Rinnai RL75iN Review

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The Rinnai RL75iN is a well performing tankless water heater from a trusted brand. It's one of Rinnai's top selling models and has a reputation of delivering solid results. If you're in the market for a tankless water heater, the Rinnai RL75iN should be on the top of your list!
If you want to investigate other models, we have compiled the best tankless water heater reviews for your reading pleasure 

Tankless water heaters are not only an excellent way to heat your home's water, but they're also significantly smaller and more energy efficient than tank-style water heaters. However, they're also more expensive, which is why buying a tankless is an investment that requires a little research. Let's take a look at the Rinnai RL75iN to see how it measures up to other tankless units on the market.

Rinnai RL75iN High Efficiency Plus Natural Gas Tankless Water Heater

The Rinnai RL75iN is part of Rinnai’s “RL” line. Rinnai RL models are a “high-efficiency plus” (HE+) line of tankless water heaters: All non-condensing and featuring the ability to recirculate heated water. 

This functionality allows RL water heaters to achieve a Uniform Energy Factor (UEF, a measurement of a heater’s energy efficiency) of 0.80 to 0.81. The Rinnai RL75iN is a sterling example of these models. It’s about the size of a suitcase and is designed for indoor use.

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Rinnai RL75iN Specifications

The Rinnai RL75iN is ultra low NOx SCAQMD Approved, and has a UEF rating of 0.81, which is a decent efficiency rating for a gas tankless water heater. And with a maximum of 180,000 BTU (British Thermal Units) this unit has plenty of power to heat your household's hot water.

As a natural gas heater, the RL75iN is a perfect choice if you already rely on this resource for your home's energy. However, Rinnai does offer the RL75iP, which is the same model except it burns propane instead.

One of the most convenient features is Circ-Logic, which is a recirculating system. This technology allows you to program your heater to match your hot water needs. On those mornings when you're ready to jump into the shower, the hot water will already be circulating through your home's plumbing. Turn on the shower, and you'll have hot water immediately!

Since the RL75iN comes Wi-Fi enabled you'll be able to add the Control-R module and download the app to control your water heater remotely from your smart phone. Adjust the temperature, troubleshoot error codes, and even have your heater monitored through a service professional. 

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With a maximum hot water flow rate of 7.5 gpm (gallons per minute), the RL75iN is ideal for supporting between two to four fixtures at once, making this an excellent water heater for a small to mid-sized family.

  • Dimensions: 26.9"H x 14.04"W x 9.27"D
  • Weight: 45.6 lbs
  • Fuel: Natural Gas
  • Location: Indoor
  • UEF: 0.81
  • Maximum Flow Rate: 7.5 gpm
  • Energy Star: No

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


The RL75iN uses non-condensing technology which means you'll need to special venting to handle the corrosive exhaust. As a general rule, non-condensing units are less expensive to purchase, but more expensive to install than condensing tankless water heaters.

However, if you're replacing another non-condensing tankless, you should be able to use the same venting, which will lower the installation costs considerably.

Rinnai RL75iN Price

Depending upon where you purchase your RL75iN, you can expect to pay somewhere between $1,100 and $1,300. Although, tankless water heaters frequently have a higher upfront cost than tank-style heaters, as a general rule, they are less expensive over the life of the heater.

If properly maintained, a tankless can last 20+ years, where a tank-style heater may only have a service life of up to 10-years. Then there's your utility savings.

Since your tankless won't need to keep the water hot when there isn't a demand, there won't be any stand-by heat loss. And, adding a recirculation pump can also save you 100's of gallons of water each year.

However, when you're considering the price of a tankless, you do need to factor in installation costs. As we mentioned earlier, non-condensing tankless water heaters are more expensive to install.

Rinnai does have a similar unit (RL75eN) which is designed to operate outdoors. Outdoor non-condensing heaters are much less expensive to install since they don't require venting. We recommend contacting a professional to help you determine the right heater for your home. 

