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Rinnai RUC98iN Ultra Series Indoor Natural Gas Tankless Water Heater, Twin Pipe

4.2 4.2 out of 5 stars 135 ratings

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Brand Rinnai
Product Dimensions 18.5"W x 26"H
Special Feature MC-91-2US controller included
Color Steel
Voltage 120 Volts
Power Source
Wind Powered
Material
Polyvinyl Chloride
Item Weight
82 Pounds
Style
Indoor

About this item

  • INDOOR installation only. Fuel Type: NATURAL GAS.
  • Concentric or PVC venting option
  • Up to 0.96 Energy Factor/Up to 0.92 Uniform Energy Factor
  • The space-saving design allows Indoor Installation type
  • Ultra low NOx emissions
  • 199,000 max BTU
See more product details

Customer ratings by feature

Easy to install
4.3 4.3
Value for money
4.0 4.0

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This Item
Rinnai RUC98iN Ultra Series Indoor Natural Gas Tankless Water Heater, Twin Pipe
Rinnai RUC98iN Ultra Series Indoor Natural Gas Tankless Water Heater, Twin Pipe
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PriceCurrently unavailable.$1,369.62$808.08$1,680.21$1,369.62$1,680.21
Delivery
Get it as soon as Tuesday, Mar 26
Get it as soon as Monday, Mar 25
Get it as soon as Sunday, Mar 24
Get it as soon as Tuesday, Mar 26
Get it as soon as Monday, Mar 25
Customer Ratings
Easy to install
4.3
4.6
4.6
3.3
Temperature Control
5.0
5.0
5.0
Sold By
Amazon.com
Amazon.com
Amazon.com
Amazon.com
Amazon.com
capacity
9 gallons
7 gallons
11 gallons
9 gallons
11 gallons
power source
Wind Powered
Battery Powered
ac dc
Battery Powered
Battery Powered
Battery Powered
style
Indoor
Natural Gas, Indoor Installation
Indoor Installation
Propane, Indoor Installation
Propane, Indoor Installation
Propane, Outdoor Installation
weight
82 pounds
62 pounds
35.4 kilograms
28.1 kilograms

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Technical Details

Additional Information

Warranty & Support

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Product Warranty: For warranty information about this product, please click here [PDF ]

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Rinnai RUC98iN Ultra Series Indoor Natural Gas Tankless Water Heater, Twin Pipe


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Product Description

Rinnai takes tankless water heating one step further with condensing technology that delivers more efficiency than ever before. Enjoy all the same tankless benefits you’ve come to expect from Rinnai, plus even greater energy savings. Features: 95% Thermal Efficiency Natural gas or propane Indoor Installation Only 98° F to 140° F Residential Temperature Range 98° F to 185° F Commercial Temperature Range Commercial Controller Must be Purchased Separately Gas Rate Input BTU's: 15,200 - 199,000 Electronic Ignition Meets California and Texas NOx Emissions Standards Compatible with Full Line of Rinnai Digital Controllers 12-Year Warranty on Heat Exchanger, 5 Year Parts, 1 Year Labor for Residential Installations Specifications: Width: 18.5" Height: 26" Depth: 10" Weight: 61.7 lbs Gas Connection: 3/4" Water Connection: 3/4"

Important information

Bulb Voltage

120 volts

Customer reviews

4.2 out of 5 stars
4.2 out of 5
135 global ratings

Customers say

Customers like the performance, ease of installation, value, and quality of the water heater. For example, they mention that it works well, provides constant hot water, and is easy to install. That said, some appreciate the energy efficiency, and speed. That being said, others are disappointed with the pump.

AI-generated from the text of customer reviews

25 customers mention18 positive7 negative

Customers like the heat of the water heater. They say that it works flawlessly, the water temperature is constant, and it's able to keep up under load. Customers are also thrilled with the speed and availability of hot water. They mention that it provides long hot showers and that it' s a great heater.

