• Bathroom
  • 5 Most Reliable Tankless Water Heaters of 2024

5 Most Reliable Tankless Water Heaters of 2024

By Eugene WilliamsLast update: 2024-07-11

Which factor do you think is the most important to consider for the most reliable tankless water heater? Brand? Warranty? Or, anything else?

In this article, we’ll share with you not just buying tips but also in-depth reviews of the top-rated options on the market. Read on!

Here are the most reliable tankless water heaters you can buy in 2024:

  • Stable Water Temp (Electric Tankless Water Heater): Stiebel Eltron 239217
  • Easy To Install (Electric Tankless Water Heater): Airthereal EVT-9K
  • Durable (Electric Tankless Water Heater): GREATBEAR ECO130W
  • Best For Multi Devices (Gas Tankless Water Heater): FOGATTI FGD24IN
  • Energy-Efficient (Gas Tankless Water Heater): Rinnai V65En
5 Most Reliable Tankless Water Heaters
Stable Water Temp
Stiebel Eltron 239217
  • Electric Tankless Water Heater
Easy To Install
Airthereal EVT-9K
  • Electric Tankless Water Heater
  • Electric Tankless Water Heater
Best For Multi Devices
  • Gas Tankless Water Heater
Rinnai V65En
  • Gas Tankless Water Heater

Stable Water Temp: Stiebel Eltron 239217

Stiebel Eltron 239217
Stiebel Eltron 239217
  • Offer stable water temperature - Advanced Flow Control feature
  • Provide unlimited hot water supply - 5GPM maximum water flow
  • Meet more specific needs - 68° to 140°F water temperature ranges
  • Not easy to install

The Stiebel Eltron 239217 offers the most stable water temperature we've found.

It stands out for using Advanced Flow Control, an industry-exclusive feature, that automatically maintains water temperature no matter how often and how long you use hot water. The 5 GPM maximum flow rate ensures unlimited supply for the whole house.

We were also impressed by the wide output water temperature ranges this water heater offers, from 68° to 140°F, which is versatile enough to meet specific needs on a day-to-day basis.

The unit makes no loud noise while operating, which is a good plus point.

Stiebel Eltron 239217 Specifications


4.63 x 16.63 x 14.5 inches

Maximum Operating Pressure

150 PSI

Temperature Range

68° to 140°F

Maximum Power Output

28.8kW, 240V

Highlight Features

Advanced Flow Control feature

5GPM maximum water flow

68° to 140°F water temperature ranges


The Stiebel Eltron 239217 earns our top ranking position due to its incredibly stable water temperature maintenance capability.

Easy To Install: Airthereal EVT-9K

Airthereal EVT-9K
Airthereal EVT-9K
  • Easy to install & helpful installation manual
  • Compact & lightweight - 16.14 x 9.84 x 2.6 inches of dimensions & 10.28 pounds of weight
  • Add a great modern touch to the space – sleek and stylish design
  • Not make as hot water as our other picks

The Airthereal EVT-9K is a tankless water heater that you can install by yourself without hiring any licensed plumber or electrician. It's straightforward and easy to install, with a clear and helpful installation manual. Just make sure that your breaker panel is 40 AMP, 240 Voltage.

Compared to our other picks in the same category, this unit is pretty compact and lightweight, so you can mount it anywhere.

The sleek, modern, and classy design also makes it easily match any room decor style.

Airthereal EVT-9K Specifications


16.14 x 9.84 x 2.6 inches

Maximum Operating Pressure

7.25 - 108.78 PSI

Temperature Range

86°F - 131°F

Maximum Power Output

9 kW

Highlight Features

Easy to install

helpful installation manual

sleek and stylish design


If you’re looking for an easy-to-install electric tankless water heater to replace your old one, consider the Airthereal EVT-9K


  • Durable & safe – ETL approval
  • Extra convenient - LED display with touch control panel
  • Not suitable for whole house use

The GREATBEAR ECO130W provides on-demand hot water in no time and offers incredibly long-term durability that its counterparts cannot.

According to the manufacturer, all parts of this tankless water heater have passed independent and vigorous quality and safety tests.

Also, they've been upgraded with multiple protections, including overheating protection, dry heating protection, high voltage protection, and sensitive leakage protection.

So, using the ECO130W, you can rest assured to expect reliable performance for years to come.

Another notable feature of this unit is its handy LED display with touch control panel.

GREATBEAR ECO130W Specifications


15.75 x 11.1 x 2.25 inches

Temperature Range

‎77-131 Degrees Fahrenheit

Maximum Power Output

13 KW

Highlight Features

ETL approval

LED display with touch control panel


The GREATBEAR ECO130W beats out the competition for its superior durability and safety.

Best For Multi Devices: FOGATTI FGD24IN

  • Powerful enough for multi-devices - 170K BTU max power output & 7.5 GPM max flow rate
  • Stable combustion – strong forced exhaust fan
  • The metal parts at the bottom of the unit could be sturdier

Providing 170K BTU with the maximum water flow of 7.5 GPM, the FOGATTI FGD24IN is able to provide constant on-demand hot water for up to four outlet points in a regular family.

