Head-to-head · Best Tankless Water Heaters

Rheem RTEX-13 vs Rinnai RU199iN

Which is the better buy? Side-by-side on rating, price, strengths, and watch-outs — with the published ratings we averaged to get there.

The short answer

Rinnai RU199iN comes out ahead by a clear margin (4.1 vs 4.5). The gap is mostly about Large households with gas service that need whole-home hot water for multiple bathrooms at once. — read the strengths below before deciding.

Ranked #5 in Best Tankless Water Heaters

Rheem RTEX-13

4.1

$278as of Jun 7

The Rheem RTEX-13 is the best bang-for-the-buck pick — Bob Vila's value choice and Reviewed's budget electric unit, praised for a '99 percent efficiency rating' at the lowest price in this group. With about 3.17 GPM it's a point-of-use heater designed, as Reviewed notes, 'to support one to two appliances in a single location, such as a shower in the bathroom.' It won't run a whole house, but for a remote bathroom, an addition, or as a booster, its compact size, efficiency, and low cost make it the obvious affordable choice.

Strengths

— Lowest price of the group — excellent point-of-use value
— Roughly 99% energy efficiency with self-modulating control
— Compact 13 kW unit easy to install near a single fixture

Watch-outs

— Only ~3.17 GPM — supports one to two fixtures, not a whole home
— Not suitable as a primary whole-house heater in most homes
— Flow drops further with cold inlet water

$278 · Check Price on Amazon Full review →

Higher ratedRanked #1 in Best Tankless Water Heaters

Rinnai RU199iN

4.5

$1,177.78as of Jun 7

The Rinnai RU199iN is the best overall gas tankless water heater for whole-home use, delivering up to 11 GPM and 199,000 BTU — enough hot water for up to five appliances or a 3-4 bathroom house running simultaneously. Bob Vila named the Rinnai SENSEI line its best overall, and reviewers consistently praise the condensing efficiency (0.95 UEF, which qualifies for the federal tax credit) and Wi-Fi control. It is the priciest pick and needs gas service and condensing venting, but for a busy household in any climate, nothing here matches its capacity.

Strengths

— Industry-leading 11 GPM flow rate handles a 3-4 bathroom home at once
— Condensing design with a 0.95 UEF qualifies for the 30% federal tax credit
— 199,000 BTU output keeps up even in cold inlet climates

Watch-outs

— Highest upfront and installation cost of the group
— Requires gas service and proper condensing venting
— Overkill for a small home or apartment

$1,177.78 · Check Price on Amazon Full review →

How they stack up

Rheem RTEX-13

The Rheem RTEX-13 is the smallest and cheapest unit here, a point-of-use heater at about 3.17 GPM versus the whole-home flow of the Stiebel Eltron Tempra 36 Plus and EcoSmart ECO 27, and far below the gas Rinnai RU199iN and Takagi T-H3-DV-N. It's not a whole-home replacement, but it's the value leader for single-fixture jobs.

Rinnai RU199iN

The Rinnai RU199iN is the highest-capacity unit here, with an 11 GPM gas flow rate that dwarfs the electric Stiebel Eltron Tempra 36 Plus (7.5 GPM), EcoSmart ECO 27, and Rheem RTEX-13. Only the gas Takagi T-H3-DV-N approaches it, and the RU199iN edges it on UEF efficiency. It costs the most upfront and, unlike the electric units, requires gas and condensing venting.

Specs side-by-side

Spec	Rheem RTEX-13	Rinnai RU199iN
Fuel	Electric	Natural gas
Power	13 kW	—
Flow Rate	Up to ~3.17 GPM	Up to 11 GPM
Efficiency	~99%	—
Control	Self-modulating, digital readout	—
Voltage	240V	—
Venting	None required	—
Use	Point-of-use / single fixture	—
Type	—	Condensing
BTU	—	15,000 - 199,000
UEF	—	0.95
Connectivity	—	Wi-Fi (Rinnai app)
Installation	—	Indoor
Tax Credit	—	Qualifies (UEF 0.95+)

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