American Tankless Water Heater Review

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If looking to buy a product with on-demand water heating, American tankless water heater, made by an American WH Company and owned by the AO Smith Corporation, might be a solution for you. See the model and feature review below...

What should you know when buying American tankless

The main reasons for buying an American are the Energy Star compliance and great energy savings, endless and continuous supply of hot water, on demand water heating at the preset temperature and the recognized name. If you want to check a review of the most advanced features and benefits, read further.


The American tankless water heater can be found in several categories, designed for residential and light duty commercial water heating (below are the new and old models). These units come with different capacities, power range and installation options. All of them are wall mounted, some are direct vented units for indoor use while other are for the outdoor installation that do not require venting.

The main advantages of the American tankless heaters over storage tank type models are the continuous supply of hot water, technology that works on demand and when it is needed; and plenty of hot water for the whole house use.

The American tankless water heater is the energy efficient gas unit with 84% or higher thermal efficiency and great performance level; it reduces the energy loss and increases money savings. All models are Energy Star compliant, and with a high efficiency, they are eligible for rebates.

Standard equipment like direct electronic ignition and accurate remote temperature control of +/-2 F are also helping in reducing energy waste.

The temperature remote controller is a standard feature. It allows you to set the temperature, monitor the operation and check if something is wrong with the heater, when the error code flashes.

Every American tankless water heater is using natural gas, which is factory set option, but can be easily converted to use propane gas. The efficient gas burner was designed to produce less NOx gases, which makes these water heaters environment friendly or "green".

Indoor models are direct vented and combustion sealed, so the outside air is drawn inside the chamber while inside air is protected from being used. At the same time the flue gases, as products of combustion, are forced out through the venting system. The venting pipes can be directed either horizontally or vertically, which adds even more flexibility in the installation.

Every American tankless water heater that is built for the residential use come with the 15-year limited warranty on heat exchanger and 5-year warranty on parts. They are used not only for potable water heating, but in hydronic heating, radiant floor heating, recirculation and combination of domestic and heating applications.

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Models and Specifications

110, 310 and 510 series

American 110, 310, 510 series

GT-110-NI and GT-110 -NE are indoor and outdoor models and are used for residential and light commercial applications. Fully modulating gas blower is a standard feature for every American tankless water heater and for 110 series it allows the power range from 19,500 to the maximum of 140,000 Btu. The heaters provide maximum of 6.6 gallons per minute of hot water, which makes them good for 1-2 bath homes, apartments, condos and cabins.

GT-310-NI is an indoor direct vent while GT-310-NE is the outdoor model, both designed with the gas input from 11,000 to 190,000 Btu and maximum water flow of 8.0 GPM, which is perfect for 2-3 bath homes.

GT-510-NI and GT-510-NE have the minimum Btu input of 11,000 and maximum of 199,000, and the water flow reaches high 10 GPM. Without using the additional accessories these models can be linked to up to 4 units for homes with a higher demand. The 510 series can be used in residential and light commercial applications, in restaurants, high demanding homes and space heating.

320 and 520 series

American 320 and 520 series

GT-320-NIH and GT-302-NEH are the high efficiency and condensing tankless water heater that use two heat exchangers for more efficient heating and energy savings. As the previous models, they produce maximum hot water of 8.0 GPM but have slightly different gas inputs; 13,000 for the minimum and 180,000 for the maximum and higher energy factor of 0.91. They are equipped with the LCD display which shows the temperature and the error codes for easy troubleshooting.

GT-520-NIH and GT-520-NEH are condensing and tankless water heaters that are able to provide high energy efficiency (EF is 0.91) and 9 GPM hot water flow rate in continuous supply. A convenient built-in display shows the temperature and error codes. Easy-Link allows up to 4 units to be connected and work as one.

305, 505 and 705 series

American tankless water heater from GT-305 series is designed to work with min 15,000 BTU/h and max. 180,000 BTU/h gas input, providing a maximum of 7.5 GPM of hot water. With energy factor, EF of 0.82, 305 models are Energy Star qualified.

Models GT-505 are designed to work within the range of min 15,000 BTU/h and max. 199,000/190,000 (propane) BTU/h gas input, providing a maximum of 9.4 GPM of hot water. With energy factor, EF of 0.82, 505 models are Energy Star qualified.

American tankless models GT-705 are designed to work with min 19,000 BTU/h and max. 237,000 BTU/h of gas, providing a maximum of 9.8 GPM of hot water. The 705 models are not Energy Star considered as the rule applies only on units up to 199,000 BTU/h.

110U, 310U and 510U series

Water heaters from 110U, 310U and 510U series are known as ultra-low NOx models.

240, 340 and 540 series

American 240, 340 and 540

GT-240, GT-340 and GT-540 are condensing tankless models that are designed with the power vent system and built-in temperature controller for the advanced diagnostics and easy troubleshooting.

All models utilize two heat exchangers and high energy factor of 0.95 for maximum efficiency and energy savings.

The best model is GT-540 as it provides a high water flow of 10 gallons per minute, and can use Easy-Link and Multi-Link system to provide even more hot water.


  • Heat exchanger

  • Heat exchanger thermistor or over-heat switch

  • Gas burner

  • Spark electrode and flame rod (it proves ignition)

  • Flue outlet

  • Combustion fan - when it is energized, it purges the combustion chamber.

  • Solenoid valves

  • Thermal fuse

  • PC board - monitors inlet and outlet water temperature inside the tankless water heater, flow rate, flame rod, fan motor frequency...

  • Frost sensing switch

  • Modulating gas control valve - modulates gas input to the required value.

  • Water flow device and sensor - send pulses to PCB when minimum water flow is established.

  • Water inlet and outlet

Safety Features

  • The overheating system shuts the tankless water heater automatically if there is an excessive temperature rise, much higher that the pre-set temperature.

  • If the above overheating system fails, a fusible link will break, shutting off the unit.

  • Flame failure system is used to shut the system off if the burner flame is not present.

  • If there is a power failure, the water heater will cut off the gas automatically.

  • In a case of over-current, the power surge glass fuse will blow and shut the tankless water heater off.

  • Freeze protection that includes electrical heating elements and intermittent firing of the burner.

(Photo credit to American Co)