The 5 tankless heaters we'd put in for the morning rushTop 5 tankless heaters → See the ranking
Compare models
Rheem RTG 9.5 GPM Natural Gas Indoor

Product images: Amazon listings

Rheem RTG 9.5 GPM Natural Gas Indoor Review

7.2Good · out of 10#5 of 5 in our Indoor Natural Gas Tankless Water Heaters ranking

Written from the listing and 88 buyer reviews, not from our own use · How we rate

We like the Rheem RTG 9.5 GPM Natural Gas Indoor for the mix: up to 9.5 GPM, temperature held within ±1 °F and built-in freeze protection. One of our top 5 indoor natural gas tankless water heaters, it is made for a family that showers back to back before school.

Variants of this model

These are sold as variants of one listing family. Each variant has its own page.

Price$1,047.92Price on Sep 30, 2026 · may have changed
Check the price on Amazon ↗ Rheem RTG 9.5 GPM Natural Gas Indoor (opens in a new tab)Affiliate link · price and stock on Amazon
Compare side by side ↗
Specifications
BrandRheem
CategoryGas tankless water heaters
FuelNatural gas
Stated mounting locationIndoor
Stated maximum flow9.5 GPM
Stated gas input199,900 BTU/h
Flow at a stated rise9.5 GPM at a 35 °F rise
Temperature hold±1 °F, per the listing
Freeze protectionStated in the listing
Stated warranty15 years on the heat exchanger
Buyer reviews88 · 4.2/5
ASINB0C828PN5K

Full listing title: Rheem RTG Series 9.5 GPM Natural Gas Tankless Water Heater Indoor | 199,900 BTUs High Efficiency On Demand, Continuous Hot Water | Non-Condensing

Listing evidence
FuelNatural Gas Full listing title
Stated mounting locationIndoor Full listing title
Stated maximum flow9.5 GPM Full listing title
Stated gas input199,900 BTUs Full listing title
Updated October 2026
Exact listing, ASIN B0C828PN5K
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 ↗

Rheem RTG 9.5 GPM Natural Gas Indoor

Rheem RTG 9.5 GPM Natural Gas Indoor

7.2Good · out of 10$1,047.92 Price on Sep 30, 2026 · may have changed
  • Stated: 9.5 GPM · 199,900 BTU/h
  • 88 buyer reviews
  • Gas tankless water heaters
This product ↑
Rheem RTGH 8.4 GPM Natural Gas Indoor

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 9.5 GPM from a 199,900 BTU burner

That's the maximum flow the listing states, at a 35 °F rise. In January the water comes in nearer 42 °F, so a 105 °F shower needs a 63 °F rise and the unit gives you less; the flow chart in the manual shows how much less. 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

±1 °F hold. The burner adjusts as the flow changes, so the shower stays where you set it when somebody opens the kitchen tap. On paper, at least: that is the seller's claim.

Freeze protection. Stated in the listing. Useful in a garage, a crawl space or a cabin that sits empty in winter, as long as the unit keeps power.

One shower at a time, or two?

Two at once: up to 9.5 GPM, and our calculator counts a shower at 2 GPM, so that's two showers and a tap on paper. The listing gives 9.5 GPM at a 35 °F rise and the seller says it serves up to 3 showers. How much of it is left in January is on the maker's flow chart, at a 63 °F rise.

One at a time: then it's more heater than you need, with the gas line and the vent to match. A smaller unit may do the job for less.

Great for you if…

  • Two showers and the dishwasher run at the same time in your house
  • A shower that suddenly runs cold drives you mad
  • It will live in a garage, a cabin or another cold spot

Skip it if…

  • Star ratings come first for you: 4.2/5 is below the 4.3 average of this ranking
  • You simply want our top pick: that's the MIZUDO 199,000 BTU Natural Gas Indoor (9.2/10)
  • You want the high-efficiency kind: the listing doesn't call it condensing

Gas, venting and what's in the box

What the Rheem RTG 9.5 GPM Natural Gas Indoor listing names:

  • Up to 9.5 GPM
  • 9.5 GPM at a 35 °F rise
  • 199,900 BTU/h input
  • Natural gas
  • Indoor mounting
  • ±1 °F temperature hold claimed
  • Freeze protection named
  • CSA, ETL or UL mark named

Warranty & support: 15-year warranty on the heat exchanger, as stated in the listing · CSA, ETL or UL certification named in the listing.

That is the maker's promise, not ours. Keep the invoice, register the Rheem RTG 9.5 GPM Natural Gas Indoor if the maker asks, and read the install conditions: many tankless warranties need a licensed install and regular flushing.

The installation manual has the last word on venting, gas line and clearances; your installer reads it before you order.

Rheem RTG 9.5 GPM Natural Gas Indoor, view 3

Price and cost per GPM of stated flow

$1,047.92 Price on Sep 30, 2026 · may have changed

At the price on Sep 30, 2026, each GPM of stated maximum flow works out at about $110.31 (price ÷ stated GPM, our arithmetic). That puts it around the middle of the 45 indoor gas tankless heaters we have a price and a stated flow for.

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 B0C828PN5K), where today's price, stock and seller apply. Sizes and variants of the same family often sit at different prices.

