Head-to-head · Best Tankless Water Heaters

EcoSmart ECO 27 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.

The short answer

Takagi T-H3-DV-N comes out ahead by a narrow margin (4.2 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 #4 in Best Tankless Water Heaters

EcoSmart ECO 27

4.2

$466.24as of Jun 7

The EcoSmart ECO 27 is the efficient electric value pick — a 27 kW self-modulating unit that This Old House rated 4.3/5 for the EcoSmart line, praising that it 'can save you up to 50% on your water-heating bill thanks to its self-modulating temperature control.' It delivers up to 6.5 GPM in warm climates, enough for a small whole home, from a compact wall-mounted box with precise digital temperature control. Its flow drops in cold-inlet regions and it needs substantial electrical service, but for warm-climate homes it's a strong, affordable electric option.

Strengths

— Self-modulating technology uses only the energy needed
— Up to 6.5 GPM in warm climates, enough for small whole-home use
— Compact 17 x 17 x 3.5-inch wall-mounted footprint

Watch-outs

— Flow rate drops sharply in cold-inlet climates (down to ~2.7 GPM)
— 27 kW draw requires significant electrical service
— Best suited to warm regions or smaller homes

$466.24 · Check Price on Amazon Full review →

Higher ratedRanked #3 in Best Tankless Water Heaters

Takagi T-H3-DV-N

4.3

$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 with a commercial-grade copper-alloy heat exchanger that suits heavier residential use like recirculation or space heating. It's Ultra-Low NOx compliant, important 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, but 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 →

How they stack up

EcoSmart ECO 27

The EcoSmart ECO 27 is the mid-tier electric option, more affordable than the whole-home Stiebel Eltron Tempra 36 Plus but with lower and more climate-dependent flow (2.7-6.5 GPM). It lacks the Stiebel's Advanced Flow Control. It outflows the point-of-use Rheem RTEX-13 but, like all electric units here, trails the gas Rinnai RU199iN and Takagi T-H3-DV-N.

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	EcoSmart ECO 27	Takagi T-H3-DV-N
Fuel	Electric	Natural gas
Power	27 kW	—
Flow Rate	2.7 - 6.5 GPM (climate-dependent)	Up to 10 GPM
Control	Self-modulating, digital (1-degree)	—
Dimensions	17 x 17 x 3.5 in	—
Venting	None required	—
Mounting	Wall-mounted	—
Best Climate	Warm / southern U.S.	—
Type	—	Condensing, Ultra-Low NOx
BTU	—	15,000 - 199,000
UEF	—	0.93
Heat Exchanger	—	Commercial-grade copper alloy
Installation	—	Indoor, direct vent
Use	—	DHW, recirculation, space heating

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