"...Pros: Efficient, small, accurate temp control, "endless" hot water, informative manual, good customer service..." Read more

"...It caps out at 120 degrees F. Which is decently hot but for cleaning it's often helpful to have 130-140...." Read more

"...Overall I am satisfied with the system, enjoying endless hot water and some extra space in my mechanical room...." Read more

"Hot water almost instantly depending on how far the run is. Once the hot water gets there, it doesn't go away!..." Read more

21 customers mention21 positive0 negative

Customers are satisfied with the performance of the water heater. They mention that it works well, has no issues, and is easy to install. Some customers also say that the basic installation works well.

"...After that, it ran perfectly every time. The unit is quiet and I couldn't be more pleased with its operation...." Read more

"...It has been working flawlessly and the water temperature is constant no matter if we use a lot or a little of water...." Read more

"...Here we are 1 year later and everything is wonderful!!!!!!!!! I'll update again at the end of 2020 or beginning of 2021!" Read more

"...Unit came on and worked flawlessly (well, almost).So my only complaint, I bought the Rinnai for 2 reasons...." Read more

16 customers mention13 positive3 negative

Customers find the installation process of the water heater to be straightforward. They appreciate the clear documentation and the instructions provided with the product.

"...It was a ~$2K risk I was willing to take. The install was straight forward...." Read more

"...(seems to be most popular), 3) customer reviews, 4) clarity of documentation for install...." Read more

"...The packaging and instructions were also great, the included checklist made my wife feel comfortable as I asked her to walk through them with me so..." Read more

"...The unit appears to work as described and the installation of it specifically went very easily indeed...." Read more

10 customers mention8 positive2 negative

Customers like the value of the water heater. They say it's worth every penny and a great buy.

"Installation was easy. Price was great. Got a $300 rebate from the gas company. All the hot water I’ll ever need. Long hot showers!!..." Read more

"State of the art tankless water heater at an excellent price...." Read more

"Worth every penny." Read more

"...I also did get the condensate neutralizer kit. Seems overpriced, but I didn't want to risk damage to any drainage pipe/septic tank...." Read more

7 customers mention7 positive0 negative

Customers are satisfied with the quality of the water heater. They mention that it's a great product, with excellent documentation. They also appreciate the endless hot showers for all.

"Awesome Quality and excellent documentation made my self installation an adventure. Would I do this again by myself? Not in a million years!..." Read more

"Great product. Produces hot water for kitchen and three bath rooms...." Read more

"These are awesome - endless hot showers for all!!!" Read more

"Great product. Love it!" Read more

5 customers mention5 positive0 negative

Customers are impressed with the water heater's energy efficiency. They mention it's quiet, good for natural gas savings, and provides endless hot water.

"...Pros: Efficient, small, accurate temp control, "endless" hot water, informative manual, good customer service..." Read more

"...Why, because they are more efficient and last longer when maintained correctly.Extremely happy with it." Read more

"...go to tankless water heaters....just makes sense and saves money on electric bill....love it!" Read more

"Good for natural gas saving but the other side you have to wait lot to get hot water after opening tap so basically wasting lots of water other side." Read more

5 customers mention5 positive0 negative

Customers are satisfied with the speed of the water heater. They mention that it provides hot water quickly, has a low flow rate to trigger, and works well. Some say that the installation process was easy.

"...It had the lowest flow rate to trigger. All the other stats were pretty similar between brands (Noritz and Takagi)...." Read more

"...Once we hooked up the good one we were thrilled with the speed and availability of hot hot water - we actually turned the unit down to 125..." Read more

"The installation was straightforward and so far the performance has been excellent. It's exactly what we were looking for...." Read more

"Works well, provides hot water quickly. Relatively easy install...." Read more

5 customers mention0 positive5 negative

Customers are dissatisfied with the water heater's pump. They mention that it wastes water, runs the water for a long time, and does not run continuously. They also say that the unit will become less efficient after three years and clog up with sediments. Customers also say the pump does not fill 1 bathtub with hot water.

