AO Smith Tankless Water Heaters

AO Smith Tankless Water Heater Reviews

If you are determined to cut down your energy bill and impact the environment less, you should switch from traditional water heating systems to tankless water heaters. The benefits are plenty, and you should keep reading for the details.

Why are tankless water heaters more and more popular?

The name is a tale-teller, and the tankless water heaters don’t need a tank for collecting hot water. They give hot water on demand, no matter when you need it.

Since they don’t use a container for collecting water nor electricity for keeping it hot, tankless water heaters use less energy. They only use energy when you’re tapping the hot water, which means a lower electricity bill.

Water doesn’t stay in the system, so it cannot damage the system as much as in the case of traditional water heating systems with tanks. It’s what makes the tankless water heaters more durable and less prone to corrosion.

Sturdy, dependable, and highly energy-efficient, tankless water heaters are always a wise investment for residential and commercial applications.

What can we say about AO Smith briefly?

It was the end of the 1800s when Charles Jeremiah Smith created the very base of a business focusing on “hardware specialties.” Little that he knew that, decades later, the company AO Smith would turn into a global manufacturer with 16,000 employers (give or take).

Top 5 AO Smith Tankless Water Heater

   1. AO Smith Electric tankless water heater

The compact size and lightweight body of the AO Smith 1055542 Signature 240-Volt, 14 KiloWatt 1.6-GPM Tankless Electric Water Heater, makes it an excellent option for install in tight spaces.

Installing the unit is a breeze, especially since it’s using typical ¾-in NPT water connections. You should consider a wall mount, most of the time.  The tankless water heater includes standard heating elements and has no moving parts, which is why it’s so easy to take care of it. The tankless water heater also comes with scale reduction technology, which reduces the risk for mineral deposits to form in the chamber assembly. There’s also a low risk for premature element failure thanks to the dry-fire protection of the unit.

The unit comes with a two-chamber design and doesn’t need venting. It’s made with Anti-Scale technology which only expands its durability. The digital display allows you to adjust the temperature friendly and comfortable every time.

The tankless water heater has a 0.89energy efficiency, and it’s mobile home compatible.

Let’s go over the parts we like most once more:

  • It’s dependable, easy to install and strong
  • It comes with Anti-Scale technology and has two chamber design
  • The digital display eases out the temperature adjustments
  • It’s lightweight, compact, and mobile home compatible

Don’t let the inherent flaws change your mind:

  • The customer service isn’t amazing
  • Many complain about an error code upon install

Regardless of the minor problems, the tankless water heater is still a reliable option for indoor applications in a home.

   2. AO Smith Propane non-condensing residential tankless water heater

AO Smith is also manufacturing propane tankless water heaters, and a valid model is the AO Smith ATO-110-P Non-Condensing Residential/Light Commercial Tankless Heater.

The tankless water heater has a maximum flow rate of 6.6GPM and a maximum input of 140,000BTUs. It’s made with non-condensing technology, and it’s Energy Star qualified.

The reliability of the unit is undeniable since it comes with a 0.83 energy factor and accomplishes the Low NOx emission requirements.

The list of features ensures smooth and straightforward operation with manual reset for the high limit (set at 194F degrees) being a significant one. The unit also features safety functions and overheat cutoff use turns the unit off when the temperature goes over the limit. The inlet and outlet thermistors provide a constant check of the heat. The built-in freeze protection protects the unit in colder temperatures, expanding its durability.

The ATO 110 series is a reliable option for one bath homes, apartments, and condos in both summer and cold climates. You can successfully install it in your RV. It also comes with remote control as standard features and allows indoor, outdoor, and direct vent install.

Let’s have another look at the positive aspects:

  • It’s energy-efficient, and Energy Star qualified
  • It runs on propane
  • It includes safety features
  • You can install it in an R.V.

The pet peeves aren’t major:

  • The energy factor could be higher
  • It’s not the most potent model

Regardless of the minor problems, this model is yet another example of extraordinary value and performance that AO Smith manages to provide.

   3. AO Smith ATI-540H-N Condensing light commercial/residential

The entire 540 series is designed for residential use, and the AO Smith ATI-540H-N Condensing Residential/Light Commercial Tankless Heater is an excellent example.

The heat exchanger tubing is made with commercial-grade copper alloy, which is why the unit can handle both residential and light commercial use. It’s a reliable option to use for domestic recirculation systems.

The unit comes with the AFR sensor, exhaust and water temperature safety control. The overheat cutoff fuse protects the unit against overheating, ensuring a more extended lifespan. It’s made with condensing technology, which explains the 0.93 energy factor.

The series offers a wide variety of installation options: outdoor or with direct vent. The unit follows the Ultra-Low NOx regulations and respects the energy efficiency requirements.

The Easy-Link system allows you to connect up to four units. The tankless water heater uses up to 199,000 BTU/hr natural gas, and it’s strong enough to sustain a three-bath household in northern regions. It can handle four baths home in southern areas.

It has a 15-year limited warranty.

