Best Rinnai Water Heater Reviews of 2021

Rinnai is a great brand, and we’ve got the ultimate review to prove it.

Are you on the lookout for a tankless water heater? Then chances are you’ve come across the name Rinnai a few times. There’s an understandable reason behind this, seeing that Rinnai is a top brand within the tankless water heater industry.

This company is behind several appliances, some of which you might already have used in the past. But their expertise remains within the tankless water heater category where they produce some of the best gas-powered units.

Today, we’ll help you figure out whether this brand is for you.

Our Top Picks

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Product Comparison Table

Product Image of the Rinnai RUC98iN Ultra Series Indoor Natural Gas Tankless Water Heater, Twin Pipe
Best Overall Water Heater
Rinnai RUC98iN Ultra
  • 199,000 BTU heater
  • Flow rate of 9.8 gal/min
  • Thermal efficiency of 95%
Product Image of the Rinnai RL94iN
Best On-Demand Water Heater
Rinnai RL94iN
  • 199,000 BTU heater
  • Flow rate of 9.2 gal/min
  • Features an external thermostat
Product Image of the Rinnai RUCS75iN
Best for Indoor Use
Rinnai RUCS75iN
  • 10,300 to 160,000 BTU
  • Flow rate of 7.5 gal/min
  • Wi-Fi control via Control-R app
Product Image of the Rinnai RUR98iN Ultra Series Condensing Indoor Natural Gas Tankless Water Heater, 9.8 Max
Best Condensing Water Heater
Rinnai RUR98iN Ultra
  • Flow rate of 9.8 gal/min
  • Includes digital remote
  • Compatible with Thermacirc360 recirculation technology
Product Image of the Rinnai R94LSi Natural Gas Indoor Tankless Water Heater, 9.4 GPM
Best for Mobile Homes
Rinnai R94LSi
  • Flow rate of 9.4 gal/min
  • Energy-saving feature
  • Small & compact

History of Rinnai

Rinnai was founded in Japan in 1920 by Kanekichi Hayashi and Hidejiro Naito. The company started out manufacturing pressurized oil stoves. By 1930, Rinnai had expanded into gas appliances as well (1).

Rinnai became a publicly-traded company in 1950 in order to expand and promote their products. In 1958, they acquired a partnership with Schwank GmbH, and soon after, the company officially became Rinnai Corporations (2).

Rinnai has always held on to the same philosophy — harmony, spirit, truth. These qualities were apparent from the beginning, and it’s probably also why Rinnai continues to lead the industry.

Customer Service and Reviews

Rinnai offers multiple ways to find help whenever needed.

On the official website, you can find a self-help center. Frequently asked questions are posted there, as well as recall information. The Rinnai website also provides phone numbers for support.

Customers, overall, are very happy with Rinnai water heaters. One common compliment was that many customers noticed a decrease in their energy bills. Many also said they got much hotter water — and faster than before.

Why Choose a Rinnai Water Heater?

When choosing a Rinnai tankless water heater, you’re choosing high quality. Rinnai sets a high standard for themselves when manufacturing. All appliances undergo rigorous testing before being shipped.

Confirming their quality, Rinnai tankless water heaters have been approved by the Canadian Standard Association. They also adhere to the strict standards of the American National Standards Institute (3).

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Which Rinnai Series Should You Choose?

Rinnai is renowned for its tankless water heaters, which is also why we’ll focus on those today. The company has four different lines of units which they categorize according to efficiency. These are: High-Efficiency, High-Efficiency Plus, Super High-Efficiency, and Super High-Efficiency Plus.

This makes it super easy to choose which product is best for your needs. All of the lines come with their own set of features and functions — although they all have some things in common.

One common element you’ll see is the uniform energy factor. All range between 0.79 and 0.95.

Additionally, all units work either on natural gas or propane.

What’s most outstanding about Rinnai’s tankless boilers is that they’re able to handle multiple fixtures simultaneously.

This is definitely the thing that makes Rinnai stand out from its competition. Most of their units can be used as a whole-house water heater.

One last thing that all current models have in common is their Wi-Fi compatibility. This makes them easily controllable from your phone via the Rinnai Control-R app.

High-Efficiency Series

Rinnai’s High-Efficiency series is probably their “economy” line. They’re highly-efficient but not fitted with as many “high-tech” features as the rest of Rinnai’s lines.

The High-Efficiency line consists of only one series of products — the V series. These are a great choice for small to average households of two to four people.

Most of the products can manage a maximum of four fixtures at a time. And they have a uniform energy factor of 0.79 to 0.82.

High-Efficiency Plus Series

This series consists of two different lines — RL and RLX.

These have a uniform energy factor of 0.80 to 0.81 and are capable of supporting a maximum of four fixtures.

What sets them apart from the V line above is that they have incorporated recirculation support. This essentially increases the models’ flow rate, delivering a faster flow of hot water.

Super High-Efficiency Series

Rinnai’s third range is their Super High-Efficiency series.

