Rinnai R75LSi Tankless With his review

Rinnai R75LSi Natural Gas Indoor Tankless Water Heater


The Rinnai R75LSi Natural Gas Indoor Thankless Water Heater is possibly the most popular thankless heater on the market today. It was designed to be able to present a whole home hot water solution for instant and limitless hot water for most American homes. It’s not the cheapest model, and it doesn’t have the most features, but it was never designed to have either. It was designed to do a great job for most homes at a good price. Does it succeed? Lets have a closer look.

About Rinnai and the Warranty
Rinnai are a company that specializes in gas hot-water appliances, and have been around for over 90 years. Success in their field for so long has led to a well-deserved reputation for quality. As a case in point Rinnai offer one of the best warranties out there – 5/2 year labor and parts warranty for commercial use and 12/5 year for residential. On the whole one of the advantages of Thankless water heaters over storage is the longevity you get with thankless.

One of the key features of this model is a good compact and simplistic design, so the Rinnai R75LSi can fit virtually anywhere. The whole unit is only 14 inches x 10 inches x 26 inches, and is a fashionable brushed aluminum in finish – not that you’ll likely be spending much time looking at it. As well as the obviously needed natural gas line in, water supply in, electricity in, and hot water out, you’ll need to put it next to an outside wall so it can vent out. That said its compact nature means you can easily mount in pretty much any indoor space that meets the above.

Ease of Use
Once installed, this unit is easy to use, with a “Goldilocks” level of features – not too many, not too few.
Lets have a look at a diagram of the control panel that you will see on the water heater:
  • “In Use Indicator”. This is juts a light that indicates whether it is being used at present
  • “Temperature display”. What temperature you want the water heated to
  • “Temperature Selection”. Change the water temperature up or down
  • “Priority”. In unusual circumstances, you might have more than one of these heaters installed in the building. In that situation this button and light is used to indicate which water heater is used to set the temperature. Most people won’t ever have to worry about this button.
  • Errors. If there is a problem and the water heater isn’t working, the temperature display will display an error code which you can use to look up the appropriate code in the user manual. The error detection here is very good with about 20 different codes, so on the off chance something goes wrong there is an excellent chance you’ll get a useful idea of what it is.
So as you can see once it’s installed there’s nothing to do except adjust the temperature now and then is desired.

How does it Perform?
Let’s open up the Rinnai R75LSi natural gas thankless water heater and see how it performs. Far from a unit for small homes, this device can crank out 7.5 gallons of hot water per minute, and so can very effectively handle a 2-3 bath home. Using dual showers and hot water in a sink at the same time will never have you screaming in a cold water blast. And this unit can maintain that level of volume even while you have several faucets running, or appliances using hot water lines. That is not just initial flow. Very good volume and heat consistency.
Just mount the Rinnai R75LSi in any room where you can vent it outside, and you don’t have to worry about messy traditional water heater pans to empty. This unit cleverly has a built-in condensate collector, and handles removal by transforming to water vapor and sending right out of its vent. This unit also cleverly uses a commercial grade heat exchanger instead of typical residential device. This means that the heat it generates is constantly recycled, there is no wasted heat.
The water heat can be regulated from 98 to 140 degrees., and it is all done digitally at the master control panel mounted into the unit itself. And should you have extreme hot water needs, these systems easily piggyback each other, with an EZ connect feature. As your family grows and your needs change, don’t worry about installing a whole new system, just add another unit.
This unit can also be installed in manufactured (or mobile) homes, making it the most versatile water heater we know of .

Saving Energy and Money
Tankless water heaters cost more money upfront than a tanked water heater. It’s all about saving you money in the long run. So it’s important to have features that save you money down the track
  • Earlier we mentioned the commercial grade heat exchanger. This is a biggie as the generated heat is recycled and not wasted
  • Electronic Ignition. What this means is that there is no pilot light running and using gas 24/7. The gas is ignited by electrcity
  • Energy Star rated.
  • Meets California and Texas NOx emissions standards.
Many users have reported savings of up to 84% off of their water heating bill, and overall utility bill savings of 15% to 30%. This means the Rinnai R75LSi natural gas tankless water heater pays itself off in as little as 2 to 3 years.


  1. I love the content of your site.In order to extend the life of your tankless water heater and keep it running optimally, I suggest performing certain maintenance.

    Tankless water heater tax credit

  2. you may want to change Thankless to Tankless! Spell checker got you.

  3. Over a year and you still can't proofread. Says something.

  4. Valuable information. Thanks for sharing such a useful post. Universal Heating Solutions