Exploring Rinnai RU Water Heaters

Explore the benefits of the Rinnai RU water heaters utilizing the tankless and condensing technology, and see the review of the top features and compare specs of the models. Compare Rinnai RU130, RU160, RU180, and RU199 to buy the best model for your home.

Rinnai RU water heaters: Things to consider

Enjoy all the comfort and high performance for less. Do you need plenty of hot water in endless supply for your new home, or as the retrofit, something that will replace an existing low efficient water heater?

Rinnai tankless water heaters from the RU series can meet or exceed all your needs for hot water, saving you money by using less energy and water while protecting the environment with reduced pollution. The units are built for heating potable water, mostly in residential applications, but can be used in light commercial and manufactured (mobile) homes as well.

Either you need hot water in the kitchen and/or bathroom of your small or large size home, even small commercial application – RU water heaters are powerful enough to deliver hot water up to 6 fixtures simultaneously, with the minimum temperature fluctuation and significantly less "cold water sandwiches." Moreover, with Wi-Fi connectivity and smart technology, heating operation can be controlled and monitored remotely.

Rinnai RU models review

Rinnai RU tankless and condensing water heaters come from the SENSEI super-high efficiency plus group and are designed in four sizes: RU130, RU160, RU180, and RU199.

Rinnai RU130 – available as indoor and outdoor models using natural gas or propane (recommended for 2-4 fixtures)

Rinnai RU160 – available as indoor and outdoor models using natural gas or propane (recommended for 2-5 fixtures)

Rinnai RU180 – available as indoor and outdoor models using natural gas or propane (recommended for 3-5 fixtures)

Rinnai RU199 - available as indoor and outdoor models using natural gas or propane (recommended for 3-6 fixtures)

By taking into account all the sizes, fuel types, and locations where they can be installed, we will see that there are 16 models total to choose from.

Rinnai RU130

Rinnai RU130 tankless water heaters are the least powerful units from all models in the RU series. As they are built compact and small, sizing 11.5 x 26.4 x 18.5, they weigh only 62 pounds, making handling and wall installation easier. 

The eco-friendly gas burner can produce between 15,000 and 130,000 BTU of power and deliver hot water with a maximum flow rate of 7.0 GPM, making them ideal for use in homes with up to 4 showers, depending on the climate.

Even being small and least powerful in this group, they can still heat water with a high energy factor of 0.95 (UEF is 0.91) and used not only for point-of-use service but multiple applications as well.

Rinnai RU160

Rinnai RU160 is another small unit with the same size and weight as the RU130 models but can generate more power of 160,000 BTU, while its minimum is the same as the above model.

Also, it can deliver more hot water - 9 GPM, which means it covers more fixtures – 3-5, working simultaneously. The high efficiency of 0.95 is unchanged, making them ultra-efficient and Energy Star compliant as well.

Rinnai RU180

Rinnai RU180 heaters come in same sizes as the above small models but are slightly heavier of only 2 pounds. They utilize a powerful gas burner that can produce between 15,000 and 180,000 BTU and generate up to 10 GPM of hot water, so it is recommended for demanding households operating up to 5 fixtures at the same time.

With the high efficiency of 0.95 and excellent water flow, these RU models are Energy Star approved.

Rinnai RU199

Rinnai RU199 tankless water heaters are the most powerful and efficient models in this RU group. They have the same size and weight as RU180. Although they produce the same minimum power of 15,000 BTU as other models, the peak power is higher - 199,000 BTU, which is the maximum acceptable to qualify for the Energy Star approval. 

With the given power range, RU199 models can deliver the maximum water flow rate of 11.0 GPM, so if you want to run 3-6 showers simultaneously, it won't be a problem. Not only that we are dealing with the ultra-high gas input and water flow, but RU199 also has one of the highest energy efficiencies in the industry - 0.96 (UEF is 0.93).

As can be seen from the above text, the maximum power water heaters can achieve is different between the RU models, but the minimum is the same – 15,000 BTU, giving you the turndown ratio in the range from 10 to 13. This is possible due to the modulating gas valve, which increasing or decreasing the power, depending on the demand and user needs.

All the models can heat water from the minimum of 98 F to its maximum (for residential use) 140 F.

