial water heating, A. O. Smith offers a broad product line from a manufacturer with more than 150 years of operation.

Product Lines

Natural Gas and Propane Storage Water Heaters

A. O. Smith natural gas and propane storage water heaters are available for residential and light commercial applications in standard efficiency and high-efficiency configurations. The product line includes power-vent and direct-vent models for applications where combustion air and exhaust routing require flexible venting options. A. O. Smith offers ProLine and ProLine XE series gas water heaters, with the XE designation indicating higher efficiency performance. Capacity ranges from standard residential 40-gallon tanks to larger 75-gallon and commercial-grade tanks suited for higher daily hot water demand.

Electric Storage Water Heaters

A. O. Smith electric storage water heaters serve residential and light commercial applications where natural gas is not available or where the project calls for an all-electric hot water system. The A. O. Smith Voltex hybrid electric heat pump water heater line uses heat pump technology to move heat from ambient air rather than generating it resistively, operating at higher efficiency than standard electric resistance units. A. O. Smith Voltex units are ENERGY STAR certified. The ProLine electric storage line covers standard residential applications where heat pump technology is not appropriate for the installation environment.

Gas Tankless Water Heaters

A. O. Smith gas tankless water heaters provide on-demand hot water by heating water only when a hot water fixture is opened, eliminating standby heat loss from a storage tank. A. O. Smith Signature 700 and Signature 500 series gas tankless units are available in a range of BTU outputs for residential and light commercial applications. The Signature 700 series is designed for higher-demand applications with greater BTU capacity. Tankless water heaters require proper venting and gas line sizing to match the BTU demand of the unit, which differs from standard gas storage water heater installation requirements.

Hybrid Electric Heat Pump Water Heaters: Voltex

The A. O. Smith Voltex hybrid electric heat pump water heater uses a heat pump to extract heat from ambient air and transfer it to the water in the tank, delivering higher energy efficiency than standard electric resistance heating. Voltex units are ENERGY STAR certified and are designed for installations in conditioned or semi-conditioned spaces where ambient air temperature can support heat pump operation. The Voltex line is available in 50-gallon and 80-gallon tank sizes for residential applications. The A. O. Smith X3 Scale Prevention Technology is incorporated in select Voltex and ProLine XE models to reduce scale accumulation on the heating element and anode rod.

Combi-Boiler and Indirect Systems

A. O. Smith offers combi-boiler and indirect water heater systems for homes with hydronic heating systems where a single appliance can serve both space heating and domestic hot water demand. Combi-boiler systems combine a high-efficiency gas boiler with a plate heat exchanger for domestic hot water production in a single wall-mount unit. Indirect water heaters use the space heating boiler as the heat source, circulating boiler water through a heat exchanger inside the indirect tank to produce domestic hot water. A. O. Smith indirect water heaters are sized to match the output of the connected boiler and the household's hot water demand.

Why Contractors Specify A. O. Smith

Contractors specify A. O. Smith water heating products for the breadth of the product line and the availability of ENERGY STAR-certified options across multiple product categories. A. O. Smith has manufactured water heating equipment since 1874 and maintains headquarters in Milwaukee, Wisconsin. The A. O. Smith Voltex hybrid electric heat pump water heater line is ENERGY STAR certified, meeting qualification requirements for applicable rebate programs. A. O. Smith offers power-vent, direct-vent, and natural-draft configurations across its gas storage product line, accommodating the venting configurations commonly encountered on residential remodel and replacement jobs. The X3 Scale Prevention Technology in select A. O. Smith models addresses anode rod service life and scale accumulation, which are common service factors on water heaters in high-mineral-content water conditions.

How to Choose an A. O. Smith Product

The most important decision variable when specifying an A. O. Smith water heater is fuel source, followed by application type, storage capacity, and efficiency tier.

