Rinnai RL75i Review

Read time: 6 minutes Last Updated: 08/10/2019

Rinnai RL75i

  • 7.5 GPM flow and 150 PSI water pressure remains stable during peak usage
  • Recirculation system increases water usage efficiency
  • 12-year residential warranty covers a large portion of unit’s expected lifespan
  • Wireless interface and display system are exceptionally user-friendly
  • Pricey, especially for first-time users
  • Bulky and requires planning for a successful installation
Dimensions & Capacity:
14 x 9.3 x 23 inches
Fuel Type:
Natural gas
Flow Rate & Water Pressure:
7.5 GPM, 150 PSI
Heating Capacity:
Up to 160 °F
Energy Efficiency Ratings & Certifications:
82%; EnergyStar, NSF, CSA
12-year residential warranty
Display Type:
Material Composition:
Our Review

A quality natural gas–powered tankless water heater can be hard to find these days . . . or at least that was the case until the Rinnai RL75i came onto the market.  This model combines many of the best qualities of its class—such as a 160 °F max heating capacity—with modern, user-friendly features—such as a wireless interface system with app-based access.

Also, this model’s 82% energy efficiency rating is very impressive for a natural gas–powered unit. Even better, this model goes beyond simply boasting about its energy efficiency by backing up its rating with certifications from EnergyStar, NSF, and CSA. With all that in mind, this model’s 12-year warranty is simply cherry on top.

On its face, you’d expect a tankless water heater that costs around $1,250 to get dinged in the ratings due to its high price. But in reality, the Rinnai RL75i is able to balance out these cost considerations with its value-added 12-year residential warranty. Also, this model was able to maintain its productive rating due to its 7.5 GPM flow rate and 150 PSI max water pressure—both of which performed better on average than other models in its class.

Read more about our how our ratings broke down for the RL75i below or checkout how it compares to other tankless natural gas water heaters.

Why Might I Want this Specific Tankless Water Heater?

First and foremost, the Rinnai RL75i has gained a fair amount of attention from homeowners with and existing natural gas delivery system in their home. That’s because this model, in addition to its core compatibility with that fuel source, carries an 82% energy factor. This communicates that the efficiently translates over 4/5ths of its input fuel into its core heating processes.

The Rinnai RL75i is also unique because it features built-in wi-fi compatibility. This allows the unit’s main computer to be accessed remotely through Rinnai’s mobile app. Therein, you’ll be able to monitor the unit’s operation and run diagnostics when a breakdown occurs – all without needing to fiddle with a bunch of knobs and buttons.

Key Specifications and Features to Look for in a Tankless Water Heater

Dimensions & Capacity

You’ll need to take physical sizing into consideration when comparing tankless units simply due their need for optimal spacing during installation. Moreover, you’ll need a well-spaced tankless unit in order to properly maintain it day to day. The Rinnai RL75i is certainly a hefty unit at 14 x 9.3 x 23 inches. Even so, this model can be mounted on most walls without trouble. We give it a 7.5/10 in this category.

Capacity won’t come into play on this (or any other) tankless unit because their categorically lack the need to store any volume of water internally.

Fuel Type

Tankless units primarily operate on either electricity, natural gas, or propane Each fuel type comes with its own benefits and drawbacks, especially when it comes to ongoing operation costs. The Rinnai RL75i is a natural gas-powered unit, making it a productive and affordable option for those living in regions where natural gas is abundant and cheap. For this, we gave it a score of 8.5/10.

Flow Rate & Water Pressure

A tankless unit’s flow rate communicates approximately how much water can pass through its heating system (as measured in gallons per minute or GPM). A higher flow rate is ideal, especially in homes with high simultaneous hot water demands, in order to prevent water pressure fluctuations. The Rinnai RL75i’s impressive 7.5 GPM flow rate provides more than enough hot water for a whopping 5 simultaneous showers. That’s enough to earn it a score of 9/10 in our book.

Heating Capacity

A tankless unit’s heating capacity is usually communicated in a range and describes the temperatures to which a given model’s heating chambers can warm groundwater. Those looking to use their tankless unit for cooking, cleaning, and bathing should pay special attention to this metric in particular. The Rinnai RL75i, for example, can heat water to a whopping 160° F, which is more than enough heat for almost all regular hot water demands. We give it an 8/10 for its ability to supply a large household with heated water.

Energy Efficiency Ratings & Certifications

A tankless unit’s energy efficiency is at the core of its operation, which is why most models carry an energy efficiency rating. Often accompanied by several regulatory certifications, this rating describes how efficiently the unit converts its fuel source into heat. The Rinnai RL75i’s 82% energy efficiency rating is fairly high compared to many other gas-powered tankless units. Even better, this rating is backed by EnergyStar. We give it 8.5/10 for energy efficiency.

Price and Warranty

While shopping for a tankless water heater, you should always compare options that meet your budget. While breaking down a unit’s price, be sure to account for the added value of a productive warranty. This value-based inflation can certainly be seen in the Rinnai RL75i, which costs under $1,250 and comes with an impressive 12-year residential warranty. We give it an 8/10 for the impressive warrant coverage.

Display Type

A user-friendly display is essential for interacting with your tankless unit if you don’t want to be persistently pulling your hair out with frustration. The Rinnai RL75i, for example, has taken user-friendliness into the 21st century by focusing most of its display functions into its proprietary app. This beats the digital and analog displays used on competing units by a longshot. For that, we give it a 9/10.

Material Composition

For its price, you better be sure your Rinnai RL75i will last you a long time. And with the premium materials this model is made of, you’re at least guaranteed that you’ll be getting your money’s worth. However, some users say as the aluminum Ubbink exhaust pipe is not immune to corrosion. On the whole, we rate the Rinnai RL75i’s material composition a 8/10.

Different Uses for a Tankless Water Heater

Decentralized In-Home Water Heating

The future of in-home hot water production can be found in a decentralized system. This type of system orientation allows homeowners to more precisely control where their hot water goes and how much of it is released as demand increases. Moreover, the modular construction of most tankless units allows a homeowner to install a unit in the proximity of high-demand areas, thus cutting down on response time.

Cutting Water and Electric Bills

Switching to a tankless water heater system is also a great way to decrease your monthly utility bills. That’s because even the larger tankless units like the Rinnai RL75i are built with energy and water efficiency in mind. The Rinnai RL75i in particular accomplishes this goal through its recirculation system, which allows water lost in the heating process to be immediately recycled back into the outgoing hot water stream.

Comparing the Rinnai RL75i to the Competition

Rinnai RL75i vs. Rinnai RL94iN

Given their common manufacturing origin, these two units both make use of many of the same durable components throughout their architecture. In fact, one of their only major differences lies in their flow rate. The Rinnai RL75i features a solid 7.5 GPM, while the Rinnai RL94iN features an even stronger 9.4 GPM. But as a tradeoff, the Rinnai RL94iN is around $100 more expensive.