What’s the Best Tankless Water Heater? (2018 Review Guide)

Some links on this page are monetized by affiliate programs - see disclosure for details.

Tankless Water Heater Review GuideLarge hot water boilers or tanks are renowned for causing headaches for homeowners and property managers. The threat of a water leak is ever-present, with many boilers and hot water tanks using natural gas to heat water, thus raising the risk of a gas leak, which could potentially lead to an explosion. Hot water heaters and boilers also need to be kept insulated, as pre-heated water slowly returns to room temperature if not “consumed”, wasting prodigious amounts of non-renewable energy sources.

Tankless water heating systems do not waste time heating water that won’t be used, instead providing homeowners and property managers with on-the-fly water heating to dramatically reduce energy loss and wastage.

Compare: The Best Tankless Water Heaters of 2018

Stiebel Eltron Tempra 24 Plus Electric Tankless Whole House Water HeaterStiebel Eltron Tempra 24 Plus
Stiebel Eltron$$$$4.9
Ecosmart ECO 27 Electric Tankless Water HeaterEcosmart ECO 27
Eccotemp L5 Portable Tankless Water Heater and Outdoor ShowerEccotemp L5 Portable Tankless Heater & Outdoor ShowerEccotemp Systems$$4.6
Rinnai RL75iN Natural Gas Tankless Water HeaterRinnai RL75iN Natural GasRinnai$$$$4.6
Takagi T-KJr2-IN-NG Indoor Tankless Water HeaterTakagi T-KJr2-IN-NG IndoorTakagi$$$$4.6
Supergreen-IR260-POU-Infrared-Electric-Tankless-Water-HeaterSupergreen IR260 POUSupergreen$$$4.5
Eemax SP3512 Tankless Water HeaterEemax SP3512Eemax$$$4.5
Eccotemp L10 High Capacity Outdoor Tankless Water HeaterEccotemp L10 High CapacityEccotemp Systems$$4.4
Rheem RTE 13 Electric Tankless Water HeaterRheem RTE 13Rheem$$4.4
Takagi-T-H3-DV-N Tankless Water HeaterTakagi T-H3-DV-NTakagi$$4.4

What is a Tankless Water Heater?

While Europe has been using tankless water heating systems for decades, this energy-saving advanced system for providing on-demand hot water is becoming increasing popular across the United States. Without any large boiler or hot water tank to worry about leaking, a tankless water heating system provides hot water instantaneously, exactly when it is needed. Standard cold water entering the house can be rapidly heated to a desired temperature on the fly, allowing homeowners and property managers to only pay for the hot water that they actually use.

Many Americans are used to the sight of a large, ugly water heater tank or boiler in their basement or garage. Connected to the gas main, it is a constant threat that could leak fumes or water at any time. Big exterior hot water tanks use tremendous amounts of energy heating water that isn’t used, wasting energy when there’s no demand for it. A tankless water heating system works by applying a very high source of heat to normal cold water as it enters the house, heating water on the spot.

Just as the gas or electric burner on a stove can be used to heat water, a tankless water heating uses a power source to quickly and efficiently heat water to a specified temperature.

What are the different types?

Some tankless water heating systems rely on propane or other gases to heat water, while other tankless water heating systems are powered via an electrical outlet in the home. A modern tankless water system is easily equipped to heat water on demand to provide sufficient hot water for a shower or operating a dishwasher, washing machine or other home appliance that requires heated water.

Other systems are more powerful, providing enough hot water on the fly to allow for multiple showers or other high-use demands on the system, while other tankless systems are less powerful and are meant to be used in an auxiliary capacity. Many tankless water systems are designed to be used to boost or aid other water heating systems, including solar, wind-powered and other “off-the-grid” renewable energy sources.

What are the advantages of owning one?

Not only are big hot water tanks and boilers a hazard, prone to leaking gas or water or potentially even exploding, but they also take up a lot of space. The so-called “footprint” of a hot water boiler or tank is usually quite large, as nothing can be kept in close proximity to a hot water boiler or tank. These systems, on the other hand, don’t take up much space as there’s no need to store large volumes of pre-heated water. Homeowners and property managers can discretely mount tankless water heating systems wherever there is a need, including in outbuildings or other structures not connected to main lines.

