The Best Whole House Electric Tankless Water Heater

Best Overall
Editors Choice
Ecosmart ECO Electric Tankless Water Heater, 27 KW at 240 Volts, 112.5 Amps with Patented Self...
Rheem RTE 13 Electric Tankless Water Heater, 4 GPM
Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco,...
Ecosmart ECO Electric Tankless Water Heater, 27 KW at 240 Volts, 112.5 Amps with Patented Self...
Rheem RTE 13 Electric Tankless Water Heater, 4 GPM
Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco,...
Best Overall
Ecosmart ECO Electric Tankless Water Heater, 27 KW at 240 Volts, 112.5 Amps with Patented Self...
Ecosmart ECO Electric Tankless Water Heater, 27 KW at 240 Volts, 112.5 Amps with Patented Self...
Rheem RTE 13 Electric Tankless Water Heater, 4 GPM
Rheem RTE 13 Electric Tankless Water Heater, 4 GPM
Editors Choice
Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco,...
Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco,...

A whole-house electric tankless water heater is the most viable solution for your family’s hot water needs. However, you first need to window shop around to get yourself the best deal and value for your money.

This article discusses 10 of the best whole house tankless water heaters on the market. Read on to understand what you should be looking for in a whole house tankless water heater.

The Best Whole House Electric Tankless Water Heater Reviews

When buying a tankless electric water heater, you should consider brands that already have a following in the market. Here is a review of ten major brands in the market.

The EcoSmart Eco 27

Ecosmart ECO Electric Tankless Water Heater, 27 KW at 240 Volts, 112.5 Amps with Patented Self...
  • Endless on-Demand Hot Water; Consistent hot water when you need it that never runs out;...
  • Save Space; EcoSmart tankless electric water heaters are 90% smaller than traditional tank...
  • Save Energy; EcoSmart tankless electric water heaters are 99% thermal energy efficient; Only...

The EcoSmart Eco 27 electric tankless water heater is a favorite for many buyers. And it is not hard to see why because this electric tankless water heater is only 4 inches wide, making it one of the smallest models. It is also energy-efficient and can help you save at least 50% on your hot water bills. This unit is one of the most affordable electric tankless water heaters on the market.

The great thing about the EcoSmart Eco 27 electric tankless water heater is that even when you have a very slow water flow, it can still heat your water. It has a 0.3 GPM activation flow, with other competitors working with a 0.5 GPM.

The unit works with a 27 kW voltage which is available in modern households. With this voltage limit, you will not incur power grid upgrade costs.


  • It’s affordable.
  • Easy to replace parts
  • It’s compact and helps to save on space
  • Comes with digital temperature controls
  • It only turns on when you need hot water
  • It’s energy-efficient


  • Some parts easily corrode
  • Users say that the power usage is high
  • Sometimes outdoes the house voltage

The Rheem RTEX-13

Rheem RTE 13 Electric Tankless Water Heater, 4 GPM
  • On-unit temperature control, LEDs indicate active element and standby mode
  • Standard 1/2" water connection
  • Rugged brass/copper heat exchanger

The Rheem RTEX-13 is the second-best model in the market. It comes with an accurate and adjustable digital thermostatic control, coupled with a LED display. The adjustable thermostatic control allows you to set your hot water temperatures according to your preferences. It also has a self-modulating power control which improves its energy efficiency.

The Rheem RTEX-13 comes with durable copper elements. The top of the elements is made of brass and is threaded to facilitate better heating. It’s also a serviceable electric tankless water heater, meaning that you won’t have to buy another one if the parts break down. The installation is straightforward because the package contains all you’ll require to set it up.

This model is 99.8% energy efficient, making it one of the most energy-efficient electric tankless water heaters. It has a shower head feature which helps you save water. The water flow for this model is 1.5 GPM.


  • It doesn’t require an overflow line.
  • Easy to install and repair.
  • Comes with durable copper immersion elements.
  • Accessible temperature settings.
  • Helps reduce water wastage.
  • It’s energy-efficient.


  • Shorter lifespan
  • It can also only heat water up to 60 degrees.

