• Home
  • |
  • Blog
  • |
  • Rinnai RL75iN Natural Gas Tankless Water Heater Review

Rinnai RL75iN Natural Gas Tankless Water Heater Review


As an Amazon Associate we earn from qualifying purchases. Learn More.

The Rinnai RL75iN tankless water heater is an indoor, non-condensing, energy-efficient unit built by a leading manufacturer in the industry. If you're looking for a powerful gas tankless that's capable of providing a nearly endless supply of hot water, you'll want to read this review.

This review will give you a deep dive into this popular gas tankless water heater and help you decide if the Rinnai RL75iN is the right purchase for your home. However, if you're looking for an outdoor model, Rinnai manufactures the exact same unit designed for outdoor installaion (RL75eN).

Rinnai RL75iN Tankless Water Heater Review


RL75iN Features

When it comes to features, the Rinnai RL75iN has just about anything you could want in a tankless water heater. There's even a couple of cool tech toys to keep the techies satisfied. Afterall, who doesn't want to control their water heater with Alexa or a Smart Phone? And, it can even send a text message when it needs maintenance.

Digital Panel

The digital control panel is straight forward and easy to use. It features an error code indicator which provides you with a specific code to help you troubleshoot a problem if something ever goes wrong.

Diagnostic Capabilities

The electronic panel is also used for diagnostics and to display error codes. The unit is wi-fi enabled so you can add Control-R and take advantage of remote monitoring and management.

The RL75iN will literally let you know if there's a problem or if maintenance is needed. If you choose, you can even connect your unit with a Rinnai dealer who can monitor your unit remotely!

Compact Design

Designed to mount onto a wall, you'll free up significant floor space, and since it measures in at 14 x 9.3 x 23 inches, the Rinnai RL75iN can fit into nearly any room. 

Venting Options

You won't be limited by venting when it comes to installation. This unit can be vented either through the roof or the wall, giving you plenty of options.

Advanced Technology

The optional 24-hour programmable digital controller will schedule around your daily usage patterns. And if your home is set up with Alexa, you can even control the unit with voice prompts!

Additional Features

  • Isolation Valves - Isolation valves are included to help you perform maintenance. 
  • Scale Detection - When it's time to flush your tankless due to lime scale build-up, you'll be alerted by a scale detection feature.
  • High Altitude - Do you live in the mountains? No problem, this tankless unit will work in altitudes up to 10,200 feet.
  • Venting Options - The unit can be vented either horizontally or vertically, giving you the choice to vent either through the roof or a wall. 
Rinnai RL Series HE+ Tankless Hot Water Heater: Indoor Installation



The Rinnai RL75iN Tankless Water Heater is designed to be a top performer. With an incoming water temperature of 57°, the unit is able to deliver a respectable 4.7 GPM (gallons per minute), and at it's peak performance, it can deliver 7.5 GPM!

Under normal circumstances, the RL75iN should be able to service 3 showers. Making this an excellent choice for 2 or 3 bedroom households.

The standard maximum temperature is 140° Fahrenheit. However, if you're a fan of warmer water, you can install an MCC-91 Controller, which will allow you to increase the temperature to a toasty 160°.

Rinnai's RL75iN should definitely help you lower your water and gas utility expenses over a tank-style water heater, and is Ultra Low NOx since it produces low levels of nitrogen oxide (NOx).    

Energy Efficiency

The RL75iN has a UEF (Uniform Energy Factor) of 0.81, which isn't bad for a gas tankless water heater. Still, many tankless water heaters have better rated models available.

Rinnia's RU199iN is a Super High Efficiency Condensing Gas Tankless with a UEF rating of 0.92. And of course, if you're really looking for stellar energy efficiency, you should look into purchasing an electric tankless, such as the Stiebel Eltron Tempra Plus 36 which has a UEF rating of 0.98!


Rinnai RL75iN Warranty

The Rinnai RL75iN comes with a limited 12-year warranty for the heat exchanger, 5-year parts, and 1-year labor. The unit must be installed by a licensed professional who has attended Rinnai Installation Training Classes. Read the full warranty HERE.

Requires Professional Installation

If you're a DIY'er you should hang up your tool belt for this project. Installing a tankless water heater needs to be done by a professional, and Rinnia's units are no exception.

Gas, plumbing, electrical and venting will all be part of the installation, and local and national codes will need to be followed. Find a licensed contractor who's trained by Rinnai to do the installation.

Not only will you have the peace of mind that the job was done right, but you can also rest assured that the warranty won't be compromised.


Consult with a Local Plumber

Get a FREE Estimate

Rinnai RL Series HE+ Tankless Hot Water Heater: Indoor Installation

Company Information

Founded in 1920 by Hidejiro Naito and Kanekichi Hayashi in Japan, Rinnai began as a pressurized oil cooking stove company. In 1964 the founders began applying their skills to water heating, and to date have over 30 million tankless water heaters installed worldwide!

Rinnai is considered to be one of the world's largest manufacturers of gas appliances. The company's headquarters are located in Japan, but they have over 100 branch and sales offices worldwide. Their commitment to the tradition of constant improvement can be seen in ther exceptional products. 

Related Posts