With a safe and reliable source of energy, and a much smaller “footprint” in the home, tankless water heaters are a tremendous benefit over older, traditional-style big hot water tanks. Since tankless water heating systems only consume energy when hot water is needed, they save homeowners and property managers in the long term by not wasting precious energy resources to heat water when there is no demand for it.

Who are the Contenders for Best Tankless Water Heater on the Market?

Eccotemp L5 Portable Tankless Water Heater and Outdoor Shower

Offers unique water heating capabilities as this portable tankless water heating system can be used both indoors and outdoors. With a generous 1.4 gallons per minute flow-through capability, the Eccotemp L5 offers anyone hot water on-demand anywhere there is a reliable supply of cold water.

Ecosmart ECO 27 Electric Tankless Water Heater

Offers unparalleled savings on water costs as it uses electricity to offer homeowners and property managers virtually unlimited hot water on demand. With a fully-equipped digital control pad, the Ecosmart ECO 27 can nearly instantly heat water to a specified temperature.

Stiebel Eltron Tempra 24 Plus Electric Tankless Whole House Water Heater

This powerful but compact tankless water heating system is designed to provide plenty of water to supply the needs of an entire household while simultaneously saving homeowners and property managers money on their monthly electric bill when used to replace traditional boiler or big hot water tank systems.

Considerations for Choosing the Right Model

  • Heating System – Different tankless water heating systems use different ways to heat water on the fly. A good tankless water heater should be powerful enough to supply hot water for normal daily usage.
  • Settings & Specifications – All models of tankless water heaters come equipped with adjustments and settings to make sure that water is heated precisely to the user’s specifications.
  • Capabilities – Often referred to as the “flow-through rate”, a good tankless water heating system should be able to provide enough volume of hot water for daily needs.
  • Advanced Features – Many of today’s modern tankless water heating systems come equipped with advanced features that allow homeowners to maximize energy costs while enjoying limitless hot water on demand.

Heating System

The Eccotemp L5 Portable

Uses liquid propane to heat water. It is also requires a connection to a source of unheated water that is under at least 20-80 PSI of pressure. Ignition is with two standard D-sized batteries, so no electricity is necessary to operate the Eccotemp L5.

The Ecosmart ECO 27

Designed to be permanently mounted to a wall or support structure and connected to the main electrical supply at the house. Drawing 27 kW at 240 volts, the Ecosmart ECO 27 is designed to quickly and efficiently heat water on demand to service all the hot water needs in the house, including showers, sinks, washing machines and other large appliances.

The Stiebel Eltron Tempra 24 Plus

Can draw up to 24kW as it fires up its powerful heaters to deliver nearly unlimited hot water on demand. The sleek design can be mounted nearly anywhere and no exterior venting is required.

Settings & Specifications

The Eccotemp L5 Portable

Once connected to a reliable source of water and the liquid propane fuel tank, the Eccotemp L5 features the ability to regulate both the gas as well as water flow with easy-to-adjust analog dials. The dimensions of the unit measure 11.5″ wide, 14.5″ tall, 4.5″ deep and the unit weighs approximately 14 pounds.

The Ecosmart ECO 27 Electric

Comes equipped with an advanced digital control pad that allows users to adjust the desired hot water temperature in one-degree increments, saving homeowners and property managers by not wasting money on unnecessary energy use.

The Stiebel Eltron Tempra 24 Plus

Features an advanced digital readout and multi-function dial to adjust water flow and peak hot water temperature to make fine-tuning energy use simple and intuitive.


The Eccotemp L5 Portable

Heats water 30-35 degrees Fahrenheit at a maximum of 1.5 gallons per minute flow through rate.

The Ecosmart ECO 27 Electric

The powerful electrical heating system is 27 KW at 240 volts. The system is self-modulating, firing up one or all three of the internal 9KW heaters to raise water temperature on demand. Although the unit is powerful enough to heat water further, it is equipped with a safety feature to limit the maximum temperature of water to 140 degrees Fahrenheit.

The Stiebel Eltron Tempra 24 Plus

Replaces traditional whole-house boilers and expensive hot water tanks, providing ample hot water on demand to supply an entire household with sufficient hot water.

Advanced Features

The Eccotemp L5 Portable Tankless

Because the Eccotemp L5 uses standard batteries to power ignition, this system allows users to heat water at remote campsites, “off the grid” locations, or even wash boats, horses and dogs in outdoor settings.

