10 Electric Tankless Water Heaters

Water heaters are vital for providing your home with warm running water year-round, but most standard water heaters feature a tank that takes time to heat, consuming a lot of energy.

Without a bulky storage tank to hold heated water, tankless options provide hot water with superior energy efficiency, saving you money and electricity every time you turn on the hot water faucet.

If you want the best in water heating technology that can save you time and money, tankless electric water heaters are the right choice for your home.

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Tankless hot water heaters run either off gas or electricity. Electric water heaters are easier to install than gas heaters and more affordable to purchase outright. However, both these styles of water heaters are far more compact and efficient than those that use a large storage tank to heat and store the water.

Stiebel Eltron Tankless Water Heater
Sio Green Electric Tankless Water Heater
Eemax Electric Tankless Water Heater
Bosch Electric Mini Tank Water Heater
Titan Electric Tankless Water Heater

The Stiebel Eltron Tankless Tempra 24 Plus is our top choice for an electric tankless heater for your water. With its patented Advanced Flow Control, it self-modulates, providing piping hot water for multiple sites in your house at the same time.

If you have a small space and don't need to have hot water for multiple spots, the Bosch Tronic 3000 is a perfect point-of-use water heater from a renowned German company that has years of engineering experience creating quality products.

One of the primary considerations you have to contend with when looking to upgrade your water heating system is the water's ground temperature in your area. The temperature of the water that comes into your house will play a significant part in which water heating system you choose.

If you live in a warmer area, the Titan Electric Tankless Water Heater will meet your needs. Robust, small, and inexpensive, this is an excellent choice for warmer climates, but if the ground temperature is below 65˚ the Titan won't be the most efficient choice.

Tankless water heaters are the most cutting-edge water heating systems, but for the latest state-of-the-art heating technology, look no further than Sio Green. The Sio Green SIO18 uses non-metal parts to heat your water with the technology developed by NASA. Infrared lasers heat water in quartz tubes to deliver boiling water any time of day or night.

If you have a small space and your water heater will be visible to guests and visitors, design may be your number one priority. The Eemax EEM24027 has all the innovative tankless water system benefits, and a blue exterior improves its compact design. Perfect for lofts, apartments, or small bungalows, the Eemax's facade coordinates effortlessly with any home decor style.

Choosing the Best Product Type

If you want piping hot water any time of day or night, but don't have the space for a conventional tank-style water heater, opt for a tankless version, the newest innovation when it comes to in-home water-heating systems.

For higher flow rates and an easy-to-install water-heating system, look no further than a tankless electric water heater. These convenient systems heat cold water as it runs through your pipes, so there's no need for a storage tank or other cumbersome add-ons.

Two of the most critical features for buying a tankless water heater are your temperature rise in the locale in which you live and the expected flow rate, which is how many gallons of hot water your heating system pumps out per minute.

Temperature rise

This is how many degrees your water heater has to raise the water temperature. This temperature increase depends mostly on the temperature of your groundwater and directly impacts the energy efficiency of the unit.

To calculate the temperature rise in your geographical location, subtract the incoming water temperature from your desired hot water temp. This number is your temperature rise.


How many gallons of hot water your water heater produces per minute depends on what kind of water heating system you have. If you want to figure out the GPM of your whole house or individual rooms, add up the GPM of each major appliance and faucet.

For example, if you have a shower that has a flow rate of 1.5 gallons per minute and a sink faucet that has a 1.0 GPM flow rate, your water heater will need to be able to manage a combined flow rate of 2.5 GPM.

Should I Get Point of Use vs. Whole House System?

When looking to swap out your water heating system, you'll need to consider whether your new tankless set-up will heat the water for the whole house or for a single faucet, which is known as point-of-use.

If you opt for a point-of-use in your kitchen, a tankless system installed under the sink minimizes the amount of time the water sits in your pipes, so you get instantaneous hot water.

With the immediacy of plentiful hot water, you also waste less water and energy. You don't have to stand there watching cold water go down the drain, waiting for it to get hot.

Factors to Consider When Choosing an Electric Tankless Water Heater

There are several reasons that savvy consumers choose tankless water heaters that run off the electric grid, with the main ones being convenience, compactness, and conservation.


People love the ease of installation and minimal upkeep for a tankless electric water heater. If you want a point-of-use heater, you can easily install this small system in a closet or under a sink. You never have to remodel to include one in your house but can install it wherever you need it. Some smaller models can even be dual-use -- you can use it in your RV and then reinstall it in your kitchen when you're back from your trip.


