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Rinnai RU98EN Review – (Outdoor / Condensing / Natural Gas)

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Rinnai RU98EN Ultra-NOx Condensing Tankless Gas Water HeaterThe RINNAI RU98EN is an outdoor natural gas-powered tankless water heater. The unit has an EF (Energy Factor) of 0.93 for natural gas or propane, up to 94 percent thermal efficiency, and an Energy Star rating, making it an energy efficient water heater unit for people looking to cut down heating expenses.

It also has a maximum BTU of 199,000 and can produce 9.8 gallons per minute, which is perfect for mid to large-sized households. At 80 pounds, the Rinnai RU98EN 9.8 GPM is bulkier than most water heaters, but it has a sleek and beautiful exterior with a dimension of 18.5 x 10.1 x 26.4 inches. While heavy, the compact design makes it easy to fit in any space.

The tankless water heater features a Condensing Technology which greatly optimizes the energy efficiency. It is environmentally-friendly and complies with California and Texas nitrogen oxide emission standards. The Rinnai RU98EN comes with advanced scale detection to reduce the chances of long-term damage to the unit.

Temperature Variations

It also features a temperature lock in the control panel to prevent unauthorized access or sudden changes to the water temperature. It allows multiple venting options like the PVC/CPVC which makes installation easier.
The residential model of the Rinnai RU98EN has a heating capacity of 98°F – 140°F while the Commercial model can heat water between 98°F to 185°F. The Heat Exchanger unit comes with a 12-year warranty; parts have a 5-year warranty as well as one year labor for residential installations.

The unit is ideal for multi-user households. With the Rinnai RU98EN, you can run two showers and the kitchen sink simultaneously, and you will continue to have hot water on demand.

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The Rinnai RU98EN comes with numerous high-end features that set it apart from other heaters in its class. Being a leader in the tankless water heater industry, Rinnai has perfected its technology over the years, giving its tankless water heaters excellent all-around qualities regarding efficiency, design, features, and output. Here are some of the benefits of Rinnai RU98EN.

  • Advanced Features

    The Rinnai RU98EN features advanced dual heat exchangers which enables it to achieve a high gas to heat conversion ratio. Thus, the heater has an energy efficiency of 93 percent, which means only seven percent of the heat energy is lost.

    With such high energy efficiency, this tankless water heater will help cut the amount of gas spent on heating water, leading to considerable savings in your utility bills. Furthermore, it allows you to use more hot water, especially during the chilly winter months.

    Also, the Rinnai RU98EN has a digital controller which allows you to set the water temperature to the desired level, shows the current water temperature and notifies you when there is an error in the operation of the unit.
    The best part is that the controller is installed inside so that you can control the unit from the comfort of your home. There is also a temperature lock which prevents accidental or unauthorized changes to the water temperature since the heater is an outdoor unit and natural factors or a human/animal can tamper with the controls from outside.

  • Compact Size

    The Rinnai RU98EN has a sleek and small size. This makes it easy to install on any spot outside of your property. Because it is an external unit, it helps you save the space you would have used to fit it in your home. Plus, you don’t have to carry out extensive and expensive retrofitting of your home during the installation process since everything happens outside.

  • Scale Detection Capability

    The Rinnai RU98EN comes with advanced scale detection to protect the unit in the long term. Water heaters are prone to mineral accumulation which causes scaling, especially in areas where water hardness is high. With industry-leading scale detection features, the unit is protected from excessive scale deposits. Which can lead to lower efficiency and ultimately high repair costs. Thus, the unit can serve you for longer in top condition without expensive repairs.

  • High Output

    The unit offers a whopping 9.8 gallons per minute. Hence, making it a perfect choice for medium to large-member households that simultaneously use multiple faucets. The Rinnai RU98EN can deliver on-demand hot water seamlessly with almost no delay.


The Rinnai RU98EN has a few shortcomings which we outline below. These are not drawbacks per se, but you need to know them when shopping for a tankless water heater.

  • Expensive

    Like most tankless units of its caliber, the Rinnai RU98EN has a hefty price tag. Which can be discouraging for people with a tight budget. However, the high cost is well worth it if you require on-demand hot water and a unit with a large output.

  • Requires Professional Installation

    The Rinnai RU98EN requires professional installation due to its complex construction. It is understandable considering the advanced electronic controls used in the heater.

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The Rinnai RU98EN is a winner in all ramifications. From the output, water heating capacity, energy efficiency, to innovative controls, the unit performs impressively. It is most certainly well worth its price tag. The sleek design, temperature lock, and exterior installation have endeared it to many homeowners and builders.

The fact that is it Energy Star Certified means you can trust this unit. Especially to deliver on-demand hot water without skyrocketing your energy bills. For people who love hot water but are space-constrained, the Rinnai RU98EN is an excellent choice.

by Water Heater Mag

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