The Stiebel Eltron Tempra 24 Plus

Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco,...
  • CONTINUOUS FLOW – Advanced Flow Control patented technology invented by Stiebel Eltron,...
  • SPACE & ENERGY SAVER – Its small, sleek white design saves space yet still provides endless...
  • EASY OPERATION – Electronic switch activates the hot water heater and it’s noise free while...

The Stiebel Eltron Tempra 24Plus has also ranked among the best whole house electric heaters for the whole house. The heater is part of the six-part series produced by German manufacturer Steibel Eltron.

The best advantage this model has over others is the Advanced Flow Control patent function. This technology is incorporated in the tankless heater to ensure that your water is hot and automatically flows. If the tank overreaches capacity, the AFC makes adjustments to increase the electric tankless water heater’s energy-efficient features.

This tankless water heater is one of the most energy-efficient brands in the market, with a 0.99 EF rate. The higher the EF rate of a product, the better it will save on energy costs. This is way better than other brands that have an EF rating of 0.95. It’s strong enough to meet whole house hot water needs and operates with a 150 A electric grid. The 24kW plus is the best model for most households.


  • It doesn’t require venting.
  • It has a thermal stat for controlling temperatures.
  • It’s compact and can fit in small spaces.
  • 7-year warranty for leakages and 3 years warranty for parts
  • Saves 15%-20% of the electricity bill.


  • Its heating capabilities depreciate over time

Rheem 240 V 2 RTEX-18

Rheem 18kW 240V Tankless Electric Water Heater
  • External digital thermostatic control with LED display (+/1 degree accuracy)
  • Most advanced self-modulation, adjust power to meet hot water demand
  • Durable Copper immersion two heating elements, field Serviceable. Flow Rate- up to 4.4 GPM

Rheem is an American company that has manufactured heaters for decades, and its products compete with other major brands in the market. The Rheem RTEX-18 whole house tankless water heater has two heating chambers and can heat up to 18kW.

The two heating chambers ensure that you have a constant supply of hot water for your household. Most households have the 18kW voltage required to operate this water heater, meaning that you might not need to upgrade your power grid.

The unit comes with an external digital thermal control feature that is complete with an LED display. The control helps you operate the unit and regulate the water temperatures to suit your preferences. You can set the temperatures between 80-140F.

The unit comes with two copper immersion heating elements which are coated with brass and are also threaded. The brass topping helps facilitate the heating process, and the threading helps to make the unit more serviceable. Your water is heated faster, making the unit one of the most convenient ones.

The GPM is high, standing at 4.4, which means that you need a great water flow. This GPM is ideal for a small or medium household, but you will require a more powerful tankless electric heater if you have a bigger household.

This unit allows you to use various appliances in the house, such as a dishwasher, a showerhead, and a standard hand sink. The installation is easy, and you will need 3/4″ NPT water connection pipes. The unit will also serve you well during the cold season. It is 99.8% energy efficient and comes with a 5-year warranty.


  • It’s great for a small or medium household.
  • Easy installation and operation
  • Affordable and reliable
  • Comes with an external digital thermal control and LED light
  • Will serve you in both hot and cold climate


  • It’s not ideal for households of more than five people
  • The installation cost can be high if you get a professional to do it
  • Some users have reported fluctuations in the water temperatures

Stiebel Eltron 15 Trend Tempra

Stiebel Eltron Tempra 15 Plus Electric Tankless Whole House Water Heater, 240 V, 14.4 kW
  • Digital temperature control
  • Proven reliability;Seismic Proof Construction
  • No venting required

This model from German manufacturer Stiebel Eltron has a 4.5-star rating on Amazon, making it a preferred whole house tankless water heater. It comes in a sleek and compact design which helps you save on space.

The model also has an accurate digital temperature display system. It also has pre-set temperature buttons that allow you to access the temperature memory settings and energy-efficient.

This model comes with advanced flow control technology, ensuring that you have a constant supply of hot water whenever you need it. This tankless water heater can comfortably heat the water for large households.

This unit can be used as a point of use water heater or a whole house heater, depending on the climatic conditions of your area of residence. If you live in cold climate areas, this unit will only serve you as a point of electric water heater. In hot areas such as Florida and the Caribbean, it can be used as a whole house water heater.

With a 3GPM flow rate and a 33F temperature rise, this unit can comfortably serve the hot water needs of a large house. It works with a minimum power of 10.8 kW when on 208V and a maximum power of 14.4 kW when on 240 V. This means that most households would not need to upgrade their power grids to use this unit.