Since you don't need a storage tank for these water heating systems, you can put them almost anywhere that you have access to your water pipes and an electrical grid.


If you have a traditional water heater, the percentage of your yearly energy usage devoted to heating water could be as high as 14%. A tankless electric water heater will lower your household energy bills drastically, up to as much as 34-40% annually. There are models available that have an Energy Star rating, and since they last up to 20 years, you won't bewasting money on repairs, and broken tanks won't fill up landfills.

Determining these factors will help you choose the perfect tankless water heating system to use with your electrical grid. It's easy to put in and rarely needs repairs or upkeep. It will help you save money, time, and water. And you will always have piping hot water any time you want.

Top 10 Product Types Reviews

Top Pick: Stiebel Eltron Tankless Water Heater -- Tempra 24 Plus -- Electric

Stiebel Eltron Tankless Water Heater
Stiebel Eltron Tankless Water Heater

This tankless heating system is a marvel of innovation. One of the biggest assets of the Stiebel Eltron Tempra 24 Plus is that, if the required flow rate exceeds what the system is capable of, this system will automatically balance out the system so you always have hot water with impressive pressure.

A patented innovation called the Advanced Flow Control revolutionized the water heating industry, regulating your heat exchanger so that you always have hot water when you want it.

The AFC couples with the condenser in the Stiebel Eltron Tempra 24 Plus for an outstanding energy efficiency rating. Whereas some of the most efficient tankless water heaters have an EF (energy factor) of around .95, the Tempra 24 Plus, with its condenser and the patented AFC, has an EF of .99. This means that for every dollar you spend on heating water, 99 cents of it goes directly into that with only .1 cent of wasted money.

With cutting-edge technology, you can monitor the temperature of the groundwater, flow rate, and the outgoing temperature of the water. To maximize efficiency, the system warms the water flow in stages.

It's easy to set this system with its simple knob and digital readout. And without any mechanical switches, the Stiebel Eltron Tempra 24 Plus runs quietly and efficiently. To focus the power of the water heating system, the Stiebel Tempra 24 Plus comes in six different sizes, so no matter what your household requirements are, you will find a perfect fit.

Although you may need to update your electrical grid for the Stiebel Eltron Tempra 24 Plus, you won't be sorry. With focused, innovative technology that enhances the heat of your water, you will save money, energy, and water with this tankless system.

Best Electric Tankless Water Heater for a Whole-House Unit: Bosch WH27 Tronic Whole House Electric Tankless Water Heater

Bosch WH27
Bosch WH27

Bosch offers two tankless water heating systems, whole house and point-of-use. Regarding ease of use, efficiency, and outstanding heat output, the Bosch WH27 Tronic is a unique electrical tankless system.

The Bosch WH27 Tronic is an excellent choice for a house with 2 to 3 bathrooms and can handle maximum temperature output for 3 simultaneously running faucets. The polymer-based heating elements on this system modulate the temperature to have a consistent, even heat all the time.

The polymers don't just help this model keep the hot water at a consistent temp, it also makes the Bosch WH27 Tronic one of the most durable choices on the market. The brand maintains that it will last for at least 20 years, and because it is so energy-efficient, with an EF of .97, it will consistently save you money over its lifetime.

Although you can't use plastic or PEX materials on your sink fixtures with the ultra-hot heating elements, it is lightweight and quiet. Once it's in, you won't even know it's there, except for the consistently hot water gushing from your taps.

All of the products come with a 15-year warranty on the heat condenser, which is the element that heats the water in the pipes. The smallest Bosch unit can handle a flow rate of 8.3 with a temperature rise of 35˚F. The largest unit can handle 12.1 GPM and has an increased energy efficiency rationing of 98.

A perfect choice for an average household with manageable water usage requirements, a Bosch WH27 Tronic is lightweight, efficient, and a great investment.

Best Electric Tankless Water Heater for Point-of-Use: Bosch Tronic 3000 Tankless Water Heater

Bosch Electric Mini Tank Water Heater Tronic
Bosch Electric Mini Tank Water Heater Tronic

The adaptability of the Bosch Tronic 3000 is one of its most attractive features. A multi-functional mounting feature lets you put this tankless water heating system on the floor, wall, under the sink, or on a shelf.

A Bosch Tronic 3000 taps directly into the cold water line, so you will have hot water at the turn of your faucet. You can even use it in conjunction with your current water heating system.

