Condensing Gas Tankless Water Heaters

Achieving high efficiency to help lower monthly gas bills through innovative durability.

Highly efficient and ENERGY STAR® Certified, State Water Heaters condensing natural gas and propane tankless water heaters are available in both indoor and outdoor configurations. State’s condensing tankless models match high efficiency with groundbreaking designs.

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A Gas condensing tankless water heater.

How Does a Condensing Gas Tankless
Water Heater Work?

Similar to other tankless models, condensing gas tankless water heaters save space and reliably deliver continuous hot water to your home. But what sets a condensing gas tankless unit apart from non-condensing technology is its second heat exchanger. The second heat exchanger captures and cools what would be wasted exhaust heat and forms it into condensation. By using the excess heat instead of venting it out, your condensing gas tankless unit conserves more energy.

State’s condensing water heater technology results in a unit receiving a Uniform Energy Factor (UEF) up to 0.95—and the unit can produce more hot water than non-condensing tankless water heaters. Alongside a 15-year limited warranty, State condensing gas tankless water heaters can reliably provide hot water to your home for years to come.

Condensing gas tankless water heaters are very energy efficient so they can contribute to savings over time, despite a higher upfront price on the unit. Total installation costs vary depending on several specific factors, including venting requirements.

Because State water heaters are built for durability, a condensing gas water heater can last up to 20 years. Regular maintenance can help your water heater live a longer life as well. Other factors such as water quality and usage will also impact its lifetime.

A number of factors determine the condensing gas tankless water heater size that will work best for your needs. Some of these factors include the number of residents in your home, the types of appliances that will be using hot water, and the incoming groundwater temperature. To help you decide, you can talk through options with a local professional installer and consult State’s online XPERT™ Product Selector.

Yes. Boasting ENERGY STAR® certification, condensing gas tankless water heaters are known for high efficiency. They also meet California’s strict emissions standards because they are designed for ultra-low NOx emissions.

Does a tankless water heater need a drain?
Discuss the need for a drain. Condensing gas tankless water heaters require a drain, while non-condensing models will not.

How do I keep my tankless water heater from freezing?
Freeze prevention is crucial. Ask your professional contractor about ways to avoid freezing. Though State tankless water heaters have freeze protection built in, heaters installed outdoors require draining water from the unit to prevent freezing during power outages. Putting these precautions in place can help you avoid damage to your unit.

Though the installation process is not complicated, we recommend hiring a licensed plumber or contractor. This is because the unit’s 15-year limited warranty is only valid if it is installed by a credentialed installer. Furthermore, proper installation and protection against improper gas line sizing and venting contribute to safety and performance. Professional installers will be able to ensure these factors are in place.

State’s condensing tankless water heaters boast some of the highest efficiency models for tankless water heaters. State condensing models have over 0.90 UEF (Uniform Energy Factor) and come with a 15-year limited warranty.

Benefits of Condensing Gas Tankless Water Heaters

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On-Demand Hot Water

Condensing gas tankless water heaters provide continuous hot water on demand. Alongside a recirculation pump and the necessary piping installed, these models can provide instant hot water.

Energy Savings

To produce hot water, condensing gas tankless water heaters use leftover heat from exhaust gases, which translates to reduced operating costs and energy savings.

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Two small children playing with bubbles in the bath.

Space Savings

State’s condensing gas tankless water heaters can be installed in small spaces both inside and outside the home, depending on your geographic location, saving you much needed space inside.

Tankless Gas Water Heater

Gas Tankless

GTS-540X3-NIH 199,000 BTU

Tank gas water heater


GTS-510U 199,000 BTU

Single Shower Length Unlimited Unlimited
Showers Back-to-Back Unlimited Unlimited
Showers at The Same Time 3.1 2.6
Maximum Tub Size Unlimited gallons Unlimited gallons
X3® Scale Prevention Technology check_circle_outline
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
Hot Water Storage Supply check_circle_outline check_circle_outline
UEF 0.93 0.81
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.

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® Learn About Tankless with X3® Scale Prevention Technology
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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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    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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