Here we have two lines — the RUCS and RUS. Both are Energy Star compliant and have a uniform energy factor of 0.90.

They have an average flow rate of 7 gallons per minute. So, although not as powerful as the RL and RLX lines, most will still be able to support three fixtures at a time. This makes them ideal in smaller households.

Plus, the models within this series are Wi-Fi ready and come with a 12-year warranty.

Super High-Efficiency Plus Series

Rinnai’s Super High-Efficiency Plus series consists of three different lines — RUC, RU, and RUR. These are the créme de la créme of Rinnai’s tankless water heaters.

The products within the lines are all Energy Star compliant as well as able to support a recirculation pump. At the lower end of this series, we have the RUC line which has a uniform energy factor of 0.92. This is followed by the RU line that sports a UEF of 0.91 to 0.93.

At the very top, in terms of efficiency, we find the RUR line. These have a UEF of 0.92 up to 0.95. Most of these will also include a ThermaCirc360 recirculation pump, adding to its efficiency.

The Best Rinnai Water Heaters of 2021

Today is going to be all about tankless water heaters, and we love Rinnai’s models. To find the top five products for you, we used our past experience with Rinnai, expert advice and user reviews.

So without further ado, here’s our top five Rinnai water heaters.

1. Rinnai RUC98iN Ultra Series Tankless Water Heater

Best Overall Rinnai Water Heater

First off is a crowd favorite — the RUC98iN from Rinnai’s Super High-Efficiency Plus series. The RUC98iN is a condensing tankless water heater designed to be ultra-efficient.

This model has a maximum 199,000 BTU and an impressive flow rate of 9.8 gallons per minute. It also has a uniform energy factor of 0.92. It’s meant as an indoor unit and complies with the Ultra Low NOx emission regulations.

The unit is quite easy to install. It’s compact considering its power, measuring 34 inches by 14.5 inches with a depth of 22 inches. It weighs 83 pounds and can easily be mounted on any sturdy wall.

Rinnai lets you choose between PVC or concentric venting to make the installation process even smoother.

This unit is made for energy savings. It features a thermal efficiency of 95 percent and its condensing technology allows it to reuse heat, further increasing energy savings.

The RUC98iN can supply enough hot water for a home with up to four bathrooms. It’s Wi-Fi ready and you can choose a temperature between 98 degrees and 140 degrees Fahrenheit for residential use.


  • Highly efficient condensing technology.
  • Suitable for a four bathroom home.
  • Complies with the Ultra Low NOx regulations.
  • Relatively compact and easy to install.


  • Some users reported that they had to wait longer than expected to get hot water through the faucet.

Additional Specs

Flow rate 9.8 gallons per minute
Fuel type Natural gas
Installation type Indoor use
Measurements 34 inches by 14.5 inches by 22 inches
Wi-Fi capable Yes

2. Rinnai RL94iN High-Efficiency Plus

Best Rinnai On-Demand Water Heater

Rinnai made the RL94iN for ultimate efficiency. It’s designed specifically to produce hot water when you need it.

It’s fitted with highly-efficient heating coils that heat the water up to 185 degrees Fahrenheit. Rinnai has made it easy to regulate the temperature using the external, digital thermostat. This will show you the exact temperature the water is heated to.

You’ll be amazed when you see just how energy efficient this is compared to a standard, tank-type unit. The RL94iN water heater uses 40 percent less energy than a regular boiler. It will conserve water as well, delivering hot water within a few seconds, depending on where you install it.

Also, the unit is powered by natural gas and has a maximum BTU input of 199,000 an hour. It’s capable of handling four fixtures at a time, delivering a flow rate of 9.2 gallons per minute.

What’s more, you can connect it to an external pump, thanks to Rinnai’s Circ-Logic. This reduces the waiting time for hot water even further. However, please note that the external pump is not included.


  • Fitted with super-efficient heating coils.
  • Saves tonnes of water by delivering hot water fast.
  • Sufficient for four bathrooms.
  • Features an external thermostat.


  • A few users mentioned that the temperature dives as soon as you open another faucet.
  • Some also wish the thermostat was easier to use.

Additional Specs

Flow rate 9.2 gallons per minute
Fuel type Natural gas
Installation type Indoor use
Measurements 23 inches by 14 inches by 9 inches
Wi-Fi capable Yes

3. Rinnai RUCS75iN Super High Efficiency

Best Rinnai Water Heater for Indoor Use

Our next choice is from Rinnai’s RUCS Super High-Efficiency series. It’s a natural gas-powered, condensing tankless water heater with a BTU input of 10,300 to 160,000 an hour.

The RUCS75iN is for indoor use only. It has a uniform energy factor of 0.90 and is Energy Star qualified. This unit is also one of Rinnai’s smallest, considering its power. This makes it easy to install in nearly any space.

With a flow rate of 7.5 gallons per minute, it’s capable of handling up to four fixtures at a time. This model has been approved for use at an altitude of 5,400 feet. However, this is significantly lower than other models approved for up to 10,200 feet.

