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Super High Efficiency 6.5 GPM Residential 130,000 BTU Natural Gas Interior Tankless Water Heater

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  • Enjoy endless hot water
  • Less space for heating gives you more space for living
  • Professional installation recommended; please call 833-746-6210
  • View More Details
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Product Details

About This Product

Welcome to ultimate efficiency. With technology that operates only when hot water is needed, super-efficient heating coils, no pilot light and no storage tank to heat and reheat water, you save on energy and utility costs. In fact, Rinnai Tankless Water Heaters use up to 40% less energy than a traditional tank water heater. Plus, with premium technology, increased energy efficiency, an improved Home Energy Rating System (HERS) Index Score and optimized LEED eligibility, our tankless solutions can increase your home's value. You can even qualify for energy efficiency rebates and tax credits. It's a smart investment for now and the future.


  • Save time with hot water whenever and wherever you need it, any size home, even for simultaneous uses at multiple fixtures
  • Save energy and reduce utility costs by operating only when hot water is needed
  • Maximum output, minimum space; suitable for installation in non-traditional spaces such as crawl spaces and attics
  • Multiple venting options available including PVC/CPVC using the Ubbink concentric to twin pipe adaptor allow for an easy installation
  • Automatic frost protection
  • Residential warranty: limited 12-year on heat exchanger, 5-year on parts, 1-year on labor (5-year optional on labor); commercial warranty: limited 5-year on heat exchanger, 5-year on parts, 1-year on labor (2-year optional on labor)
  • *Note. Rinnai is changing the language in its warranty terms and conditions found in the current User Installation manuals. The existing statement will be replaced by the following: "This Limited Warranty applies only to products that are installed in the United States and Canada. Improper installation may void this Limited Warranty. It is recommended that a trained and qualified professional who has attended a Rinnai installation training class complete your installation." All warranties (old or new manual) will be honored as written above.
  • You can be confident in choosing to install Rinnai tankless technology in your home; our commitment to quality has made us the #1 selling tankless water heating brand in North America; your family deserves nothing less
  • Professional installation recommended; please call 833-746-6210
  • Rinnai branded accessories will ensure optimal performance of your Rinnai Tankless Water Heater.
  • Click here for more information on Electronic Recycling Programs
  • Return Policy
  • California residents
     see Prop 65 WARNINGS

Product Information

Internet # 306655615

Model # RUCS65iN


Dimensions: H 26 in, W 18.5 in, D 10.1 in


Product Depth (in.)

10.1 in

Product Height (in.)

26 in

Product Width (in.)

18.5 in

Vent diameter (in.)

3 in

Water Connection Size (in.)

3/4 in


Application Type


BTU Rating


Efficiency Level


Finish Family


First Hour of Delivery (gallons/hr)


Flow Rate @ 35°F Rise (gallons/min)

6.5 gal (US)/min

Flow Rate @ 45° Rise (gallons/min)

5.3 gal (US)/min

Flow Rate @ 55° Rise (gallons/min)

4.3 gal (US)/min

Flow Rate @ 65° Rise (gallons/min)

3.8 gal (US)/min

Fuel Type


Gas Connection Size

3/4" MNPT

Gas Type

Natural Gas

Heat Exchanger Warranty

12 Year



Maximum Temperature (F)

185 F

Minimum Activation Rate (gpm)


Minimum Temperature (F)

98 F

Number of Showers


Pack Size


Product Weight (lb.)

57.3 lb

Required Volt Connection

120 volt



Total BTU (Btu)

130000 Btu

Uniform Energy Factor


Vent Type

Single Wall

Water Heater Features

Freeze Protection, Overheat Protection, Ultra LoNox, Wall Mounted, WiFi

Warranty / Certifications

Certifications and Listings

CSA Listed

Labor Warranty

1 Year

Part Warranty

5 Year

Questions & Answers

Q:What size is the exhaust vent
by|Dec 29, 2023
1 Answer
Answer This Question

A:  Hello, the venting connection is a 2 in. (51 mm) nominal PVC/Polypropylene or 3 in./5 in. Concentric venting. - Thank you, Rinnai Customer Care

by|Jan 4, 2024
    Q:What is the difference between the Model# RUCS65iN and the Model# RUCS65iP
    by|Dec 13, 2023
    1 Answer
    Answer This Question

    A:  Hello, the N vs P is to identify gas type the unit is set up for, example : RUCS65iN is (Natural Gas) vs RUCS65iP (Propane Gas). - Thank you, Rinnai Customer Care

    by|Dec 16, 2023
      1 found this answer helpful
      Q:Is this unit (6.5GPM) enough for a 1.5 bathroom condo? There is only one shower.
      by|Jul 17, 2023
      1 Answer
      Answer This Question

      A:  Hello Maria, Rinnai offers a tool on our website to assist in selecting a product that best fits your needs please click on the following link https://www.rinnai.us/residential/solution-selector and a Live chat agent to assist also. - Thank you, Rinnai Customer Care

      by|Jul 18, 2023
        Q:is inside garage considers an indoor installation or outdoor?
        by|May 31, 2023
        1 Answer
        Answer This Question

        A:  Hello Naren, this is a great question. For garage installation Rinnai recommends an indoor model and the exhaust and air intake come from the outdoors. Thank you, Brittany.

        by|Jun 6, 2023
          Showing 1-4 of 17

          Customer Reviews

          4.3 out of 5

          • 4.3 out of 60 reviews
          • 67% recommend this product
          Filter by:
          Showing 1-10 of 60 reviews
          I hope 1 is poor and 5 is great. I have a 4 becaus
          I have had it installed for 6 months now. Takes up less room and water is not alway having to be heated in a tank. Dislike,the wasted water waiting for hot water to heat up.
            System was horrible needed to be reset daily. Don't walk RUN!!
            Response from Rinnai Product ExpertMar 7, 2024
            Hi Gustavo, I am concerned with your statement and not sure why the system needed to be reset daily. That is not a normal occurrence for our product. Please have your installer speak with our technical support to help resolve your issues. RinnaiAmerica
            • Verified Purchase
            Tankless WH
            Wish I was recommending to the recirculating model. Long time getting hot
              Very Satisfied
              I’ve owned several different manufacturers of tankless water heaters. Rinnai definitely has the best product as well as Terrific Product Support. I highly recommend Rinnai to anyone that is looking to save energy and reduce utility bills.
                Great except for surge suppression
                I love having a tankless water heater. The only problem is that it needs to have better surge suppression. We had a power "blink" at our house and it did something to the mother board and the whole unit had to be replaced. If the electronics are that fragile/sensitive, it needs to have a built in surge suppressor.
                  Overall: nice!
                  Nice unit, Installation went well and seems to be working fine for a few months now. I wish it had a lower minimum flow rate so I could get hot water in the shower with a low flow shower.
                    Install your own Rinnai tankless water heater
                    Don't like plumbers charging outrageous fees to install a tankless water heater? If you are a moderately skilled DIY person (can sweat a copper pipe properly), Rinnai's customer service people will answer your questions, even ten of them. I saved more than $1500! Took me parts of two days and only needed help to lift the unit over the mounting hardware.
                      Great Tankless with great instructions!
                      Had it 6 months. I should have considered the next best model with 2” venting instead of the 3”. Would have been easier and cheaper to install. Next best model also came with circulating system too. This is a first class product! I replaced a 15 year smaller unit.
                        Indoor heater
                        On demand, no tank. Had in new construction since Nov 2022
                          Rinnai 130,000 btu Tankless Water Heater (Replaced
                          Installed 11/2022 and comments after 3+ months of use
                            Showing 1-10 of 60 reviews

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