Compare tankless water heaters and find the best model for all your hot water needs. The review covers several popular brands and available models designed for point-of-use and whole-house water heating in residential applications.
We review the top manufacturers of tankless water heaters such as Bosch, Rheem, Rinnai, Noritz, and Takagi, compare the benefits and main features, and extract what is specific for that particular model.
While we were reviewing and comparing tankless water heaters we have found many standard features and benefits:
The Rinnai manufacturer offers quite an extensive line of tankless water heaters utilizing simple on-demand and condensing technology for residential and commercial use.
Rinnai V (HE series) and RL models (HE+ series) are economy and non-condensing models that are used mainly in small and medium-size homes, where high demand for hot water is not required. While they have a higher energy factor than the tank-type, ranging between 0.79 and 0.82, they are not considered as Energy Star.
Tankless water heaters from the V series are also the simplest models that do not have voice activation capability, isolation valve for easy service, or Circ-logic option for fast hot water delivery, as the RL series.
Both V and RL series utilize one heat exchanger, integrated temperature controller, and flexible venting options. Models are available in both natural gas and propane.
Rinnai RUCS and RUS models (SE series) are coming from the condensing group, which gives them the ability to heat water with higher efficiency of close to 0.9, making them Energy Star compliant, but like the V series, these tankless models do not include a voice control system, isolation valve, and Circ-logic option. They also lack a decent size of the temperature display.
The most advanced models are coming from the RUC, RU, and RUR series, so they include all the best features that Rinnai offers. Also, all the models are ultra-efficient with an energy factor of over 0.9, which makes them Energy Star approved.
The ThermCirc360 technology makes the RUR series unique, so recirculation is possible with or without a dedicated line.
All the models use the Wi-Fi option for remote control and monitoring.
Rinnai RUR199i and RUR199e are the largest indoor and outdoor models from Rinnai that can provide hot water to up to six features simultaneously.
There are two main groups of Rheem tankless water heaters: condensing and mid-efficiency.
Condensing models are further divided into Professional Prestige, Performance Prestige, and Performance Platinum group. Customers can get a tankless water heater that produces hot water with a flow rate ranging from 8.4 to 11 GPM, an efficiency of over 90%, and power ranging from 157,000 to 199,000 BTU. The size of the model you need depends on how many applications you want to use at the same time. No matter which one you choose, keep assured that you are getting models with the most advanced features and cutting-edge technology which will bring the highest efficiency and savings.
When talking about the Mid-Efficiency series, there are two groups; Tankless Mid-Efficiency and Performance Mid-Efficiency, both offering three sizes where the water flow goes from 7.0 GPM to 9.5 GPM and maximum power from 160,000 to 199,900 BTU. The maximum Energy Factor on the Rheem Mid-efficiency tankless water heaters is 0.82, lower than condensing but still providing substantial savings when comparing to tank-type. The main difference is that condensing has two heat exchangers, while this group has only one.
Rheem RTGH-RH11DVLN models (indoor and outdoor) are the most advanced tankless and condensing water heaters from this North American manufacturer. As the above Bosch, it comes with an energy efficiency of over 90%, environment-friendly gas burner, and recirculation for fast hot water delivery.
Noritz, a Japanese manufacturer of tankless water heaters, offers three categories of devices for residential water heating, supporting different home sizes and customer needs.
The Noritz NR series is recommended for homes with moderate usage or homes with up to 3.5 baths. While they can get a power of 199,900 BTU and a water flow rate up to 9.8 GPM, they are considered as mid-efficient models whose energy factor is around 0.81. They utilize only one heat exchanger.
The Noritz EZ series is the best to use when replacing a tank-type water heater of 40, 50, and 75 gallons while retrofitting an existing water heating system. The top-mounted connections, for example, make the transition easier, faster and cut the cost and time. EZ models use two stainless steel heat exchangers and condensing technology.
NRCB combination boilers are ideal for those homeowners who would like to heat both space and domestic water at the same time. All the models are condensing, so they can heat water with extremely high efficiency without polluting the environment as the standard type.
The Noritz NRCP line of tankless water heaters is the group offering cutting-edge technology for ultra-efficient heating. The condensing models use an internal pump for water recirculation for faster hot water delivery. As the above models, they are also Energy Star and can deliver hot water in large volumes.
Noritz NRCP1112 is the residential condensing and tankless water heater with the built-in recirculation pump with two modes – with and without the return line. It allows shorter delivery time of hot water and a better user experience.
The Bosch Group is a reputable German manufacturer of Bosch tankless water heaters for residential and commercial use.
There are several models available to the consumers, which include non-condensing and condensing models grouped in the Therm and Greentherm series.
Greentherm 9000 series is the newest line of seven condensing and tankless water heaters that come with state-of-the-art engineering, superior energy efficiency, exceptional performance, and long life.
The Therm series includes several models:
Therm C 1210 ES is the condensing model which offers the power of up to 225,000 BTU, a high water flow of 12.1 GPM, and an efficiency of up to 98%. For the high-demanding homes, an Intelligent Cascading allows the combination of up to 24 units into one system.
Therm 940 ES and 830 ES are two of the smallest and non-condensing models offering the maximum efficiency of 83%, resulting in savings up to 50% on utility bills. Both are suitable for residential and commercial applications.
Bosch Greentherm T9900I (SE 199) is the most powerful residential tankless water heater from this manufacturer, with the highest performance and water flow. It is small, lightweight, but ultra-efficient due to its condensing technology.
Takagi is the third company from this list made by Japan.
Takagi offers two groups of tankless water heaters; non-condensing (T-KJr2, K4, D2, 110, 310, and 510) and condensing (H3M, H3J, H3S, H3, and 540P), heating domestic water in homes with up to 4.5 showers. Some models could be used in commercial applications.
Non-condensing models come with one standard-type heat exchanger and stainless steel venting, efficiency around 0.8, and low NOx emission.
Condensing models are high efficiency and ultra-low NOx models that come with high energy factors of over 0.9 and maximum water flow of 10 GPM, making them Energy Star compliant. All the models have an integrated temperature controller in indoor models and remote controllers supplied to outdoor units. They come with a 15-year warranty when used in residential applications or 5-year when used in a commercial.
The best models are equipped with high-quality elements such as the Air-Fuel Ratio (AFR) sensor that monitors and maintains proper gas combustion all the time, a primary commercial-grade heat exchanger, and secondary made of stainless steel.
As can be seen in this comparison, the benefits of any tankless water heater are vast. From continuous water heating and on-demand supply to high-efficiency operation and long-lasting service, tankless are built with customer satisfaction in mind. They can also save you money, time and nerves, due to the great diagnostic system.
Now when it comes to choosing the best tankless water heater, any model from above is a great option, while Rinnai, with the greatest selection, is our pick. That is why we recommend Rinnai RUR199 or similar RUR98, as you will get the most powerful and "greenest" unit, the highest energy efficiency with savings, and the ability to control its work using the smartphone.