Rinnai RL75 Tankless Water Heater Review

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Rinnai Corporation is one of the leading manufacturers of tankless water heaters in North America with over 2 million heaters installed in the continent as of this year.

Founded in 1920 in Japan, Rinnai has demonstrated a pattern of consistent improvement in its products since then. It has its US headquarters at Peachtree City, GA.

The Rinnai RL75 is a powerful and compact gas tankless water heater that is best suited for homes with two or three bathrooms.

In this model, there are 4 different sub-models available based on the location of installation and the type of fuel used.

Rinnai RL75 Key  Specifications

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

There are four types in the Rinnai RL75 model of gas tankless water heater namely RL75eN, RL75eP, RL75iN, and RL75iP.

In these models, ‘i’ and ‘e’ denote indoor or outdoor installation respectively and ‘N’ and ‘P’ represent natural gas or propane as the fuel.

Irrespective of the model, the RL75 is capable of producing an output flow rate of 7.5 GPM. It is capable of providing hot water simultaneously to two to four fixtures. It is approved for use at high altitudes up to 10,200 ft.

It is capable of providing default outlet temperatures between 98˚F to 120˚F, but with a controller upgrade, it can provide up to 160˚F.

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

It has very low NOx emissions of less than 20 ppm and has AHRI, ANSI Z21.10.3, and CSA 4.3 certifications.

The other key specifications of this product are given below.

Dimensions (inches) 14.04 W x 22.95 H x 9.27 D
Weight (pounds) 43.6
Minimum Gas consumption (BTU/h) 10,300
Maximum Gas consumption (BTU/h) 180,000
Minimum Flow rate (GPM) 0.26
Maximum Flow rate (GPM) 7.5
Uniform Energy Factor 0.81
Service connections ¾ inches NPT
Ignition Direct electronic ignition
Minimum Water supply pressure (psi) 20
Maximum Water supply pressure (psi) 150
Electrical requirements (Normal) 57 W
Electrical requirements (Stand-by) 2 W
Electrical requirements (Freeze protection) 104 W
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Assemble / Installation

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

The Rinnai RL75 can be installed either indoors or outdoors depending on the model type. The indoor installation is trickier than external installation due to adjustments required for venting.

Rinnai encourages its customers to hire a certified professional to do the installation procedures.

The installation consists of basic steps of choosing the right location, freeze protection, mounting the heater, venting and condensate configurations for indoor models, plumbing, gas supply, and electrical connections.

Ensure that the instructions given in the manual are properly followed during installation. Also, make sure that you adhere to the state and local codes throughout the process.



Rinnai offers limited warranty services for a period of 12 years for the heat exchanger, 5 years for the other parts, and one year for labor.

This warranty period is cut down to 3 years if the heater is used in a hot water circulation loop as a circulating water heater.

There are also several other events that may void the warranty of the product. Read these terms before purchasing the product.

To avail warranty, contact your place of purchase, visit www.rinnai.us, call 1-800-621-9419, or write to Rinnai at 103 International Drive, Peachtree City, Georgia 30269.

Consumer Comments

The Rinnai RL75 has generally favorable reviews from its customers but has inevitably received some critical responses as well.

Users are quite satisfied with the output flow rate of the product, which is sufficient for moderate homes.

Some users are also happy with the fact that Rinnai provides warranty even if the installation was a DIY process done properly.

However, go through the installation manual carefully and take your time to install the heater for proper performance.

Users have reported cheaper gas bills on water heating with the use of this product. The payback from this unit is one year.

Consumers who have purchased this heater are content with the simultaneous use of the heater for multiple applications.

The one negative review that most customers seem to have is the poor quality of customer service from Rinnai.

Users have claimed that Rinnai has failed to provide warranty for the product even before the expiration of the warranty period.

This issue can be prevented by careful installation of the product with the help of a trained professional.



Rinnai RL75IN, Large, Natural Gas
184 Reviews
Rinnai RL75IN, Large, Natural Gas
  • Comes standard with MC-91-1US Digital Controller with Error Code Indicator
  • 82% Thermal Efficiency
  • Residential Temperature Settings: 98°F - 140°F



  • Capable of saving up to 40% of energy. Gas consumption is less and the payback for the unit takes as less as one year.
  • Capable of installation in high altitudes.
  • It is Wi-Fi enable and can be used with Control-R feature (optional) for remote temperature adjustments, receiving alerts on your phone, etc.
  • The scale detection feature alerts you if it is time to flush the heater.
  • The venting can be done through the roof or the wall depending on your convenience.


  • The installation can be quite tricky for the user and professional installation may be expensive.
  • The cost of the unit is high in comparison with other tankless water heaters.
  • Regular maintenance is necessary.


Recommended Accessories

Remote Control for temperature adjustments is available for this model :

Rinnai MC-91-2W Standard Remote Controller - Residential or Commercial, 98-Degree -140-Degree F, White


Control-R Wi-Fi module allows remote adjustments to be made to the heater and receive alerts about the heater on smartphones, tablets, etc.




Can I use the Same Vent as the Older Tank-style Water Heater?

No. Rinnai tankless water heaters have their own type of venting configurations that must be done during installation. The existing vents must be upgraded for this product.

With this Heater, how many Showers can run at once?

This depends on the flow rates of the fixtures and the temperature at which you need to run the shower. Usually, 3 – 6 showers can be used simultaneously with this product.

What is the Life Expectancy of this Heater?

With proper installation and regular maintenance, this tankless water heater can last up to 20 years.

Will the Warranty be Terminated if the Product was Installed by a Homeowner?

If the installation is carried out as described in the manual with no damages to the heater, the warranty is still applicable. However, you can avoid any risks by getting a hired professional to perform the installation procedure.

Does this Unit have a Pilot Light?

No. Rinnai RL75 uses an electrical ignition system to avoid unnecessary expenditure of energy with a pilot light.

Our Recommendation

For users who are looking to purchase a powerful, energy-efficient tankless water heater capable of providing unlimited hot water on multiple applications simultaneously, the Rinnai RL75 is a choice that should definitely be considered.

With proper installation, operation, and maintenance, this gas tankless water heater can help you save energy and money on heating bills.


Last update on 2022-12-01 / Affiliate links / Images from Amazon Product Advertising API

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