"...Otherwise this unit will start to become less efficient after 3 years and will clog up with sediments after 7 years...." Read more

"...Since the pump doesn't run continuously, the water temperature does fluctuate a bit at first; it would be nice if the unit had a small holding tank..." Read more

"...Again if starting temp is 100 degrees. This will not fill 1 bathtub with hot water! Will be replacing it tomorrow with a standard water heater" Read more

"...also slow to heat water making you run the water a long time, wasting alot of water. I called the company and was told that is the way it is SORRY!" Read more

Self Install, Works as Expected
5 Stars
Self Install, Works as Expected
I installed this on my own with my Pops. Was quoted at $3K-4K to get it professionally installed. I specifically called Rinnai customer service about the warranty being void if it isn't professionally installed and they stated that this was not true. (although everywhere you look it says it should be installed by a professional) It is only void if it is found to be installed incorrectly. It was a ~$2K risk I was willing to take. The install was straight forward. Expect a couple trips to the local hardware store and some frustration but it truly isn't that complicated. Just read through the manual, it is pretty in depth and helpful. Fired the machine up for the first time and it ran like a champ. Shut the water off and turned it back on - it gave me error code 11 and wouldn't work again. Turns out my furnace (rated no more than .5 PSI) has been running on 2 PSI of natural gas for many years and the Rinnai was having none of it. It's rated for about .1ish to .4ish. Bottom line is it's worth a call to your local gas company to make sure you'll have the right pressure and supply. Once I had the pressure adjusted, it worked immediately. It has been running as expected the last couple days. There is a slightly longer delay to get the hot water (worst case, 2 stories up, morning, takes about 50 seconds to get hot at the faucet). But, this is something you'll want to come to terms with and for me, I'll take the savings over time. But 50 seconds is worst case, most of the time I don't even notice. I also did get the condensate neutralizer kit. Seems overpriced, but I didn't want to risk damage to any drainage pipe/septic tank. We have a well and sediment is what got our last tanked heater so I do plan on flushing this device at least twice per year. I think that is what gets a lot of people. Need to maintain your equipment so it can help maintain you!Pros: Efficient, small, accurate temp control, "endless" hot water, informative manual, good customer serviceCons: Small increase in time it takes to heat water, very slight dip in water pressure2 YEAR UPDATE:Overall, I've been extremely pleased. I have had zero issues with this water heater. Some notes:- This thing absolutely sips natural gas. To put it in perspective, only two devices use gas in our home - The water heater and a ~25 year old furnace (yeah, it's on its way out). During the winter our gas bill can be upwards of $90 for cold months. In the summer, when the only device using any gas is the heater, our bill is as low as $12 and that's with an $8 flat fee. Every home and family is different - we only have two adults and no dishwasher. But, I'm very satisfied and believe this thing will pay for itself.- I flush the water heater twice per year. This seems to work well. Personally, I wouldn't want to do it less frequently. We have well water and it's pretty hard. Once per year I will open it up and inspect the internals.- Speaking of a well... This is important information if you have one, too. If you're familiar with how a well works, the well pump kicks on when the pressure dips below a certain threshold and pumps water into the system until the pressure rises to another threshold, then stops. The heater must adjust the burners as the pressure increases to keep the outlet pressure at a steady temperature. The heater tries hard to do this, but isn't perfect. We have a shower probably 6 feet of pipe away from the outlet. In this shower, you can hear the well pump turn on and the pressure increases. The heater keeps up, but actually overshoots some. It's not scalding hot, but it's noticeable. So, it gets hotter for no apparent reason if you're not expecting it. This is ONLY true for appliances/sinks/showers RIGHT next to the heater. We have another shower directly above (10-14ft of pipe?) and the temp change is non-existent. The temperature dissipates by the time it gets there. I don't mind this, I actually kind of like it, but I completely understand if someone would be bothered by this.
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Top reviews from the United States