  • High energy efficiency
  • Has a sleek and compact design to save on space
  • 10-year comprehensive warranty
  • Can service a large household.


  • Hard to install for some users
  • It has a low GPM output
  • It can only serve as a whole house heater for homes in hot climate areas.

EcoSmart ECO 18 Tankless Electric Water Heater

EcoSmart ECO 18 Electric Tankless Water Heater, 18 KW at 240 Volts with Patented Self Modulating...
  • The product is highly durable
  • The product is easy to use
  • Manufactured in China

The EcoSmart ECO 18 tankless electric water heater is one of the most affordable water heaters in the market. A natural gas tankless water heater is expensive to run, which is why a budget-friendly pick would be electrically powered. This is mostly applicable for you if you live in a place where the water temperatures are warm.

This whole house electric tankless water heater works on a 2.5 GPM and can support two showers simultaneously, especially in warm climate areas. If your water temperatures are 60F and above, this unit will produce 2.5 gallons per minute with an output temperature of 105F.

This unit has one-degree increment digital controls to help you set the right temperature for your water. The smart design on this unit helps you save 50% of your monthly electric water heating costs, making it very energy efficient.

It can be installed and maintained easily and comes in a compact design that saves on space. The parts are made from copper and stainless steel, making the unit durable.


  • Budget-friendly option
  • Ideal for small households
  • Easy to install and maintain
  • Storage-efficient
  • Energy efficient
  • Digital controls to make your temperature setting work easier
  • Durable parts


  • It has a limited capacity
  • Most viable for hot climate areas

Stiebel Eltron DHC-E 12

Stiebel Eltron 230628 240V, 12 kW DHC-E12 Single/Multi-Point-of-Use Tankless Electric Water Heater
  • Set the knob on the front cover and enjoy water temperatures between 86DegreeF (30DegreeC) and...
  • The three years parts warranty is unique in the industry
  • Due to its small dimensions and attractive housing the DHC-E can be left unconcealed in many...

This is the smallest low Amp whole house electric tankless water heater. If you are looking to save on space and hot water costs, this is the model you need to look at. However, it is not ideal for a large household.

This whole house electric tankless water heater runs on 12kW, which means you won’t have to upgrade your electric grid. Despite the low electric power usage, you can run the shower and one faucet simultaneously. This heater is powered by a 240 V voltage and 50 A.

The minimum activation flow for the Stiebel Eltron DHC-E 12 is 0.3. If your faucets are the low GPA type, you can still get hot water with this model. And the great thing is that you can get your hot water between 86-140F.

This whole house electric tankless water heater can be used as a point of use electric heater, as well as a whole house electric water heater, depending on the size of your household. It also comes with self-modulating flow technology, making it energy efficient. You can get one of these pieces for $300, making it one of the most affordable models in the market.

This unit is one of the easiest to use. You can key in the codes for your desired water temperature, supported by the sophisticated advanced technology feature. You can get water as hot as 140F when you need it because it ensures that what you key in is what you get. If the water gets too hot, you can adjust the temperatures so you won’t have to deal with scalds!

The unit comes with a flow sensor and a pair of temperature sensors to regulate water flow and temperature settings in your unit. Their readings are sent to the proprietary microprocessor control allowing you to get your water in the right flow and temperature.


  • It is conveniently small in size
  • Comes with a temperature adjustment feature
  • High energy efficiency features and saves on space.
  • It is affordable
  • A simple plumbing and installation design
  • Reliable performance


  • Not appropriate for big households
  • Does not support multi-point use beyond two outlets.

SIO Green SIO18 V2

Sio Green is the first company to manufacture infrared electric tankless water heaters using NASA technology. The SIO 18 V2 uses electric power to fire up infrared lights, which simultaneously heats water in the Quartz tubes in the heater. Initially, the technology was for commercial use, but SIO has outdone using it on residential electric tankless water heaters.

This electric tankless water heater uses 240V of electricity and operates well with an 80 A power grid to satisfy the hot water demand in your household. This means that you may not have to upgrade your power grid. It uses 3/4 inch NPT water pipes which is similar to most other models in the market.

