Rinnai RUC98i Review

Read time: 8 minutes Last Updated: 09/18/2019

Rinnai RUC98i

  • 95% energy efficiency rating
  • Tight output temperature range between 98° F - 140° F
  • Maintains water pressure even when multiple appliances are in use
  • 12-year warranty on heat exchanger expands lifespan substantially
  • Older homes may require retrofitting to properly install
  • Customer service team is less than reliable
Dimensions & Capacity:
10 x 18.5 x 26 inches
Fuel Type:
Propane or Natural gas
Flow Rate & Water Pressure:
9.8 GPM, 150 PSI (max)
Heating Capacity:
98° F - 140° F
Energy Efficiency Ratings & Certifications:
95%, EnergyStar
Price and Warranty:
Under $1,500; 12-year on heat exchangers, 5-years on parts, 1-year on labor
Display Type:
Digital/ analog mix
Material Composition:
Reinforced metal components with anti-corrosion coatings
Our Review

Homeowners with high daily hot water demands don’t need to suffer the annoyance of running dry if they opt for a Rinnai Ruc98i. This model was undeniably designed with simultaneous demands in mind, given its reliable 9.8 GPM and 150 max PSI ratings. All water output from this unit will also be piping hot within its 98° F – 140° F, regardless of your regional groundwater temperature. This means everyone can enjoy hot water at maximum pressure no matter where they are in the house, at any time.

The Rinnai RUC98i’s EnergyStar rating is a point of pride, as well. This certification is not given out to just any tankless water heater, indicating that this model’s advertised 95% energy efficiency rating fully meets expectations. This high energy efficiency rating is applicable regardless of the user’s chosen fuel source, given that this unit is compatible with both natural gas and propane. Keep in mind that the Rinnai RUC98i is pretty tricky to install. It’s a powerful unit, which means it’s also heavy and bulky. You’ll definitely need some help setting this heater up. However, you’ll be able to enjoy excellent high-efficiency once you’ve done so.

Read more about our how our ratings broke down for the RUC98i below or checkout how it compares to other tankless natural gas water heaters.

You’re enjoying a relaxing shower after a long day at work when suddenly, the warm water begins to dissipate. You adjust the hot water knob and then…nothing. Thereafter, you’re forced to finish your shower with cold water that is less than pleasing. When an incident like this one occurs on a regular basis, you may be in a worthwhile position to consider a modern in-home water heating solution.

Specifically, you should consider taking this opportunity to say goodbye to your subpar tank water heater and hello to a reliable tankless water heater like the Rinnai Ruc98i. In fact, the Rinnai Ruc98i is considered to be one of the best water heating solutions for those looking to centralize this crucial process and save money on their utility bills in the process.

Why Might I Want this Specific Tankless Water Heater?

As you’ve likely heard by now, tankless water heaters, in general, are becoming increasingly popular with homeowners in all parts of the country due to their distinct ability to replace a traditional hot water production system without compromising on efficiency. In fact, most modern units provide instantaneous hot water production in order to meet the simultaneous needs of an active household.

The Rinnai Ruc98i is certainly capable of living up this base level expectation based upon its remarkable 9.8 GPM. In context, that’s enough hot water exiting this unit every minute to run several showers and sinks at once without a single user experiencing a drop in water pressure or temperature. Speaking of which, the Rinnai Ruc98i features a tighter-than-usual temperature range between 98 °F and 140°F to minimize sporadic fluctuations in output water temperature.

Also, many prospective users are quick to note the fact that this model is built with propane and natural gas compatibility. As such, this unit will not cost you extra in terms of installation if you situate it near an existing fuel line. When running on either fuel source, this unit is 95% fuel-efficient. This alone was enough to earn the Rinnai Ruc98i a coveted EnergyStar rating.

Of course, there are even more features and specifications that make the Rinnai Ruc98i a desirable addition to your home. Be sure to read on through the rest of this review in order to gain a fully-fledged understanding of how each of these factors come together to create this high-performing tankless water heater.

