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Rinnai RU199iN Condensing Review

Name: Rinnai RU199iN Condensing
Brand: Rinnai
SKU: B07CW426QZ

7.8Very good · out of 10#3 of 5 in our Indoor Natural Gas Tankless Water Heaters ranking

Written from the listing and 388 buyer reviews, not from our own use · How we rate

If you're after an 11 GPM maximum flow, the Rinnai RU199iN Condensing delivers, with condensing efficiency on top. It made our top 5 indoor natural gas tankless water heaters: a great match for a busy house where two showers and the dishwasher overlap.

See current price ↗Prices change often: the listing shows today's.

Check the price on Amazon ↗Affiliate link · price and stock on Amazon

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Specifications

Brand	Rinnai
Category	Gas tankless water heaters
Fuel	Natural gas
Stated mounting location	Indoor
Stated maximum flow	11 GPM
Condensing design	Stated in the listing title
Wi-Fi	With an optional module
ENERGY STAR	Stated in the listing
Buyer reviews	388 · 4.4/5
ASIN	B07CW426QZ

Full listing title: Rinnai RU199iN Condensing Tankless Hot Water Heater, 11 GPM, Natural Gas, Indoor Installation

Listing evidence

Fuel	Natural Gas Full listing title
Stated mounting location	Indoor Full listing title
Stated maximum flow	11 GPM Full listing title
Condensing design	Condensing Full listing title

Updated October 2026

Exact listing, ASIN B07CW426QZ

Rating from a published formula

Compared with its closest rivals

The two picks next to it in our indoor natural gas tankless water heaters ranking, with their rating and a dated price.

Compare side by side ↗

Rinnai RU199iN Condensing

7.8Very good · out of 10See current price ↗

Stated: 11 GPM
388 buyer reviews
Gas tankless water heaters

This product ↑

Ranein 190,000 BTU Natural Gas Indoor

7.9Very good · out of 10$699 Price on Sep 30, 2026 · may have changed

Stated: 8.5 GPM · 190,000 BTU/h
710 buyer reviews
Gas tankless water heaters

See the review ↗

Rheem RTGH 8.4 GPM Natural Gas Indoor

7.3Good · out of 10$1,168.99 Price on Sep 30, 2026 · may have changed

Stated: 8.4 GPM · 157,000 BTU/h
60 buyer reviews
Gas tankless water heaters

See the review ↗

Up to 11 GPM

That's the maximum flow the listing states, and headline flows are usually quoted at a mild temperature rise. Up north in winter, 42 °F water has to climb 63 °F to reach a 105 °F shower, and the flow drops with it. Ask for the flow chart and read that line. Counting 2 GPM per shower, as our calculator does, that's room for three showers at once, fewer when January water comes in cold.

Why it made our list

What changes in the morning shower rush

Condensing. A second heat exchanger pulls heat out of the exhaust before it leaves, so more of the gas you pay for ends up in the water. The exhaust runs cool enough for plastic vent pipe, and the condensate needs a drain.

One shower at a time, or two?

Two at once: up to 11 GPM, and our calculator counts a shower at 2 GPM, so that's two showers and a tap on paper. How much of it is left in January is on the maker's flow chart, at a 63 °F rise.

One at a time: a smaller unit covers that for less money.

Great for you if…

Two showers and the dishwasher run at the same time in your house
You care about the gas bill as much as the hot water
You trust a long track record: 388 buyer reviews

Skip it if…

You want a tight temperature hold: the listing claims no ±1 °F control
You simply want our top pick: that's the MIZUDO 199,000 BTU Natural Gas Indoor (9.2/10)
The far bathroom already waits a minute for hot water: no built-in recirculation is named

Gas, venting and what's in the box

What the Rinnai RU199iN Condensing listing names:

Up to 11 GPM
Natural gas
Indoor mounting
Condensing
Wi-Fi with an add-on module

Read the installation manual for the vent, the gas line size and the clearances before you order; it overrides anything above.

Price and availability

See current price ↗

We have no recent price on file for this listing, so we don't print an old one.

Count the install in the budget: vent pipe, possibly a 3/4" gas line, and a licensed plumber or gas fitter.

The button opens the exact listing (ASIN B07CW426QZ), where today's price, stock and seller apply.

A better fit for your house?

No easy route for a vent pipe? The A. O. Smith 10 GPM Natural Gas Outdoor (8.0/10) mounts on an outside wall, per its listing.

On propane, not natural gas? The Rheem RTGH 9.5 GPM Propane Indoor (7.8/10) runs on propane.

Only one bathroom? The ThermoMate CZ422LP Propane Indoor (7.8/10) states up to 5 GPM.

Our take

The verdict

What we'd buy the Rinnai RU199iN Condensing for is an 11 GPM maximum flow, with condensing efficiency as a bonus. 388 buyers back that up with 4.4/5, about as reassuring as a review record gets. The one thing that bugs us: no stated temperature hold, while most picks here claim ±1 °F. We'd pick it if two showers and the dishwasher run at the same time in your house; otherwise, put it next to the Ranein 190,000 BTU Natural Gas Indoor first.

Check the price on Amazon ↗Affiliate link · price and stock on AmazonSee the indoor natural gas tankless water heaters ranking →

Living with it

Install day

Old tank out, unit on the wall, vent through the wall or the roof. a licensed pro handles it, and often a permit.

The first shower

Hot water arrives after the cold already in the pipes, then stays. A trickle from a bathroom tap may not light the burner; open it a bit more.

The first winter

January water comes in colder, so the same unit gives fewer GPM. Stagger the showers if you sized it tight.

Once a year

Flush the heat exchanger with a pump and a descaler (the service valves make it an hour's job), check the condensate drain and the neutralizer, and clean the inlet filter. Our flushing and descaling guide has the checklist.

