Head-to-head · Best Tankless Water Heaters

Rheem RTEX-13 vs Takagi T-H3-DV-N

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

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The short answer

Takagi T-H3-DV-N comes out ahead by a narrow margin (4.1 vs 4.3). The gap is mostly about Homes with gas service wanting a rugged, high-capacity condensing unit, including for recirculation. — read the strengths below before deciding.

Ranked #5 in Best Tankless Water Heaters

Rheem RTEX-13

4.1

2 sourcesall derived$271.48as of Aug 1

The Rheem RTEX-13 is the best bang for the buck, 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. At 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. For a remote bathroom, an addition, or 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

$271.48 · Check Price on Amazon Full review →

Higher ratedRanked #3 in Best Tankless Water Heaters

Takagi T-H3-DV-N

4.3

2 sourcesall derived$1,500as of Jun 7

The Takagi T-H3-DV-N is Bob Vila's best condensing gas pick: a 10 GPM, 199,000 BTU unit built around a commercial-grade copper-alloy heat exchanger that suits heavier residential use like recirculation or space heating. It's Ultra-Low NOx compliant, which matters in strict-emission states, and Bob Vila praised that it 'provides plenty of heating power for most households.' Its 0.93 UEF trails the Rinnai RU199iN slightly and it lacks the Rinnai's smart-app polish. As a rugged, high-capacity condensing gas heater, it's an excellent whole-home choice.

Strengths

— Condensing gas design delivering up to 10 GPM
— 199,000 BTU handles most whole-home demand
— Commercial-grade copper-alloy heat exchanger for heavy use

Watch-outs

— Slightly lower UEF (0.93) than the Rinnai RU199iN
— Requires gas service and condensing venting
— Professional installation needed

$1,500 · Check Price on Amazon Full review →

Derived means the reviewer published no score, so one was inferred from their written verdict. Everything else is a number the publisher printed. How we rank.

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.

Takagi T-H3-DV-N

The Takagi T-H3-DV-N is the second gas unit here, matching much of the Rinnai RU199iN's 199,000 BTU output at a slightly lower 10 GPM and 0.93 UEF. Like the Rinnai it far outflows the electric Stiebel Eltron Tempra 36 Plus, EcoSmart ECO 27, and Rheem RTEX-13, but it offers fewer smart features than the Wi-Fi-equipped Rinnai.

Specs side-by-side

Spec	Rheem RTEX-13	Takagi T-H3-DV-N
Fuel	Electric	Natural gas
Flow Rate	Up to ~3.17 GPM	Up to 10 GPM
Efficiency	~99%	0.93
Power	13 kW	199,000 BTU/H
BTU	2.3-2.3 GPM	15,000 - 199,000
Type	Electric	Condensing, Ultra-Low NOx
Installation	Indoor, point-of-use	Indoor, direct vent
Dimensions	8.25"W x 12.62"H	17.75"W x 22.5"H

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