Tankless Water Heater Condensing Ultra-Low NOx Indoor 199,000 BTU Natural Gas

Tankless Water Heater Condensing Ultra-Low NOx Indoor 199,000 BTU Natural Gas

Model ATI-540H-N

Tankless Water Heater Condensing Ultra-Low NOx Indoor 199,000 BTU ATI-540H-N is rated 4.8462 out of 5 by 13.
Rated 5 out of 5 by from endless hot water one shower in the house and three girls to get ready in the morning you run out of hot water with the old tank,so after lots of investigating on tankless units, this is the one that always came out on top, and highly recommended by many plumbers.
Date published: 2014-11-28
Rated 4 out of 5 by from Space Saving Replaced a tank water heater due to crack in tank and ruined basement floor. put in tankless due to leak feature to not ruin floor again when heater fails.
Date published: 2014-11-22
Rated 5 out of 5 by from lots of hot water it never ends We love our new water heater it is great never runs out.
Date published: 2014-11-18
Rated 5 out of 5 by from Very Please with our purchase This tank was recomended by our heating/plumbing contractor. Wonderful at supply of hot water, GPM excellant.
Date published: 2014-11-13
Rated 5 out of 5 by from So far, so good... I purchased this unit the summer and just had it installed a couple of weeks ago. I am impressed with the unit so far. I purchased it to replace my very old standard NG water heater and due to putting in a large whirlpool bath tub that will take a large amount of hot water to fill.
Date published: 2014-11-02
Rated 5 out of 5 by from too soon to evaluate The unit seems to be made well and easy to operate.It is much too soon to evaluate, it's only installed 2 days
Date published: 2014-08-25
Rated 4 out of 5 by from Much more powerful than the previous Bosch product Had to replace a Bosch tankless that quit all of a sudden. This model is more efficient and more powerful than the Bosch.
Date published: 2014-07-01
Rated 5 out of 5 by from Wonderful with a large family We bought this product and had it installed professionally in March of 2014 for our home that has 3 full baths and 7 people (three children, my wife and I and grandparents). Our plumber set it such that we kept our original electric tank water heater that came with the house and attached the new tank-less water heater to it. The heated water from the new tank-less heater goes into the original tank water heater which now serves essentially to store the heated water. This way we always have instant hot water. Our electric bill has certainly decreased as well.Before installing this product we always had problem with cold water when two showers are on at the same time or after my daughter had taken her typical long shower. After the tank-less water heater was installed, however, this has not been a problem at all. We get consistent hot water even when three showers are on, while the dishwasher and laundry washer are on at the same time. It is fantastic!! It is very quit and aesthetic as well.
Date published: 2014-06-14

The 540H is well suited for residential/commercial applications such as small restaurants and beauty salons. Utilizing HRS35 copper alloy for the heat exchanger tubing, the 540H is also suitable for heavier-residential usages such as space heating or domestic recirculation systems. Remote control included as a standard feature. Indoor models are certified up to 10,100 ft. altitude. Thicker heat exchanger drum and utilizes HRS35 (heat-resistant) copper for the heat exchanger tubing. Provides a variety of installation options: outdoor and direct vent. Includes a pump control port, ensuring efficient operation of all circulation pumps. Complies with Ultra-Low NOx regulations and meets the energy efficiency requirements of ASHRAE 90.1b-1992. Easy-Link System capable up to 4 units. Multi-Link System capable up to 20 units.

The ATI-540H-N tankless water heater uses up to 199,000 BTUs of natural gas to deliver a max flow rate of 6.6 GPM. It utilizes condensing technology to achieve an Energy Factor of 0.95, and is ENERGY STAR® qualified. This model meets Ultra-Low NOx emission requirements, and comes with a 15-year limited warranty.

Where to Buy

Where to Buy

Woodbridge, NJ 07095

Location #1

Jersey Pipeline Plumbing & Heating Inc.

Freehold, NJ

More Info >>
Location #2

Authorized Heating

Brooklyn, NY

More Info >>
Location #3

All Season Energy Service LLC

Scotch Plains, NJ

Offers Consumer Financing Se Habla Español

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Product Features & Options

Dual Heat Exchanger

The primary heat exchanger is constructed of commercial-grade HRS35 copper, which is stronger than standard copper and more resilient against erosion. Condensing models feature 316L stainless steel secondary heat exchanger, providing additional protection against corrosion.

Safety Features

Includes freeze, overheat, surge protection and troubleshooting diagnostic codes.

Space Savings

A. O. Smith tankless water heaters take up much less space that your conventional tank-style water heater. With no tank to steal valuable storage space, our wall-mount design allows for additional storage and flexibility.

Endless Hot Water

The comprehensive line of A. O. Smith tankless water heaters are an excellent whole-home water heating solution that supply endless hot water.

How it Works

The comprehensive line of A. O. Smith tankless water heaters provide hot water on-demand.

• A hot water tap is opened
• The opened tap allows water to flow through the water heater. An internal water flow sensor detects this flow
• Upon flow detection, the flow sensor sends the activation signal to the computer board
• The computer automatically ignites the burner
• As water flows through the heat exchanger, it absorbs heat from the burner
• By the time the water exits the heater, it has reached the designated set temperature
• When the hot water tap is closed, the water heater automatically turns off




limited warranty


energy factor

CSA International Low Lead Content Certification in compliance with U.S. and Canadian safety standards on gas components
AHRI Air-Conditioning, Heating and Refrigeration Institute
CSA International Design Certification The CSA Blue Star indicates the product is certified to applicable U.S. standards for appliances using gas or other petroleum fuel
CSA International Certification in compliance with U.S. and Canadian for gas appliances and other liquid petroleum, LP, propane products

Product Specifications

Tech Specs
Emissions: Ultra-Low NOx
Maximum BTUs: 199,000
Minimum BTUs: 15,000
Limited Heat Exchanger Warranty: 15 Years
Limited Parts Warranty: 5 Years
Water Connection Location: Bottom
Water Connection Size: 3/4"
Heat Exchanger: HRS35 Copper Alloy
Secondary Heat Exchanger: Stainless Steel
Voltage: 120
Energy Factor: 0.95
Digital Display: Yes
Remote Control: Yes
Technology: Condensing
Dimensions & Venting
Type: Space Saving
Height: 23 5/8"
Width: 17 3/4"
Depth: 11 1/4"
Product Weight: 59lbs/27kg
Shipping Weight: 63lbs
Vent Type: Direct Vent
Vent Length: 70 feet at 3 diameter
100 feet at 4 diameter
Vent Material: PVC, CPVC, PP, ABS, SS


Rebate and incentive programs provide cash-back to consumers for the purchase of appliances that meet certain energy efficiency standards. Often, these standards are tied to the ENERGY STAR® program.

Cash for Appliances is designed to encourage the purchase of energy efficient appliances. Consumers who purchase ENERGY STAR® or CEE qualified appliances can receive cash rebates. Most states are offering rebates in the $50 to $250 range.


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Need More Hot Water?

There's no reason to run out of hot water. If you're not sure that the ATI-540H-N provides enough hot water for your needs, consider these:

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Vertex™ Power Vent 50-Gallon Gas Water Heater

  • 6 Year Limited Warranty
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