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Rinnai Tankless Water Heater Reviews with Focus on High Efficiency


In my previous post, I have introduced you to the best tankless hot water heaters but today I will go further in the same direction. In this post, I will focus on several models of a single brand Rinnai, one of the big names in the water heating industry. Rinnai Tankless Water Heater Reviews, what this guide is on, will shed special light on the most high-efficient and the super high-efficient models of Rinnai hot water solution. It’s very urgent to know about something before making a final purchase that will be a company for years. The more you know, the more profitable would your deal be. Anyway, I am not telling you more rather I am telling you about something very basic and urgent when you are contemplating a hot water unit for your apartment, house, office, and resort.

An efficient hot water unit is meant to save time and money. So it is something next to necessary to be well aware of the effect and energy factor. Before getting into the full detail of the highly efficient models and condensing technology that makes a hot water efficient, suffice it to know that condensing hot gases to extract the most heat out of it makes a water heater excel in heating water.

How is efficiency defined?

The very name of the machine Water Heater/Hot Water Unit is suggestive enough to make us clear that it is an appliance to deliver hot water. It heats water by producing steam or flue gases out of combustion.  The steam or hot gases exchange heat to the water traveling through the coiling pipe around the heat exchanger. But the steam or flue gases generated by combustion process doesn’t/can’t discharge the full amount of heat while heating the water moving around the heat exchanger and so the unused or trapped heat (15-20%) goes out through the exhaust pipe. Rinnai Tankless Water Heater Reviews will highlight water heaters which are high efficiency/super high-efficiency hot water units irrespective of being condensing or not condensing.


Now if that unused heat can anyhow be extracted before the exit, we will have more warm water with the same energy input. The only way to keep and utilize that heat inside is to make the exit pipe longer or using a second heat exchanger. Then more heat will be there to boil the water. That is known as the energy efficiency of a water heater that is producing more heat without consuming added energy. The water heaters that can extract extra heat from the flue gases by any means with the assigned energy incorporation are the highly efficient water heater. So the efficiency means the thermal efficiency of a water heater.

The water heaters that can extract more than 90% of heat from the hot gases produced by the combustion are called highly efficient water heaters. None but the tankless water heaters can do this. Conversely, the hot water unit that can trap only 80-82% of heat is called standard water heater. Some of the tankless water heaters can extract as high as 98% of the heat out of the combustion-produced hot gases earning the tag of ultra high efficient heaters.

Condensing vs Non-condensing water heaters

Whatever way you apply to extract additional heat from the flue gases prior to its exit to the air, these will cool down. So when steam is cooled, it will condense and turn into water. Condensing technology requires a second heat exchanger. The benefit is that you are getting more from the amount of energy consumption.

Non-condensing is quite the opposite that is trying not to extract extra heat from the steam produced through combustion heating. Thus your tankless water heater will have only 82% of the total combustion heat to boiling water instantly. The benefit of not going for the Non-condensing tankless water heater is that no extra piping is necessary to bear the corrosive acid water.

Now let us march on reviewing several (super) high efficiency (condensing) and high efficiency (Non-condensing) models of Rinnai tankless hot water units.

Rinnai Tankless Water Heater Reviews of condensing and super high-efficiency models

All the water heaters of Ultra series – RUS, RUCS, RU, RUR, and RUC enjoy energy factor more than 0.9.  From these super-capable hot water units, we will pick RU80 and RU98, most famous among the condensing models, for our Rinnai Tankless Water Heater reviews for super high-efficiency tankless water heaters.

✔ Rinnai RU80iN

Buying any condensing water heater brand for commercial set up or bustling house means to save time and money. Condensing hot water models stand for high efficiency having the least 92% and the max 98% thermal efficiency. These are the core hot water systems in this Rinnai Tankless Water Heater Reviews. So go for the top features, benefits, and specifications of ultra high efficient model Rinnai RU80iN.

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Energy & Efficiency:

Like all HE water heating systems, Rinnai RU80 utilizes two heat exchangers to extract the max heat out of the flue gases. Rinnai RU80 is engineered as RU80i indoor and RU80e outdoor types. Due to the condensing technology, both the models boast of the topmost energy efficiency 96% claiming super high efficient water heater in the industry.

