Rinnai RUC98iN Review


Rinnai RUC98iN offers an attractive looking and very innovative as well as technologically sound water heating solution for indoor usage. It is a space-saving, sleek, compact and energy efficient unit that offers flexible venting options, that is, both concentric and twin pipe installations. This unit weighs 80pounds, contains MC-91-2US digital controller and operates on natural gas. Efficiency wise this heater is superior to other gas powered models with 9.8GPM flow rate. For indoor use both in commercial and residential areas, this unit is ideal because it supplies endless hot water supply. It is equipped with all the necessary trappings of tankless water heaters. 

Some key features

  • Versatile venting options i.e Concentric or PVC
  •  0.96 Energy Factor
  • Compact design and space saving attribute
  • Minimal NOx emissions
  • 199,000 max BTU

The Pros & Cons of the Rinnai RUC98iN


  • Its 0.96 energy factor ensures that it is an economical and efficient unit
  • Low carbon dioxide emissions makes it an eco-friendly option
  • Supplies hot water without interruption to multiple taps
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    Concentric/Twin pipe PVC Venting options in a single unit makes it highly innovative and usable
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    It utilizes 199,000BTU and produces around 9.8GPM hot water and therefore this product is suitable for large families
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    12 years heat exchanger , 5-years parts and one to five years after sales service warranty for domestic users and 5years heat exchanger, 5 years parts and 1-2 years servicing warranty for commercial users.


  • The unit is very sensitive and installation is rather intricate
  • The heater is expensive, which although is reasonable considering the high level of features that it offers, but many users cannot afford it due to the price tag
  • You will need the services of a professional and certified Rinnai repair personnel for repairing purposes if the unit breaks down

Installation and Specifications

The unit is so light weight and compact that you can easily install it anywhere and carry along whenever you need to shift its position. You can install it anywhere around the house or your commercial property and offices since the unit offers two different venting options in a condensing water heater design. Rinnai is the only brand that offers both concentric and PVC venting option in a single unit, which adds to the heater’s usability and user-friendliness. You don’t need to have an adaptor and the package includes everything that you may require for installing it. Since it has two different venting options therefore assembling becomes easier and


Assembled Depth10"
Assembled Height26"
Assembled Width18.5"
Product Depth10"
Product Height26"
Product Width18.5"
Vent diameter0"
Water Connection Size1/2"
Finish FamilyGray
Flow Rate @ 35 F Rise (gallons/min)9.8 gal (US)/min
Flow Rate @ 45 F Rise (gallons/min)9.5 gal
Fuel TypeGas
Gas Connection Size3/4"
Gas Product TypePoint of Use
Gas TypeNatural Gas/Propane
Maximum Temperature (F)140
Minimum Activation Rate (gpm)0.4
Minimum Temperature (F)98
Product Weight (lb.)70.5 lb
Residential/Commercial/industrial UseResidential or commercial
Total BTU199000.000
Water Connection LocationBottom
Water Heater FeaturesWall Mountable
Vent TypeSingle Wall

Common Problems

Like other gas powered tankless heaters, this unit is also not free from problems. The cold sandwich effect is a problem that might occur since the heater is unable to maintain constant hot water backup and thus, you have to wait for about two minutes to get hot water pouring in consistently. Moreover, the high price of this heater makes it an expensive option for a majority of families. Nonetheless, if you can afford it then it is an ideal solution to meet all sorts of your hot water demands without compromising on size, weight, design and innovation. The unit is also environmentally friendly and is a good choice for large families.


All in all, the Rinnai Tankless Water Heater is a fantastic way to meet all of your hot water needs without having to resort to bulky, costly and environmentally unfriendly tank water heaters, and will ensure that the days of rationing hot water based on whatever needs it most are a thing of the past. Hot water when you want it, where you want it and however much of it you want, and all for only $200 more than the standard tank heater which will pay for itself with all of the money you will save in the long run.

You can buy the Rinnai RUC98iN on Amazon.

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