Best Tankless Water Heater Reviews (Choose the Best)

There are dozens of tankless water heater brands today. Americans are buying the water heaters in large numbers thanks to the fact that they provide hot water whenever you need it, they are more durable and more energy efficient. But while they certainly are a worthwhile investment, it is important that you do due diligence to get the best tankless water heater for your home. Without proper research, you may undersize your home or pay too much for a heater that is not worth it. Fortunately, we are about to go through everything you need to know about these heaters. Read on also for our tankless water heater reviews.

Keep in mind that the following six heaters are best-selling in various online retail stores. All you need to do is compare them in terms of features and water heating capabilities, and you will probably spot one to fulfill your home’s water heating needs.

tankless water heater reviews
  • Eccotemp L5
  • Power: gas
  • Dimensions: 14.5" x 11.5" x 4.5"
  • Max flow rate: 1.5 GPM
  • Other: 37,500 BTUs, 3V (D cell batteries), 11 kW, safety shutoff timer
top rated tankless water heaters
  • Takagi T-KJr2-IN-NG
  • Power: gas
  • Dimensions: 6.7" x 13.8" x 20.3"
  • Max flow rate: 6.6 GPM
  • Other: 140,000 BTUs, surge and overheat protection, inlet and outlet thermistors, 0.81-0.83 energy factor
best tankless water heater
  • EcoSmart ECO 27
  • Power: electric
  • Dimensions: 17" x 17" x3.75"
  • Max flow rate: 3 GPM
  • Other: 27 kW, 3 x 8 AWG wire gauge, 3 x 40 AMP required breaker, 99.8% energy efficiency
best on demand hot water heater
  • Stiebel Eltron Tempra Plus
  • Power: electric
  • Dimensions: 16 5/8" x 14 1/2" x 4 5/8"
  • Max flow rate: 4.5 GPM
  • Other: 24 watts, wire size 2 x 6/2 AWG, circuit breakers 2 x 50 A, digital temperature control
best instant hot water heater
  • Rinnai RL75iN
  • Power: gas
  • Dimensions: 14" x 9.3" x 23"
  • Max flow rate: 7.5 GPM
  • Other: 10,300 - 180,000 BTUs, digital controller, 82% Thermal Efficiency
tankless electric hot water heater
  • Rheem RTGH-95DVLN
  • Power: gas
  • Dimensions: 18.5" x 9.8" x 27.5"
  • Max flow rate: 9.5 GPM
  • Other: 11,000 - 199,900 BTUs, 94% energy efficiency, electronic controls, Low Nox version

Top 6 Tankless Water Heaters Reviewed

EcoSmart ECO27 Tankless Water Heater

best tankless water heaterEcoSmart ECO27 is EcoSmart’s best-selling tankless water heater. It is also one of the best rated tankless water heaters in the market today, thanks to its ability to deliver hot water in the coldest of environments. Eco27 was largely designed to help keep water fixtures supplied with hot water in cold areas. But even in warm areas, the tankless water heaters supply hot water to multiple fixtures at the same time. According to reviewers online, Eco27 is a reliable heater. You can use it as your sole tankless water heater and never get disappointed.

  • Stable water supply. According to EcoSmart, the ECO27 can deliver hot water at 3 GPM during the winter season. In warm areas, the heater is designed to deliver hot water at 6 GPM. With these flows, your family of 3-5 can have enough water for all needs whenever you need it.
  • Efficient. Eco27 is designed with copper and stainless components that help improve hot water delivery all year round. Most online reviewers also praise the unit for being efficient even during cold environments. The only time you could feel dissatisfied by the unit is when you have guests and have multiple showers running.
  • Digital Temperature control and self modulating flow sensor. The unit features smart features like a digital temperature control that allows you to regulate temperatures in increments of 1 degree. The self modulating technology is another smart feature meant to conserve on water usage when you are not using any fixtures in the house.


