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A. O. Smith 10 GPM Natural Gas Outdoor Review

Name: A. O. Smith 10 GPM Natural Gas Outdoor
Brand: A. O. Smith
SKU: B06XZXYFNG

8.0Very good · out of 10Rated from the listing's specs, no buyer reviews yet

Written from the listing's specs, not from our own use · How we rate

On paper, the A. O. Smith 10 GPM Natural Gas Outdoor gets the important things right: a 10 GPM maximum flow, condensing efficiency and outdoor mounting that skips the flue. With a 15-year heat exchanger warranty as well, it suits a family that showers back to back before school.

Price$1,599.99Price on Sep 30, 2026 · may have changed

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

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Specifications

Brand	A. O. Smith
Category	Gas tankless water heaters
Fuel	Natural gas
Stated mounting location	Outdoor
Stated maximum flow	10 GPM
Stated gas input	199,000 BTU/h
Condensing design	Stated in the listing title
Stated warranty	15 years on the heat exchanger
ENERGY STAR	Stated in the listing
ASIN	B06XZXYFNG

Full listing title: A. O. Smith Tankless Water Heater Natural Gas - On Demand Hot Water - 10 GPM - Outdoor 199,000 BTU Condensing - ProLine® XE ATO-540H-N

Listing evidence

Fuel	Natural Gas Full listing title
Stated mounting location	Outdoor Full listing title
Stated maximum flow	10 GPM Full listing title
Stated gas input	199,000 BTU Full listing title
Condensing design	Condensing Full listing title

Updated October 2026

Exact listing, ASIN B06XZXYFNG

Rating from a published formula

Compared with its closest rivals

Two gas tankless heaters on natural gas too, with about the same flow, closest to it on our rating, each with a dated price.

Compare side by side ↗

A. O. Smith 10 GPM Natural Gas Outdoor

8.0Very good · out of 10$1,599.99 Price on Sep 30, 2026 · may have changed

Stated: 10 GPM · 199,000 BTU/h
Gas tankless water heaters

This product ↑

Rheem RTG 8.4 GPM Natural Gas Outdoor

7.7Very good · out of 10$964.10 Price on Sep 30, 2026 · may have changed

Stated: 8.4 GPM · 180,000 BTU/h
Gas tankless water heaters

See the review ↗

Westinghouse Natural Gas Outdoor

7.5Very good · out of 10$799.96 Price on Sep 30, 2026 · may have changed

Stated: 8.1 GPM · 180,000 BTU/h · 120 V
Gas tankless water heaters

See the review ↗

Up to 10 GPM from a 199,000 BTU burner

That's the maximum flow the listing states, and headline flows are usually quoted at a mild temperature rise. With January water coming in at 42 °F and a 105 °F shower, the rise is 63 °F and the real flow is lower; the maker's flow chart has that number. At 2 GPM a shower (our calculator's figure), the headline means room for three showers at once, fewer when January water comes in cold.

What it has going for it

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.

Mounts outside. No vent pipe through the roof or the rim joist: it hangs on an outside wall and breathes on its own. In a cold climate, ask what keeps it from freezing.

Mild winters or hard freezes?

Mild winters: hang it outside and you skip the vent run through the rim joist and the combustion-air questions indoors.

Hard freezes: the listing names no freeze protection, so ask the seller what keeps it from bursting before it goes on a north wall.

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
There is no good vent route inside your house

Skip it if…

You want a tight temperature hold: the listing claims no ±1 °F control
Your winters freeze hard and the outside wall has no power for freeze protection
You'd rather wait for buyer reviews: none are captured for this listing yet

Gas, mounting and what's in the box

What the A. O. Smith 10 GPM Natural Gas Outdoor listing names:

Up to 10 GPM
199,000 BTU/h input
Natural gas
Outdoor mounting
Condensing
PVC venting named

Warranty & support: 15-year warranty on the heat exchanger, as stated in the listing · ENERGY STAR named in the listing.

That is the maker's promise, not ours. Keep the invoice, register the A. O. Smith 10 GPM Natural Gas Outdoor if the maker asks, and read the install conditions: many tankless warranties need a licensed install and regular flushing.

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

Price and cost per GPM of stated flow

$1,599.99 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 $160.00 (price ÷ stated GPM, our arithmetic). That puts it in the pricier third of the 32 outdoor tankless heaters we have a price and a stated flow for.

Outside mounting saves the vent pipe; the gas line, the water lines and a weatherproof outlet are still a separate bill.

The button opens the exact listing (ASIN B06XZXYFNG), where today's price, stock and seller apply.