It has a steady capacity of 152000 BTUs gas unit amounting to 41/42 electric watts.

Heat & Flow Rate:

This Rinnai water heater delivers 8 gallons of hot water per minute enabling several appliances active simultaneously. It can serve with the required amount of hot spa in a house of at least three bathrooms that makes it a First-hour Rate hot water unit.

Both Rinnai RU80i and RU80e deliver max 8 GPM at 98ᵒ-140ᵒF making clear of fluctuated flow rate at Arctic regions where the temperature is low.


Rinnai exclusive direct vent sealed combustion and easy installation options make it possible to set it against inside or outside wall stretching the vent length up to 41” ft. Mind its actual lifespan of a gas burner mostly depends on its authentic installation necessitating a trained or Rinnai only plumber or installer.

Earth-friendly Design:

Rinnai Ultra series or super high-efficiency models are earth-friendly and so emits less NOx and CO greenhouse gases. These advantages have duly claimed Rinnai a green hot water unit company and a world leader in the water heating industry. Moreover, Rinnai lasts longer lifespan than the rival brands over a period of 20 years.

Rinnai RU98

Our second model to review from the Rinnai ultra series is the Rinnai RU98, equipped with condensing technology, whole house hot water solution. This one has the largest storage capacity and the topmost thermal efficiency. In response to any query about tankless hot water unit, I suggest Rinnai RU98 super high-efficiency model with added enthusiasm. While researching for the article on Rinnai Tankless Water Heater Reviews, the features, benefits, and exclusive specifications of Rinnai RU98 lurk in my mind.

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Specifications: This thermally efficient hot spa system has some mind-blowing numbers to note.

  • It offers the biggest flow rate of all Rinnai hot water units and it pours out as high as 9.4 gallons of water per minute. With its hot hose, this can ably meet the First-hour rate easing the morning chorus of people shouting for hot water. Rinnai RU98 can deliver all the appliances be those – shower heads, a laundry of clothes, dishwashing, and cooking simultaneously. But the flow rate will go down to 6 GPM in cold climates.
  • Rinnai RU98 is a hefty and sturdy unit in terms of weight and size. 18.3*26.4*10.1 inches dimensions and 70 pounds weight speak volumes for the bulkiness it is given to. Despite the huge size and weight, this gas water heater can set up both indoor and outdoor space.
  • As is said at the beginning that Rinnai RU98 is the most highly efficient one and designed with condensing technology. It can take around 95% heat out of the flue gases making it the super high-efficiency water heater. Rinnai requires up to 199000 BTUs to run with an energy factor of .94.


Where the standard whole house units serve multiple bathrooms simultaneously, this thermally efficient heater flows 9.4 gallons of hot water per minute enabling several appliances and four bathrooms go smoothly. As high as 199000 BTUs gas unit incorporation will not let Rinnai RU98 suffer drop or fluctuate at the hot pouring down even in colder regions.


This condensing Rinnai model stands out glaring along the Rinnai Tankless Water Heater Reviews as it comes out to us with a detailed and well-printed installation manual with an added gift of specially engineered isolator valves free of cost. As you know that the gas tankless water heater cost you more in installation, condensing will add to the amount requiring a second heat ex-changer.

Heat Flow:

The well-known fact about hot water system is that the unit needs to work hard to yield hot water in cool climates. To be more informed, you can know temperature ranges- for both the commercial and household set up.  Residential units serve the best at 98ᵒ-140ᵒF and at 98ᵒ-185ᵒF the commercial units.

Now let’s see both sides of the models already reviewed for our Rinnai Tankless Water Heater Reviews article.


  • Extract more heat with the same energy cutting bills down
  • Fit for both indoor and outdoor installation
  • Hot water delivery can suffice both for domestic and business set up
  • Exclusive NOx system makes it safer
  • Energy Star certified heater


  • Cause added cost inventing
  • Condensing water inside requires saturation
  • Not affordable for all users
  • Tough to install and necessitates a certified technician

Rinnai Tankless Water Heater Reviews of Non-condensing but high-efficiency models

Rinnai value series models having no condensing technology built inside are at best able to extract heat from the flue gases a little over 80%. Comparing to the traditional tank water heater efficiency of 60%, those Rinnai models can duly claim themselves to be high-efficiency hot water system. So now Rinnai Tankless Water Heater Reviews will include Rinnai on condensing high energy four V94 models.

