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Residential Gas Tank & Tankless Water Heaters

The complete A. O. Smith line of natural gas and liquid propane water heaters consists of over 150 different models. From high-efficiency ENERGY STAR® certified water heaters to economical standard efficiency gas water heaters, A. O. Smith has the gas water heater to fit your needs

Gas Tankless High Efficiency

Residential Gas Tankless Water Heaters

In 2010, A. O. Smith introduced its full line of natural gas and propane tankless water heaters that continue to be an innovative part of the full A. O. Smith product family today. Engineered to deliver continuous hot water when you need it, propane and natural gas tankless water heaters are easily installed in tight spaces, including closets, bathrooms and even outdoors in appropriate climates.

The new Adapt premium gas tankless hot water heater image made to look like a swiss army knife.


Ultra Flexible. Fewer Trips. More Savings.

Introducing the new Adapt™ Premium Condensing Gas Tankless Water Heaters with X3® Scale Prevention Technology.

Rebates & Tax Credits

Up to $850 in Local Utility Rebates may be available in your area!

What Our Customers Are Saying

Benefits of Gas Tankless Water Heaters

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Continuous Hot Water

Gas tankless water heaters give you continuous hot water on demand. When paired with a recirculation pump, they provide guaranteed instant hot water.

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Space Savings

A. O. Smith’s natural gas and propane tankless water heaters can be mounted inside or outside (depending on your region) to save space within your home.

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Energy Savings

Gas tankless water heaters only heat your water when you need it, which can reduce energy costs. Paired with A. O. Smith’s 15-year tankless limited warranty, gas tankless models can be a smart, money-saving solution for your home.

How it Works

Adapt gas tankless water heater cutaway showing internals

When a natural gas tankless water heater or propane tankless water heater is installed in your home, it is attached directly to the water line to deliver on-demand hot water. When you open a hot water tap, the water flow sensor within your water heater is triggered and the burner is activated. The water within your system begins to circulate through the heat exchanger, heating your water to the designated temperature and providing you with continuous hot water. Once you turn off your water tap, the unit shuts down to save energy.

Still Have Questions?

A gas tankless water heater is more efficient than a conventional tank water heater, as it doesn't require energy to keep a reservoir of water heated around the clock. Water flows to a heat exchanger that immediately heats the water using hot exhaust gasses. According to the U.S. Department of Energy, a tankless water heater is up to 34% more energy efficient than a tank water heater for homes using less than 41 gallons of water per day and up to 14% more efficient for homes using 86 gallons of water daily. It's also more compact than a tank water heater, saving space.
A tankless water heater offers significant energy savings because it only heats water when you turn on an appliance or hot water tap. It heats water as soon it passes through the heat exchanger, quickly providing a continuous supply of hot water. Installation of tankless water heaters can oftentimes be more expensive because of the reconfiguration of gas piping, etc. However, not only do our tankless models have 15 year limited warranties, our newest condensing models come equipped with X3® Scale Reduction Technology that prevents scale buildup, eliminates the need for regular scale-related maintenance, and extends life up to three times longer..
A. O. Smith tankless water heaters boast industry-leading 15 year limited warranties. While the lifespan of a gas tankless water heater can vary, factors like water conditions, usage rates and maintenance all contribute to your water heater’s health. New condensing units come equipped with X3® Scale Reduction Technology that extends life up to three times longer.

Tankless water heaters have different flow rates measured in gallons per minute (GPM), which indicate the amount of water they can deliver at a time. Because these water heaters don't maintain a supply of hot water in a tank, you need to choose an appropriately sized tankless model based on household needs. The ideal output rate for your home depends on the number of people in the residence, the appliances you use, and the original temperature of the water being heated. Some people install more than one tankless water heater based on their requirements. Check out our water heater selector to help choose the best water heater for your needs.

  • What do I need?
  • Before installation, you will need to determine the incoming ground water temperature, the ideal location in your home, and the correct water heater size required for your needs.
  • Where to install?
  • A tankless water heater can be installed anywhere in your home with the correct piping—closets, garage, bathrooms, etc. In warmer climates where there is no risk of freezing, a tankless water heater may be installed on the exterior of the home to save on interior space.

Product Comparison

Adapt XE
Standard Non-Condensing Gas Tankless Water Heater
Adapt XE Premium Condensing Gas Tankless Water Heater with X3® Technology
Standard Non-Condensing Gas Tankless Water Heater
Adapt Premium Condensing Gas Tankless Water Heater
Single Shower Length
Showers Back-to-Back
Showers at the Same Time
2.6 showers
3.1 showers
Maximum Tub Size
X3® Scale Prevention Technology
Continuous Hot Water
Space Savings
Energy Efficiency
Hot Water Storage Supply
15 Years
15 Years

*Many factors affect the actual performance of a water heater. This represents our closest approximation of your likely experience with this water heater in your local area, but actual performance may vary depending on factors beyond our ability to control or estimate.

Plumbing Professional

Find A Local Water Heater Pro

A. O. Smith water heaters are professionally installed by local independent contractors.

High-Efficiency Condensing Gas Tankless Water Heaters

High-Efficiency Condensing Gas Tankless Water Heaters

Learn more about A. O. Smith’s full line of high-efficiency condensing gas tankless water heaters.

Non-Condensing Gas Tankless Water Heaters

Non-Condensing Gas Tankless Water Heaters

Learn more about A. O. Smith’s full line of non-condensing gas tankless water heaters.

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Not sure which product is right for you?

Take our water heater selector quiz to find the correct water heater for your home.

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Pro Toolkit

*Gas water heaters with UEF of 0.82 or higher OR with a thermal efficiency of at least 90%. Local utility rebates available in limited geographical areas. For information on the Federal Tax Credit, go to: Check with your tax advisor for applicability. Offer details and expiration may vary. See Rebate Center for details.

Why A. O. Smith?

Market Leader

A. O. Smith is a leading manufacturer of both residential and commercial water heating technologies, including the #1 most specified commercial water heater.

Commitment to Innovation

For more than 145 years, we’ve developed state-of-the art products that push new boundaries and improve the lives of our customers.

Best-In-Class Support

We combine cutting-edge technology with committed people who take pride in providing the very best support for our customers.

Unmatched Quality

Our products are put through rigorous quality and endurance testing so now matter where hot water is needed, A. O. Smith can provide a solution you can count on.

Learn more about A. O. Smith