Close this search box.
Close this search box.

Rinnai RUR98iN Ultra Review (January 2024) ~ Tankless Water Heaters

Product At A Glance

Rinnai RUR98iN 9.8 Max GPM Ultra Series Condensing Indoor Natural Gas Tankless Water Heater with Recirculation
View On Amazon

Top Perk > High Efficiency

If you’re looking for a tankless water heater that uses less energy to deliver hot water when you need it, then you won’t a better choice than the Rinnai RUR98iN Ultra Series. This system has been described by many customers as the most energy efficient unit and we couldn’t agree less.

Besides being qualified by ENERGY STAR, this machine has an energy rating of 96% which obviously separates it in its own class. Just like other models from Rinnai, this unit gives you a range of choices for PVC and concentric venting. It all depends on what you want.

In addition to its high energy factor, this unit also produces lower emissions of CO2 and NOX through an advanced technology. Although highly priced, the value it provides quickly makes up for this.

  • 9.8/10
    Efficiency - 9.8/10
  • 8.8/10
    Ease of Use - 8.8/10
  • 9.6/10
    Value - 9.6/10
  • 9.8/10
    Features - 9.8/10

Rinnai RUR98iN

Cost: $$$$

Model Number: RUR98iN

Weight: 81.6 pounds

Size: 12.5 x 10 x 26 inches

Water Consumption: 9.8 gallons

Water Flow Rate: 9.8 gallon per minute (GPM)

Usage: Indoor

Fuel Type: Natural Gas

Similar model: RUC98iN

Warranty: Residential: Limited 12-year on heat exchanger, 5-year on parts, and 1-year on labor (5-year optional on labor). Commercial: Limited 5-year on heat exchanger, 5-year on parts, and 1-year on labor (2-year optional on labor).

Detailed Review


One of the best ways to cut down on your utility bill is to install a tankless water heater. Compared to a traditional hot water tank, a tankless water heater can help you save more than 30% of the money you spend on energy every month. How?

Energy is consumed all day by the hot water tank, whereas, a tankless heater only uses energy on demand. In order words, it’s only when you need hot water that power will be used. So if you stay throughout a whole day without using hot water, then you will not have to pay for hot water that day.

However, this is not the case with the traditional counterpart. Since power is being drawn to heat and sustain the hot water, you will have to pay for the used energy whether you are using the hot water or not.

But that’s only part of it.

With a hot water tank, you’re limited to the amount of water you can get depending on the tank’s capacity. Once the storage is emptied, you have to refill and heat up again; which may not always be convenient. However, with a tankless water heater, you have an unlimited access to hot water anytime you need it.

This explains why so many homeowners are switching over to tankless water heaters. And peradventure you’re still in the old age of traditional tanks, there’s no better time than now to take advantage of the power and efficiency of these heaters.

If you’re looking for the most powerful energy efficient tankless heater in the market that can easily meet your large family needs, then the Rinnai RUR98iN Ultra Series is your top shot. With a rated efficiency of efficiency up to 96% and an innovative recirculation technology that ensures an endless supply of hot water, this unit is definitely one you should never miss out on.

The Rinnai RUR98iN is equipped with a good number of advanced features that really separates it as a tankless water heater in its own class. Some of them include a built-on circulation pump for added efficiency, an internal by-pass pipe for internal recirculation, and a Wifi control that can be connected over your home’s network.

With the Wifi network, you can conveniently monitor and adjust your heating settings. Like we mentioned earlier, the use of an innovative re-circulation technology ensures that the machine is able to provide continuous supply of hot water enough to serve medium to large sized families. By the way, you should consider getting a smaller model if you have a small family because you may find this system too powerful.

The Rinnai RUR98iN comes with a water flow of 9.8 GPM which can simultaneously support multiple bathrooms or sinks without any noticeable drop.

The increased efficiency of this unit makes it the perfect choice if you want a tankless heater that will give your additional savings on your bills without compromising performance. It is very easy to install and use; which is not surprising considering the fact it’s a product from Rinnai. And with all its amazing perks, we had no choice but to include it first on our list of the best tankless water heaters.


Anything a regular tankless heater does, you can expect to get from the Rinnai RUR98iN and even more. The unit is specially designed to support the whole house with reliable delivery to multiple bathrooms (up to four) at the same time without any fluctuation in water flow provided the temperature outside is favourable.

You can also be rest assured that won’t be enough time to grow goose bumps while doing the dishes or laundry due to delayed supply of hot water. This system delivers on demand.

The addition of a special ultra-low NOX gas burner in the design of this unit tackles the emission problem. In order words, you can set it up inside the house without worrying about the release of harmful fumes within your home. This is one of the major advantages the Rinnai RUR98iN has over most of its competitors.

This model has a rated water flow rate up to 9.8 gallon per minute and can produce maximum power of 199,000 BTU, which explains why it’s mostly suitable for households.

But just in case you don’t have so much demand for hot water, you can reduce the power and flow rate through the modulating gas valve on the device. You can reduce the 190,000 BTU power to 15, 200 BTU and the 9.8 GPM water flow rate to 0.26 depending on your specific needs.

In addition, this unit enables you to monitor and alter the heating settings over your home network through Wifi. The incorporation of ThermaCirc360 recirculation technology allows you to get how water whenever you need it and for as long as you want. There are very few products that can offer you the same value.


