Rinnai Condensing Water Heaters
Review and Buying Tips
(updated 2018)

A review of Rinnai condensing water heaters from RUR, RU, RUC, RUCS and RUS series. Check out the advantages and benefits when buying one of the Rinnai water heaters with the tankless and condensing technology.

Rinnai condensing tankless water heaters are coming from the "Ultra" series, a series of the most advanced and efficient models. The condensing models have the same modern and stylish look as other tankless and non-condensing models, same size of 18.5" x 26" x 10", lightweight design ranging from 57 to 73 lbs, and flexible installation options either outside or inside a home.

Rinnai condensing difference

Rinnai condensing water heaters kept the same advantages and benefits of the tankless technology; heating water on demand, delivering hot water in endless and continuous supply at a preset temperature, simultaneous hot water delivery to the multiple appliances without temperature fluctuation and unpleasant "cold-water sandwiches."

So what makes them truly different is the ultra high energy efficiency and efficiency reaching high 0.96 energy factor, such as this RUC98iN model.

An ultra-efficiency is possible because of the Rinnai condensing technology that utilizes two heat exchangers; copper heat exchanger gets the heat energy from the gas burner, while the other, stainless steel one gets the heat from the exhaust flue gases. The secondary heat exchanger is actually used to pre-heat the incoming cold ground water. Also, since it is exposed to the acidic nature of the condensate, it is made of the durable stainless steel.

The result of this condensing technology is the higher efficiency of up to 0.96, as opposed to the standard tankless units which can provide EF of up to 0.82. Also, the unit produces flue gases with the lower temperatures so the unit can use different vent types, such as; PVC, ABS, and CPVC, replacing the expensive stainless steel.

The flexible venting options make the installation faster, cost lower and with the zero clearance from combustible - safer.

These models can also be used for home heating, if combined with the hydronic furnace, even manufactured housing.

Models review

There are several groups of Rinnai condensing water heaters, designed for heating potable water from mid- to large-sized homes, or homes with up to five bathrooms/fixtures. Due to the high performance and superior energy factor, all the models are Energy Star compliant.

  • Rinnai RUR models
  • Rinnai RUC models
  • Rinnai RU models
  • Rinnai RUCS (RUS) models

Rinnai RUR water heaters

Rinnai RUR condensing tankless water heaterRinnai RUR

Rinnai RUR models, are known as the Super High-Efficiency Plus water heaters, that are designed to provide an energy factor of 0.95, and are one of the most efficient tankless and condensing units from this manufacturer.

What makes them unique and recommended by the experts, is the ThermCirc360 recirculation system, which, no matter of the plumbing configuration, provides hot water in less time and energy waste, than the units without this system.

The maximum capacity is 9.8 GPM so they can be used in homes with up to 4 bathrooms. The powerful burner with the maximum gas input of 199,000 BTU is capable to heat water fast and efficiently, with the ultra-low NOx gas emission and in the temperature ranging from 98 F to 140 F.

Available models:

  • Rinnai RUR98iN - an indoor model using natural gas
  • Rinnai RUR98eN - an outdoor model, using natural gas
  • Rinnai RUR98iP - an indoor model using propane gas
  • Rinnai RUR98eP - an outdoor model, using propane gas

Rinnai RUC water heaters

Rinnai RUC tanklessRinnai RUC

Rinnai RUC series is another group of super-efficient tankless water heaters, that, as the above RUR models, are recirculation and WiFi capability and Energy Star compliant. Depending on the size, RUC models heat water with the gas input ranging from 152,000 BTU to 199,000 BTU, delivering hot water from 8 to 9.8 GPM, and when used in commercial applications, reaching temperatures of 185 F (140 F for residential).

The controller, as opposed to RUR models, is integrated. They also have the same size but with the lower weight of close to 10 lbs.

Rinnai RUC water heaters are designed in three sizes but only as the indoor models:

  • Rinnai RUC98iN - an indoor model using natural gas
  • Rinnai RUC98iP - an indoor model using propane gas
  • Rinnai RUC90iN - an indoor model using natural gas
  • Rinnai RUC90iP - an indoor model using propane gas
  • Rinnai RUC80iN - an indoor model using natural gas
  • Rinnai RUC80iP - an indoor model using propane gas

Both Rinnai RUR and RUC models are the only tankless water heaters that offer two venting configurations on the same unit - one concentric PP and dual-pipe PVC/CPVC system.