Eccotemp L5 On Demand Hot Water Heater

tankless water heater reviewsEccotemp L5 is probably the only tankless water heater that comes with a shower. Call it a marketing gimmick, but the outdoor shower is a big reason why people buy the unit. Being a portable water heater, however, it lacks the powerful performance other top tankless water heaters attract. It delivers hot water at a modest 1.5 GPM. It is powered by a 2D battery and features several useful digitally controlled features. With these features, Eccotemp L5 is an ideal unit for your RV, camping by a lake house or even for cleaning your car.

  • Reliable Water heater. While it delivers hot water modestly, it is a reliable unit. According to many reviewers, Eccotemp’s L5 will provide hot water on the go no matter where you are.
  • Portable. Eccotemp L5 is a compact and small tankless water heater. It is designed that way so that you have an easy time setting it up at the campsite or wherever you take it. And to further ease installation, the unit comes with all the accessories you will need for its installation.
  • Battery Powered. Being a camping water heater, it is only reasonable to have a battery power source. The 2D battery is light and adds little to the unit’s overall weight. In addition to being light, the use of a battery power source makes it a great emergency water heating source.
  • Custom settings. Ecotemp L5 is a modern device with settings meant to ease your operation with it. The heater allows you to choose from one of its multiple spray settings. It increases water temperatures fast and shuts down after 20 minutes of usage.


Takagi T-KJr2-IN-NG High Efficiency Tankless Water Heater

top rated tankless water heatersIf you are looking for a home tankless water heater that won’t cost you too much, consider checking out this model. It is one of the best tankless heaters from Takagi. It delivers hot water on the go at a high 6.6 GPM, which makes it an ideal water heater for a family of 3-5. Coming at slightly less than $500, the heater is cost effective. There are probably few other tankless water heaters with the same capabilities that cost within the price range. The Takagi model is also a customer favorite. According to many online reviewers, the gas powered water heater maintains a stable hot water supply rate both in cold and warm seasons.

  • Light and Compact. You will have an easy time installing this unit if you choose to buy it. Measuring 6.7*13.8*20.3 inches, the unit is medium in size and compact. It comes with all the accessories needed to install it and a manual to help you install it accordingly.
  • Efficient. The Takagi model uses a 140,000 BTU rated gas input to help it keep up with all the hot water demands you might have at home. Delivering hot water at a maximum 6.6 GPM, the heater can help you accommodate 2 simultaneous showers or sinks with no water inconveniences.
  • Energy efficient. The water heater has an energy factor of between 0.81-0.83, which is the highest energy efficiency a gas powered water heater can get.
  • Quality engineered for safety. If you have the unit installed properly by a professional, you may never have any safety concerns about from the unit.


Stiebel Eltron Tempra 24 Plus Instant Hot Water Heater

best on demand hot water heaterStiebel Eltron is a German tankless water worth of good praise. The unit incorporates technology and quality engineering to offer you a machine able to deliver hot water consistently at 4 GPM. According to its manufacturer, the unit uses highly advanced technology to make it super efficient and easy to use. Many online reviewers seem to agree with the claim, noting that it is a best-selling product on the online marketplace. As already mentioned, the Stiebel product incorporates several useful digital controls and settings meant to make more reliable.

  • Highly Efficient. Stiebel Tempra is a high efficiency tankless water heater. The unit operates at a bare minimum of 0.58 GPM, and improves to 2.13 GPM when the temperature is increased to 770 F. At maximum, the German device delivers hot water constantly at 4GPM. Thanks to the incorporation of a microprocessor technology, the unit is able to work efficiently even when your home’s incoming water flow keeps on varying in temperature.
  • Compact for easy Installation. The Stiebel model is by no means the best designed tankless water heater. However, it is compact and very easy to install. You need no venting to install it. But you will need a 200A power service and 2 AWG copper circuit breakers for safety reasons. Since it is a complicated device, it is advisable that you call in a professional to install it.
  • Digital Controls. Stiebel Tempra is engineered with technology infused in it. It has digital controls to help you regulate temperatures and a digital display to help you monitor its performance.