Quick Tips

The tankless water heater market has grown crowded over the last several years, not least due to growing demand for these efficient home appliances. However, this rise in options has made it more challenging to identify the best model to fit your needs and your budget. These quick tips should help you identify any worthwhile unit and consequently compare it to the Rinnai Ruc98i:

  • Evaluate the Installation Space – Always pre-measure your prospective installation location to certify that there will be plenty of room for adding in all necessary connection lines and vents. The Rinnai Ruc98i measures 10 x 18.5 x 26 inches, making it a fairly compact when it comes to wall-mounted installations
  • Select a Fuel Source – Tankless water heaters are often designed to interface with only one fuel source, so be sure to select a model that will be compatible with a locally affordable fuel option. The Rinnai Ruc98i is actually compatible with two types of gaseous fuel, providing a prospective user with even greater flexibility when it comes to affordable operation
  • Compare Heating Capacity and Flow Rate – If you anticipate a high average demand on your home’s hot water, then you’ll want to pick a model with a high GPM rating. Along the same lines, you’ll want to pick out a unit (such as the Rinnai Ruc98i) with a broad heating capacity that won’t dip under high demand.

Key Specifications and Features to Look for in a Tankless Water Heater

Dimensions & Capacity

Physical dimensions can make a major difference when it comes to installing a new unit, which needs plenty of bumper space to ensure that it can be properly equipped with all necessary input and output lines. The Rinnai Ruc98i measures 10 x 18.5 x 26 inches, placing it on the larger side of the still comparatively compact unit size spectrum. The Rinnai Ruc98i, like all tankless water heaters,” do not have a “capacity” simply because they lack the need to store water internally.

Fuel Type

Most modern tankless water heaters run on propane, electricity, or natural gas sources. Often, the best option to meet your needs will depend on local utility prices. The Rinnai Ruc98i runs on either propane or natural gas, allowing twice as many prospective users the chance to take advantage of their home’s existing utility delivery infrastructure when installing this unit.

Flow Rate & Water Pressure

Flow rate describes how much water can be pumped through a given unit in a minute, often measured in gallons per minute (GPM). A unit like the Rinnai Ruc98i with a high peak GPM rating at 9.8 GPM can be counted on to always provide an optimal volume of heated water. At the same time, this high GPM rating points to this unit’s ability to handle simultaneous use without dropping the operational water pressure.

Heating Capacity

A unit’s heating capacity is the range of output temperatures a given unit is able to achieve when interacting with a groundwater source. The Rinnai Ruc98i, for example, features a 140 °F peak temperature, which is a key indicator that its several heating chambers are efficient when fully engaged with cool groundwater.

Energy Efficiency Ratings & Certifications

An energy efficiency rating describes how capable a given unit is when it comes to transforming its input energy into heat. The Rinnai Ruc98i features a 95% energy efficiency rating, which is more than enough to qualify it for an EnergyStar regulatory certification from the US EPA.

Price and Warranty

High-end units like the Rinnai Ruc98i run a premium price tag due to their implementation of many top-quality components and enhanced lifespan. However, this price can offset slightly when taking into consideration this model’s multifaceted warranty policy that covers the unit for a decade or more.

Display Type

A practical display is essential for controlling a heater unit with any degree of accuracy. The Rinnai Ruc98i’s interface is a mix of digital and analog components, ensuring that it can interact with by both novice and veteran tankless water heater users alike.

Material Composition

As with any home appliance, internal and external durability is essential when it comes to expanding your unit’s practical life span. The Rinnai Ruc98i makes use of a variety of reinforced metallic components throughout its internal array, many of which are covered with corrosion-resistant coatings.

Different Uses for a Tankless Water Heater

Decentralized In-Home Water Heating

Tank water heaters have always made it difficult to set up a home’s hot water delivery system without miles of inefficient plumbing. A tankless unit like the Rinnai Ruc98i eliminates this waste by decentralizing the entire hot water production process. Each modular Rinnai Ruc98i can be installed directly in a heavy-use room, allowing for more faster, hotter water to always make it to the tap.

Cutting Water and Electric Bills

Almost all tankless water heaters, including the Rinnai Ruc98i, advertise their ability to decrease a home’s utility bills in both the short and long terms. Though precise savings will vary from home to home, the Rinnai Ruc98i’s 95% energy efficiency rating indicates that it barely wastes any energy created within the unit. The lack of tank on the Rinnai Ruc98i also decreases how much spare water is wasted when the unit is not in use.