Since the Bosch Tronic 3000 is a point-of-use unit, the hot water coming from the heating system doesn't have to travel far, so it doesn't lose heat in transit. It's eco-friendly as well as being efficient as the CFC-free foam insulation decreases its eco-footprint. The interior of the tank is lined with glass, making it last as long as possible.

With a pressure-relief valve, you never have to worry about your safety. The maximum temperature output of the Bosch Tronic 3000 is 145˚F, so you never have to wait for the hot water.

From the 4 different models available, you'll easily find the right water heating system for your needs. Depending on the flow rate, the 12kW can either provide a temperature rise of 45˚F at a flow rate of 1.8 GPM, or it can handle a 75˚F temperature rise at a flow rate of 1.1 GPM.

The Bosch Tronic 3000 is valuable for its adaptability. Install it under the sink, in the closet, on the floor, vertically, or horizontally; it's small enough not to be obstructive and produces super-hot water instantaneously.

Best Electric Tankless Water Heater for an Eco-Friendly System: EcoSmart ECO 27

EcoSmart ECO 27
EcoSmart ECO 27

This slightly larger unit can act as a whole-house or point-of-use unit, depending on your needs. If you have a small household, this is an excellent whole-house unit, whereas if your hot water requirements are slightly more, you could use this system for one part of your home.

The lower activation flow of 0.3 GPM means that you get instant hot water, even at very low flow rates. Comparable devices usually have an activation rate of 0.5, so the EcoSmart will deliver hot water at whatever flow rate you desire.

The EcoSmart ECO 27 has a high flow rate of 6.6 GPM with an energy efficiency of 99.8, and at such an affordable price, it's hard to beat this highly eco-friendly tankless water heater. The copper and stainless steel heating elements make this durable as well as kind to the environment.

This water heating system is top-notch when it comes to efficiency. It can be adjusted by 1˚F increments, making it exact down to the degree.

Although it's slightly larger than other models, it has a lifetime warranty on the heating elements, as long as you have it professionally installed.

Best Electric Tankless Water Heater for Small Spaces: Rheem 240V 2 Heating Chambers RTEX-18

Rheem RTEX 18
Rheem RTEX-18

This tankless electrical heating system can fit into any nook or cranny and is an ideal water heating system for a small household at 8.5 lbs.

It is as powerful as larger units with a temperature fluctuation of 80˚F to 140˚F. You can adjust your desired water temp by degree increments, so you can tailor the heat of your water to your specific needs.

And you won't need to update your electrical grid to use the Rheem RTEX 18, which is a major benefit and makes installation a cinch. The Rheem RTEX 18 uses standard voltage and only uses 75A. Most tankless water heating systems use 100A or 200A, but the Rheem RTEX 18's low amperage creates an outstanding balance between power and efficiency.

Although it only has a combined GPM of 4.4, which supports a showerhead and a faucet, the Rheem RTEX 18 has excellent self-modulation for a water heating system, so the power is adjusted automatically. This is a small but mighty water heating system that only uses 18 kW to get to full heating potential with two chambers. 

This is a reliable, compact, and powerful water heating system with a 99.8% efficiency rating and durable copper heating elements.

Best Electric Tankless Water Heater for High-Tech Construction: Sio Green SIO18-220v/80A/18kW - Infrared Electric Tankless Water Heater

Sio Green Electric Tankless Water Heater
Sio Green Electric Tankless Water Heater

If you want the most cutting-edge technology, the Sio Green SIO18 is an ideal choice. Electricity fires up infrared lasers, which in turn warms up water inside quartz tubes.

The no-metal construction of the Sio Green SIO18 means that it holds up incredibly well to general wear and tear without frequent maintenance. One of the most useful aspects of this unique construction is that the quartz tubes will not corrode, and calcium deposits won't build up inside them.

Since there are no metal parts to maintain, you will have lower maintenance fees associated with your Sio Green SIO18. It's also very energy efficient, so you save money on your electric and water bills.

Usually, these types of tankless water heaters are reserved for commercial uses, but Sio Green has scaled down this model for residential purposes. The electrical needs of the Sio Green SIO18 are manageable for most electrical grids using 240V and with an 80A electrical grid.

There is a high level of sophistication that goes into this tankless water system, with technology designed by NASA, and the infrared lasers heat the water in the quartz tubes in an instant. The only disadvantage is that this model is heavier and more expensive than most other tankless models. 

