Rinnai Tankless Water Heater Reviews

Tankless water heaters have gained popularity throughout the world over the last few decades. A lot of consumers love them because they come in a compact design and have fantastic energy-saving efficiency. Tankless models only heat water when necessary, thus no waste of energy keeping the water in the tank warm when not required.

The name Rinnai is a common brand that has remained at the forefront of the tankless water heater technology. The company has manufactured some of the most efficient tankless water heater models on the market. Our Rinnai Tankless Water Reviews today will focus exclusively on the Rinnai RUC98iN Ultra-Series Natural Gas Tankless Water Heater model with Twin Pipe.

Rinnai Tankless Water Heater Reviews – At a Glance

Product Title Rinnai RUC98iN Water Heater
Features• Energy Efficiency
• Supply Inlets
• Gas Burn Rate
• Water Heating Capacity
Weight82 pounds
Dimensions10 x 18.5 x 26 inches
Voltage120 volts
Check Price in Amazon With Discount Rate

Rinnai RUC98iN: Product Overview

The Rinnai RUC98iN is an efficient tankless water heater for indoor use on commercial and residential applications. The unit utilizes a state-of-the-art technology that makes it possible to make significant energy savings and minimize expenses on electricity bills. The product operates on natural gas or propane and comes installed with multiple venting options.

Moreover, the Rinnai RUC98iN highlights a sleek and compact design for effortless storage in any spot. The item measures (10 x 18.5 x 26) inches and weighs 82 pounds. Although it has a sleek and compact design, this unit is not as lightweight as expected. It showcases a gunmetal exterior with controls nested on the lower end of the front panel.

These controls comprise a digital display, a power button, gas control buttons, and water control buttons. It allows you to regulate the temperature of hot water exiting the unit or lock the temperature button to avoid unauthorized access. This model has dual venting options comprising both concentric and twin-pipe PVC options.

rinnai tankless water heater maintenance

Key Features of Rinnai RUC98iN

Energy Efficiency

The RUC98iN Rinnai tankless water heater model is a unique unit that leaves an impeccable impression when it comes to energy efficiency. This model is Energy Star Certified with energy factor rating of 0.95.

Although it is a bit heavier compared to other tankless water heaters on the market, it still provides more regarding power. It may use natural gas or propane and comes installed with twin-pipe PVC or concentric venting option.

Supply Inlets

The RUC98iN Rinnai tankless water heater features more significant water and gas supply inlets than many other tankless water heaters available today. The unit, which complies with nitrogen oxide emission regulations, uses an electric ignition system. It draws only 2 watts of electric power in the standby mode.

But, when powered on and put to work, it consumes up to 64 watts of power. It also needs about 146 watts of electric power to prevent its parts from freezing in winter.

Gas Burn Rate

The Rinnai RUC98iN Ultra-Series has a vast minimum-to-minimum gas burn rate, which often varies from 15,200 to 199,000 BTU. Furthermore, this tankless water heater model has a wide hot water flow range of between 0.26 and 0.98gpm.

The Rinnai RUC98iN has only 0.4gpm minimum activation flow rate. Based on these figures, it is evident this Rinnai tankless water heater has what it takes to power multiple showerheads and faucets. Thus, you can use it in multi-bathroom households without any disruption to hot water flow.

rinnai tankless water heater problems

Water Heating Capacity

The Rinnai RUC98iN Ultra-Series standard model can heat water up to temperatures of between 95 and 140 degrees Fahrenheit. The commercial model of this tankless water heater is capable of providing water as hot as 185 degrees Fahrenheit.

Keep in mind that the RUC98iN model is an expensive tankless water heater option. Most homes have regular 0.5-inch gas and water connections. However, this pricy water heater demands up to 0.75-inch MNTP gas and water connections.


The RUC98iN Ultra-Series comes with the smart safety system, which is why it is highly recommended for residential and commercial use. The unit has a scale detection system, so it proves useful if your water composition calls for frequent descaling.

The system can automatically shut off to prevent any damage to the unit. What’s more, the RUC98iN comes with an in-built leak detection system that prevents the possibility of water damage.


  • Serves multiple bathrooms and faucets simultaneously
  • Energy Star Rate
  • Two useful venting options – concentric or PVC
  • Compact & space-saving design
  • Advanced technology prevents excessive gas emissions
  • Easy conversion from gas to propane and vice versa
  • Simple controls – temperature control buttons, a power button, and a digital screen


  • Extremely expensive
  • Difficult to install
  • Needs frequent maintenance from certified Rinnai personnel

Rinnai Tankless Water Heater Maintenance

The RUC98iN Rinnai model needs two types of periodic maintenance to keep the tankless water heater in proper shape:

  • The in-line screen filler needs regular checking and cleaning of debris
  • The entire unit requires flushing periodically to remove lime and scale, which can shorten its lifespan over time

All these maintenance processes must be performed by a certified service technician or a professional installer. Also, note that the maintenance schedule is dependent upon the water quality in your home.

Rinnai Tankless Water Heater Problems

Tankless water heaters like Rinnai can develop several problems including mineral buildup, system overload, flame failure, air supply or exhaust blockage, and ignition failure among other common hitches. Generally, tankless water heaters are efficient and require low maintenance, but problems can occur. You can get in touch with Rinnai customer support anytime should you encounter Rinnai tankless water heater problems.

Rinnai Tankless Water Heater Troubleshooting No Hot Water

Rinnai tankless water heater can fail to ignite for several reasons. More often than not, the gas supply causes the issue, so be checking to ensure your propane tank is full before you start any troubleshooting. The ignition failure may also result from gas or water valves that are not fully opened.

In the event your Rinnai produces no hot water, you should first try checking the electric power, water, and gas supply to the unit. Also, check whether the shut-off valves are in the closed position. See if there is an error code on the control panel, which could be blocking the heater from operating normally.

Rinnai Tankless Water Heater Warranty

Rinnai now offers optional extended warranty labor coverage on selected tankless water heater models. The RUC98iN model brings a 12-year warranty on heat exchangers plus another 12-year warranty for labor from the time of purchase. The company offers a total of 24 months warranty from the time of purchase.

Final Verdict:

The RUC98iN Rinnai model is an excellent water heater suitable for residential and commercial applications. It is compact and lightweight so that you can store it anywhere with absolute ease. It is capable to heat water on multiple bathrooms and faucets making it an ideal choice for busy commercial settings and large homes.

This unit is specially designed to provide constant, non-fluctuating hot water through several plumbing outlets simultaneously. It has an enhanced scale detection that reduces the possibility of long-term or severe damage to the unit. Most importantly, temperature lock control prevents accidental changes or unauthorized access to water temperature.

Kathy Smith

Hi, I am Kathy Smith. I am chief chef in KitchenGearPros. I am also a freelance blogger. I share my cooking related experience and knowledge.

Click Here to Leave a Comment Below 0 comments

Leave a Reply: