The Best 5Aggregated review·11 sources·updated July 7, 2026·checked July 29, 2026

Best Tankless Water Heaters

Top tankless water heaters ranked by aggregate score from 11 published reviews across gas vs electric, GPM flow rate, efficiency, and value.

This guide aggregates 11 published reviews across 5 products; the thinnest-sourced pick rests on 2. How we rank.

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.

Quick answer

Stiebel Eltron Tempra 36 Plus is our top pick for tankless water heaters — an averaged 4.5/5 across 3 published reviews at about $712.73. Runner-up: Rinnai RU199iN (~$1,532.8).

Read the Stiebel Eltron Tempra 36 Plus review →$712.73 · Check Price on Amazon

At a glance

Tap any product for the full review

#	Product	Rating	Price	Best for
1	Stiebel Eltron Tempra 36 PlusTop Score	4.5 3 sources2 derived	$712.73	All-electric homes in moderate climates that need whole-house hot water without gas or venting.	$712.73 · Check Price on Amazon
2	Rinnai RU199iN	4.5 2 sourcesall derived	$1,532.8	Large households with gas service that need whole-home hot water for multiple bathrooms at once.	$1,532.8 · Check Price on Amazon
3	Takagi T-H3-DV-N	4.3 2 sourcesall derived	$1,500	Homes with gas service wanting a rugged, high-capacity condensing unit, including for recirculation.	$1,500 · Check Price on Amazon
4	EcoSmart ECO 27	4.3 2 sources1 derived	$538.18	Warm-climate homes wanting an efficient, affordable electric unit for small whole-home use.	$538.18 · Check Price on Amazon
5	Rheem RTEX-13	4.1 2 sourcesall derived	$271.48	Single-fixture point-of-use needs — a remote bathroom, addition, or booster on a budget.	$271.48 · Check Price on Amazon

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.

At a glance5 products ▾

1Stiebel Eltron Tempra 36 PlusTop Score

4.5

3 sources2 derived

$712.73Best for: All-electric homes in moderate climates that need whole-house hot water without gas or venting.

$712.73 · Check Price on Amazon

2Rinnai RU199iN

4.5

2 sourcesall derived

$1,532.8Best for: Large households with gas service that need whole-home hot water for multiple bathrooms at once.

$1,532.8 · Check Price on Amazon

3Takagi T-H3-DV-N

4.3

2 sourcesall derived

$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

4.3

2 sources1 derived

$538.18Best for: Warm-climate homes wanting an efficient, affordable electric unit for small whole-home use.

$538.18 · Check Price on Amazon

5Rheem RTEX-13

4.1

2 sourcesall derived

$271.48Best for: Single-fixture point-of-use needs — a remote bathroom, addition, or booster on a budget.

$271.48 · Check Price on Amazon

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.

Reviews aggregated from

BobvilaReviewedThisoldhousePexuniverse

The full ranking

How we rank →

#1 · Top Score

Best for: All-electric homes in moderate climates that need whole-house hot water without gas or venting.

Stiebel Eltron Tempra 36 Plus

4.5

3 sources2 derived$712.73as of Aug 1

The Stiebel Eltron Tempra 36 Plus is the clear frontrunner for whole-home electric tankless heating, good for 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 the silent operation and the Advanced Flow Control that dynamically reduces flow rather than letting cold-water sandwiching happen when demand exceeds capacity. It needs serious electrical service and performs best in moderate climates. 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

▾Why it's ranked here

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

$712.73 · Check Price on Amazon Full review →vs. Rinnai RU199iN →

★ Premium Pick

Best for: Large households with gas service that need whole-home hot water for multiple bathrooms at once.

Rinnai RU199iN

4.5

2 sourcesall derived$1,532.8as of Aug 1

The Rinnai RU199iN is the best overall gas tankless water heater for whole-home use, good for up to 11 GPM and 199,000 BTU, enough hot water for up to five appliances or a 3-4 bathroom house running at once. 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. 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

▾Why it's ranked here

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

$1,532.8 · Check Price on Amazon Full review →vs. Stiebel Eltron Tempra 36 Plus →

Best for: Homes with gas service wanting a rugged, high-capacity condensing unit, including for recirculation.

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

Watch-outs

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

▾Why it's ranked here

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 Amazon Full review →vs. Stiebel Eltron Tempra 36 Plus →

Best for: Warm-climate homes wanting an efficient, affordable electric unit for small whole-home use.

EcoSmart ECO 27

4.3

2 sources1 derived$538.18as of Aug 1

The EcoSmart ECO 27 is the efficient electric value pick, a 27 kW self-modulating unit that This Old House rated 4.3/5 across 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 runs 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. Flow drops in cold-inlet regions and it needs substantial electrical service. 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

▾Why it's ranked here

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

$538.18 · Check Price on Amazon Full review →vs. Stiebel Eltron Tempra 36 Plus →

Best for: Single-fixture point-of-use needs — a remote bathroom, addition, or booster on a budget.

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

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

▾Why it's ranked here

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

$271.48 · Check Price on Amazon Full review →vs. Stiebel Eltron Tempra 36 Plus →

Reviews aggregated from

BobvilaReviewedThisoldhousePexuniverse

Spec comparison

5 products

Spec	Stiebel Eltron Tempra 36 Plus	Rinnai RU199iN	Takagi T-H3-DV-N	EcoSmart ECO 27	Rheem RTEX-13
Fuel	Electric	Natural gas	Natural gas	Electric	Electric
Flow Rate	Up to 7.5 GPM	Up to 11 GPM	Up to 10 GPM	2.7 - 6.5 GPM (climate-dependent)	Up to ~3.17 GPM
Power	36 kW	—	199,000 BTU/H	27 kW	13 kW
Type	Tankless Electric	Condensing	Condensing, Ultra-Low NOx	—	Electric
BTU	—	15,000 - 199,000	15,000 - 199,000	—	2.3-2.3 GPM
Efficiency	—	0.95	0.93	99.8	~99%
Installation	—	Indoor	Indoor, direct vent	—	Indoor, point-of-use
Dimensions	—	18.5"W x 30.11"H	17.75"W x 22.5"H	17"W x 17"H	8.25"W x 12.62"H

Spec	Stiebel Eltron Tempra 36 Plus	Rinnai RU199iN
Fuel	Electric	Natural gas
Flow Rate	Up to 7.5 GPM	Up to 11 GPM
Power	36 kW	—
Type	Tankless Electric	Condensing
BTU	—	15,000 - 199,000
Efficiency	—	0.95
Installation	—	Indoor
Dimensions	—	18.5"W x 30.11"H

Frequently asked questions

What's the top-rated tankless water heater right now?

Stiebel Eltron Tempra 36 Plus holds the top score for tankless water heaters — 4.5/5 averaged from 3 published reviews. The Stiebel Eltron Tempra 36 Plus is the clear frontrunner for whole-home electric tankless heating, good for 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 the silent operation and the Advanced Flow Control that dynamically reduces flow rather than letting cold-water sandwiching happen when demand exceeds capacity. It needs serious electrical service and performs best in moderate climates. For an all-electric home, it is the top whole-house pick.

When was this guide last updated?

This guide was last re-checked in July 2026. Prices, links, and source ratings are re-verified on a rolling basis, and the ranking updates when the underlying scores change.

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