A. O. Smith’s non-condensing gas and propane tankless water heaters provide endless hot water for your home. All non-condensing tankless water heaters from A. O. Smith offer a water heating solution that is built to last.

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Diagram of the interior of a tankless water heater.

How Does a Non-Condensing Tankless Water Heater Work?

An A. O. Smith non-condensing tankless water heater saves space and supplies continuous hot water for your home. Non-condensing technology utilizes a single heat exchanger to heat the water to the desired temperature. Water flows through a heat exchanger where it is heated to the desired temperature by the hot exhaust gases. The excess heat that is not transferred to the water is expelled through the exhaust venting. This exhaust is higher temperature than on a condensing tankless heater to lessen the risk of corrosion. However, non-condensing heaters generally require metal exhaust venting to withstand the higher temperatures. Paired with a 15-year limited warranty, an A. O. Smith non-condensing tankless water heater can provide years of hot water for your home.

Condensing tankless heaters use a dual heat exchanger design to make maximum use of the energy delivered to the system. Non-condensing tankless water heaters utilize a single heat exchanger so they vent more heat in the exhaust gases.

When sized appropriately, a tankless water heater can deliver a continuous flow of hot water.

Do tankless water heaters need a drain?
A condensing tankless water heater will need a condensate drain, while a non-condensing water heater will not.

How do I keep my tankless water heater from freezing?
All A. O. Smith tankless hot water heaters have built-in freeze protection. However, if the heater is installed outdoors, during a power outage you will need to drain the water from the unit to prevent freezing.

What do I need?
Before installation, you will need to determine the incoming ground water temperature, the piping of 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.

The proper size of a tankless water heater depends on a number of variables, including type of appliances you own, number of people in your home, and incoming water temperature. You should discuss with your installer, but you can also consult our online XPERT Product Selector that can also be found as a downloadable app.

Condensing tankless models represent the highest efficiency platform for tankless water heaters, and all A. O. Smith condensing models have over 0.90 UEF (Uniform Energy Factor).

Benefits of Non-Condensing Tankless Water Heaters

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Continuous Hot Water

Non-condensing tankless water heaters produce continuous, on-demand hot water for your home and can provide instant hot water through the installation of an accessory hot water recirculation pump.

Space Savings

A. O. Smith’s non-condensing tankless water heaters can be mounted in small or tight spaces, either inside or outside of your home, to better utilize and save space.

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A dog being washed in a bathtub.

Energy Savings

Non-condensing tankless water heaters vent away the excess heat produced during the heat exchange process, causing less corrosion and deterioration of the water heater and resulting in a longer life span.

Compare:
Condensing tankless gas water heater

Non-Condensing Gas Tankless:

ATI-510U

199,000 BTU

Non condensing Tankless gas water heater

Condensing Gas Tankless:

ATI-540H

199,000 BTU

Single Shower Length* Unlimited Unlimited
Showers Back-to-Back* Unlimited Unlimited
Showers at the Same Time* 2.6 showers 3.1 showers
Maximum Tub Size* Unlimited Unlimited
Continuous Hot Water check_circle_outline check_circle_outline
Space Savings check_circle_outline check_circle_outline
Energy Efficiency check_circle_outline check_circle_outline
UEF 0.82 0.93
Warranty 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.
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Additional Reading

Contractor Resources

  • Screwdriver and wrench icons.

    Installation Guide

    Download our gas tankless water heater installation instructions.

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    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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