The Quartz tubes are excellent because they do not gather calcium deposits, neither do they corrode. On the downside, the NASA technology used to make this tankless water heater makes it one of the most expensive models you can buy.


  • Made with NASA technology and uses Quartz tubes
  • Low maintenance costs
  • High energy efficiency
  • It currently has two options in the market, 9kW, and 18kW
  • No need for a power grid upgrade


  • Bulky construction
  • It’s expensive

Eemax EEM24027

Eemax SPEX3512 FlowCo Tankless Electric Water Heater, White
  • Temperature output based on flow rate, 41°F Temp. Rise @ 0.5 GPM
  • SafeStart technology. Recommended Wire Size-10
  • Mounts in any orientation

This is one of the most color-appropriate electric tankless water heaters on the market. Most manufacturers do not consider aesthetics when manufacturing water heaters, but this model outshines other models in aesthetics.

The model comes with self-modulating technology, which is designed for optimum hot water use. It can work with 27kW, 240V and requires and 112.5 A electric grid to meet your hot water demand. This, however, means that you might have to upgrade the electric grid in your house.

This tankless water heater is ideal for a large household and is great because it comes in a compact, slim design. Here are the pros and cons of this model.


  • Stylish design
  • Energy efficient
  • It has a great power/weight ratio


  • It is only available in the 27kW model

The Bosch Tronic 6000 C WH 27

Bosch Thermotechnology - WH27 Tronic 6000 C Electric Tankless Water Heater - Eliminate Time for Hot...
  • CONVENIENT TANKLESS HOT WATER HEATER: 26.9 kW tankless whole house electric water heater...
  • EASY INSTALLATION: Can be installed virtually anywhere for commercial or residential...
  • CONSISTENT TEMPERATURE: Polymer encased elements & built-in flow sensor ensures constant output...

Bosch has manufactured one of the most convenient hot water solutions for your home. And the best thing is that it will not consume a lot of space in your house. With the Bosch Tronic 3000 C WH27 water heater, your house will have a constant supply of hot water at the right temperatures.

This electric tankless water heater features a simple-to-use interface for installation and operation. It is designed to replace a 40 gallons tank-style water heater. The model can work with a temperature rise of 45F and achieve a 3.5 GPM of hot water.

The Bosch Tronic 3000 C WH 27 comes with 2 solid copper heat exchangers alongside brass fitting. It also has a thermal cut switch which serves as a safety feature and protects the fittings from electric damage. It comes with a sleek and compact design and has a built-in flow sensor and polymer encased elements that maintain a constant output temperature.


  • Great temperature range
  • A great sleek and compact design to save on space
  • High energy efficiency features
  • Can work simultaneously to serve different needs


  • High activation flow

Factors To Consider When Buying the Best Whole House Electric Tankless Water Heater

Before you settle for a whole house electric water heater, you must scout the market, compare different brands and prices to find the most appropriate one for your needs. Here are some of the points you should consider.

1. Size

The size of the electric tankless water heater you choose determines the amount of hot water your family will be getting. The size of the heater translates to the temperature flow rate. You measure the temperature flow rate by considering how hot the heater can make your water if fed with a specific number of gallons per minute. The number of people in your household should also determine the size and strength of the water heater you pick. It should meet their hot water demands comfortably whenever they need it.

2. The Flow Rate (Gallons Per Minute)

How much hot water does your household need in a day, and what is the heating capacity of your desired whole house tankless water heater. Compile the GPM flow rate of all the water outlets in the house to get the average usage of hot water in your home.

It is advisable to calculate your flow rate during the peak hour in your house. This could be in the morning, or the evening, or whatever time your family uses to water the most. Calculate how many gallons are used from every outlet, such as showerheads, dishwashers, washing machines, and kitchen faucets. The total will be the GPM of your household, which will help you understand your flow rate.

3. Temperature Range

The electric tankless water heater’s role in your house is to heat your water to your desired temperature. Before spending money on a brand, be sure to meet the temperature rise requirements in your house.

To measure the temperature range needs in your home, measure the water temperature in the pre-tank pipes of your home, and subtract it from the temperatures you want your water to be after being heated. This will help you pick the most appropriate whole house electric tankless water heater for your household.