Rinnai RL 75iN Whole House Tankless Water Heater

best instant hot water heaterThere are two main Rinnai RL75 tankless water heaters. They almost have similar features but the RL75iN is unique for several major reasons. Besides its sleek, shiny construction, the instant hot water system uses a high 180,000 BTU of gas power to deliver hot water in medium and large homes. With the unit’s ability to deliver water at 7.5 GPM, you can run two showers and two sinks simultaneously with not inconveniences. One of the reasons that make the RL 75iN a unique unit is that you don’t have to incur high energy costs when you only need one or two water fixtures served with hot water.

  • High Performance. Say no more to hot water inconveniences in your home once you have this tankless water heater. The whole house tankless water heater is designed to deliver hot water at two rates. You can set it to deliver water at 7.5 GPM, or lower the flow rate when you only have a few water fixtures running. Additionally, the unit performs consistently well both in warm and cold environments.
  • Energy Efficient. While the Rinnai model delivers hot water at such high rates, it is an environment friendly device. The unit has a thermal efficiency of 82-83 despite the fact that you can adjust temperatures up to 1400F high.
  • Installation. While it features multiple advantages, easy installation is not one of them. You will need a professional to install it for you.
  • Can be powered by either natural gas or propane.


Rheem RTGH-95DVLN Point of Use Water Heater

tankless electric hot water heaterIf you are looking for nothing but the best instant hot water heater, invest your money in this device. It is among the best rated tankless water heaters in online retail stores. Customers love it, and its ratings are some of the best on the online water heater market. Before you buy it, however, it is important that you carefully look at its performance details. Yes, it has a high water delivery rate, but can you accommodate its power needs? And as you would expect, the unit comes at a slightly high price of $1200.

  • High Water Flow rate. Rheem RTGH delivers hot water at 9.5 GPM. This makes it one of the best performing instantaneous water heaters in the market. You can regulate this water flow downwards, but the bottom line is that you will never lack hot water in your home.
  • Energy Efficient. Besides having the best performing hot water heater on the market, you will also have one of the most energy efficient units. Rheem 95DVLN model draws heat from exhaust gases in your house, making it a long term cost efficient model as well. In energy efficiency terms, the unit attracts 94% energy efficiency.
  • Intelligent Digital controls. The 79 pounds weighing device features high tech controls to help you increase energy efficiency and safety in your home.
  • Expensive. The hot water device is best suited for someone with a large family or house.


Best Tankless Water Heater Comparison Chart

Product namePowerMax flow rateDimensionsOther
Eccotemp L5gas1.5 GPM14.5" x 11.5" x 4.5"37,500 BTUs, 3V (D cell batteries), 11 kW, safety shutoff timer
Takagi T-KJr2-IN-NGgas6.6 GPM6.7" x 13.8" x 20.3"140,000 BTUs, surge and overheat protection, inlet and outlet thermistors, 0.81-0.83 energy factor
EcoSmart ECO 27electric3 GPM17" x 17" x3.75"27 kW, 3 x 8 AWG wire gauge, 3 x 40 AMP required breaker, 99.8% energy efficiency
Stiebel Eltron Tempra Pluselectric4.5 GPM16 5/8" x 14 1/2" x 4 5/8"24 watts, wire size 2 x 6/2 AWG, circuit breakers 2 x 50 A, digital temperature control
Rinnai RL75iNgas7.5 GPM14" x 9.3" x 23"10,300 - 180,000 BTUs, digital controller, 82% Thermal Efficiency
Rheem RTGH-95DVLNgas9.5 GPM18.5" x 9.8" x 27.5"11,000 - 199,900 BTUs, 94% energy efficiency, electronic controls, Low Nox version

What Is a Tankless Water Heater?

what is a tankless water heaterA tankless water heater is a heater that provides water on demand. The heaters lack a tank to hold water, meaning that it won’t produce the standby energy losses incurred when you have a tank water heater.