What buyers say

Buyers give it 4.4/5, a strong record, above this ranking's 4.3 average. And with 388 reviews behind it, that number is hard to argue with.

The numbers

Buyer rating: 4.4/5
Reviews: 388
This ranking's average: 4.3/5

The one thing we'd check first

Before you order the Rinnai RU199iN Condensing, check your winter flow: 11 GPM is a best case, so run your January numbers in our calculator first.

Before you buy

Your winter flow

Count the fixtures that run together on a busy morning (our calculator uses 2 GPM a shower, 1.5 for the kitchen), then compare with the maker's chart. Our sizing guide shows how.

Vent and gas line

A licensed plumber or gas fitter confirms the vent route, the combustion air and a gas line that can deliver its full input. Get that quote before you order; our installation guide lists what they will ask.

The condensate

A condensing unit drips acidic water that needs a drain, often through a neutralizer. Our condensing guide explains the extra parts.

Flushing

Hard water scales the heat exchanger. Service valves on the water lines turn the yearly flush into an hour with a bucket and a pump; our flushing and descaling guide shows the routine.

How it compares

How the Rinnai RU199iN Condensing stacks up against the closest alternative in our ranking, the Ranein 190,000 BTU Natural Gas Indoor.

Criterion	Rinnai RU199iN Condensing	Ranein 190,000 BTU Natural Gas Indoor
Our rating	7.8/10	7.9/10
Max flow	11 GPM	8.5 GPM
Gas input	Not stated	190,000 BTU/h
Efficiency	Condensing	Not stated
Warranty	Not stated	2 years
Buyer reviews	388 · 4.4/5	710 · 4.2/5

Pick the Ranein 190,000 BTU Natural Gas Indoor if you want our higher-rated option (7.9/10), with a bigger burner (190,000 BTU/h) and a longer stated warranty (2 years); stay with the Rinnai RU199iN Condensing for more flow (11 GPM) and a condensing design.

Compare side by side ↗See the Ranein 190,000 BTU Natural Gas Indoor review →

The score in detail

How we rated it

Our score: 7.8/10

Buyer rating (45%)

39.6 / 45

4.4/5 average

Review volume (35%)

24.5 / 35

388 buyer reviews

Documented specifications (20%)

14.0 / 20

70/100 listing documentation score

Our rating is an evidence index on a 0–10 scale. It is not a buyer star rating, and we have not used the product ourselves.

Buyer rating (45%): the captured average for this exact listing, damped when there are fewer than 50 reviews.
Review volume (35%): more reviews mean more reliable evidence, on a logarithmic scale up to 5,000 reviews.
Documented specifications (20%): how completely the exact listing documents the attributes that matter.

Our editors then look at how it compares with the other heaters we rate. A commission is never an input to the rating. Read the full methodology.

Read the methodology →

Frequently asked questions

Is the Rinnai RU199iN Condensing any good?

We rate it 7.8/10 (very good), #3 of 5 in our indoor natural gas tankless water heater ranking. It is based on 388 buyer reviews averaging 4.4/5 and the specifications stated in the listing.

How much hot water can the Rinnai RU199iN Condensing deliver?

The listing states a maximum flow of 11 GPM. The headline flow is a mild-weather number: with cold winter water coming in, the same unit gives you less. Read the maker's flow chart at your winter rise, or let our flow-rate calculator do the sums.

Can the Rinnai RU199iN Condensing be installed indoors?

Yes, the listing says indoor mounting. That means a vent route to the outside, combustion air and a gas line sized for the unit, all as the maker and your local code require. A licensed plumber or gas fitter sorts that out.

What do you get with the Rinnai RU199iN Condensing?

Its listing states up to 11 GPM and a condensing heat exchanger. These are the seller's figures, not our measurements: how steady the temperature is in your shower and how it copes with your winter water can't be read from a listing.

What should I check before ordering the Rinnai RU199iN Condensing?

Your winter flow: count the fixtures that run together on a busy morning (our calculator uses 2 GPM a shower, 1.5 for the kitchen), then compare with the maker's chart. Our sizing guide shows how. Vent and gas line: a licensed plumber or gas fitter confirms the vent route, the combustion air and a gas line that can deliver its full input. Get that quote before you order; our installation guide lists what they will ask. The condensate: a condensing unit drips acidic water that needs a drain, often through a neutralizer. Our condensing guide explains the extra parts. Flushing: hard water scales the heat exchanger. Service valves on the water lines turn the yearly flush into an hour with a bucket and a pump; our flushing and descaling guide shows the routine.

Where can I buy the Rinnai RU199iN Condensing?

We link to the exact listing on Amazon, where today's price, stock and seller apply. It is an affiliate link, and it has no effect on the rating.

Have you used the Rinnai RU199iN Condensing yourselves?

No, we haven't used it ourselves. Everything on this page comes from its listing and 388 buyer reviews, read line by line and weighed with our published formula.

Keep comparing

If the Rinnai RU199iN Condensing hasn't sold you yet, see where it ranks, read the guides that feature it or browse all gas tankless water heaters.

Where it ranks

Best Tankless Water Heaters in 2026 →Best High-Efficiency Condensing Tankless Water Heaters in 2026 →Best Gas Tankless Water Heaters in 2026 →Best Whole-House Tankless Water Heaters in 2026: Gas and Electric →

Read this before you buy

Tankless water heater buying guide: how to choose one →Gas vs electric tankless water heater: which should you buy? →Tankless water heater sizing: how many GPM do you need? →Condensing vs non-condensing tankless water heaters: the difference →

Gas tankless water heaters ↗All Rinnai products Comparison tool All product reviews