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

Model ATO-540H-N

The 540 series is well suited for residential use. Utilizing commercial grade copper alloy for the heat exchanger tubing, the 540 series is also suitable for heavier-residential usages such as domestic recirculation systems. Remote control included as a standard feature on all Outdoor models. Indoor models are certified up to 10,100 ft. altitude. Provides a variety of installation options: outdoor and direct vent. Complies with Ultra-Low NOx regulations and meets the energy efficiency requirements. Easy-Link System capable up to 4 units.

The ATO-540H-N tankless water heater uses up to 199,000 BTU/hr of natural gas to deliver an endless supply of hot water for a 3 bath home in northern climates and up to a 4 bath home in southern climates (one shower head per bath). Utilizing condensing technology, this heater is extremely efficient with a Uniform Energy Factor of 0.95. With an industry leading 15-year limited warranty, the ATO-540H-N tankless water heater provides years of hot water through innovation and quality.

Where to Buy

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Fairfield, CT 06828

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single shower length

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showers

back-to-back

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showers

at the same time

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maximum tub size

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estimated energy cost

Many factors affect the actual performance of a water heater. This represents our closest approximation of your likely experience with this water heater in Fairfield, CT, but actual performance may vary depending on factors beyond our ability to control or estimate. To view or adjust our assumptions of the most common factors that impact this product’s performance in Fairfield, CT, please view the advanced settings. *Annual energy costs are estimated from the energy efficiency of each water heater, your household’s estimated water usage & set temperature, the average groundwater temperature for your location, and residential energy prices as reported by the Department of Energy.

Product Features & Options

Dual Heat Exchanger

The primary heat exchanger is constructed of commercial-grade 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

Certifications

year

limited warranty

0.95

Uniform 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 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
UEF:	0.95
Limited Heat Exchanger Warranty:	15 Years
Limited Parts Warranty:	5 Years
Water Connection Location:	Bottom
Water Connection Size:	3/4"
Heat Exchanger:	Commercial Grade Copper
Secondary Heat Exchanger:	Stainless Steel
Voltage:	120
ENERGY STAR®:	Yes
LEED Rating:	1.5
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:	69
Vent Material:	PVC, CPVC, PP, ABS, SS

Technical Documents

Tankless Condensing 540H Spec Sheet (AOSRG46835)Tankless Condensing Spec Sheet 240H/340H/540H (Canada) (CANRG46835) (Not all units available)Tankless Condensing Ultra-Low NOx 540H Manual (2000534710)

Marketing Resources

Tankless Product Guide (AOSBG80000)Canadian Residential Catalogue (CANRB80000) (Not all units available)Tankless High Efficiency Condensing Sales Sheet (AOSBG71006)Tankless Sales Sheet (AOSRG71004)Residential and Commercial Full Line Pocket Catalog (AOSAA80000)

Incentives

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.