Best Tankless Water Heaters 
Review and Buying Tips
(updated 2020)

A review of the top 3 gas-powered on-demand water heaters.

Are you looking for the best tankless water heater to buy for your home to enjoy long showers and save? Since there are many tankless brands and models, we will focus only on the most advanced and popular ones: Rinnai, Noritz, and Takagi. We will find, review, and select the best models that offer quality elements and features, long warranty, reasonable price, significant savings, and many positive user reviews.

The best tankless hot water heaters are helping users meet their needs for hot water, and that includes plenty of hot water anytime, fast delivery, no headaches in operation, and savings. If you buy one of the top-notch condensing units, you will get an Energy Star model, which ensures ultra-efficiency and ultra-low NOx gas emission.

What's great about condensing water heaters is the ability to utilize heat from flue gases that would otherwise be lost, and use it for preheating the cold incoming water.

The temperature of the flue gases significantly decreases, so cheaper PVC vent is used instead of the expensive metal ones. The best models are designed with many innovative features and quality elements, which ensure energy savings, better performance, reliability, long life, and low emission of greenhouse gases.

Review of the best tankless water heaters

Rinnai RUR199i

The best tankless water heater from Rinnai comes from the "Ultra" RUR series, a series that features the ultra-efficient condensing technology.

The Rinnai RUR199i model is built as the condensing tankless water heater and is recommended for larger homes with high hot water demand – up to five showers. With the maximum gas input of 199,000 BTUs, this unit provides a thermal efficiency of up to 96%, making it extra efficient and Energy Star qualified.

The Rinnai RUR199i is equipped with the two innovative heat exchangers, so more heat is captured (including heat from the flue) and transferred to water, while the water flow of up to 11 GPM (with parameter adjustments) ensures plenty of hot water in showers, for dishes and other applications. The heater comes with the built-in circulation pump, bypass line, and the valve allowing faster hot water delivery than other tankless models that do not have these features, saving you time and money.

RUR199 models (indoor and outdoor) are recommended for residential homes, light commercial applications, mobile homes, and in regions where the products with the low gas emission are mandatory - the RUR models are ultra-low.

In 2010 in "Builder's Magazine," Rinnai was chosen as the best tankless water heater for its efficiency and quality, while Rinnai RUR199i, according to the specs, features, quality, and user reviews, is the best of Rinnai.


Noritz NRCP1112

The best tankless water heater from Noritz is NRCP1112. This is a direct vent and condensing model that is coming from the high-efficiency series and is recommended for larger homes delivering hot water to up to 5 baths or showers.

Noritz NRCP1112 is the largest and most efficient tankless unit from this manufacturer that provides over 11 gallons of hot water per minute and 96% energy efficiency, without sacrificing hot water output. It is also a preference of eco-conscious homeowners due to the low carbon footprint.

The Noritz NRCP1112 model utilizes the stainless steel heat exchanger that guarantees superior heat transfer and resistance to sediment deposits, also quality pre-mix burner for the reduced temperature fluctuation, and maximized heat output.

The tankless is equipped with the advanced electronics that includes the computer board, sensors, and control panel with the LCD interface. This is what is helping users and installers making the proper set up, monitor and control the operation; by programming, changing the temperature and modes, checking the status, troubleshoot, getting the diagnostic info, and more.

The unit utilizes an internal pump for recirculation, either using the external or internal mode, allowing faster hot water delivery and more convenience.

Most of the components are commercially-grade so that the model can be used for both residential and commercial applications.

It is designed as the direct vent with an option to be converted to SV, or single vent for indoor installation, vented horizontally or vertically, with a single or dual pipe system. It is a factory set up to use natural gas but can be easily converted to propane LP gas.

The Quick Connect Multi-System allows the installation of two units together, if more hot water is needed, and one unit cannot deliver.


Takagi T-H3

Takagi T-H3-DV tankless and condensing water heater is one of the top models from this manufacturer, and also an Amazon Choice when it comes to buying the best on-demand model.

Takagi T-H3-DV is another excellent water heating device that can produce up to 199,000 BTU of power, heat water up to 185 F, and deliver high 10 GPM of hot water. The powerful and modulating gas burner is capable of providing an extremely high energy efficiency of 0.93, so users, when using the tankless and condensing technology, it can save even more while protecting the environment due to the ultra-low NOx emission.

Such a high water flow rate makes it ideal for homeowners who would like to have a continuous delivery of hot water, supplying up to four bathrooms not only in residential, but commercial applications.

For more power and hot water delivery, Takagi T-H3-DV has an option to use an Easy-Link and connect up to four models to work as one, and if using the Multi-Unit Controller, a Multi-Link option will allow connection of up to 20 units into one system.

This Energy Star approved model is small, wall-mounted, and can fit almost anywhere. The DV option allows direct venting to the outside, and with the computerized features, no worries for the owner.

The best of Takagi - T-H3 comes with a limited warranty of 15 years on the heat exchanger against leaking.

Comparison

Models/
Specs
Rinnai RUR199i Noritz NRCP1112 Takagi T-H3-DV
Power (BTU) 15,000-199,000 18,000-199,000 15,000-199,000
Water flow rate
(GPM)
0.26-11 0.5-11.1 0.4-10
# of baths 3-4.5 3-4.5 3-4.5
Efficiency 0.96 0.94 0.93
Warranty (years) 15 12 15

Things to consider when selecting the best tankless water heater

Quality

The best tankless water heater is durable - it can last over 20 years, and most of its components are replaceable and recyclable, which is not the case with the storage tank type. The best model is equipped with quality components, which are strong, reliable, and long-lasting.

When comparing the unit's features (elements), look for the "commercial grade" or "professional" as such elements guarantee the quality and make the heater an excellent choice for installers and users.

The perfect example is a Japanese manufacturer of tankless water heaters Noritz with its commercial-grade heat exchanger and low NOx and modulating gas burner. One of their top models - NRCP1112 is reviewed above, which shows several powerful features.

The most important elements on one tankless water heater are the gas burner and heat exchanger. The best tankless unit has both elements made of the high-grade stainless steel that can resist increased thermal stress, perform, and last longer than those made of the cheap materials.

The best models have the eco-friendly burners, which burn the gas efficiently while emitting less CO and NOx gases for a cleaner and greener environment.

Versatility

The best tankless water heater is also a versatile unit. It can be used for water heating, space heating, radiant heating, as the single unit or combined with more units, for higher hot water demand.

Most of these on-demand models are factory set to use natural gas. The best tankless heater uses both fuels, and the conversion kit is included in the package so you can always convert the heater to use the propane gas.

Advanced features

Advanced electronics, as the brain of the heater, is a major element that ensures that everything works perfectly, and the heating operation is safe. The best tankless water heater is equipped with such a small computer so it can collect all the necessary information from its sensors, and it ensures that the heating process is smooth and efficient.

The intelligent diagnostic system in top models is factory built for safe and reliable operation, programming, control, monitoring, diagnostics, and troubleshooting.

Efficient venting

The best tankless water heater uses the high performing concentric vent. These vent systems are designed for flexible installation, which allows heaters to be mounted almost anywhere. They are designed to provide zero-clearance venting, so the vent pipe is cold to touch. No need for the expensive, stainless steel vents, you can use cheaper PVC pipe instead.

3 best selling tankless models on Amazon

Summary

I hope this article helped you find the answer who makes the best tankless water heater and what is the best model to buy. The top models, as you can see, are coming from the industry leaders in tankless technology, and are designed to offer the best quality, features, and performance. The top-selling models are selected from one of the most popular online stores Amazon.com.

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