If you are looking for a condensing unit, then we have a RUC98iN review for you to browse over


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Where to Buy

Rinnai is a popular tankless water heater and many of their models, including the RL75iN can be purchased in home improvement stores like Home Depot, Lowes and other online vendors such as Amazon.

Where ever you choose to purchase your new tankless, make sure that you are buying from an authorized Rinnai dealer. Failure to do so, may negatively impact the validity of your warranty. Many homeowners prefer to contact a professional to help them through the purchasing and installation process.

RL75iN Warranty

As noted in our Rinnai review, they offer one of the best warranty's in the industry, and the tankless heaters within the HE+ series is no exception. With residential use, the heat exchanger is covered for up to 12-years, parts and components for 5-years, and 1-year of labor.

As you might expect, Rinnai requires that regular maintenance occurs, and that the heater is properly installed for the warranty to be valid.  Check out the warranty to make sure you understand your coverage.

To claim warranty service, you'll either need to provide a dated sales receipt OR register your tankless within 30-days of purchase. This can be done on Rinnai's website or by calling 1-800-621-9419. If your Rinnai heater was installed in a new home construction, the initial home buyer may use a copy of the closing papers to claim warranty service.

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

Rinnai RL75iN Problems

Rinnai is a trusted and well-respected brand in the water heating industry. The RL75iN has proven itself to be a popular model in Rinnai's HE+ series, for a large part, because of its reliability and the company's focus on manufacturing high quality, well designed products.

With that said, there are a few concerns that potential buyers should consider, although these issues are not exclusive to the RL75iN.


All indoor non-condensing tankless water heaters are expensive to install. As much as we like the RL75iN, and we think it's a great unit, we wouldn't recommend purchasing it unless you're replacing another non-condensing tankless and you already have the venting in place.

We recommend either purchasing the outdoor model (RL75eN), or a condensing tankless water heater, such as the RU130iN. These heaters are typically easier and less expensive to install.

Scale Build-up

All water heaters develop scale build-up, but it can be a major problem for tankless water heaters. Although, Rinnai's heaters are challenged by this problem as well, they have built in a "scale detection" feature into the heaters hardware to alert you when it's time for a lime-scale maintenance session.

You can either flush your heater yourself, it's not too difficult, or you can call a professional to do it for you.  

Rinnai RL75iN Energy Efficiency

Most gas tankless water heaters have a UEF rating between 0.70 to 0.95. The RL75iN comes in at 0.81, which is right in the middle. What does this mean? Well, the higher the UEF rating the better. 

Higher UEF's are always better, as they indicate better energy use for water heating and a lower energy bill for you. But 0.81 is considered a solid performer. Can you purchase a tankless with a higher UEF rating, absolutely, but it'll most likely have a higher price tag too.

It's all a trade off, but unless you are trying to squeeze every bit of efficiency from your water heater, the RL75iN performs respectably.

Energy Star Rating

Energy Star compliant devices are better for the environment and your monthly energy bill. Unfortunately, the RL75iN is not Energy Star Compliant, as it must have a UEF rating of 0.87 or higher to qualify.

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

Rinnai RL75iN Installation

Tankless water heaters, particularly gas heaters, should be installed by a licensed professional. Many DIYers want to get their tool boxes and save a few dollars, but in truth, these are complicated appliances that require expert knowledge in plumbing, electrical, gas and ventilation.

If a tankless water heater isn't installed correctly you don't only risk a declined warranty, but you also risk the safety of your family and home. In addition, a poorly installed tankless will not operate as efficiently as it should and will likely not reach it's estimated service life of 20-years.

In most cases, trying to save a few dollars up front will likely cost you more in the end. Tankless water heaters aren't inexpensive, and investing in having it properly installed is money well spent.

RL75iN Manual

Each Rinnai comes with a installation and operation manual. Although we  recommend tucking it away for future reference, Rinnai does have a great deal of documentation online, including this manual.


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