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The Best 5Reviewed by Mike Hunter·May 24, 2026

Best Tankless Water Heaters

Top tankless water heaters reviewed and ranked across gas vs electric, GPM flow rate, efficiency, and value.

Quick answer

Rinnai RU199iN is our top pick for tankless water heaters — an averaged 4.5/5 across 3 published reviews at about $1,177.78. Runner-up: Stiebel Eltron Tempra 36 Plus (~$789.11).

Read the Rinnai RU199iN review →$1,177.78 · Check Price on Amazon

At a glance

Tap any product for the full review
1Rinnai RU199iNTop Score
(3 sources)
$1,177.78Best for: Large households with gas service that need whole-home hot water for multiple bathrooms at once.
$1,177.78 · Check Price on Amazon
2Stiebel Eltron Tempra 36 Plus
(3 sources)
$789.11Best for: All-electric homes in moderate climates that need whole-house hot water without gas or venting.
$789.11 · Check Price on Amazon
3Takagi T-H3-DV-N
(3 sources)
$1,500Best for: Homes with gas service wanting a rugged, high-capacity condensing unit, including for recirculation.
$1,500 · Check Price on Amazon
4EcoSmart ECO 27
(3 sources)
$466.24Best for: Warm-climate homes wanting an efficient, affordable electric unit for small whole-home use.
$466.24 · Check Price on Amazon
5Rheem RTEX-13
(3 sources)
$278Best for: Single-fixture point-of-use needs — a remote bathroom, addition, or booster on a budget.
$278 · Check Price on Amazon
Verdict is reader-supported. As an Amazon Associate we earn from qualifying purchases. Some links on this page are affiliate links — if you click through and buy, we may earn a small commission at no extra cost to you. Our ratings are sourced from independent publications, not sponsors.
Reviews aggregated from
BobvilaReviewedThisoldhouseRinnai.usTakagi.comPexuniverse.comAmazonSupplyhouse.com

The full ranking

How we rank →
Rinnai RU199iN
#1 · Top Score
★ Premium Pick
Best for: Large households with gas service that need whole-home hot water for multiple bathrooms at once.
Rinnai RU199iN
from 3 sources$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
Watch-outs
  • — Highest upfront and installation cost of the group
  • — Requires gas service and proper condensing venting
$1,177.78 · Check Price on AmazonFull review →vs. Stiebel Eltron Tempra 36 Plus →
Stiebel Eltron Tempra 36 Plus
#2
Best for: All-electric homes in moderate climates that need whole-house hot water without gas or venting.
Stiebel Eltron Tempra 36 Plus
from 3 sources$789.11as of Jun 7

The Stiebel Eltron Tempra 36 Plus is the clear frontrunner for whole-home electric tankless heating, delivering up to 7.5 GPM from its 36 kW heating element. This Old House rated the Stiebel Eltron electric line 4.4/5, and Bob Vila named it best electric, both praising its silent operation and standout Advanced Flow Control, which dynamically reduces flow rather than letting cold-water sandwiching occur when demand exceeds capacity. It needs serious electrical service and performs best in moderate climates, but for an all-electric home it is the top whole-house pick.

Strengths
  • — Best whole-home electric option, up to 7.5 GPM at 36 kW
  • — Advanced Flow Control throttles flow to prevent cold-water sandwiching
Watch-outs
  • — Needs substantial electrical service — often a panel upgrade
  • — Flow rate drops in cold climates with high temperature rise
$789.11 · Check Price on AmazonFull review →vs. Rinnai RU199iN →
Takagi T-H3-DV-N
#3
Best for: Homes with gas service wanting a rugged, high-capacity condensing unit, including for recirculation.
Takagi T-H3-DV-N
from 3 sources$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
Watch-outs
  • — Slightly lower UEF (0.93) than the Rinnai RU199iN
  • — Requires gas service and condensing venting
$1,500 · Check Price on AmazonFull review →vs. Rinnai RU199iN →
EcoSmart ECO 27
#4
Best for: Warm-climate homes wanting an efficient, affordable electric unit for small whole-home use.
EcoSmart ECO 27
from 3 sources$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
Watch-outs
  • — Flow rate drops sharply in cold-inlet climates (down to ~2.7 GPM)
  • — 27 kW draw requires significant electrical service
$466.24 · Check Price on AmazonFull review →vs. Rinnai RU199iN →
Rheem RTEX-13
#5
Best for: Single-fixture point-of-use needs — a remote bathroom, addition, or booster on a budget.
Rheem RTEX-13
from 3 sources$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
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
$278 · Check Price on AmazonFull review →vs. Rinnai RU199iN →

Spec comparison

5 products
SpecRinnai RU199iNStiebel Eltron Tempra 36 PlusTakagi T-H3-DV-NEcoSmart ECO 27Rheem RTEX-13
FuelNatural gasElectricNatural gasElectricElectric
TypeCondensing—Condensing, Ultra-Low NOx——
Flow RateUp to 11 GPMUp to 7.5 GPMUp to 10 GPM2.7 - 6.5 GPM (climate-dependent)Up to ~3.17 GPM
BTU15,000 - 199,000—15,000 - 199,000——
UEF0.95—0.93——
InstallationIndoor—Indoor, direct vent——
Power—36 kW—27 kW13 kW
Control—Advanced Flow Control + self-modulating—Self-modulating, digital (1-degree)Self-modulating, digital readout
Voltage—240/208V——240V
Venting—None required—None requiredNone required
Mounting—Wall-mounted—Wall-mounted—
Use——DHW, recirculation, space heating—Point-of-use / single fixture

Frequently asked questions

What is the best tankless water heater?
Rinnai RU199iN is our top pick for tankless water heaters, with an averaged rating of 4.5/5 from 3 published reviews. 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.
Is there a cheaper alternative worth considering?
Rheem RTEX-13 (around $278) rates 4.1/5 in our analysis. 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.
How does Verdict rank these products?
Every rating on Verdict is the numerical average of scores published by independent review sites, YouTube reviewers, and Reddit buyer reports. No editor adjusts the order — the ranking is whatever the source data produces. See our methodology page for the full process.
When was this guide last updated?
This guide was last re-checked in May 2026. We re-run our research pipeline for each category on a rolling basis so prices and rankings reflect current market reality.

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