  • Rinnai V94XiN
  • Rinnai V94iP
  • Rinnai V94eN
  • Rinnai V94eP


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The first two models are indoor tankless water heaters and the last two are outdoor hot water sources. The downside of condensing hot water system is its by-product – the acidic water. Acidic water, being strong and corrosive, reduces the lifespan of internal parts resulting in a new set up sooner than the regular one. That is why Rinnai has recently devoted its team to introduce none condensing value series and the latest offers are these V94 models. They are identical in all the features and benefits except in the installing type. I will just show the features in a table rather than going into the model by model description.

Here go the specifications of the said models in the table below.

Manufacturer Trade Model

Rinnai V94XiNRinnai V94iP

Rinnai V94eN

Rinnai V94eP
Gas TypeNatural GasPropaneNatural GasPropane
Recirculation CapableNoNoNoNo
Residential Energy StarNoNoNoNo
Energy Efficiency81%81%81%81%
Energy Input10300-199000 BTUs10300-199000 BTUs10300-199000 BTUs10300-199000 BTUs
Hot Water Flow Rate (Max)9.8 GPM9.8 GPM9.8 GPM9.8 GPM
Gas Line Diameter1/2˶ 1/2˶ 1/2˶ 1/2˶
Wifi facilityNoNoNoNo
SCAQMD ApprovedYesYesYesYes
WarrantyHeat Exchanger120 Months120 Months120 Months120 Months
Labor12 Months12 Months12 Months12 Months
Parts60 Months60 Months60 Months60 Months
Remote Control -----
Low NOx EmissionYesYesYesYesYes

Now let us check the pros and cons equations.


  • Easy to install compact models
  • Highest flow rate
  • Budget-friendly
  • .82 energy factor
  • Low NOx discharge
  • Comes with value and comfort


  • Requires additional installation cost
  • Flow rate at the mercy of the climate
  • Not wifi compatible
  • Gas only water heater

Buying Guide

It will be pointless to make buying guide longer in the current  Rinnai Tankless Water Heater Reviews because I have discussed all the basic and advanced buying considerations in my first post. So as of now, I will just talk about the crucial points to be aware of when you are considering to buy highly efficient condensing and not condensing hot water machines.

Water heaters with condensing technology are meant to be highly energy efficient but they come with their price. Rinnai Ultra series require costly internal set up as the condensing water heaters have to deal with the strong acidic condensed water after cooling. They need a second heat exchanger making the flue gases travel longer inside.

While the noncondensing boilers don’t have to bear the acidic water, you must arrange stainless steel ventilation pipes for them to let the 300 Fahrenheit flue gases go out. So, this one too causes additional set up charge. But it doesn’t reduce the lifespan of the residential parts thus saving money over the long term.

Throughout the course of my research to write Rinnai Tankless Water Heater Reviews, I came come to know condensing hot water units are a bit over priced but they save up to 40% of energy consumption and so decrease your energy bill. For many households, saving energy is the go of life. It is like switching the lights off at bed time and unplugging the electronic appliances if not necessary. Noncondensing water heaters are budget priced but they charge extra bill by consuming more energy than the condensing one to deliver the required amount of hot water.

The prices of the reviewed water heating models range from 900- 1500 dollars. For the latest price update, we suggest you visit

FAQs to answer

  • How to handle the temperature of hot the water?

  • Ans: Every quality tankless water heater comes with a temperature control feature. These units are not different. So you can control the temperature and the diagnostic codes that help perform better.
  •  Can the existing venting do?

  • Ans: Pipes. Moreover, It is advisable to follow specified venting approved by the particular manufacturers.


Rinnai Tankless Water Heater Reviews are a perfect answer to the ruin a cold water shower does. The morning chorus across the world is for saving hot water. Rinnai condensing and not condensing models reviewed in this article can make cold showers and high energy costs a distant memory. I am not saying these systems are flawless but it is no denying a fact that the downsides are too minimal to take into account comparing to the benefits.


There are complaints about cold water sandwiches but the consumers are utterly satisfied with the hot delivery and energy efficiency and full of other positive feedback’s.

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