Rinnai RL75iN & RL94iN Natural Gas Tankless Water Heater Review

Another Versatile Natural Gas Tankless Water Heater

With so many tankless water heaters on the market, how can you be sure that you're buying the right model for the right price? Between BTU, GPM and other strange acronyms, you might not know which way to turn.

The good news is that the Rinnai RL94iN / RL75iN will put these questions to rest.

If you're looking for the best natural gas tankless water heater on the market, your search can stop here.


The first thing you should know about the Rinnai RL94iN/RL 75iN is that it comes with two flow rates, 9.4 gallons per minute and 7.5 gallons per minute respectively. Larger homes will need the former; smaller homes might only require the latter.

There are also slight differences in their BTU:

  • The 9.4: 9,900 - 199,000 BTU
  • The 7.5: 10,300 - 180,000 BTU

You'll find differences in the physical size of the heating unit, too:

  • The 9.4: 50lbs, 9.3 x 14 x 23"
  • The 7.5: 45lbs, 14 x 9.3 x 23 "

Aside from these figures, however, both models come with the same functions and features. For example, they both have 82-83 percent thermal efficiency, and their residential control settings range from 98°F - 140°F. Commercial settings can climb to 185°F.


If you don't already know, natural gas tankless water heaters work by heating cold water as it passes through your pipes. Internal sensors detect when cold water needs to be warmed, and natural burners trigger a heat exchanger that will get your water to just the right temperature before sending it through the tap.

The Rinnai RL94iN follows this process to a tee. Furthermore, it's known as a "workhorse" brand around the market, meaning that it's the kind of tankless heater that people install and then forget about because it functions so quietly and efficiently.

The 9.4 model can handle up to five bathrooms at a time; the 7.5 model can handle between two and three.

You won't have to worry about simultaneous usage with this heater: You can take showers, run dishwashers and even do your laundry at the same time.

Heat Output and Flow

The heat output of the Rinnai RL94iN is quite impressive. In a residential home, you can make your water as hot as 140°F; in commercial settings, this figure climbs to 165 - 185°F. You may or may not need a special controller to unlock these temperature settings.

The flow rate is another plus. Like it says in the name, the 9.4 model can pump more than nine gallons per minute throughout your home, which is enough to comfortably serve multiple bathrooms and appliances.

Customers do report slight (~30 second) flow delays when using the Rinnai RL94iN. They say it needs a moment to "boot up" for the day. Once it's going, however, the hot water won't stop, so it's a small sacrifice for unlimited hot water.


One drawback of the Rinnai RL94iN is that it needs to be installed very carefully. This is true of all natural gas tankless water heaters; since they use open flame that produces emissions, you don't want to cut any corners when it comes to pumps and vents. Many buyers just leave the installation in the hands of a certified Rinnai technician.

You might need to run a second gas line to accommodate this model. It depends on the demands that your current gas line can handle.

Vent kits and valve kits can be ordered with the unit.

General Use

As with any decision, you should look at the pros and cons of a tankless water heater before ordering. Here are a few of the basics:


  • Serves multiple bathrooms simultaneously
  • High flow rates are perfect for large homes
  • Can be converted to propane if you don't like natural gas


  • Slight (~30 second) flow delays at the tap
  • GPM decreases as water temperature climbs
  • System requires careful installation with many bells and whistles

Customer Reviews

On the whole, customers report being very satisfied with their purchase of a Rinnai RL94iN.

There are some complaints about the nitty-gritty details of installation, and a few users aren't happy with the limitations of the heating unit, but generally speaking, customers are pleased with the Rinnai brand and happy that they've bought a unit that doesn't require constant care.

With a Rinnai, simply install it and let it work.

What's the bottom line?

The 7.5 model handles less bathrooms but also requires less power to operate, so it's a trade-off.

Despite a few problems, the Rinnai RL94iN is one of the strongest and most worthwhile natural gas tankless water heater on the market. Also the other model, Rinnai RL75iN would be the most suitable choice for most of them with a lesser price tag . But you don't have to take my word for it:

Check out both the Rinnai RL94iN and the Rinnai RL75iN model on Amazon to see their specs, reviews and usage details for yourself.

Image credits: Rinnai

Also read: Rinnai V65EN Review

  1. Can the rl94 ne coverted to propane

  2. I have had a Rinnai tankless system for the past 5 years. Just 2 weeks ago, all the water sources in the house started running hot, then cold, then hot, then cold, etc. The only tap that works proper is the basement laundry sink. I have had the rental company send people twice, so far, and they people they send have no idea how to fix the thing, just tell me it is my taps. Funny that all my taps stop working at the same time. I have called the rental company probably 15 times in the past 2 weeks, they say they will send someone and no one shows. Then they send the same repairman twice. If he couldn’t fix it the first time, why would he be able to the second time?
    Anyway, the tankless system is very annoying, you have to let the water run about 5 – 10 minutes in the morning to get hot water up to the main bath for a shower. Also, during installation, the installers had to put an ugly exhaust pipe out the front of my house. They said it was small and ended up being huge.
    The reason I went tankless as the salesman stated how much money will be saved on gas to heat water, but he didn’t account for the extra water you have to run while you are waiting for hot water.
    I think Rinnai should replace or fix this unit, as I can not get any cooperation from the rental company.
    My suggestion is to stay with a regular hot water tank since the service technicians will know how to fix it if you have problems.

  3. I would like to put my right night in the loop I have a three-story house and Renada is in the basement can you help me

  4. The RL 75 was mounted on the wall to our master bedroom. It continually hums and echos throughout the room. I feel I live in the pool house. What can be done?

    • Hello Bob,

      When you say that it continually hums, that doesn’t sound right. I have a Rinnai at my cabin and it is silent until a faucet is turned on, but it is also mounted in the laundry room. I would suggest that: 1) that you contact your installer/plumber for their thoughts, 2) you write a review under the product on Amazon (sometimes the seller will provide an answer there), and/or 3) contact Rinnai directly (https://www.rinnai.us/support). I absolutely love my Rinnai. Good luck! DEK

  5. […] Read full review on Rinnai RL75iN […]

  6. The hum is from the feature that heats the water in the popes. We use the timer now so it only comes on at certain times.

  7. I have a 3 season mobile home with some not so good well water smell would you recommend this appliance instead of the traditional hot water heater?? * which has to be drained every fall *

    • Thank you for your question, Lee. I’m guessing your water is sitting in your tank water heater while you are not there. Any time water sits, it has the opportunity to smell more than it normally would. However, any unfiltered water will smell if it sits without being flushed out regularly. So the simple answer is since a tankless water heater does not hold water, you shouldn’t get that smell.

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