Rinnai R75LSi, a Rinnai tankless water heater review

Image from Amazon

Looking to invest in a high-end tankless water heater like the Rinnai R75LSi? And looking for a good deal? If so you are at the correct site! In view of my focus on green products, I have decided to research and provide information about Rinnai R75LSi below in this review.

The Rinnai R75LSi might be not so readily available in local shops so shopping online is still the best way. So without further a due, here is my unbiased review on this Rinnai tankless water heater to help you decide if it is for you.

Benefits Of Owning A Rinnai R75LSi

Production Capacity of 7.5 GPM

It has a production capacity of 7.5 gallons per minute (GPM) of hot water. Production of hot water has also been said to be almost instantaneously by consumers upon the opening of the faucet, with a satisfying whoosh sound!

Compact and sleek design

Rinnai R75LSi is a tankless water heater with a compact and sleek outer design that allows for easy installation indoors in any room for your home or office buildings. The Rinnal R75LSi can also be installed in mobile homes.

Digitally controlled temperature design

Adjusting and troubleshooting of this Rinnai tankless water heater is also controlled digitally via the standard MC-91-1US controller and ranges from 98 Degrees Fahrenheit to 140 Degrees Fahrenheit. Like all LS models of Rinnai tankless water heater, it comes with a commercial heat exchanger that allows for installation indoors for residential, commercial and even for mobile homes.

The consumer can also upgrade the controller can also be upgraded to MCC-91 for commercial purposes that will increase the maximum temperature to 160 Degrees

Runs on Natural Gas or Propane

As compared to oil and coal, natural gas is the cleanest fossil fuel in terms of emission, with the least emissions in terms of sulphur dioxide and nitrogen oxides, with virtually no ash or particulate matter released. Propane is also earmarked to be a viable alternative fuel source.  

Both fuel sources release lower levels of carbon dioxide, carbon monoxide, and other reactive hydrocarbons as compared to oil and coal therefore will have a lesser impact on the environment.

Green Product

Rinnai R75LSi is an Energy Star certified product with a thermal efficiency of 84% and energy factor of 0.82. This tankless water heater qualifies you for up to 300 USD federal tax credit for installing. It also meets California and Texas NOx emissions standards. You will also be happy to know that installation of all Rinnai tankless water heaters, with the exception of Rinnai R98LS, will qualify you for the above federal tax credits in terms of their energy efficiency.

The Rinnai R75LSi, like all Rinnai products, also last much longer than those traditional tank water heaters; up to 20 years more. You will also be glad to know that the primary components that make up all Rinnai tankless water heaters like the digital panel and heat exchanger are also all recyclable!

Summary of Specifications for R75LSi

Dimensions Height = 22.9 in.
Width = 14 in.
Depth = 9.6 in.
Weight = 51 pounds
Hot Water Capacity 0.26 to 7.5 GPM
Minimum Activation Rate0.4 GPM
Minimum/Maximum Gas Rate (Input BTU/h)9,900 – 180,000 (Natural Gas)
10,300 - 180,000 (Propane)
Minimum/ Maximum Water Pressure 20 – 150 PSI (Recommended water pressure 30-80 PSI)
IgnitionDirect Electronic
Temperature Settings98°F - 120°F (factory default)
98° F - 160° F with MCC-91-2US
Type of ControllerMC-91-2US (included)
MCC-91-2US (optional for Commercial or Hydronic Applications)
MC-100V-1US Deluxe Controller (optional)
BC-100V-1US Bathroom Controller (optional)
ElectricalAC 120 Volts, 60 Hz
Electrical Consumption Normal: 76 Watts
Standby: 2 Watts
Anti-Frost Protection: 184 Watts
Service Connections Gas Supply: 3/4 Inch MNPT
Cold Water Inlet: 3/4 Inch MNPT
Hot Water Outlet: 3/4 Inch MNPT
Venting Direct Venting
Approved Gas TypesNatural Gas or Propane
Energy Star Certified Yes
Energy Factor 0.82 for Natural gas or Propane

Customer Reviews for Rinnai R75Lsi

I have read many customer reviews for Rinnai R75LSi and have summarised them below.

The Pros

Most customer reviews of the R75LSi are positive; ranging from its space-saving design, consistent hot water production, and almost instantaneous hot water the minute you turn on the faucet. Other positive reviews also include visible savings on the utility bills and this unit’s ability to support a wide range and capacity of usage.

Being an Energy-Star certified product also entitles you to tax credits that will be a welcome relief to the relatively higher initial cost of purchasing this unit.

The Cons

The price of the R75LSi has been mentioned as one of the main issue. Other shortcomings encountered by consumers include brief spurts of cold water, plus the waste of water caused by the delay between turning on the faucet and getting hot water. However to be fair most of these problems arise from improper installation especially its position from the faucet.

Installation of this unit is also more expensive with the venting and materials; it is a different technology with differing installation procedures from a conventional water heater. So it will be good if your installer has prior experience in installing a tankless water heater. Another point to consider is the region where you come from that might determine the temperature of your inherent water supply; if your region is too cold, the maximum temperature of 160 Degrees Fahrenheit might not be sufficient.

Next will be the mixed reponses with respect to the savings in utilities, this have been mentioned by customers as either too long a duration before there are any visible cost savings to almost no savings at all. This is not surprising as research studies conducted by ConsumerReports showed that tankless water heaters are efficient but might not be economical.

How does Rinnai R75LSi rate on popular websites?


30 reviewers at Amazon gave Rinnai R75LSi 4.1 stars out of 5 stars. Comments were mostly positive with 21 reviewers giving it 5 stars out of 5 stars.


A survey carried out in 2007 by BuilderOnline.org showed that Rinnai tankless water heater was ranked first in terms of quality ahead of popular brands like Rheem and A.O Smith.

 (Download results of the survery here)


Okaloosa Gas District

Practical tests were carried out by Okaloosa Gas District in 2002, comparing tankless water heaters by Rinnai with a natural-gas, storage-tank water heater and an electric water heater, based on the average use of a four-person household. Results of the tests showed that the Rinnai tankless water heater is superior to both storage-tank models in terms of both fuel costs and also the amount of hot water delivered.


There is a limited warranty that comes with the Rinnai R75LSi. The heat exchanger is covered for 12 years for residential usage only, 10 years for residential and space heating, and 5 years for commercial settings. There is a 5 year warranty for the other parts and 1 year labour warranty coverage.

Best Deals for Rinnai R75LSi

During my research on the Rinnai R75LSi, I discovered that the best place to get it online especially vis reputable sites like Amazon. Comparison between online sites that carry this tankless water heater also reveal that Amazon generally offers a lower price ensuring you get the lowest prices and the best deals for this product.

So if you are interested, here’s the link offered by Amazon for Rinnai R75LSi: Rinnai R75LSi Best Deals

 (Download the Specification Sheet for Rinnai R75LSi here)



Wilson Yeo

I am the admin of Green Energy Helps and I possess a keen interest in how green energy and how leading a green lifestyle can help to reduce our individual carbon footprints. From my website, I will provide useful information about green energy and tips that allow you to leave the green way. Besides that, I will provide unbiased reviews about green products and whether they are suitable for you!

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