Here’s what we like the most about it:

  • It’s made with condensing technology for higher energy efficiency
  • It can serve for light commercial or residential use
  • It comes with several safety features
  • It’s Easy-Link compatible

The shortcomings aren’t something to worry much:

  • You need to buy the remote
  • You should get professional help for the installation

Loaded with safety features and made with high-quality materials, the unit is always a wise buy for any household.

   4. AO Smith Non-condensing residential/light commercial

For those of you interested in using a non-condensing tankless water heater in their home, the AO Smith ATO-310-P Non-Condensing Residential/Light Commercial Tankless Heater is a keeper.

The tankless water heater is small and compact and weighs less than 40 pounds. It’s why it’s so easy to find the perfect storage space for it. The stainless body is highly insulated, protecting the parts inside. Non-condensing technology is energy efficient, rending the unit to present a 0.82 energy factor.

The heat is excellent, and the temperature remains constant since there’s a sufficient balance between the flor rater and the heat transfer. Should overheating develop, the fuse in the case is going to activate, for better performance of the unit?

When it comes to safety features, the unit doesn’t disappoint. It includes overheating fuse for reducing the risk of scalding, but also comes with inlet and outlet thermistors. They allow you to control the temperature at all times. The unit is made with anti-freeze technology and maintains the pipe functions.

Operating the unit is straightforward, and you may manually reset the high limit, according to your needs.

The tankless water heater is well made and comes with a 12-years warranty for the heat exchanger and five years warranty for the parts.

We’ve shortened the right parts to the following:

  • It’s small, lightweight, and compact
  • It comes with safety features and sturdy body
  • You may manually reset the high limit
  • It’s well made and durable

The inherent downsides shouldn’t worry you:

  • The flow rate is a bit lower than expected
  • You need professional help for service

The good outweighs the bad once more, and the unit manages to be a reliable model for anyone valuing the non-condensing technology.

   5. AO Smith Residential Condensing ATI-340H-N

The 8GPM flow rate and the low profile of the AO Smith ATI-340H-N 8 GPM Residential/Commercial Condensing Natural Gas are only some of the many good things about the unit.


The tankless water heater comes with a built-in temperature controller and power cord (installed in the factory. You may use it with Category III or IV power direct venting, with 3″ or 4″ size.

Thanks to the electronic ignition, the unit has no pilot light, which means less worry for you. The list of safety features is long and explains the durability of the tankless water heater. The unit comes with constant temperature monitoring, overheat cutoff fuse, and air-fuel ratio rod.

The build doesn’t disappoint either with the primary heat exchanger being made with commercial-grade copper and the secondary being made with stainless steel. The primary heat exchanger ensures better heat transfer and resistance to erosion as well.

You can confidently use the unit for 3.5 bath home in southern areas or 2.5bathrooms home in northern regions.

The unit can be used up to 10,100ft above sea level and has a 0.95 energy factor. It’s made only for indoor installation. It respects the Ultra-Low NOx regulations and includes a 15-year limited warranty on the heat exchanger.

We should check the positive aspects once more:

  • It’s powerful and dependable
  • It’s compact and has a slim shape
  • It comes with safety features
  • It’s highly reliable and energy-efficient

We wouldn’t call the pet peeves deal breakers:

  • It’s only for indoor installation
  • It’s not very lightweight

The unit is dependable, durable, and easy to operate, which should be enough for most.

FAQs on AO Smith tankless water heaters

Q: How many types of water heaters does AO Smith make?

A: AO Smith tankless water heaters are made for light commercial and residential use. Most of the models use natural gas but can also run on liquid propane. However, there are some alterations that you need to do while using the right conversion kit.

There are several types and sizes of tankless water heaters that AO Smith manufactures. You can choose from non-condensing models (within the economy line), condensing units (they come with built-in recirculation pump), and ultra-low NOx. The last two are included in the ProLine X.E. series.

Q: What are the safety features of AO Smith tankless water heaters?

A: AO Smith tankless water heaters come with many safety features that ensure the performance. They present protection for overheat, power failure, flame failure, internal freeze, and come with power surge fuse and Air Fuel Ration Sensor (AFR). The sensor provides the appropriate gas/propane mixture for the clean gas combustion inside the combustion chamber.

Q: Do the AO Smith tankless water heaters come with a remote control?

A: The remote control is a typical feature for some models. It displays the outlet temperature and the current inlet, but also flow rate and error codes. This way, you may increase/decrease the temperature of the outgoing hot water, which is always a useful feature.

Q: What can we say  about the warranty of AO Smith tankless water heaters?

A: AO Smith tankless water heaters typically include a 15-year limited warranty for the heat exchanger, in case of residential use. For the commercial applications, the warranty is six years (except for the 510 and 540 models that come with ten years warranty). There’s a 5-year warranty for all parts.

Q: Do AO Smith tankless water heaters manage to be “green”?

A: Operating on a half-of inch gas line, the new AO Smith tankless models come with temperature controls and vents with PVC. The features lower the installation costs and ease out the installation process too. The high quality of materials and modular technology, with easy to replace parts, expand the lifespan for up to two decades.

The new condensing tankless units heat water only when you need it and are 10 to 15% more effective than the non-condensing models.

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