8 Small Tankless Water Heaters – (Easy to Install & Powerfull Units)

On our quest to find the best small tankless water heater, we’ve been looking from point of use heaters, to small holding tanks and those that are easiest to install and those that are the most powerful. You will find all of these in our list of 8 products below, with a pretty low threshold of a price range that should fit easily into your budget for a tankless water heater project.

We’ve done our absolute best to comb through the manufacturer information as well as confirmed user reviews to give you all the important details about the features you want, as well as the must-know specifications of each unique model.

A variety of users—all the way from those living off the grid and wanting to use battery power instead of electricity to heat water to those wanting the convenience of instant, right now hot water at a distant tap or even in a boat or RV can find what they need on our list of small tankless water heaters. Feel free to peruse our impressive list below to find the best heater that fits your unique needs.

  • 4.5 Customer Rating
  • Rheem RTEX-13
  • Dimensions: 4 x 9 x 13 inches
  • Flow Rate: 1.5 GPM
  • Power Source: Electric-Powered
  • Weight: 4 pounds
  • Made In: USA
  • Warranty: Manufacturers
  • 2.5 Customer Rating
  • Atmor AT-900-03
  • Dimensions: 11.9 x 8.7 x 4.2 inches
  • Flow Rate: 0.5
  • Power Source: Electric-Powered
  • Weight: 4.6 pounds
  • Made In: USA
  • Warranty: Manufacturers
  • 3.5 Customer Rating
  • A.B Crew 110V
  • Dimensions: 12 x 8.4 x 4.2 inches
  • Flow Rate: N/A
  • Power Source: Electric-Powered
  • Weight: 1.81 pounds
  • Made In: N/A
  • Warranty: Manufacturers
  • 4 Customer Rating
  • Ariston GL4S
  • Dimensions: 13.8 x 13.5 x 13.8 inches
  • Flow Rate: N/A
  • Power Source: Electric-Powered
  • Weight: 23.1 pounds
  • Made In: Italy
  • Warranty: 6-year warranty, 1 year on parts
  • 3 Customer Rating
  • Stiebel Eltron Mini 3
  • Dimensions: 6.5 x 3.8 x 7.5 inches
  • Flow Rate: N/A
  • Power Source: Electric-Powered
  • Weight: 3.44 pounds
  • Made In: USA
  • Warranty: Three year limited warranty
  • 4 Customer Rating
  • EcoSmart ECO 11
  • Dimensions: 6.5 x 13.5 x 10 inches
  • Flow Rate: N/A
  • Power Source: Electric-Powered
  • Weight: 6.5 pounds
  • Made In: USA
  • Warranty: Lifetime Warranty on electronics, exchanger and element

Rheem RTEX 13 Electric Tankless Water Heater

This tiny little electric unit will amaze you with what it can do. Do not let its small size (9 by 10 by 5 inches) or price deceive you—this unit can get the job done. The RTEX-13 would be best for a single occupant or even one of those trending tiny homes, or a small office or studio with low hot water needs.

The RTEX 13 is usually used for a single shower application, but don’t let that restrict you. Others have successfully used the RTEX 13 for myriad uses, as it pulls about 240 volts and use about 13 KW of energy if it’s at its max temperature. It offers a 4.0 GPM maximum flow rate, but unless you stagger your hot water use, don’t expect it to give hot water to multiple hot water tap points simultaneously.

The RTEX 13 has a high price point in the range of our small tankless water heater review, but it does offer the power that backs up the price. Those 4.0 GPMs are a good spot to be for a range of hot water demands in the home or commercial space. Don’t forget about including the installation costs of copper piping and the electric parts for the panel hookup. Conveniently included by Rheem is a pre-wired 2-foot power supply cord. You’ll need to safely run a 60 amp service for the RTEX 13.

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Atmor AT-900-03 Tankless Electric Instant Water Heater

The AT-900-03 falls at the very lowest end of Atmor’s line of small tankless water heaters. At just 3 kilowatts and 110 volts, it can be expected to heat water for something rather small, like a low-flow faucet at a sink. This would be ideal for a workshop sink, an animal or crop barn, maybe an office, or even a small retail application. You could use it for a mobile truck business like a washing service or food truck. Equivalent to its small size, it also comes in at the very low end of the price range.

