Tankless water heaters belonging to Rinnai RUR series have taken the market by storm. They are incredibly powerful units that are capable of meeting the hot water requirements of a large household. At the same time, their energy consumption competes with that of much smaller units.

Take the example of Rinnai RUR98. Here is a model that is capable of delivering a flow-rate of up to 9.8 gallons per minute (GPM). But that doesn’t stop this heater from boasting an ultra-high efficiency of 0.96. Nor does it gives it an excuse to jack up its annual energy cost.

This heater’s compliance with Energy Star helps it reduce energy usage by up to 40%. Its decision to use two heat exchangers (stainless steel and copper) allows it to provide hot water on demand. This means you won’t have to deal with any bursts of cold water on its startup.

Want to know more? Then check out our detailed review of Rinnai RUR98.

Rinnai RUR98 Review – Pros and Cons

Here are the positive and negative points of Rinnai RUR98:


  • Supports both concentric and PVC installation
  • Capable of recirculating water with or without a recirculation line
  • Wi-Fi compatible
  • Energy Star compliant


  • High activation flow rate

Rinnai RUR98 Review – Features

Here are the worth-noting features of Rinnai RUR98:  

  • Huge and instant hot water flow

As stated at the start of this review, the Rinnai RUR98 is capable of providing up to 9.8 gallons of hot water per minute. This means you can count on this natural gas heater to provide a steady supply of hot water to up to 4 water fixtures at the same time.

That isn’t where the good news end. This unit has a built-in 360 Therm Recirculation system that empowers it to provide instant hot water. Its internal and external recirculation modes minimize the wastage of water as well.

Also on offer is an integrated circulation pump. It makes sure that the water entering the unit quickly goes through the heating phase before delivering it to your faucet. This means that you won’t have to wait long to receive hot water at the tap.

  • Smart operation

The Rinnai RUR98 has a built-in microprocessor that takes the data of your hot water consumption and regulates the heater’s operation based on the same. It comes with advanced diagnostics that will help you troubleshoot any problems by showing easy-to-decipher codes.

You might find it useful to note that this model is Wi-Fi ready. It comes with a Control R-2.0 app which you can download on your tablet on your smartphone. The app lets you remotely control the unit, gives you access to its timers and helps you in setting schedules. 

The app also has a feature that lets you give control of the heater to a technician remotely. Aside from that, the RUR98 gives you the option to control it with your voice. It is equipped with 20 built-in voice commands that you can issue to regulate its operation.

  • Flexible venting system

Some natural gas heaters you see on the market come with only concentric venting option. You are left with no choice but to find a plumber who is experienced in it. Other models support only PVC/CPVC venting options and therefore dictate your choice of a plumber.

The Rinnai RUR98 is different. This natural gas tankless water heater supports both the above mentioned – concentric and PVC/CPVC – venting options. But that isn’t the only aspect of this model’s design that makes it flexible and easy to install.

Instead, it is the isolation valves that are included in its package that make this heater’s installation, maintenance and service a cinch. The valves are installed on both hot and cold water sides and can be easily disconnected from the system when you plan to flush it. 

  • Tankless condensing operation

How many natural gas heaters on the market come with two heat exchangers? This one does. It contains stainless steel and copper heat exchangers to readily and quickly heat water. It also uses the latent heat from flue gases to preheat water.

This approach of not letting the exhaust gases escape at their boiling point provides two benefits. First, since their heat is being used to preheat water, the time the heater requires to raise the temperature of water to your desired setpoint nosedives. You, therefore, get an instant supply of hot water.

Second, when the exhaust gases are emitted at low temperatures, they aren’t as damaging to the environment as if they’d had they been exhausted at a high temperature.

  • High efficiency

The last thing you’d expect from a model offering everything the Rinnai RUR98 offers is for it to be energy efficient. Yet that is precisely what this tankless water heater is. It boasts an ultra-high efficiency of 0.96 and has an annual energy consumption cost of $171.

What is more, this product is Energy Star compliant as well. Perhaps that is the reason why, when compared to tankless water heaters offering similar water flow rates, the energy usage of this tankless heater is 40% lower.

  • Easy temperature control

You have three options using which you can control the temperature of this model between 98 and 140*F. The first one is the traditional modulating gas valve. It lets you increase/decrease the supply of natural gas to the heater’s burner. 

Also on offer is a built-in digital controller. It is present on the large LCD display of this unit and gives you the freedom to increase/decrease the heater’s setpoint with increments of 1*F. If both these options fail to catch your imagination, you can turn to the smartphone app we talked about previously.

Final Verdict

In our review of the Rinnai RUR98, we have unveiled everything you need to know about this natural gas tankless water heater. It is one of those models that are built for large households but still manages to keep a lid on its energy consumption. What more can you ask for!

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Rinnai RUR98 tankless water heater
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Rinnai RUR98