This unit isn’t fitted with an adjustable thermostat. Instead, it features a small monitor at the front. Here you can see the temperature as well as different maintenance codes.

It is Wi-Fi ready but you will need to purchase Rinnai’s Wi-Fi module. This will allow you to control the heater from your phone via their Control-R app.


  • Unit is Energy Star Qualified and fitted with Green Technology.
  • Relatively compact and easy to install.
  • Provides endless hot water for a household with three bathrooms.


  • Is only approved to an altitude of 5,400 feet — much lower than other Rinnai water heaters.
  • There’s no fitted temperature controller, you have to buy the separate Wi-Fi module.

Additional Specs

Flow rate 7.5 gallons per minute
Fuel type Natural gas
Installation type Indoor use
Measurements 26 inches by 18.5 inches by 10 inches
Wi-Fi capable Yes

4. Rinnai RUR98iN Ultra Series Tankless Water Heater

Best Rinnai Condensing Water Heater

If you’re moving into your newly finished home and need a water heater, this is well worth a look. Rinnai specifically recommends its RUR line for use in new homes, or as an upgrade from an existing, less efficient unit. This model is an excellent choice for the growing family.

It provides endless hot water for three to six fixtures — sufficient for multiple showers, a bath, perhaps even a hot tub. This unit can do all this while still saving on your utility bill.

With its uniform energy factor of 0.92, it’s powered by natural gas. The unit also has a strong flow rate of 9.8 gallons per minute.

What’s different about this heater is that it’s compatible with the ThermaCirc360 — a recirculation technology. Plus, it delivers hot water instantly.

And the RUR98iN is, of course, Wi-Fi capable. So you can control it from afar via your phone. This boiler is also fitted with a digital controller which you can set to fit your specific needs.


  • It’s capable of handling three to six fixtures, enough for four bathrooms.
  • A powerful flow rate of 9.8 gallons per minute.
  • Compatible with the ThermaCirc360, allowing the unit to produce more hot water while using less energy.
  • Comes with an included digital remote.


  • The unit is quite noisy, especially if you get the ThermaCirc360 option.

Additional Specs

Flow rate 9.8 gallons per minute
Fuel type Natural gas
Installation type Indoor use
Measurements 34 inches by 14.5 inches by 22 inches
Wi-Fi capable Yes

5. Rinnai R94LSi Natural Gas Indoor Tankless Water Heater

Best Rinnai Water Heater for Mobile Homes

This is an example from Rinnai’s High-Efficiency series — the R94LSi. This compact unit is perfect for small to medium homes. It has a humble flow rate of 9.4 gallons per minute.

This small unit combines some of the best advantages in Rinnai. It’s a combination of value, comfort, and high-efficiency. It comes with a preset temperature of 120 degrees Fahrenheit and is designed as an outdoor unit.

Although the unit comes with a preset temperature, you can regulate it up to 140 degrees Fahrenheit.

The R94LSi saves up to 40 percent of energy and complies with the NOx emission regulations of California and Texas.


  • Provides a sufficient flow for small to medium homes (approximately two bathrooms).
  • Small and compact — easy to install.
  • Energy-saving feature.
  • Complies with the NOx emission regulations of California and Texas.


  • There might be a slight delay of hot water to the fixture.

Additional Specs

Flow rate 9.4 gallons per minute
Fuel type Natural gas
Installation type Outdoor use
Measurements 31 inches by 17.5 inches by 12.75 inches
Wi-Fi capable No

Rinnai Water Heater Comparison Chart

Product Award Flow rate Fuel type Installation type Measurements Wi-Fi capable
Rinnai RUC98iN Overall Choice 9.8 gal/min Natural gas Indoor 34″ x 14.5″ x 22″ Yes
Rinnai RL94iN On-Demand 9.2 gal/min Natural gas Indoor 23″ x 14″ x 9″ Yes
Rinnai RUCS75iN Indoor Use 7.5 gal/min Natural gas Indoor 26″ x 18.5″ x 10″ Yes
Rinnai RUR98iN Condensing Heater 9.8 gal/min Natural gas Indoor 34″ x 14.5″ x 22″ Yes
Rinnai R94LSi Mobile Homes 9.4 gal/min Natural gas Outdoor 31″ x 17.5″ x 12.75″ No

Hot Water On Demand

Rinnai is a giant within the water heating industry, where they produce some of the best tankless water heaters. The company puts a lot of focus on efficiency, dividing their different products up in series, depending on their efficiency ratings. No doubt, there’s a Rinnai water heater for every household.

We hope that you enjoyed our Rinnai water heater review and found it useful. Have you ever owned a Rinnai product? Do you want to own one after reading our guide? Feel free to leave your answer or any questions you might have below.

Headshot of Peter Gray

About the Author

Peter Gray

Peter has been a homeowner for 35+ years and has always done his own repair and improvement tasks. As a retired plumber, Peter now spends his time teaching others how they can fix leaks, replace faucets, and make home improvements on a budget.