With a 45 degree temperature rise, like those common with a water inlet temperature of 60 degrees in moderate or warmer climates, you can anticipate 0.5 gallons per minute (GPMs) for a water flow. That is a pretty good flow for a faucet, so even if you’re in a colder climate, you could still use this product. For your install, you’ll need to allocate 30 amps on a breaker. The AT-900-03 is designed to be hard-wired to a dedicated circuit breaker. It has ½ inch NPT water connections on the bottom of the unit. This nifty little tankless water heater will only weigh 3.4 pounds and take up a small amount of space with dimensions of 7.29 inches of length by 11.82 inches of width by 3.55 inches of height.

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AB Crew Tankless Electric Hot Water Heater Faucet

Now here is a neat product not often considered, but once you see it—you’ll definitely want one for your kitchen or handwashing sink. The electric hot water heater faucet is described as a small lateral inflow model, which really just means it has a small faucet length as it arches into the sink. If you have a distant bathroom far from your water heater and want hot water at the tap, especially in cold winter months, this might solve your problem.

A.B. Crew offers an awesome digital LED display for showing you the temperature as you use it, and it is measured in Celsius. The hot water heater faucet uses 110 volts and comes standard with a plug to start your hot water enjoyment right away. You’ll find all you need to install this right at your local big box or plumbing hardware store, and it shouldn’t be too difficult for a DIY homeowner to plug this in and get going.

The faucet of this product is made of plastic. The heater will need time to heat up the water, so it works best if you open the water flow to a slow flow to trigger the heater, and then eventually turn it up to your water flow needs. This product is made in China and ships from there. For a low price, you can have hotter water right at your tap, but you won’t find much customer support or reliable information from the manufacturer.

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Ariston GL4S Electric Mini-Tank Water Heater

For those who would like to try a point-of-use water heater, this Ariston GL4S model is one of the easiest to install. Simply plug the unit into the wall near the sink, with no hard wiring required. Use the cold water line to attach this mini heater, and you are ready to go. It holds 4 gallons of hot water right at the faucet where you will need it. It is virtually effortless to get your hot water quickly. This updated version of the Ariston GL now has a sensing probe that more accurately maintains the proper temperature and can adjust the temperature more quickly. The manufacturer does offer a 6-year limited warranty on the heating exchanger and a 1 year limited warranty on the parts.

Because of its size and holding tank, this Ariston GL4S mini tank is priced at about the mid-high of the price range of our small tankless water heaters. For installation, you will need enough room for the 14 inch x 14 inch size. A good application for the Ariston GL4S is if you have a sink that is far from your hot water heater, and it takes a long time to run the faucet and get hot water to the tap. Other places to install the Ariston GL4S would be at your kitchen sink, or near a large Jacuzzi tub or shower with multiple sprayers.

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Stiebel Eltron Mini 3 Electric Tankless Water Heater

For a good electric tankless water heater, using the Stiebel Eltron Mini 3 will give you a German-made product right about in the middle of the price range. Stiebel Eltron has designed the Mini 3 to be aesthetically pleasing, so it can be mounted right in plain sight without any distasteful parts sticking out.

The Mini 3 model comes standard with a 0.5 GPM pressure compensating flow reducer that must be installed, and it can offer hot or warm water right at the point of use. It is usually used for a hand wash or utility sink, in a home or retail application. Or, if you are heavily using your laundry area or have a small cabin or boat or RV where you’d like an electric tankless, the Mini 3 is worth consideration. Let’s say you own a small business and want to reduce your water loss or hot water heating bill—you can just install the Mini 3 right at your position and voila; instant hot water!

The Mini 3 is 7.5 by 6.5 inches, and draws 25 amps for energy. Voltage used can range from 110-120 volts, and you can expect about 3.0 kilowatts. Stiebel Eltron also offers a generous 7-year warranty against leakage and a 3-year warranty for parts. Be sure to check your owner’s manual for all the little warranty details. At a 40 degree temperature rise, you can expect about 0.5 gallons per minute (GPM), and as the heating rise drops to 10 degrees, you can get up to 2.0 GPM out of the Mini 3.

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EcoSmart ECO 11 Electric Tankless Water Heater

If you have lower hot water needs but still want the ease of an electric tankless, the EcoSmart ECO 11 is ideal for a small apartment-size space. The ECO 11 can be used for multiple or single applications depending on your climate. You can likely factor it to provide hot water for two faucets at 1.3 GPM in the coldest climates, or a shower and two faucets simultaneously in warmer climates at 2.7 GPM. Expect the ECO 11 to pull 13 kilowatts for its power needs. It draws 57 amps, and requires a 60 double-pole for installation.