4. Recirculation

All-electric tankless water heaters should have a recirculation system that loops back any cold water into the heating unit. This helps to heat all the water instantly, so you won’t have to run water through the drain.

Recirculation of the water also helps to reduce water wastage. No water passes through the heater and is not heated, ensuring that no electric power is wasted in the process.

5. Durability

Most of the electric heaters are made from metals and are insulated with hard plastics. However, if you are looking for durability, insist on a stainless steel model as the main component. Stainless steel is less likely to rust, saving you maintenance costs.

The stronger the material making the water heater, the more likely it is to have a longer service life. The buying price and installation costs of electric heaters could be high, and you do not need to add extra expenses by buying substandard materials. The low-quality materials would cost you more in maintenance costs.

6. The Type of Home

Your home determines the best electric tankless water heaters you can install. A whole-house tankless water heater is most appropriate for an existing home. However, some traditional homes may not meet the power voltage needs of a particular water heater. You may have to incur extra costs in upgrading your power grid. Scout the market till you find an electric water heater that will serve you without incurring extra costs.

7. Frequency of Use

The frequency of hot water use in your household should also guide you when buying a whole-house electric tankless water heater. If your household consumes a lot of hot water at a go, you may need to go for a heater with a higher voltage and higher GPM flow rate. Such a heater ensures a constant supply of hot water when all the outlets are being used.

On the other hand, if your household requires hot water all through the day but at different intervals, a smaller voltage heater might be enough. For instance, if the dishwashing, laundry, and baths are handled at different times in the house, then the GPM rate and voltage for the heater do not have to be high.

8. Warranty of the Heater

Different manufacturers have different warranties for their products, and the time limit to waive those warranties is different. While looking for the best whole house tankless water heater in the market, go for the model with the most favorable warranty period.

Most of the manufacturers will require that you have your heater registered. They also require that it should be installed professionally for you to use the warranty. If you don’t use a professional plumber to do the installation, you risk getting the process wrong or faulting some parts. If this happens, most warranties will not cover the damage.

Compare all the warranties for all the whole house tankless water heaters. A good warranty should have at least 10 years on the heat exchanger, 2 to 5 years on the other parts, and at least 1 year on labor. Some models in the market offer a lifetime warranty to their customers. Any model that does not meet this baseline could be risky to invest in.

9. Climatic Conditions

Your area of residence’s climatic conditions also determines the type of a whole house electric tankless water heater you will get for your household. The water temperatures in your area determine how much power your heater should have to convert the cold water to hot water. The different GPM ratings mean that different electric water heaters with different electric capacities should be used in different areas.

The water temperature could drop to negative degrees Fahrenheit, and you need to ensure that your family has access to endless hot water. Buy a whole house electric tankless machine with at least 27 kW power to heat water in the winter.

10. Ease of Installation

When you pick a water heater from the dealer, be sure to pick a model that doesn’t need advanced tools or expertise to install. If you pick a model with a complicated installation process, you may incur extra costs getting it properly installed. Such units might also be hard to repair. If you do not have a local professional to do the job, request the dealer to connect you to one.

Most manufacturers also require that the water heater be installed professionally for the warranty to be usable. A professional installer will also make sure that all the safety measures are met. They will guide you on what to do in case the heater needs some maintenance. It is also less likely for the heater to break down soon after installation if done by a professional.

Frequently Asked Questions

1. What is the best electric tankless water heater?

The best electric heater is the EcoSmart Eco 27 model.

2.What should I look for in an electric tankless water heater?

A good electric water heater has a good power capacity to heat water in all climatic conditions. High-quality electric heaters should heat water instantly and easy to install, operate and maintain.

2. What brand of tankless water heater is the most reliable?

There are many brands of tankless water heaters in the market, and it can get confusing. Nevertheless, Ecosmart makes high-performing tankless water heaters.

3. Are tankless water heaters good for large homes?

A tankless heater is one of the best investments you can make for your home. For once, the family will constantly need instant hot water, which is hard to maintain with the tank water heater. You also have a large household and should take every opportunity to reduce wastage and be more energy-efficient.

4. Are tankless electric water heaters worth it?

Electric tankless water heaters are worth your every dollar. For starters, they are more energy-efficient than gas-powered heaters. They also help you to reduce your carbon print because they do not consume any fossil-generated fuels.

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