A better fit for your house?

Hard freezes where you live? The MIZUDO 199,000 BTU Natural Gas Indoor (9.2/10) is an indoor unit, out of the frost.

Only one bathroom? The Ranein 130,000 BTU Propane Outdoor (7.5/10) states up to 5.3 GPM.

Want to spend less? The Rheem RTG 8.4 GPM Natural Gas Outdoor (7.7/10) was listed at $964.10 on Sep 30, 2026.

Our take

The verdict

Our favourite thing about the A. O. Smith 10 GPM Natural Gas Outdoor is a 10 GPM maximum flow, closely followed by condensing efficiency. No buyer reviews yet, so the A. O. Smith 10 GPM Natural Gas Outdoor has to win you over on paper. Honestly, the catch: 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 FOGATTI Outdoor Propane Tankless first.

Check the price on Amazon ↗Affiliate link · price and stock on AmazonAll gas tankless water heaters →

Living with it

Install day

It goes on an outside wall, with gas, water and power run to it. Plan the gas line for 199,000 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. 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 clear leaves and wasp nests from the cabinet vents. Our flushing and descaling guide has the checklist.

The one thing we'd check first

Before the A. O. Smith 10 GPM Natural Gas Outdoor ships, check your gas line: 199,000 BTU/h is a lot of gas at once, so ask your plumber whether the existing line can feed it.

Before you buy

Your winter flow

10 GPM is the headline. In a northern January the water comes in near 42 °F, so a 105 °F shower needs a 63 °F rise and the real flow drops. Our flow-rate calculator runs the numbers for your house.

The outside wall

Pick a wall away from windows and doors, with power for the controls. Our indoor vs outdoor guide compares the two installs.

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 A. O. Smith 10 GPM Natural Gas Outdoor stacks up against the closest alternative, the FOGATTI Outdoor Propane Tankless.

Criterion	A. O. Smith 10 GPM Natural Gas Outdoor	FOGATTI Outdoor Propane Tankless
Our rating	8.0/10	9.1/10
Max flow	10 GPM	Not stated
Gas input	199,000 BTU/h	120,000 BTU/h
Efficiency	Condensing	Not stated
Temperature hold	Not stated	±1 °F stated
Buyer reviews	None captured	166 · 4.0/5

Pick the FOGATTI Outdoor Propane Tankless if you want our higher-rated option (9.1/10), with a stated ±1 °F hold; stay with the A. O. Smith 10 GPM Natural Gas Outdoor for more flow (10 GPM) and a bigger burner (199,000 BTU/h).

Compare side by side ↗See the FOGATTI Outdoor Propane Tankless review →

The score in detail

How we rated it

Spec-based rating on a 4.5–8.5 scale: 4.5 + average of the 4 criteria × 0.4. Capped at 8.5 because no customer evidence is included.

Key specifications

9 / 10

Build, warranty & certifications

8 / 10

Listing documentation

9 / 10

Fit & compatibility

9 / 10

This product has no captured buyer-review record yet, so its rating comes from the documented listing alone: four criteria scored out of 10 (key specifications; build, warranty and certifications; listing documentation; fit and compatibility), placed on a 4.5–8.5 scale. Read the full methodology.

Read the methodology →

Frequently asked questions

Is the A. O. Smith 10 GPM Natural Gas Outdoor any good?

We rate it 8.0/10 (very good). The rating comes from its documented listing alone, as no customer-review record is captured yet.

How much hot water can the A. O. Smith 10 GPM Natural Gas Outdoor deliver?

The listing states a maximum flow of 10 GPM and a gas input of 199,000 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 A. O. Smith 10 GPM Natural Gas Outdoor be installed indoors?

The listing says outdoor mounting. It only goes inside if the maker lists that exact model for indoor use, with the venting it specifies; a licensed gas installer confirms the spot under your local code.

What do you get with the A. O. Smith 10 GPM Natural Gas Outdoor?

Its listing states up to 10 GPM, a condensing heat exchanger, outdoor mounting that skips the flue 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 A. O. Smith 10 GPM Natural Gas Outdoor?

Your winter flow: 10 GPM is the headline. In a northern January the water comes in near 42 °F, so a 105 °F shower needs a 63 °F rise and the real flow drops. Our flow-rate calculator runs the numbers for your house. The outside wall: pick a wall away from windows and doors, with power for the controls. Our indoor vs outdoor guide compares the two installs. 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 A. O. Smith 10 GPM Natural Gas Outdoor?

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 A. O. Smith 10 GPM Natural Gas Outdoor yourselves?

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

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