10 Reasons to Buy Rinnai RUC98 Tankless Water Heater

Coming from the Ultra series of condensing water heaters, the Rinnai RUC98 tankless model is a perfect unit for large homes and demanding applications.

The RUC98 is designed to give you endless hot water while helping you save, even for simultaneous uses at multiple fixtures.

One of the most advanced models, Rinnai RUC98 (buy it from amazon.com) can provide savings of over 40% using the Eco-friendly and modulating gas burner. It is ideal for those looking for fast, hot water delivery, remote control, Wi-Fi connectivity, and Energy Star compliance.


1. High water flow

  • Unlimited hot water supply
  • Maximum water low of 9.8 GPM, minimum 0.26 GPM
  • Ideal for high demanding homes and up to 4 bathrooms
  • Great for point-of-use and whole-house applications

2. Instant and fast hot water delivery

  • Rinnai Circ-Logic technology allows users to set the recirculation pattern
  • Recirculation program cycles external pump for faster hot water delivery
  • Comfort and Economy recirculation modes for shorter and longer time intervals

3. Smart technology

  • Built-in microprocessor
  • Integrated controller with the display and push buttons, with the optional advanced controllers
  • Advanced diagnostics with error codes for easy troubleshooting
  • Utilizing the Wi-Fi connectivity, RUC 98 models can now be remotely monitored and controlled using the smartphones and Rinnai App
  • Remote diagnostics and maintenance
  • Voice activation using integrated Amazon Alexa

4. Tankless & condensing

  • On-demand, tankless water heating with the fresh hot water delivery
  • Stainless steel and copper heat exchangers
  • Water preheating in the condensing exchanger, using the heat from exhaust gases
  • Low temperatures of exhaust gases allow the use of cheaper vents

5. High efficiency

  • Super high efficiency of 0.92
  • Direct electronic ignition instead of an old-fashioned pilot light
  • Thanks to the innovative technology, RUC 98 can use up to 40% less energy than traditional models.
  • Buying a RUC 98 is a smart investment as it might increase your home's value, and also get rebates and tax credits.
  • Energy Star approved

6. Easy temperature control

An integrated controller allows users to set the temperature between 98 and 140 F, or up to 185 F with the commercial controller. Additional controllers can be installed.

7. Powerful gas burner

  • Strong and Eco-friendly gas burner
  • Power modulation from 15,200 to 199,000 BTU

8. Environment-friendly

  • Ultra-low gas emission contributes to cleaner air and a greener environment
  • The model can last over 20 years
  • All the components are easily replaceable and recyclable, so there is less waste in landfills
  • The higher efficiency of over 90% results in less energy waste
  • Reduced water consumption
  • Low noise level of 41 dB

9. Flexible installation

  • Small and compact design - 18.5” X 26” X 10”
  • Lightweight construction – 61.7 lbs
  • Installed on the wall, so more space is available for other use
  • Designed for indoor and outdoor installation, including crawl spaces and attics
  • Used in residential, commercial and mobile home applications
  • Dual direct venting option allows concentric and dual pipe venting
  • PVC and CPVC vents with lengths up to 100 ft.
  • ½” gas line compatible
  • Isolation valves are provided for easy installation and service
  • High altitude installation up to 10,200 ft.

10. Durable

  • Long lasting – over 20 years
  • All the components are replaceable
  • Freeze protection against temperatures as low as -22 F
  • 12-year warranty on the heat exchanger and 5 on other parts

Highlights of customer reviews


  • Excellent performance
  • Constant temperature. One of the users tested the unit running several applications at the same time, and was getting hot water at the steady temperature.
  • Low rate. Rinnai RUC98 has an excellent flow rate (low) to trigger heating.
  • Noticeable savings when compared to electric.


  • Expensive to buy. Higher price if installing a dedicated return line, especially in the retrofit situations.
  • There is more delay in hot water delivery than the tank unit (some users suggest getting a RUR model with the internal pump and recirculation).
  • For amateurs, it might take a long time to install.

Note: Professional installation is recommended. No tax rebate if the installation was not done by the professional.

You might like these