For more than 80 years, A. O. Smith has led the industry in water heating innovations. Tankless water heaters continue to grow in popularity, providing continuous hot water on demand and offering a compact and space-saving solution for your water heating needs. Best of all, A. O. Smith’s longer-lasting, energy-efficient gas tankless water heaters come with an exceptional 15-year limited warranty to support you for years to come.

A. O. Smith has a rich 145-year-old history that has positively contributed towards America’s product innovations and resilience as a nation.

“We cannot believe we didn't switch over sooner! We have had zero issues with this product. Our water heats very fast and maintains temperature endlessly.”


Benefits of Tankless Water Heaters

  • Children washing hands.

    Continuous Hot Water

    Tankless water heaters deliver continuous hot water. If sized properly, you’ll never run out of hot water again.

  • Filling a glass of water.

    Energy Savings

    A. O. Smith tankless water heaters heat your water only when you’re using it, reducing energy costs depending on your hot water usage.

  • Father brushing teeth with daughter.

    Space Savings

    Due to their significantly smaller size, tankless water heaters save a tremendous amount of space compared to a traditional water heater and can be mounted in various spaces around your home.

  • Washing a dog with a hand-held shower.

    On-Demand Hot Water

    The heating technology within
    A. O. Smith tankless water heaters provides on-demand hot water by heating the water when you need it.

  • Mother helping children wash their hands.

    Instant Hot Water

    A. O. Smith tankless water heaters with built-in recirculation pumps offer instant hot water when installed with the proper piping.

  • Feet up relaxing in a bubble bath.

    Innovation & Reliability

    A. O. Smith has a long, rich history of reliability and innovations that have led the water heating industry for decades.

A Closer Look

Diagram of the interior of a tankless water heater.

How Do Tankless Water Heaters Work?

When installed, a tankless water heater is attached directly to the water line within your home to deliver continuous hot water on demand. When you open a hot water tap, the burner or heating element within your tankless unit is activated. As water flows through the heat exchanger it absorbs the heat and rapidly reaches the preset temperature. Due to this quick and direct heat exchange, tankless models provide long-lasting, on-demand hot water.

Both tank and tankless water heaters have specific advantages. You should consider your usage preferences, energy supply, space considerations, and other factors when making a decision.

One important consideration before purchasing is your energy supply. For whole home water heating, gas tankless is more cost effective if you already have natural gas or propane hookups in your home. A key consideration for electric is whether you have to add 240V electric service. Talk to your professional installer to discuss all of the considerations involved in making the best choice for your application.

There are several variables impacting cost, but generally you have a higher upfront cost on tankless with potential savings over time that is dependent on usage, local energy costs, incoming groundwater temperature, and other factors.

In most circumstances, yes. Tankless water heaters only consume energy when hot water is needed rather than keeping a tank of water hot 24 hours a day. You'll save on energy costs when using the same energy source between tank and tankless.

A. O. Smith tankless water heaters boast industry-leading warranties. While the lifespan of a tankless water heater can vary, factors like water conditions, usage rates and maintenance all contribute to your water heater’s health.

Energy savings, lower space requirement, and endless hot water are the main advantages of tankless water heaters.

Most units will require annual descaling maintenance.

Given the popularity of tankless water heaters, you can expect this to be a very attractive feature to a prospective homebuyer.

Before purchasing a tankless water heater, it’s important to first understand what kind of energy source your home runs on—electric or gas.

Depending on the size of your home and the number of people who live in it, you'll require an energy input that is based on your home's maximum hot water usage.

The great thing about tankless water heaters is that they can be installed almost anywhere in a home due to their compact size. One thing to consider is that the closer the water heater is to the shower or sink fixture the faster hot water will arrive.

Gas tankless water heaters generally use different venting than gas tank heaters. Consult a contractor to determine the best venting options for your home.

Tankless vs. Tank

Take a closer look at the advantages of each type of water heater.

A group of tankless water heaters

Tankless Water Heater

  • Continuous hot water
  • Energy efficient
  • Space savings
  • Environmentally friendly
  • X3® Scale Prevention Technology


A group of tank water heaters

Tank Water Heater

  • Low initial investment
  • Energy-efficient options
  • Easy installation
  • Wide range of tank sizes from 30 to 95 gallons
  • Hot water storage supply
A tankless water heater

Gas Tankless
Water Heaters

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Learn about A. O. Smith gas tankless water heaters and if they are the right fit for your home.

Electric Tankless
Water Heaters

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Learn about A. O. Smith electric tankless water heaters and if they are the right fit for your home.

A tankless water heater
A tankless water heater

Never Descale Again. Ever.

Introducing X3® Scale Prevention Technology on our Condensing Gas Tankless Water Heaters. Over 15 years Learn About Tankless with X3® Scale Prevention Technology life with no maintenance.

View All Tankless Models with X3®
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Additional Reading

Contractor Resources

  • Screwdriver and wrench icon.

    Installation Guide

    Download our gas tankless water heater installation instructions.

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  • Set square icon.

    Resource Guide

    Match the flow rate to your customer’s needs.

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    Cross-Reference Tool

    Search for NAECA-compliant replacement options.

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