Rinnai RUCS75iP Tankless Hot Water Heater, 7.5 GPM, Propane, Indoor Installation

(10 customer reviews)


Product details

Brand Rinnai
Power Source Gas Powered
Item Dimensions LxWxH 22 x 14.5 x 34 inches
Color White
Material Polyvinyl Chloride
Item Weight 57.3 Pounds

  • Endless Hot Water: Enjoy unlimited hot water flow throughout the house; compact, durable, and easy to install; professional installation recommended
  • Energy and Space Efficient: Space-saving design conserves energy as it heats only when necessary
  • Optimal Water Pressure: High-performance 7.5 GPM hot water flow rate for a powerful, constant stream
  • Multiple venting options available including PVC/CPVC using the Ubbink Concentric to Twin Pipe adaptor allow for an easy installation
  • Guaranteed to Last: 12-, 5-, and 1-year residential factory warranty for heat exchanger, parts, and labor respectively


Rinnai’s super high-efficiency indoor models offer the most advanced technology in condensing propane fueled tankless water heaters. Unlike tank heaters which accumulate rusty sediments, this RUCS75iP compact water heater has a longer lifespan since water is heated on demand only which saves on energy costs. Rinnai products provide peace of mind with warranties that surpass the competition.

From the manufacturer


tankless heater

constant hot water

lasts twice as long


Never run out of hot water again

With Rinnai, hot water is always available to you, no matter how much or how often you need it

Smarter, more durable than a tank

Rinnai tankless water heaters last up to twice as long, and save energy-heating water only when needed

The Rinnai difference

Individually tested for quality before shipping, Rinnai makes the vast majority of our key components, unlike our competitors, allowing for better, more consistent quality

energy efficient

super high efficiency

space saving design

Enjoy energy saving benefits

Rated by a Uniform Energy Factor (UEF), our tankless water heaters are highly energy efficient, saving you from expensive power and water costs

Super high efficiency

Super high-efficiency models offer sleek design, maximum output, and an array of features ideal for the hot water demands of large homes

Saves valuable space

Our suitcase-sized compact wall units fit neatly in, freeing up more usable areas in your home

Additional information

Weight 57.3 kg
Dimensions 22 × 14.5 × 34 cm


Power Source


Item Dimensions LxWxH

22 x 14.5 x 34 inches




Polyvinyl Chloride

Maximum Flow Rate

7.5 Gallons Per Minute

Item Depth

10.1 in 257 mm


Propane Indoor Installation

Part Number


Item Weight

57.3 Pounds

Product Dimensions

22 x 14.5 x 34 inches

Country of Origin


Item model number



7.5 GPM





Item Package Quantity


Included Components

Water Heater

Batteries Required


Warranty Description

See Manufacturer



Date First Available

June 23 2015



10 reviews for Rinnai RUCS75iP Tankless Hot Water Heater, 7.5 GPM, Propane, Indoor Installation

  1. F. Parisi

    Love it!I installed this with the help of a friend who had installed tankless water heaters before. Not too difficult for DIY. No leaks, no problems. It fired up + has worked flawlessly! It provides hot water as quickly + steadily as our tank WH. The default 120* water temp is about what I had before. Just love that the gas shuts off as soon as you close the faucet, instead of heating water that won’t be used right away. I have applied for a rebate from the gas company, available because of the efficiency of this model.

  2. C. H.

    Hot water on demand of courseI purchased the RUCS7i to attempt to save some $ on electric. After 3 solid weeks it appears the saving are there albeit minimal. According to the WWW the average savings is ~$100/year. It appears I will be getting $10-$15 / month savings. Of course this will be offset somewhat by the gas increases. Here in Florida the gas company gives rebates on changing from electric to gas…which we did, therefore expecting a $650 rebate to offset the costs. We do not expect water savings since the demand for our family will not change.Several things for me to note on the unit purchased.I like the efficiency rating, Ill get some tax break up to $300.The unit arrived damaged – mostly cosmetic dents as it looked dropped. Called Amazon and they gave me some refund. The unit works fine.Installation can be a pain due to installing the condensing vent and drain.There are no easy temperature adjustments and are varied by either setting dip switches or purchase of extra parts. There is only a single LED readout for displays….not even a power on / off switch. You just plug it in or not.I wish we could turn down the temperature. Minimum is 120 degrees. Here in FLA the ambient water temp during summer is already 75+ degrees. Not much hot water is needed to shower and adjusting for less hot water has shut off the water heater due to its minimal needed flow thus resulting in a luke warm shower which is too cold on some days.