Due to the quality elements, Rinnai provides warranties of 15 years on the heat exchanger, 5 years on all other parts, and one year on labor.


Easy installation with the flexible venting system

All Rinnai RU water heaters designed for indoor use utilize one or two venting systems; direct vent or non-direct vent system.

Direct vent systems come in two configurations; concentric or pipe inside the pipe and two pipe systems, one pipe for air intake and one for the exhaust.

In the case of the non-direct models, the only difference is that the water heater gets the combustion air from the indoor room air, not from the outside.

The concentric type is easier to install and is offered with the installer in mind. Either one you choose, the maximum vent lengths can reach high 150 ft., from the heater to the spot where it ends to release the exhaust gases.

In the case of the outdoor models, the situation is simpler because they are ventless, so they push the exhaust gases directly to the surrounding atmosphere. They are usually installed inside the recess box for protection against the elements.

Dual heat exchangers

Rinnai RU water heaters come with the condensing technology that utilizes two heat exchangers; condensing heat exchanger that pre-heats the incoming cold water by using the heat from the flue gases, and the primary heat exchanger that is made of copper, where the water is heated and from where it is delivered to the fixtures.

Due to the condensing technology, energy efficiency is much higher than in the non-condensing type. For example, Rinnai RU199 tankless water heaters have the highest energy factor of 0.96 while others have an EF of 0.95, resulting in up to 40% energy savings and making them, depending on the home size, a good buy.

Temperature controller

A digital temperature controller MC-91-2US comes as the standard feature and is used in residential and commercial applications. It allows users to choose desired temperatures between 98 F and 140 F and check out the status using its display. Higher temperatures of up to 185 F can be achieved if the commercial controller MCC-91 is installed (sold separately).

Advanced electronics

All models are Wi-Fi compatible, which means you can control the unit remotely, check or have it checked via remote diagnostics. This amazing feature will give you peace of mind, enhance your comfort, and improve savings.

Faster hot water delivery with the recirculation option

As the Rinnai RU models are equipped with the Rinnai Circ-Logic technology, which uses an external circulation pump, users will get hot water delivered instantaneously, saving you time, water, and energy.

Features highlights

  • Direct electronic ignition eliminates the need for the pilot light.
  • Environment-friendly and Ultra-Low NOx burner that complies with the 20 ppm NOx emission levels.
  • Digital temperature controller MC-91-2US is used to monitor the temperature, adjust the settings and display the error codes for easy troubleshooting.
  • Improved detection of the lime-scale in the heat exchanger.
  • Built-in Rinnai Circ-Logic recirculation program that cycles an external pump for faster hot water delivery, better comfort, and higher efficiency.
  • Temperature lock feature that prevents accidental or unauthorized temperature changes.
  • Water flow sensor, electronic water control device, and electronic by-pass control.
  • Safety features such as flame and boiling protection, combustion fan check, remaining flame OHS, automatic frost protection (protects the unit when the outside temperature is up to -22 F).
  • Diagnostic system helps in service.
  • Wi-Fi ready for remote control.

Specifications - Technical data

Model/Specs Rinnai RU199i/RU199e Rinnai RU180i/RU180e Rinnai RU160i/RU160e Rinnai RU130i/RU130e
Gas input (BTU) 15,000-199,000 15,000-180,000 15,000-160,000 15,000-130,000
Water flow (GPM) 0.26-11 0.26-9 0.26-8 0.26-7
Number of fixtures 3-6 3-5 2-5 2-4
Energy factor 0.96 0.95 0.95 0.95
Temperature setting (F) 98-140 98-140 98-140 98-140
Noise level (dB) 48/53 47/52 47/52 47/52
Max. vent length (ft) 150 150 150 150
Size (inch) 18.5x11.4x26.4 18.5x11.4x26.4 18.5x11.4x26.4 18.5x11.4x26.4
Weight (lbs) 64 64 62 62
Warranty (years) 15/5/1 15/5/1 15/5/1 15/5/1


The price of the Rinnai RU water heaters is between $1000 and $1500, and the installation is around $1000. According to the user reviews, RU water heaters are a suitable replacement for the tank-type or less efficient tankless models. The condensing technology and advanced electronics can improve savings and comfort of the household and help in fast problem diagnostics.

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