5 Best Electric Tankless Water Heaters [Top Picks]

Electric tankless water heaters are a popular choice for homeowners seeking an energy-efficient and eco-friendly alternative to traditional tank-based water heaters.

These appliances heat water on demand, providing a continuous stream of hot water up to the unit’s flow limit without the need to store and maintain a large tank. An electric tankless heater needs no gas line or vent, but it does need a lot of power: most whole-house models need 240 volts and a large circuit, so plan on an electrician.

Stay tuned as we explore our top picks in electric tankless water heaters to help you make the best choice.

Buying Guide: How to Choose the Best Electric Tankless Water Heater

One of the key advantages of electric tankless water heaters is their ability to save space in your home. With no bulky tank to contend with, these compact units can be easily installed in a closet, garage, or even an outdoor space.

Additionally, electric tankless water heaters typically have a longer lifespan than their tank-based counterparts, not maintenance-free: EcoSmart’s manual says hard water means more frequent maintenance, and Rheem puts tankless life at 15 to 20 years or more against 8 to 12 for a tank.

When selecting the best electric tankless water heater for your needs, consider the following important factors:

Capacity and Flow Rate

Determine your household’s hot water requirements by calculating the maximum flow rate (gallons per minute) you will need. Keep in mind the number of fixtures and people using hot water in your home. Higher flow rates typically cater to more significant demands.

Energy Efficiency

Look for a water heater with a high Uniform Energy Factor (UEF) rating, the figure on current spec sheets. The higher the UEF, the more efficient the unit will be in converting energy to heat.

In addition, electric tankless water heaters turn almost all of their electricity into heat, but what you pay depends on whether electricity or gas costs less where you live. They generally have better energy efficiency than those powered by gas.

Ease of Installation

Electric tankless water heaters need no gas line or vent, but whole-house models need heavy 240-volt wiring, so have a licensed electrician do the install.

Ensure you choose a suitable size and design for your home and check whether any additional electrical or plumbing modifications are needed.

Temperature Controls

Select a unit with precise temperature controls, especially if you live in colder climates. Keep the setting at 120°F or lower where you can: EcoSmart’s manual warns that hotter water increases the risk of scalds.

Having a digital display and adjustable thermostat can help you easily set and monitor the desired water temperature.

Warranty and Reliability

A good warranty is a sign of a reliable product. Look for units with longer warranty periods and check customer reviews for feedback on the unit’s reliability and durability.

Best Electric Tankless Water Heaters

Discover our top picks for the best electric tankless water heaters, ensuring you always have instant hot water in your home while saving energy and space.

EcoSmart ECO 11 Electric Tankless Water Heater

The EcoSmart ECO 11 is a budget-friendly electric tankless water heater that suits a single shower or one or two sinks, depending on the climate.

✅ Pros

• Endless on-demand hot water
• Compact design saves space
• Energy-efficient operation

❌ Cons

• May struggle in colder climates
• Inlet temperature can impact performance
• Limited flow rate for multiple applications

The EcoSmart ECO 11 electric tankless water heater is a convenient and cost-effective solution for those looking to save space and energy in their home. With its patented self-modulating technology, this water heater provides endless hot water without consuming much energy. I recently installed it in my home, and it has been a game-changer.

In warmer climates, the ECO 11 is best suited to one shower or a sink or two. An 11 kW heater can warm only about 2 gallons a minute by 35 degrees (11,000 watts x 3.412 ÷ 500 ÷ 35), less than two showers need, and the flow falls further as the incoming water gets colder. If you live in an area with colder incoming water, plan on a single application such as a bathroom sink. Regardless, the digital temperature control allows you to set your desired temperature in increments of 1 degree, ensuring personalized comfort.

Installation was quite straightforward, and I appreciated not having a bulky tank taking up precious space in my home. The compact design allows for wall-mounting or point-of-use installation, giving you added flexibility in where you place it. It is also far smaller than a tank heater, which is a definite plus.

One potential downside of the EcoSmart ECO 11 is that its performance can be impacted in colder climates, as it may struggle to provide sufficient hot water for more than 2 applications at once. Additionally, the flow rate might be limiting for larger households with multiple simultaneous hot water needs.

Overall, the EcoSmart ECO 11 electric tankless water heater is an excellent choice for those who value energy efficiency, space-saving design, and on-demand hot water. Just be sure to consider your climate and household needs before purchasing.

Rheem 18kW 240V Tankless Electric Water Heater

This Rheem electric tankless water heater is definitely worth considering, with its advanced self-modulation and user-friendly installation.

✅ Pros

• Accurate external digital thermostatic control with LED display
• Advanced self-modulation to adjust the power according to hot water demand
• Simple installation with 3/4 inch NPT water connections

❌ Cons

• May not be suitable for homes with very high hot water demands
• Requires sufficient electrical power to operate efficiently
• Increased electricity consumption

When you replace your old water heater with the Rheem 18kW 240V Tankless Electric Water Heater, you’ll immediately notice the extra space you’ll have. Its slim profile and compact design easily free up room, making it perfect for those looking to declutter their homes.

One of the key features that you’re sure to appreciate is the external digital thermostatic control, which provides you with a precise temperature readout on an LED display. The advanced self-modulation capability adjusts power levels to meet your hot water needs, to help keep the water hot when demand changes, up to the unit’s flow limit.

The 3/4 inch NPT water connections are standard, and the copper immersion heating elements are designed for long life. The wiring is the hard part: an 18 kW unit draws about 75 amps at 240 volts (watts divided by volts), so have a licensed electrician do it. However, keep in mind that it’s essential to have sufficient electrical power to run this tankless water heater efficiently, as it consumes a notable amount of electricity.