Rinnai RU water heaters

Rinnai RU outdoor condensing water heaterRinnai RU

Rinnai RU condensing water heaters are available in three sizes also, but only for the outdoor installations:

  • Rinnai RU98eN - an outdoor model using natural gas
  • Rinnai RU98eP - an outdoor model using propane gas
  • Rinnai RU90eN - an outdoor model using natural gas
  • Rinnai RU90eP - an outdoor model using propane gas
  • Rinnai RU80eN - an outdoor model using natural gas
  • Rinnai RU80eP - an outdoor model using propane gas

As the above RUC models, RU water heaters are also designed to provide hot water from 8 to 9.8 GPM, with the maximum efficiency of 0.96, gas input of 199,000 BTU, and reaching temperatures of hot water up to 185 F in commercial applications.

The temperature controller is provided with the purchase, it is not integrated.

Rinnai RUCS (RUS) water heaters

Rinnai RUSRinnai RUS

Rinnai RUCS and RUS models are the "smallest" tankless and condensing water heaters from the Rinnai manufacturer (considering the power and water flow delivery), and are available as:

  • RUCS65iN - indoor model using natural gas
  • RUCS65iP - indoor model using propane gas
  • RUS65eN - outdoor model using natural gas
  • RUS65eP - outdoor model using propane gas
  • RUCS75iN - indoor model using natural gas
  • RUCS75iP - indoor model using propane gas
  • RUS75eN - outdoor model using natural gas
  • RUS75eP - outdoor model using propane gas

They all have the same dimensions (as the above models) but a lower weight of 57.3 lbs. The maximum power goes from 130,000 to 160,000 BTU, energy factor of 0.93, and producing up to 6.5/ 7.5 GPM of hot water making them ideal for residential homes with up to 3 bathrooms max. While the above models can be used to the higher altitude of up to 10,200 ft, RUCS and RUS models are approved for much lower altitudes of up to 5,400 ft.

As opposed to the above models equipped with the temperature controllers, RUCS and RUS models include only a small status monitor at the front of the unit, while the controller is optional. RUCS models are also recirculation capable, allowing faster hot water delivery.

As other Rinnai tankless models, condensing water heaters are built with the green technology in mind, so that they can produce less greenhouse gases, such as NOx and CO2.

Rinnai condensing water heaters are durable and reliable; they can run for over 20 years with no problem. Even if something happens to its elements, they are replaceable, no need to get rid of the whole unit. They are backed up with the 12-year limited warranty on the heat exchanger and 5-year on labor and parts when used in residential applications.

Safety features

Safety features from below can be found on all Rinnai condensing water heaters.

  • If there is an excessive temperature increase inside the water heater, an Overheat feature will turn the unit OFF.
  • If the burner flame goes out for any reason, Flame Failure will turn the unit OFF.
  • Power Failure will cut the gas OFF if the unit loses the electrical power.
  • Overcurrent protection.
  • Fusible link will break and shut the unit down if the overheat feature does not react when the temperature rises above the maximum allowable.
  • Automatic freeze protection.
  • Rinnai condensing water heaters are already equipped with a condensate trap and condensate drain line.

Why should you buy one of the Rinnai condensing water heaters?

Rinnai tankless water heater was awarded the "Best" in the industry... "...chosen by home builders in Builder Magazine".

Rinnai condensing technology brings the optimum heating and ultra high performance as it utilizes the heat from the flue gases and pre-heats the incoming ground-water. The result is an incredible Energy Factor of up to 0.96. The reliability is increased so as the durability, while the maintenance is reduced.

According to the US Department of Energy high-efficient condensing tankless water heaters, such as those from Rinnai have the average annual operating costs of $171, non-condensing have $200 and standard 50-gal tank, around $273. This fact, great specs, and many advanced features are making the condensing water heaters a good buy.

If you would like to look for an alternative to Rinnai, check out the condensing water heaters from Navien, Noritz, and Takagi.

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