  3. Anne Sheridan

    Stay AwayI bought this to replace a smaller Rheem. It worked well for approximately 18 months, with a few minor annoyances. First one was in order to get hot water in the kitchen, we had to turn on a bathroom faucet, so Rinnai’s claim of working well with lower water pressure aren’t accurate. Irritating, but not necessarily a deal breaker. Another annoyance was the fact that you can’t adjust the temperature lower than 120 F. I called customer service and was told to install a mixer faucet. I was hoping to use the line I had installed for the previous Rheem to use outside for washing pets. I had to replace that due to the water being too hot for that purpose. Annoying, but not that big of a deal. Well, last month the unit had a small explosion inside that burned up all its wiring and likely ruined the control board. The explosion was significant enough that it shook the house, knocking things off of the shelves. I called the propane company out and they pressure tested the line up to the unit and found no leaks. That means of course that a leak developed inside the unit. At the direction of Rinnai I had their technician come out to look at the unit. He had no way of testing it, just eyeballed it and stated that he didn’t think Rinnai would back their warranty on it because the units are tested at the factory. He stated that he would contact them and find out. Three weeks have gone by with no word or contact from either Rinnai or their technician, so we have to assume that they have no intension of backing their own warranty or of dealing with the situation in any way. Now keep in mind that this was an explosion in their unit. A situation that could have burned down the house causing injury or death, but this company wasn’t even interested in taking the unit in to inspect it. I would be satisfied if the company had just gone this far. If at this point they stated that the unit didn’t have a leak, I would accept that there must have been a leak below the unit that caused the buildup of gas in the bottom of its cabinet. Keep in mind however that the unit was perfectly installed and maintained, and still had rubber gaskets in place in the bottom where the wires exit, so the likelihood of propane, heavier than air, somehow wafting upward into the unit is extremely low.This water heater was over $1,000. at the time. It was installed with all proper clearances. It actually exploded under strange circumstances. While it worked adequately for 18 months, not as well as the lower priced Rheem, but acceptable, the fact that I am still paying for it on my Amazon account and it is a pile of junk that could have burned our house down, and that Rinnai couldn’t care less about the situation, makes it a scary choice for anyone.

  4. Kevin Kretzmar

    Worth itWe did a ton of research when our old “shorty” gas water heater went out. They no longer make short full sized gas water heaters so we had to make a change. Electric would have been expensive to install and run. Standard gas would have required excavation of our crawl space. Tankless would be something I wasn’t real familiar with installing and expensive to vent.We learned that the condensing units like this one can be vented with schedule 40 PVC.This thing is smaller than a microwave and never runs out of hot water. We have much more room in the crawl space now.I learned a bit too late that this unit is not approved for Use above 5,500 feet altitude. We are at 6,000.It takes a minute or two to get hot water from the tap but we can both shower while we do laundry etc. Highly recommend.

  5. Pam

    Great ProductAs a plumber I’ve installed a number of these units for homeowners, as well as for myself. Items to note:The unit requires 5 connection points. One for a 3/4″ gas line, 2 water lines, 3/4″ line for PRV blow down, 1/2″ line for condensate drainage. This unit is so efficient that 95% plus of the BTUs are used in the water heating process, this then leaves little heat which creates condensate. If you fail to install the 1/2″ line the unit shuts down as the condensate reservoir fills w water. Depending on the availability of connections, this unit can be installed in 6 hours or less.

  6. Rob

    Lots of hot waterThis unit was replacing a 24 year old power vent tank water heater. I was able to install this while my old unitwas still working. It was leaking so I knew it was only a mater of time. I had to take out a section of black gaspipe to add a 3/4 inch tee so I could run a 3/4 in CSST line to it. Other then that I took my time and gotevery thing installed beside the old tank. I used Pex pipe to the old copper for the cut over. I did this on a Saturdayafternoon. Plugged it in and I had hot water. This is a very quite unit.

  7. Crystal

    If your on the fence, go for itWe were on the fence about buying something like this thru amazon. We have had it for 3 mom that now, and I am still impressed. We did have it installed by our plumber. He was not too familiar with the brand, but he did some research, and is now switching to rinnai. He said installing was very easy, with multiple venting options. We have two large bath tubs, plus the normal house hold, dishwasher etc. we can fill both bath tubs, and run the dishwasher, and kitchen sink. Temp only drops 1.5 degrees.Definitely happy with the purchase!

  8. Tom

    Lots of hot waterLikes: Lots of hot water.With rebate and tax credit it was a good value.Dislike: During install I forgot to turn on the gas before I plugged it in. When it fired up it got an error 11.Nothing I could do to reset the error. I finally found the “secret reset buttons and instructions on the internet (not on rinnai) and got it up and running.BTW.. Dont forget to pipe the condensate drain…

  9. mike gerlach

    garden bath full of hot waterInstalled it myself. Directions are pretty straight forward but read them online before you buy so you know what you have to do. Install time with my sons help was only 4 hrs in the attic. Unit heats water fast and there is no additional delay for hot water than I had with my tank. It’s very quiet. I have run big tubs and a sing full blast hot for over 20 mins to test it out with no issues.

  10. Don

    Happy with this purchasePros: Endless hot water, takes up less space, possible money savings in the long termCons: small increase in the time until hot water, need for condensation drainageNote: both types require yearly maintenance, but the on-demand ones will fail quicker if you don’t do it. Some say the on-demand units cost more but that isn’t true if you compare high-efficiency units.The benefit of never running out of hot water outweighs everything for us. We never plan to go back to a tank heater

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