You might expect that a powerful gas tankless water heater like this model will eat up a lot of energy, making your electricity bills steeply up. It doesn't.

Its forced exhaust fan works excellently to avoid unwanted impact of external wind and ensure stable combustion.

FOGATTI FGD24IN Specifications


26.2 x 17.1 x 7.3 inches

Maximum Operating Pressure

150 PSI

Maximum Power Output

170000 BTU

Highlight Features

170K BTU max power output

7.5 GPM max flow rate

strong forced exhaust fan


If you’re in need of a reliable gas tankless water heater for multiple devices in your home, our recommendation is the FOGATTI FGD24IN

Energy-Efficient: Rinnai V65En

Rinnai V65En
Rinnai V65En
  • Energy-efficient - UEF over 0.82
  • Prevent potential damage to the product - Error Code Indicator
  • Ability of Wi-Fi control
  • High price

The Rinnai V65En offers the best value among the gas tankless water heaters we tested.

Outside of its strong flow rate and unlimited on-demand hot water supply capability, this unit is superbly energy-efficient, with UEF over 0.82. It offers 32% higher uniform energy than regular tank water heaters to save your precious water and power costs.

There's more, the V65En has the longest lifespan, up to 20 years, and is the rare water heater built with Error Code Indicator to prevent any potential damage to the unit.

Best of all, you can pair it with a control module for wireless control.

Rinnai V65En Specifications


17.5 x 30 x 13 inches

Maximum Power Output

10,300- 150,000 BTU

Highlight Features

UEF over 0.82

Error Code Indicator

Ability of Wi-Fi control


Our testers like the Rinnai V65En because it’s well-built, highly energy-efficient, and durable.

How To Choose The Most Reliable Tankless Water Heater?

Power Source

When it comes to power sources of tankless water heaters, there are three common options:

  • Electricity
  • Propane
  • Gas

Gas and propane tankless water heaters are pricier than electricity models, but are far more powerful and energy-efficient.

According to the U.S. Department of Energy, a natural gas and propane unit saves around $100 per year while an electric-powered one saves $40 per year.

Therefore, natural gas and propane tankless water heaters are commonly used for providing on-demand hot water for the whole house.

If you decide to purchase an electric tankless water heater, make sure that it suits your electric system. In general, old systems are weak, meaning that a whole-house electric tankless water heater might overload them.

Energy Efficiency

To know how energy-efficient a tankless water heater is, you should look at its EF rating.

EF stands for energy efficiency.

This rating was established by the US Department of Energy, with the scale ranging from 0.5-2.0. The higher the number, the more energy-efficient the unit.

Flow Rate

The flow rate of a tankless water heater is measured in gallons per minute, or GPM.

To determine this factor, you need to determine which household devices will require hot water from the water heater at a time, and the peak flow rates of those devices.

For example, if you typically need hot water to run a shower rated at 1.5GPM and a dishwasher at 2.5 GPM, then you should choose a tankless water heater at no under 4 GPM.


Check the warranty of the tankless water heater you’re about to buy.

As you’ll use the unit on the day-to-day basis, make sure to pick a unit with a quality warranty. If you’re using hard water, it’s recommended choosing a tankless water heater with an extended warranty.

Which Brands Make The Most Reliable Tankless Water Heater?

Stiebel Eltron

Founded in 1924, Stiebel Eltron is a Germany-based company dedicated to offering efficient solutions for hot water, renewables (ventilation and heat pumps), room heating, and more.

They're well-beloved for the helpful customer service and the superb quality of their diverse products.


Established in 2018, Airthereal is a company dedicated to manufacturing HEPA air purifiers and water heaters, aimed to improve the air and hot water in everyone's home.


Fogatti is the world's leading provider of innovative and dependable tankless water heaters with cutting-edge technology and features. All of their products are safety proven and known to help improve customers’ lifestyle quality.


While Rinnai Corporation is a Japan-based multinational company, they are the 1st main tankless water heater brand to manufacture in the USA. They’re also the longest-standing brand in this industry, since 1920, with over 100 years of experience.

What set them apart are durability (their tankless water heaters are known to last up to 20 years—twice longer than traditional tanked models), efficiency, and quality.


Which tankless water heater has the longest warranty?

A.O. Smith is known for offering tankless water heaters with the longest warranty, up to 15 years.

What is the life expectancy of a Rheem tankless water heater?

The life expectancy of a Rheem tankless water heater is 15-20 years.

Do tankless water heaters need maintenance?

Yes, they do.

To maximize their lifespan and performance, it’s recommended to maintain tankless water heaters at least twice a year if you have hard water and once a year if you don't.

What maintenance should be done on a tankless water heater?

Here are the three important maintenance tasks for tankless water heaters:

  • Descale and flush the system
  • Clear the air filter
  • Clear or alternate the water line filter

How often should I flush my tankless water heater?

You should flush your tankless water heater at least once a year.


That’s all for this article. We hope that this rigorous testing and intensive review was helpful for you to find the most reliable tankless water heater for your hot water needs and budget. Thanks for reading!

Related Articles