Fuel source determines the product family. For homes with natural gas or propane service, A. O. Smith gas storage and gas tankless water heaters are the applicable lines. For all-electric homes or projects specifying electric hot water, the A. O. Smith Voltex hybrid heat pump line or ProLine electric storage units are the options. The Voltex is the higher-efficiency choice for electric applications where the installation space maintains ambient temperatures above 40 degrees Fahrenheit year-round. In spaces that regularly drop below 40 degrees, or where the heat pump's cooling effect on the installation space is undesirable, the ProLine standard electric storage unit is more appropriate.

Capacity sizing follows daily hot water demand. A. O. Smith sizing guidance at aosmith.com provides first-hour rating (FHR) calculations for matching tank capacity to household demand. For residential applications, 40-gallon tanks commonly serve households of one to three people, while 50-gallon to 75-gallon tanks serve larger households or higher-demand usage patterns.

For tankless applications, the A. O. Smith Signature 700 series handles higher BTU demand typical of larger homes or commercial applications. The Signature 500 series serves standard residential demand. Sizing a gas tankless unit requires confirming the BTU output against the maximum simultaneous hot water demand at the installation.

For homes with hydronic heating systems, an A. O. Smith indirect water heater paired with the existing boiler or an A. O. Smith combi-boiler system may provide the most efficient overall water and space heating configuration. A. O. Smith sizing tools and engineering documentation at aosmith.com support specification for these combination systems.

FAQs

Where is A. O. Smith headquartered and how long has the company been manufacturing?
A. O. Smith is headquartered in Milwaukee, Wisconsin and was founded in 1874, giving the company more than 150 years of manufacturing history. A. O. Smith produces residential and commercial water heaters and distributes through plumbing and HVAC contractors and supply houses across North America.

What warranty does A. O. Smith offer on residential water heaters?
A. O. Smith warranty terms vary by product line and model. Warranty documentation for specific A. O. Smith products is available at aosmith.com. For current warranty coverage periods and conditions applicable to a specific ProLine, Voltex, or Signature series model, the manufacturer's published warranty documentation at aosmith.com is the authoritative reference.

What is the difference between the A. O. Smith Voltex and ProLine electric water heaters?
The A. O. Smith Voltex hybrid electric heat pump water heater uses heat pump technology to move heat from ambient air to the water in the tank, operating at higher efficiency than standard electric resistance heating and qualifying for ENERGY STAR certification. The A. O. Smith ProLine electric storage water heater uses standard electric resistance heating elements and is designed for applications where heat pump technology is not appropriate, including spaces that remain below 40 degrees Fahrenheit or where the heat pump's cooling effect on the installation space is a concern.

What size A. O. Smith water heater is right for a family of four?
For a family of four, an A. O. Smith tank water heater in the 50-gallon to 75-gallon capacity range may be appropriate, depending on usage patterns and peak demand. The first-hour rating (FHR) is the most relevant sizing metric. A. O. Smith sizing tools at aosmith.com provide FHR-based guidance for matching the A. O. Smith tank capacity to household demand.

Can A. O. Smith gas tankless water heaters replace a storage water heater?
A. O. Smith gas tankless water heaters can serve as replacements for gas storage water heaters in many residential applications, though the installation requirements differ. Gas tankless units require proper venting and gas line sizing matched to the unit's BTU input. Confirming that the existing gas supply, venting configuration, and installation space meet the requirements for the specific A. O. Smith Signature 700 or Signature 500 series unit being specified is required before replacement.

What is A. O. Smith X3 Scale Prevention Technology?
A. O. Smith X3 Scale Prevention Technology is a feature incorporated into select A. O. Smith ProLine XE and Voltex water heater models that is designed to reduce scale accumulation on heating elements and extend anode rod service life. A. O. Smith's published claim for X3 is 300% longer life compared to standard units under qualifying conditions. X3 Scale Prevention Technology is relevant for installations in areas with high mineral content water where scale buildup accelerates anode rod consumption and reduces heating element efficiency over time.