Rheem RTG 9.5 GPM Natural Gas Indoor, view 4

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.

Want the high-efficiency kind? The Rinnai RU199iN Condensing (7.8/10) is a condensing unit, per its listing.

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

Our take

The verdict

The Rheem RTG 9.5 GPM Natural Gas Indoor earns its place with up to 9.5 GPM and temperature held within ±1 °F. Only 88 buyers have rated it so far (4.2/5), so treat the score as an early read. Honestly, the catch: their 4.2/5 average sits under the 4.3 of this ranking. We'd pick it if two showers and the dishwasher run at the same time in your house; otherwise, put it next to the Rheem RTGH 8.4 GPM Natural Gas Indoor first.

Check the price on Amazon ↗ Rheem RTG 9.5 GPM Natural Gas Indoor (opens in a new tab)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. Plan the gas line for 199,900 BTU/h; a licensed pro handles it, and often a permit.

The first shower

Hot water arrives after the cold already in the pipes, then stays (within ±1 °F, per the listing). 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. The listing's 9.5 GPM is at a 35 °F rise; a northern winter asks for about 63 °F. 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), and clean the inlet filter. Our flushing and descaling guide has the checklist.

What buyers say

Buyers give it 4.2/5, a solid record, slightly below this ranking's 4.3 average. 88 reviews is still a modest pile, so a handful of new ones can move it.

The numbers
Buyer rating
4.2/5
Reviews
88
This ranking's average
4.3/5

The one thing we'd check first

Before the Rheem RTG 9.5 GPM Natural Gas Indoor goes in your cart, check your winter rise: it is rated 9.5 GPM at a 35 °F rise, and a northern winter asks for nearer 63 °F.

Before you buy

Your winter flow

Find your winter inlet temperature (your water utility or a thermometer at the cold tap in January), subtract it from 105 °F, and read the maker's flow chart at that rise. 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 199,900 BTU/h. Get that quote before you order; our installation guide lists what they will ask.

The warranty terms

15 years are stated on the heat exchanger. Read what it requires: a licensed install, the gas type and regular flushing are the usual conditions.

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 Rheem RTG 9.5 GPM Natural Gas Indoor stacks up against the closest alternative in our ranking, the Rheem RTGH 8.4 GPM Natural Gas Indoor.

CriterionRheem RTG 9.5 GPM Natural Gas IndoorRheem RTGH 8.4 GPM Natural Gas Indoor
Our rating7.2/107.3/10
Max flow9.5 GPM8.4 GPM
Gas input199,900 BTU/h157,000 BTU/h
EfficiencyNot statedCondensing
Buyer reviews88 · 4.2/560 · 4.4/5

Pick the Rheem RTGH 8.4 GPM Natural Gas Indoor if you want our higher-rated option (7.3/10), with a condensing design and a higher buyer rating (4.4/5); stay with the Rheem RTG 9.5 GPM Natural Gas Indoor for more flow (9.5 GPM) and a bigger burner (199,900 BTU/h).

Compare side by side ↗See the Rheem RTGH 8.4 GPM Natural Gas Indoor review →
The score in detail

How we rated it

Our score: 7.2/10

Buyer rating (45%)

37.8 / 45

4.2/5 average

Review volume (35%)

18.4 / 35

88 buyer reviews

Documented specifications (20%)

15.8 / 20

79/100 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 shown on this variant's own listing page (not shared with the other Rheem RTG variants), 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 Rheem RTG 9.5 GPM Natural Gas Indoor any good?

We rate it 7.2/10 (good), #5 of 5 in our indoor natural gas tankless water heater ranking. It is based on 88 buyer reviews averaging 4.2/5 and the specifications stated in the listing.

How much hot water can the Rheem RTG 9.5 GPM Natural Gas Indoor deliver?

The listing states a maximum flow of 9.5 GPM and a gas input of 199,900 BTU/h. 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 Rheem RTG 9.5 GPM Natural Gas Indoor 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 Rheem RTG 9.5 GPM Natural Gas Indoor?

Its listing states up to 9.5 GPM, temperature held within ±1 °F, freeze protection and a 15-year heat exchanger warranty. 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 Rheem RTG 9.5 GPM Natural Gas Indoor?

Your winter flow: find your winter inlet temperature (your water utility or a thermometer at the cold tap in January), subtract it from 105 °F, and read the maker's flow chart at that rise. 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 199,900 BTU/h. Get that quote before you order; our installation guide lists what they will ask. The warranty terms: 15 years are stated on the heat exchanger. Read what it requires: a licensed install, the gas type and regular flushing are the usual conditions. 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 Rheem RTG 9.5 GPM Natural Gas Indoor?

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 Rheem RTG 9.5 GPM Natural Gas Indoor yourselves?

No, we haven't used it ourselves. Everything on this page comes from its listing and 88 buyer reviews, read line by line and weighed with our published formula.

Keep comparing

If the Rheem RTG 9.5 GPM Natural Gas Indoor hasn't sold you yet, see where it ranks or browse all gas tankless water heaters.

Where it ranks

Best Tankless Water Heaters in 2026 →
Gas tankless water heaters ↗All Rheem productsComparison toolAll product reviews