If you're looking for a highly durable tankless electric water heater that uses the same type of technology to get humans into space, the Sio Green SIO18 is a superb appliance.

Best Electric Tankless Water Heater for Warmer Climates: Titan Electric Tankless Water Heater

Titan Electric Tankless Water Heater
Titan Electric Tankless Water Heater

This tankless electric water heater is small but mighty. With an energy rating of 99.5%, this water heater can serve a household with up to 3 bathrooms. The Titan's maximum flow rate is 4.0 GPM, and it can handle a 20˚F temperature rise. The average flow rate and temp rise are 2.3 GPM and a 45˚F rise.

The Titan has an easy-to-use display, with a button to set the temperature and a high-to-low graph to monitor your water temperature. It should only be used in locales with warmer climates, as the groundwater temperature needs to be about 65˚F for this water heater to be effective.

The Titan also has a sampling system so that you get a consistent water temperature. This built-in system monitors the input and output to have the same high temperature every time you turn on a tap.

The company that makes the Titan only specializes in tankless systems and has 8 different products on the market. The top-of-the-line products have a digital interface to monitor diagnostics and are more expensive, but these premium tankless water heaters are suitable for all climates, even the coldest parts.

The Titan is small and lightweight and can be mounted on a wall or under a sink. This is an easy, prudent method to heat your water if you live in a warmer climate.

Best Electric Tankless Water Heater for Enchanting Design: Eemax EEM24027

Eemax Electric Tankless Water Heater
Eemax Electric Tankless Water Heater

Eemax is a company that has been making water heaters for decades and acquired EcoSmart, another water heating system company. This unit is an excellent choice for small households or point-of-use water heating needs. It has the same efficiency and energy benefits as most of the tankless water heaters on the market, but instead of just a silver, white, or grey design, this water heater is a stylish blue.

Since you can mount this almost anywhere, the sleek design and attractive blue appearance make this suitable for households looking to have a compact water heater using the most energy-efficient technology in a visible location.

The Eemax has self-modulating technology to make sure that you always have all the hot water you need. This is a unit made for smaller households so that it won't suffice with more than two showers or faucets running at once. However, with energy needs of 240V and 112.5A electric grid, you may need to update your electrical grid.

This unit warms up fast and cools down quickly as well. You won't be wasting energy heating unnecessary water that will only go down the drain.

If you live in a small space where your water heater will be noticed daily, this compact but high-powered tankless water heater is just what you need to keep the hot water running.

Best Electric Tankless Water Heater for Safest Heater: Atmor AT-D18TP-AZ Thermopro

Atmor Electric Tankless Water Heater
Atmor Electric Tankless Water Heater

Although the Atmor is a relative newcomer to the water heating industry, this model is one of the safest tankless water heaters on the market. It has an IP54 certification, which guarantees it is safe from splashes so that you can install it near the shower or sink.

The Atmor can handle groundwater temperatures that other models cannot. With a flow rate of 1.9 and a temperature rise of 37˚F, it's not just the added safety features that make this great value for money.

It's easy to install this tankless model and easy to use for any skill level with its digital readout. You can be as precise as you like by setting the ambient temperatures in your house in 1˚ increments. You can choose between 4 temperature levels to match the season, so your hot water supply is guaranteed no matter what month it is.

Although the Atmor isn't great in households that run two showers simultaneously, this is an ideal choice for a loft, duplex, or apartment. Atmor is known for its high-quality inline heaters in the water heating industry and can even be used for low-flow showers.

Best Electric Tankless Water Heater for a Budget: Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater

Rheem Water Heater
Rheem Water Heater

This tankless water heating system gives you a lot of versatility for an affordable price. The RTEX-13 from Rheem is ideal for small to medium households with a flow rate of 4.0 for one shower and one sink running simultaneously.

Pinpoint your exact comfort level down to the degree with the RTEX-13's simple user interface sporting a digital display and control panel. Its highly accurate design doesn't sacrifice simplicity to be precise and save money without a lot of hassle.

It's uncomplicated design also leads to a quick installation. And since the RTEX-13 is field serviceable, you don't have to uninstall the unit to service it. Copper heating elements are highly effective and safe, and the kit comes with ½ NPT adapters, ½" compression water connectors, and a 3' cable.

You can use the RTEX-13 as a point-of-use unit or for a small household, and it's ideal for apartment dwellers. With an energy efficiency of 99.8% and a sleek design, the RTEX-13, much like its older brother, the Rheem RTEX-18, is a well-designed machine that's worth the investment.

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