Overall, the Rheem 18kW 240V Tankless Electric Water Heater is an excellent choice for those wanting a reliable and space-saving hot water solution. Just be sure to assess your home’s electrical capacity and hot water consumption before making a decision, as these factors will influence the overall performance of this water heater.

Stiebel Eltron Tankless Water Heater – Tempra 29 Plus

The Stiebel Eltron Tempra 29 Plus is a whole-house electric tankless water heater that replaces the Tempra 24 Plus we used to list, which Amazon no longer carries.

✅ Pros

• Advanced Flow Control trims the flow instead of letting the water go cold
• Compact, no venting, two temperature memory presets
• Made in Germany

❌ Cons

• 28,800 watts at 240 volts: three 40-amp breakers, 8-gauge copper and a minimum 200-amp service
• Hard-wired 240 or 208-volt work for a licensed electrician, not a DIY job
• Like every electric tankless unit, the flow drops when the incoming water is cold

Stiebel Eltron’s listing calls for a hard-wired 240 or 208-volt supply with a maximum draw of 28,800 watts at 240 volts (21,600 at 208), on three separate dedicated 40-amp breakers with 8-gauge copper wiring, and a minimum 200-amp service to the house. Have a licensed electrician check your panel before you buy.

In use it is quiet, with a digital display and preset buttons, and its Advanced Flow Control reduces the flow slightly if hot water demand exceeds what the unit can heat, so the temperature holds rather than the shower going cold.

Rheem RTEX-24 24kW Electric Tankless Water Heater

The Rheem RTEX-24 is a reliable option for those seeking energy-efficient hot water on demand.

✅ Pros

• Compact design saves space
• Digital temperature control for precise adjustments
• Continuous hot water supply without waiting

❌ Cons

• Professional installation required
• May need additional wiring
• Might not provide hot water at full flow rate during colder months

The Rheem RTEX-24 24kW 240V Electric Tankless Water Heater is an energy-efficient solution to your hot water needs, providing on-demand heated water in a compact and sleek design. Its modern and unobtrusive appearance easily blends into your home’s setup, saving you space while still performing effectively.

One feature that stands out is its digital temperature control, which allows for precise and convenient adjustments to suit your preferences. You can easily set the desired temperature for your showers or chores, ensuring that you never have to wait for hot water again.

Despite its many advantages, the Rheem RTEX-24 needs to be installed by a licensed electrician and plumber, and your panel may need more capacity. A 24 kW unit draws about 100 amps at 240 volts. It’s essential to consider these costs when deciding if this tankless water heater is the best choice for you.

Additionally, during colder months, you might need to reduce the flow rate to maintain your desired water temperature. However, its energy efficiency and on-demand hot water supply still make it an attractive option for many households.

EcoSmart ECOS 27 Tankless Water Heater

The ECOS 27 is EcoSmart’s current 27-kilowatt model, replacing the ECO 27 we used to list, which Amazon no longer carries. Choose it if you’re looking for an energy-efficient, space-saving, and consistent source of hot water in your home.

✅ Pros

• Endless on-demand hot water
• Compact and space-saving design
• EcoSmart lists it as 96% thermal energy efficient

❌ Cons

• Requires a 200-amp electrical panel
• Installation costs may be high
• Warranty is 5 years on leaks and 1 year on parts

The EcoSmart ECO 27 Tankless Water Heater is ideal for those seeking a constant and reliable source of hot water for whole-home applications. With its advanced temperature monitoring and flow rate control, this heater provides an endless and consistent supply of hot water within one degree of the selected temperature. You’ll appreciate the convenience of always having hot water when you need it.

The compact design of the ECO 27 is a great advantage, as it takes up far less space than traditional tank heaters, leaving more room for other appliances or storage. This makes it suitable for smaller homes or apartments where space is at a premium. Like other electric resistance heaters, this one turns almost all the electricity it uses into heat. Because it heats only the water you use, it can cost less to run than a tank heater, depending on your hot water use and electricity rates.

However, the ECO 27 does require a 200-amp electrical panel and three 40 Amp Double Pole breakers, which might entail additional installation expenses, depending on your current setup. Make sure to consider these factors before purchasing.

Finally, it is important to note that the EcoSmart ECO 27 Tankless Water Heater offers a Limited Lifetime Warranty on electronics, exchangers, and elements. However, some users have reported difficulty with the warranty registration process, so it’s a good idea to follow the instructions carefully and keep a record of your registration to ensure you’re covered.

FAQs about Electric Tankless Water Heaters

What are the top brands?

Some of the top brands for electric tankless water heaters include Rheem, Stiebel Eltron, and EcoSmart. These companies are well-known for their high-quality products, excellent customer service, and reliable performance.

How do Electric Tankless Water Heaters compare to gas heaters?

Electric tankless water heaters need no gas line or vent, which can lower installation cost, but whole-house models draw roughly 75 to 150 amps at 240 volts, so a panel upgrade can add a lot to the bill.

However, gas heaters can produce a higher flow rate and may be more cost-effective in terms of energy consumption, depending on your location and utility rates.

Which is the most energy-efficient Electric Tankless Water Heaters?

Almost all the electricity an electric tankless heater uses becomes heat, so efficiency ratings are high and close together. Compare the UEF printed on each model’s label or spec sheet.

How to choose the right Electric Tankless Water Heaters size?

To choose the appropriate size for your electric tankless water heater, you need to consider the flow rate (measured in gallons per minute or GPM) and the temperature rise required.

First, add up the flow rates of all the fixtures you want to be supplied simultaneously by the heater. Next, determine the temperature rise by subtracting the incoming water temperature from the desired output temperature. Use these values to choose a model that can meet your specific needs.