How to Find the Best Tankless Water Heater: Review and Buying Tips

Rinnai RUR199Rinnai RUR water heater

Looking for a reliable and efficient way to heat water for your home?

In this review, we've handpicked the top 3 tankless water heaters from leading brands Rinnai, Noritz, and Takagi. Our selection is based on a range of factors including quality, features, warranty, price, savings, and positive user reviews. With our help, you can find the best tankless water heater to enjoy longer showers and energy savings for your home.

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To meet the demands of users looking for ample hot water, fast delivery, ease of operation, and energy savings, the best tankless water heaters are the way to go. For the ultimate in efficiency and eco-friendliness, consider a top-notch condensing unit that boasts an Energy Star rating and ultra-low NOx gas emissions.

Condensing water heaters are particularly noteworthy for their ability to capture heat from flue gases that would typically be lost in traditional systems. This captured heat is then used to preheat incoming cold water, resulting in significantly reduced flue gas temperatures and allowing for the use of more affordable PVC vents instead of costly metal ones.

The top models on the market feature innovative designs and high-quality components that offer superior performance, energy savings, reliability, longevity, and minimal greenhouse gas emissions.

A review of the best tankless water heaters and features to look for

Rinnai RUR199i tankless water heater

Best tankless water heater: Rinnai RUR199Rinnai RUR199 tankless water heater

The Rinnai Ultra RUR series offers the best tankless water heater in the company's lineup, boasting ultra-efficient condensing technology. Specifically, the RUR199i model is ideal for larger homes with high hot water demands, delivering up to 199,000 BTUs and achieving a thermal efficiency of up to 96%, which earned it an Energy Star certification.

One of the standout features of the RUR199i is its two innovative heat exchangers, which capture and transfer more heat, including heat from the flue. This results in a high water flow rate of up to 11 GPM, making it one of the most efficient tankless water heaters on the market. Additionally, with its built-in circulation pump, bypass line, and valve, the RUR199i offers faster hot water delivery than other tankless models, saving you time and money.

Designed to be used in residential homes, light commercial applications, and mobile homes, the RUR199 series (both indoor and outdoor) is ultra-low emission and compliant in regions with strict gas emission regulations.

In 2010, Builder's Magazine named Rinnai the best tankless water heater for its efficiency and quality, and the RUR199i model is the best of the Rinnai tankless water heaters. Its top-notch features, quality, and positive user reviews make it a standout choice for homeowners looking for a reliable and efficient way to heat water.

Noritz NRCP1112

Noritz NRCP1112 tankless water heaterNoritz NRCP1112 tankless water heater

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

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

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

The tankless unit is equipped with advanced electronics that include a computer board, sensors, and a control panel with an LCD interface. This helps users and installers to make the proper set up, monitor and control the operation, by programming, changing the temperature and modes, checking the status, troubleshooting, getting the diagnostic info, and more.

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

Most of the components are commercial grade, allowing the model to be used for both residential and commercial applications.

It is designed as a 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 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 water heater

Takagi T-H3 tankless water heaterTakagi T-H3 tankless water heater

The Takagi T-H3-DV tankless and condensing water heater is one of the top models from this manufacturer and an "Amazon Choice" for the best on-demand model.

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

This high water flow rate makes it ideal for homeowners who want a continuous delivery of hot water, supplying up to four bathrooms in residential and commercial applications.

For more power and hot water delivery, the Takagi T-H3-DV has the option to use an Easy-Link and connect up to four models to work as one. If the Multi-Unit Controller is used, a Multi-Link option will allow the 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 for direct venting to the outside, and with the computerized features, there are 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.

Comparing Rinnai vs. Noritz vs. Takagi

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
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


The best tankless water heaters are durable, lasting over 20 years, and their components are mostly replaceable and recyclable, unlike storage tank models. Look for models with quality components labeled "commercial grade" or "professional" as they guarantee reliability and longevity, making them an excellent choice for installers and users alike.

A prime example of this is Noritz, a Japanese manufacturer of tankless water heaters, which features commercial-grade heat exchangers and low NOx and modulating gas burners. Their top model, the NRCP1112, which was previously reviewed, has several powerful features.

The two most important components of a tankless water heater are the gas burner and heat exchanger. The best tankless units have both of these elements made of high-grade stainless steel that can withstand increased thermal stress, perform optimally, and last longer than those made of cheaper materials.

Furthermore, the best models come equipped with eco-friendly burners that burn gas efficiently, emitting fewer CO and NOx gases, contributing to a cleaner and greener environment.


The best tankless water heater is also a versatile unit that can be used for water heating, space heating, radiant heating as a 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. However, the best tankless heater uses both fuels, and a conversion kit is included in the package, so you can always convert the heater to use propane gas.

Advanced features

Advanced electronics, serving as the brain of the heater, are a critical element that guarantees perfect operation and safe heating. The best tankless water heater is equipped with a computer that collects all necessary information from its sensors, ensuring a smooth and efficient heating process.

Top models have an intelligent diagnostic system that is factory-built for safe and reliable operation, programming, control, monitoring, diagnostics, and troubleshooting.

Efficient venting

The best tankless water heater uses a high-performing concentric vent that provides flexible installation options, allowing the heater to be mounted almost anywhere. These vent systems are designed to offer zero-clearance venting, ensuring the vent pipe remains cold to the touch. This eliminates the need for expensive stainless steel vents, as cheaper PVC pipes can be used instead.

3 best selling tankless models on Amazon

  • Rinnai RL75iN
  • Eccotemp 45HI-NG
  • Marey GA10LP


In conclusion, tankless water heaters offer a multitude of benefits for homeowners looking to save energy, space, and money. With continuous hot water on demand and minimal maintenance requirements, they can last for over 20 years. When selecting the best tankless water heater, it is crucial to consider factors such as flow rate, energy efficiency, size, durability, and advanced features.

With so many options available, choosing a reputable brand with quality components and excellent customer support is essential. Two industry leaders in tankless technology are Rinnai and Takagi, with top-selling models that offer exceptional quality, features, and performance. As noted in our reviews above, these brands offer reliable options that are worth considering.

We hope that this article has provided valuable insights into the best tankless water heaters and helped you make an informed decision on the perfect model for your needs. Investing in a tankless water heater can provide long-term savings, energy efficiency, and convenient hot water access, making it a wise investment for any homeowner.

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