Rinnai RUC98iN Ultra Series Tankless Water Heater Review

Product Name:RUC98iN Ultra Series Natural Gas Tankless Water Heater
Power Source:Natural Gas
Use Type:Indoor
Capacity:9.8 GPM
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The Quick Review

The Rinnai RUC98iN Ultra Series is the “Cadillac” of Tankless Water Heaters, that is to say, it is the very best you can find, anywhere, period. Of course, you should expect to pay more for the best in class. With the higest possible flow rate at a whopping 9.8 GPM, this single unit could easily heat nearly any average home in North America. Backed by an industry leading warranty and supported by nearly all local plumbers and contractors, this is simply the best Tankless Water Heaters powered by Natural Gas you can find.


With the absolute leading flow rate of 9.8 GPM, capacity isn’t much of a concern with this premium water heater.


Since this tankless water heater requires a gas line hook up, you will require professional installation. We do not recommend an amateur attempt to install this unit as working with gas lines can be very dangerous. That said, for a professional, this installation is quite straight forward and shouldn’t run up a large labor bill. Many individuals on Amazon has reported that they were able to install it themselves with ease.


This is a product for people who are looking for long-term value and the best tankless water heater that will last. Being one of the most expensive units in the market, on a $ / GPM rate and energy savings, there is tremendous value in paying a little bit more for this fantastic water heater.

Over the long run, the extreme efficiency of this unit using natural gas will be much less expensive than electric hot water tanks.

The Misses

Most tankless water heaters take a while for the water to heat up when you turn on the faucets, and this unit is no exception. It can take up to 20 seconds (in the winter) for the water to heat up, which is slower than conventional electric water tanks. While no manufacturer has really “cracked the nut” of instant heat at high GPM rates, we expect the industry leader to be able to solve this.

We also have to mention that being the most expensive, we’d love to see the price come down 🙂

Our Recommendation

We recommend this unit to people who want nothing but the best for their home and are willing to pay a little bit more for that peace of mind.

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