Having not tanks, a tankless water heater is a small device. Most of them weight 70 pounds or less, and they will hardly be larger than your car’s tool box. Perhaps the biggest and most unique benefit of the tankless water heater is its ability to deliver hot water instantly whenever you need it. Another big advantage of having these heaters is that they are more energy efficient. They don’t produce standby energies, which mean that you will never incur such costs. According to the US Department of Energy, you could save in excess of $100 with a gas powered tankless energy water heater. With a tankless electric hot water heater, you could save more than $40 in energy bills every year.


They are small in size and deliver hot water on demand but at a cost. Sometimes ago, the average tankless water heater cost three times a conventional water heater. Today, the prices have evened up and you could find a quality tankless model for less than $500.

How Do Tankless Water Heaters Work?

A typical tankless water heater consists of a gas burner or an electric heating element. When you turn on your home’s cold water tap, water is delivered through the water heater’s pipes into the burner or heating element. The heating elements are often made from copper or other heat conductors so that it is heated instantly and delivered into your shower or sink. With this simple flow, a tankless water heater will always deliver hot water when you need it. There is no waiting for a tank to get filled up.

how does a tankless water heater workWhile tankless water heaters share the same water heating technology, they are not all the same. Some are top rated, some are poorly rated. Some are designed for large homes; some are designed for use in camps. So, what makes tankless water heaters different? It all lies in the technology used to make the heater’s burner or heating element.

Gas powered tankless water heaters extract heat from natural gas or propane. They use a burner that draws heat measured in British Thermal Units. If the heating burner can draw a high number of BTU per hour, it will perform adequately enough in providing a stable water flow rate. If the heater draws in gas at a low BTU rate, it will most probably deliver hot water at a lower rate.

Electric tankless water heaters don’t vary much either. The heater will be powerful or weak depending on the technology used to make it. Electric water heaters are traditionally also weaker in delivering on demand hot water in large homes. Most of them are also inefficient in cold areas. To overcome this problem, manufacturers install microprocessors or elements that keep the water heater at ideal temperatures to perform.

Tankless Water Heater Advantages

tankless water heater advantagesIf you find your current tank hot water heater wasteful in energy, you will be impressed by the benefits to expect once you buy a tankless water heater. Basically, expect a tankless water heater to offer everything that your current water heater lacks.

  1. Cost Efficiency

    People will tell you that a tankless water heater is expensive, but they won’t explain the long term cost efficiency you gain with it. Let’s say you invest in a tankless gas powered model at $500. The Department of Energy estimates that you save approximately $100 with a small tankless water heater every year. In five years, you will have saved enough money to upset the initial costs you incurred on the heater. Isn’t that effective? Keep in mind that tankless water heaters can last for 20 or more years. Even with an electric heater, you can save between $30 and $50 every year. In over the 20 years, the heater could serve you, you will have saved a lot of money.

    In addition to helping you save on energy bills, tankless water heaters are easier to maintain. With some models, you simply install the unit and never have to maintain it in no way for the rest of its service life.

  2. Space Saving

    If you have always felt you need some extra space in your garage, a tankless water heater will help you achieve that. With no tank to worry about, you could save a large surface area previously occupied by your conventional water heater. Modern tankless water heaters are so small that you almost don’t have to worry about a place to install them. With the extra space you have in your garage, outdoors or even on a wall, different tankless water heaters can be installed in a variety of places around your home.

  3. Reliability

    Bid goodbye to waiting for a water heater to fill up its tank before you can have a shower. Tankless water heaters supply water on demand. The very best point of use water heaters won’t delay even for half a minute. With one touch of your faucet’s button and you will have enough hot water flowing to help you clean dishes. To have a reliable water heater, you must, however, have the right water heater. We shall help you buy the right heater next. But keep in mind that as long as you have the right quality tankless water heater, you can be certain of its reliability.

