Best Tankless Water Heaters 
Review and Buying Tips
(updated 2018)

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

Looking for the best tankless water heater to buy for a home? Many are available, but which one to select: Rinnai, Noritz, Takagi, Navien, Paloma, Rheem, or Bosch? This is how we can help; we will find, review and select the best models by checking the quality, available features, warranty, price, savings and user reviews.

The best tankless hot water heaters are condensing units resulting in ultra-efficient operation and Energy Star compliance. What's great about condensing water heaters is the ability to utilize the 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 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 the greenhouse gases.

Review of the Best Tankless Water Heaters

Noritz NRCP1112

The best tankless water heater from Noritz is  NRCP1112 - direct vent and condensing model that is coming from high-efficiency series, designed for larger homes with 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.

Noritz NRCP1112 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 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 external or internal mode, allowing faster hot water delivery and more convenience.

Most of the components are commercially grade so 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-non direct 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 installation of two units together, if more hot water is needed, and one unit cannot deliver.

Rinnai RUR98i

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

Rinnai RUR98i model is built as the condensing tankless water heater, recommended for larger homes with high hot water demand - up to four showers. With the maximum gas input of 199,900 BTUs this unit provides thermal efficiency of up to 96%, making it extra efficient and Energy Star qualified.

Rinnai RUR98i is equipped with the two innovative heat exchangers so more heat is captured (including the heat from the flue) and transferred to water, while the water flow of up to 9.8 GPM ensures enough hot water in showers, for dishes and other applications. It comes with the built-in circulation pump, bypass line and the valve allowing faster hot water delivery than other tankless models without these features, saving you time and money.

It is recommended for residential homes, light commercial applications, mobile homes and in regions where the low gas emission products are mandatory - the RUR models are actually ultra-low.

In 2010 in "Builder's Magazine", Rinnai was chosen as the best tankless water heater for its efficiency and quality, while Rinnai RUR98i, according to the specs, features, quality and user reviews, is the best of Rinnai.

Navien NPE-240S

The best tankless water heater from Navien, NPE-240S is another model with the condensing and green technology. It has one of the highest energy factors - 0.99 and water flow rates - 11 GPM, which ensures low energy waste, plenty of hot water for multiple fixures, long-term operation and maximized savings.

Navien NPE-240S is equipped with the two stainless steel heat exchangers, much more durable than copper-made found on cheaper models. Navien incorporates unique features such as the Eco Pre-mixed Burner that has three phases for optimal gas combustion and significant reduction of NOx gases. See the price here.

Navien NPE-240S uses two microprocessors that provide better heat control, maintain the uniform hot water temperature and enhance the safety. Air and gas pressure sensors maximize the efficiency by maintaining the combustion on the optimal and stable level. Navien offers the optional built-in recirculation system with the buffer tank, which significantly reduces "cold water sandwiches" as no minimum flow rate is required.

Things to consider when selecting the best tankless water heater


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 the quality components which are strong, reliable and long-lasting. When comparing unit's features (elements) look for the "commercial grade" or "professional" as such elements guarantee the quality and make the heater a great 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 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 cleaner and greener environment.


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 cool to touch. No need for the expensive, stainless steel vents, cheaper PVC pipe is what is available to you.

3 Best selling tankless models on Amazon


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

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