Rinnai RU80 Water Heaters Review

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Rinnai RU80 tankless water heaters with the second largest capacity of all Rinnai that utilize the condensing technology for the ultra efficient water heating. See the review of the top features and compare specs between the indoor and outdoor models.

Models review

Rinnai RU80 water heaters are designed as the indoor RU80i and outdoor RU80e type both models utilize two exchangers; one that pre-heats the incoming water by using the temperature of the flue gases, and the other that heats water inside the main, made of copper exchanger. As other Rinnai tankless heaters, RU80 also uses a modulating burner or gas valve, which allows power adjustments from its minimum to the maximum value, depending upon the water flow. Due to the condensing technology, the energy efficiency is much higher than in non-condensing type. They are mainly used in homes with up to three bathrooms.

The warranty on either RU80 is 12 years on the heat exchanger when used in residential applications, or 10 years if used in potable water and space heating.

Rinnai RU80i

Rinnai RU80i

Rinnai RU80i are indoor direct vent water heaters that are designed to use either a two pipe system; one pipe for the air and one for flue gases, or coaxial type (a pipe inside the pipe). Its design allows a flexible installation due to the long vent pipe, while the layout can be vertical or horizontal.

These units come with the built-in MC-91-2US type controller while the MCC-91-2US is optional and is used in commercial and hydronic applications. The controller MCC-91-2US allows heating water up to the temperature of 185 F.

How to Buy

The price range for Rinnai RU80IN, as the natural gas model, and the RU80IP, as the propane model, is from $1100 to $1300 found on Amazon.com, both models having an average 4-5 star reviews.

Rinnai RU80e

Rinnai RU80e

Rinnai RU80e doesn't require pipes for the air intake or exhaust as they are already installed outside. The digital temperature controller is not a built-in, but it is provided with the unit.

How to Buy

The price range for the Rinnai RU80EN, as the natural gas and outdoor model, and the Rinnai RU80EP, as the propane model, is from $1000 to $1300 found on Amazon.com, both models having an average 4-5 star reviews.

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Features review

  • Automatic ignition when all the conditions are met.

  • Environment friendly and Ultra Low NOx burner that complies with the 20 ppm NOx emission levels.

  • Digital temperature controller MC-91-2US is used to monitor the temperature, adjust the settings and display the error codes.
  • Improved detection of the lime-scale in the heat exchanger.

  • Built-in Rinnai Circ-Logic recirculation program that cycles an external pump for better comfort and higher efficiency.
  • Temperature lock feature that prevents accidental or unauthorized temperature changes.

  • Water flow sensor, electronic water control device and electronic by-pass control.

  • Safety features such as the flame and boiling protection, combustion fan check, remaining flame OHS, automatic frost protection (protects the unit when the outside temperature is up to -22 F).

  • Diagnostic systems helps in service.

  • Electric PC board.

Specifications - Technical Data

RU80i RU80e
Gas Input
15,200 – 152,000 15,200 – 152,000
Water Flow
0.26-8.0 0.26-8.0
Energy Factor
0.96 0.96
Activation rate
0.4 0.4
Temp. settings
98-140 98-140
Electric consumption
42 41
Max. vent length
41' - one pipe system
42' - two pipe system
Altitude height
10200 10200
18.3x26x10 18.3x26x10
70.5 70.5

(Photo credit to Rinnai)