EcoSmart’s sizing offering is based on a 240 volt electrical service. Be sure to check your existing electrical panel to ensure you have adequate electrical draw space for the ECO 11. With a 50% savings in water heater costs, the ECO 11 should help you reduce your electric water heating needs fairly quickly. This unit will also save a sizable amount of space in the utility area, coming in at 6.5” high x 13.5” wide x 10” deep. Especially if you’re removing an existing tank, it would be nice to have that extra space for storage or ease of access to other utilities in your basement or utility closet.

An electric hot water heater from EcoSmart will also give you one of the most extensive product warranties on the market. If you’re new to tankless water heaters, a reputable manufacturer may be important to you. Customers are very happy with the customer service support from the team at EcoSmart—technicians are easily available to help with sizing, installation and maintenance questions. They will offer a lifetime warranty on the electronics, the stainless steel exchanger, and the heating element.

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Rheem RTE 9 Electric Tankless Water Heater

Let’s say you are on the search for the best small tankless water heater for your kitchen sink—be sure to include the Rheem RTE 9 in your comparison. The RTE 9 is a great little unit to install for point-of-use heating near a distant bathroom, by your kitchen sink or clothes washer, or even in your RV or boat.

Out of our list of products, the RTE 9 falls on the higher end of price, but if you’re looking for that 3.0 GPMs of flow rate, you might already be familiar with the range of money you’re looking to spend for that. The temperature control is right on the front of the unit, and Rheem again is including the 2 feet of pre-wired power supply cord.

You can expect the RTE 9 to pull about 240 volts and use about 9 KW of energy if it’s at its max temperature. You will need to dedicate 40 amps for a breaker for the electrical installation of the RTE 9. Rheem designed this with a brass and copper heat exchanger, and it does feature the modulating heat technology for quickly heating up your hot water to just the right temperature. The plumbing connections to install this powerful RTE 9 are standard ½” pipe fittings.

Eccotemp L5 Portable Tankless Water Heater and Outdoor Shower

The Eccotemp L5 is a very unique unit as it combines the convenience of a tankless water heater with a showerhead sprayer and hose. This all-in-one unit is also very reasonably priced at the low end of the dollar spectrum. The L5 is a best seller thanks to its reliability and reasonable price. Water will flow at a rate of 1.5 GPM on the maximum setting. Eccotemp has designed the L5 meaning for it to be used as a recreational and portable unit, so it will work well for hand washing stations, cleaning animals outdoors, or of course an outdoor shower.

For those wanting to live a bit more off the grid, the ignition works with two D cell batteries, so no need to use electricity to start it. This is also an outdoor shower unit, so it has specific venting requirements of a 2 inch clearance from a wall, 1 foot side to side from anything flammable, 3 feet from a window as well from an overhang and 18 inches from the ground.

You can expect the propane fuel to heat the water up to 37,500 BTU with the L5, a very comfortable temperature range for a hot shower. Eccotemp has included a CSA regulator for use with a standard 20 pound propane grill tank. Users have noted that the L5 does come with a 20 minute automatic safety shutoff valve, so you will have to manually turn the unit on and off again if you want more hot water. You can also hook up the outdoor shower with a garden hose, as an adapter is included with the L5 unit. Eccotemp also offers a 1 year manufacturer warranty on the L5.


After reading through our small tankless water heater review, we hope you have found a choice that will be just what you need for your home or commercial space. So many different people use these heaters from those living off the grid to nontraditional water heating needs, like workshops or remote lake cabins, or even luxury boats or RVs and campers.

As much of the rest of the globe has already found, branching away from the typical huge hot water heater tanks used in the United States might just not be the most efficient way to get hot water. If you’re really serious about cutting your total water waste and becoming more energy efficient in your home, it is really an easy first step to start using a small tankless water heater. That way, you won’t be investing a large sum of money and be worried that your expectations will not be met. The price point of these small heaters is manageable enough for those who are just wanting to get their feet wet in the tankless world, no pun intended.

Our in-depth look at the best features of each of these tankless water heater options should give you the information necessary to choose either an inline unit, a plug-in unit, or even a battery-powered tank. You should be able to balance your fuel source for power with your budget and how much hot water you’ll be using to be able to whittle down the list and get the exact right product ordered and installed.