The Ecosmart ECO 27 Electric Tankless

The self-regulating modulator means that the Ecosmart ECO 27 uses a specially-engineered three stage system to heat the water to precisely the degree desired. A digital control panels gives homeowners and property managers complete control over the operation of the Ecosmart ECO 27.

The Stiebel Eltron Tempra 24 Plus Electric Tankless

The digital readout and advanced multi-function dial give homeowners and property managers precision control over their energy use and desired maximum water temperature. Compact enough to be mounted nearly anywhere, the Eltron Tempra 24 Plus comes with a simple installation process that most homeowners can perform without professional assistance.

Conclusion: Final Tankless Water Heater Reviews

Eccotemp L5 Portable Tankless Water Heater and Outdoor Shower – Best Cheap Option

Eccotemp L5 Portable Tankless Water Heater and Outdoor ShowerAnyone wanting to instantaneously add a hot water system to a pressurized system of cold water can install the Eccotemp L5 and be taking a luxurious shower just 10 minutes later. Because the Eccotemp L5 is designed to be portable, it can be used in both indoor and outdoor settings, bringing hot water to cabins and other undeveloped properties.


  • Weighing in at just 14 pounds and small to mount on the wall, the Eccotemp L5 can be installed and used in mere minutes
  • Batteries give users complete independence from the electrical grid, allowing campers and cabin dwellers to enjoy the luxury of a hot shower or machine-washed clothes
  • With the ability to heat 1.5 gallons on the fly, anyone with a pressurized water system can enjoy the benefits of hot water with an Eccotemp L5
  • The Eccotemp L5 comes equipped with a safety feature that automatically shuts off the heating element after 20 minutes


  • Because the Eccotemp L5 uses gas, it cannot be installed in tight quarters or in close proximity to exterior walls or sources of flames

Ecosmart ECO 27 Electric Tankless Water Heater – Best Value for the Money

Ecosmart ECO 27 Electric Tankless Water HeaterThe Ecosmart ECO 27 is a fantastic electrically-powered home tankless water heating system. With three internal 9KW heaters, the Ecosmart ECO 27 is capable of providing enough hot water on demand to supply even the longest showers. Once installed, the Ecosmart ECO 27 is designed to provide years of reliable service with only minimal maintenance.


  • This is definitely a powerful tankless water heating system, able to raise water to near-scalding temperatures in just seconds
  • Even high-flower showers pumping out hot water for lengthy bathing sessions will not run out of hot water with the Ecosmart ECO 27
  • Although not included, the Ecosmart ECO 27 supports a remote thermostat for enhanced safety and peace of mind
  • Weighing in at just 17 pounds and only 20 inches high, the Ecosmart ECO 27 can be easily and simply attached to any home water plumbing system


  • The Ecosmart ECO 27 is rated at 240 volts, which means it needs a dedicated 240V circuit rated at 40 amps or better

Stiebel Eltron Tempra 24 Plus – Best Overall

Stiebel Eltron Tempra 24 Plus Electric Tankless Whole House Water HeaterThis powerful water heating system is highly engineered to both provide maximum water heating and save homeowners money long-term with reduced operating costs compared to traditional boiler or hot water tank systems.


  • Whole house can get unlimited hot water without having to worry about expensive wastage or storage costs from traditional boilers or hot water tanks
  • The Eltron Tempra 24 Plus can be installed even by non-professionals, and there’s plenty of hot water to get washing done, take showers, or use sinks throughout the entire house


  • As this tankless water heating system draws 240 volts, it must be installed on a separate electrical circuit in the home that is rated to safely handle the current load of the Eltron Tempra 24 Plus

In Conclusion

Homeowners and property managers know how expensive traditional boilers and big hot water tank systems are, which use up lots of valuable space in the basement or other areas of the home, and have the potential to leak water or dangerous gases. Powerful tankless water heating systems like the Eltron Tempra 24 Plus can easily replace those clunky old boilers and hot water tanks, efficiently providing plenty of hot water to satisfy the needs of an entire household.

With a top-rated powerful 24 kW heating system, the Eltron Tempra 24 Plus is the best choice for homeowners and property managers who want to save money long-term on their energy bills while simultaneously equipping the home with a virtually infinite supply of abundant hot water. The family can relax in comfort and security knowing that the Eltron offers them unlimited on-demand hot water at precisely the temperature desired.