As indicated earlier, the heat outflow of this unit is 9.8 GPM which may fluctuate depending on the weather condition outside the house. Generally, with cooler temperatures, you are likely to experience

As previously mentioned, you’ll enjoy up to 9.8 GPM with the RU98IN. This number might fluctuate depending on the temperature outside.

The temperature of the unit can be anywhere between 98F to 185F depending on where you are using the system. In residential homes, you can expect temperature between 98F to 140F, with higher upper limit for office buildings at 185F.

The RUR98IN is also equipped with a programmable digital controller that allows you alter temperature and save energy in the process. You can use the remote control provided to adjust temperature to your preferred choice.

This unit has been labelled as an “ultra-efficient” heater and we can’t agree any less. Two heat exchangers are employed to adequately heat the incoming water in a condensing mode where the flue gases are used to preheat the water in the secondary heat exchanger. As a result, the exhaust temperature is greatly reduced leading to higher efficiency of the unit.


With the Rinnai RU98IN, installation is less of a hassle. But of course, you still require a basic technical knowledge to go through with the project.

An installation manual is provided which contains a detailed instruction on how to set up the system. You may also want to watch the video tutorial online.

However, if you don’t feel confidence to carry out the project especially if don’t have any DIY skill set, then you may want to consider hiring someone else to do the installation. We recommend hiring a Rinnai technician; and don’t worry, it won’t cost you much.

The Rinnai RU98IN weighs 70 pounds and has a dimension of 18.5 x 10.1 x 26.4 inches which is quite massive. So you will need to make some space to install the unit; though not as much space as you need for a tanked water heater.

Although you will be freely provided with special isolator valves, other components that are required to successfully set up the unit will have to be ordered by you.

Some of the things you will need to get started include:

  • Weather proofing equipment
  • Circuit breakers
  • Ground lines
  • Exhaust pipes

You may actually need other parts or less, depending on what you already have at home. Like we mentioned earlier, even though the installation has been made as simple as possible, you may want to hire a professional to do it for you because any little mistake can void the product warranty.

Visit the company website to download the installation manual.

Other features

  • Twin pipe PVC/CPVC configuration for greater flexibility
  • Comes with safety features like thermal fuse, flame rod and combustion fan rpm check
  • Has boiling and frost protection
  • Has OHS and over-current protection.


  • Doesn’t require a lot of space
  • Highly energy efficient (saves water and uses less electricity)
  • Delivers hot water on demand and doesn’t makes noise
  • Delivers up to 9.8 GPM which is pretty massive
  • Special system to greatly reduce NOx emission makes it super safe
  • Multiple applications- home or office buildings
  • Doesn’t require expansion kit
  • Great warranty
  • Comes with dual pipes for added efficiency


  • Very expensive
  • System requires venting during installation and no venting kit is provided
  • Not suitable for small homes
  • You may need to hire a professional for installation
  • Requires scheduled maintenance by a certified repair personnel certified from Rinnai.

Frequently Asked Questions

Q: Is this a direct vent system?
A: Yes
Q: What is the max temperature and flow rate of this unit?
A: The temp is set at a 120 max at the factory but can be increased to 140 by changing the SW6 in DIPSW 1 to on. As far as the GPM there are a lot variables such is water pressure line diameter and length which will affect the output.
Q: What else is needed to install this?
A: Valve kit, proper gas pipe sizing and venting per your local plumbing codes
Q: Can I use the existing circulating pump to augment the hot water circulation?
A: Yes you can.
Q: Can I install this unit myself?
A: Most homeowners hire a professional to install the device. However, it does come with an installation manual so that you can install it yourself.
Q: Does the unit installation guide say anything about voiding the warranty if not installed by a licensed installer?
A: The installation guide says: “A licensed professional must install the appliance, inspect it, and leak test it before use. The warranty will be voided due to improper installation.”
Q: What's the difference between RUR98i and C199i?
A: C199 is a commercial unit and does not have a recirculation system. The C199 is equivalent to the RUC98in, but the C199 has a commercial warranty and can also reach higher temps right out of the box. RUR98IN is the residential model and has a recirculation pump built in.
Q: Does this require 3/4 inch gas pipe and a 5 inch vent pipe?
A: Depends on your gas pressure and BTU, and if you use 3 or 4 inch PVC to vent the model. This model is 1/2 inch gas line compatible, but you must make sure your half inch line gets the unit what it needs. Additionally, venting this unit with Rinnai pipe or PVC will also need to be decided.
Q: How noisy is this unit?
A: It is extremely quiet. Produces small humming noise, coming from recirculation pump, but if that is a problem; you can mount it with rubber standoffs.
Q: What kind of return valve I should use?
A: This unit comes with its own bypass/return valve. Per the instructions, it is to be placed at the furthest fixture from the unit. It is a threaded composite bodied unit you would install between the hot and cold supply lines, for instance, under a sink.
Q: Can I install this unit with a 1/2 inch gas line?
A: You cannot use 1/2 inch for this product. It will not supply enough gas fast enough to heat the water to the desired temperatures.

Bottom Line

If you have a large family and you’re looking for a powerful water heater that will meet your household needs, then the Rinnai RUR98iN will make a great buy. You will be fascinated by its great power and high energy efficiency, compact size and environmental friendliness. Though you may find the price a little too high, the value it provides makes it well worth the investment.  This unit is one of the best tankless heaters (if not the best) you can rely on to provide you with continuous supply of hot water whenever you need it, no matter how long. With this unit in your home, your bills will never skyrocket anymore!

Water Divider

Related Posts