Natural Gas Tankless Water Heater Review Rinnai R75LSi

Rinnai R94LSi Natural Gas Indoor Tankless Water Heater


Rinnai R75LSi is more than just another natural gas tankless water heater. It comes with decent features usually found only in commercial-grade water heaters. This 84% efficiency water heater is able to deliver 7.5 gallons per minute of hot water.

The heat exchanger and the construction of this unit are of commercial-grade, ensuring durability even for commercial use. Thanks to its sleek design, Rinnai r75lsi can be mounted in any room. You can make it vent directly to the outside either by a single wall or roof penetration.

Rinnai R75LSi Natural Gas Indoor Tankless Water Heater

This is a great tankless water heater for:

People with 2-3 bathrooms home.
People looking for commercial-grade natural gas tankless water heater
People living in manufactured/mobile homes

Here are some great features of Rinnai R75LSi :

Commercial-grade Heat Exchanger for Residential and Commercial Applications
Comes standard with MC-91-1US Digital Controller with Error Code Indicator
Pre-set at 120°F
EZConnect® (connects two units together)
Energy Factor of 0.82
Compatible with Full Line of Rinnai Digital Controllers
Temperature Range with Controllers: Residential (98°F – 140°F); Commercial (98°F – 160°F )
12-Year Warranty on Heat Exchanger, 5 Year for Parts, 1 Year Labor for Residential Installations

There is a digital temperature control included with this unit that provides monitoring and troubleshooting for temperature ranging from 98 degree F to 140 degree.

If you switch over from the traditional tank-type water heater to this gas tankless unit, you will not experience any more late-night showers (because your family member has used all the hot water). Now you can use hot water any time, as much as you want. This Rinnai indoor heater heats the water to the maximum of 140 F which is hot enough not only for showers, but for dishes as well.

If you wish to use this for commercial application, you can buy the commercial version of the controller. It will support temperatures from 98 degrees to 160 degrees.

The Pros:

Unlimited hot water
Instant hot water when a faucet is opened
Can be set at a precise temperature
Extremely quiet

The Cons:

Can be only installed indoor

Here is a helpful review from Edward G., who bought this unit and installed it by himself:

I have owned this unit for one year. It has performed flawlessly. We have four people living in the house and frequently have two showers running at the same time. Rinnai R75LSi provides more than enough hot water even during our cold Ohio winters. Plus, there’s always enough hot water for the dishwasher or another shower immediately following those two showers. The Rinnai water heater has exceeded my expectations. I highly recommend it. (Edward G.)

Please note that the Rinnai R75LSi water heater is an older model and it is currently not offered for sale on Instead, you can check out other great water heaters from Rinnai, or its newer version – model Rinnai RL75iP HE+ High-Efficiency Tankless Water Heater. It is a propane model and it needs to be installed indoors. There is currently a $100 rebate available for this Energy Star model.

I can also recommend the Rinnai R94LSi Natural Gas Indoor Tankless Water Heater. This new model can also deliver even more hot water – 9.4 gallons of water per minute instead of 7.5 GPM

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