Reviewed in the United States on February 15, 2017
Customer image
5.0 out of 5 stars Self Install, Works as Expected
Reviewed in the United States on February 15, 2017
I installed this on my own with my Pops. Was quoted at $3K-4K to get it professionally installed. I specifically called Rinnai customer service about the warranty being void if it isn't professionally installed and they stated that this was not true. (although everywhere you look it says it should be installed by a professional) It is only void if it is found to be installed incorrectly. It was a ~$2K risk I was willing to take. The install was straight forward. Expect a couple trips to the local hardware store and some frustration but it truly isn't that complicated. Just read through the manual, it is pretty in depth and helpful. Fired the machine up for the first time and it ran like a champ. Shut the water off and turned it back on - it gave me error code 11 and wouldn't work again. Turns out my furnace (rated no more than .5 PSI) has been running on 2 PSI of natural gas for many years and the Rinnai was having none of it. It's rated for about .1ish to .4ish. Bottom line is it's worth a call to your local gas company to make sure you'll have the right pressure and supply. Once I had the pressure adjusted, it worked immediately. It has been running as expected the last couple days. There is a slightly longer delay to get the hot water (worst case, 2 stories up, morning, takes about 50 seconds to get hot at the faucet). But, this is something you'll want to come to terms with and for me, I'll take the savings over time. But 50 seconds is worst case, most of the time I don't even notice. I also did get the condensate neutralizer kit. Seems overpriced, but I didn't want to risk damage to any drainage pipe/septic tank. We have a well and sediment is what got our last tanked heater so I do plan on flushing this device at least twice per year. I think that is what gets a lot of people. Need to maintain your equipment so it can help maintain you!

Pros: Efficient, small, accurate temp control, "endless" hot water, informative manual, good customer service

Cons: Small increase in time it takes to heat water, very slight dip in water pressure

2 YEAR UPDATE:
Overall, I've been extremely pleased. I have had zero issues with this water heater. Some notes:
- This thing absolutely sips natural gas. To put it in perspective, only two devices use gas in our home - The water heater and a ~25 year old furnace (yeah, it's on its way out). During the winter our gas bill can be upwards of $90 for cold months. In the summer, when the only device using any gas is the heater, our bill is as low as $12 and that's with an $8 flat fee. Every home and family is different - we only have two adults and no dishwasher. But, I'm very satisfied and believe this thing will pay for itself.
- I flush the water heater twice per year. This seems to work well. Personally, I wouldn't want to do it less frequently. We have well water and it's pretty hard. Once per year I will open it up and inspect the internals.
- Speaking of a well... This is important information if you have one, too. If you're familiar with how a well works, the well pump kicks on when the pressure dips below a certain threshold and pumps water into the system until the pressure rises to another threshold, then stops. The heater must adjust the burners as the pressure increases to keep the outlet pressure at a steady temperature. The heater tries hard to do this, but isn't perfect. We have a shower probably 6 feet of pipe away from the outlet. In this shower, you can hear the well pump turn on and the pressure increases. The heater keeps up, but actually overshoots some. It's not scalding hot, but it's noticeable. So, it gets hotter for no apparent reason if you're not expecting it. This is ONLY true for appliances/sinks/showers RIGHT next to the heater. We have another shower directly above (10-14ft of pipe?) and the temp change is non-existent. The temperature dissipates by the time it gets there. I don't mind this, I actually kind of like it, but I completely understand if someone would be bothered by this.
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283 people found this helpful
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Reviewed in the United States on May 27, 2018
19 people found this helpful
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Top reviews from other countries

andrew szatkowski
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Reviewed in Canada on December 4, 2015
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Christopher
5.0 out of 5 stars Great product, great service
Reviewed in Canada on November 8, 2015
3 people found this helpful
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Marco
5.0 out of 5 stars Great unit at an unbeatable price
Reviewed in Canada on November 21, 2015
One person found this helpful
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al
5.0 out of 5 stars Simply installed it turned it on and it has worked ...
Reviewed in Canada on March 26, 2018
Excellent product
5.0 out of 5 stars I love Rinnai products, great value for money and absolutely reliable!
Reviewed in Canada on December 29, 2018