  4. Eco friendly

    One of the biggest concerns among people with conventional water heaters is that they are not eco-friendly. Fortunately, manufacturers of tankless water heaters these days ensure that their products are as energy efficient as possible. Most of the top rated tankless water heaters on the market have an energy efficiency rate of between 80% and 95%. Electric heaters are particularly very eco-friendly as they don’t require venting of any kind. Gas powered heaters may be a little bit energy efficient but they are far better off than conventional water heaters.

Best Tankless Water Heater Buying Guide

tankless water heater buying guideAs we have emphasized throughout this guide, your dream to have a cost effective, on demand hot water heater will only come true if you buy the right one. With a small heater, you will probably never have enough hot water in your shower and sink at the same time. If you buy a very expensive device, you will end up feeling like you made the wrong decision. In the next few minutes, read on to view the features and factors that should guide you to buy the right water heater for your home.

Gas/Electric/Propane Powered

A hugely important factor to keep in mind as you buy a water heater is its source of power. Most home use tankless water heaters are powered by natural gas, propane, or electricity. Natural gas is the preferred choice for people looking for a high efficiency water heater. Gas water heaters are more powerful than their electric powered counterparts. They also do well in both cold and warm areas.

By contrast, many electric water heaters are only ideal for small families. They are cheaper and mostly efficient in warm areas. However, modern models feature technologies that make them quite powerful and reliable in both cold and warm areas. Many Takagi models, for example, have microprocessors that help the unit stay efficient even in the coldest of environments.

If you are not comfortable using natural gas for your tankless heater, propane may be a good alternative. Propane gas is easily available at many gas stations. Propane is also durable.


Technically, all tankless water heaters are smaller than conventional water heaters. That means even if you invest in a large tankless model, you will still save space for installation. However, it is important to determine the size of water heater you want. A small sized heater will be easier to install. Larger, more complicated gas water heaters, on the other hand, ask for more complex installation. Buy a heater that can meet your installation space. If you are looking for a portable heater, look for the lightest.

Water Flow

To determine the water flow rate your ideal tankless water heater delivers, add up the flow rate for different fixtures in your home. Showers consume most of the hot water. On average, a high flow shower consumes 2.5 GPM per minute. A faucet consumes 1GPM. If you mostly use these two fixtures the most, then you will need a water heater that can deliver at least 3.5 GPM. If you have a washing machine that you constantly run as you clean the dishes, consider buying a machine with a higher flow rate.


Ecosmart, Ecotemp, and Takagi are some of the most popular brand manufacturers of tankless water heaters. Rheem, Marey, and Rinnai are also popular brand manufacturers. You can choose a product from one of these manufacturers and feel confident in it. However, do more research to learn the benefits that come with buying from each brand. Some have great customer services, while others are good in delivering quality products.


A warranty gives you the reassurance that you can get your money back if the product fails to meet your expectations.

Tankless Water Heater Installation

tankless water heater installationTankless water heaters ask for higher power lines than a conventional heater would. They also in demand for powerful and larger gas supply lines. Also, expect to incur heavily in retrofitting your house to accommodate a gas tankless water heater. With that in mind, consider calling a technician over to handle the work for you if it looks all too complicated. After all, the validity of your warranty will largely be influenced by how well the unit was installed.

  1. Step 1: Turn off your home’s water supply lines

    Turn off the water supply from your home’s main source. Disconnect supply to the old heater too and uninstall it. Note that there is always some water left in the old water lines. Place a bucket underneath the ends of the pipes to collect this water.

  2. Step 2: Place the hardware and all necessary installation accessories for the new heater close to you

    Read the unit’s manual to determine where and how you should best install it. Most of the units are designed to be installed on a wall. For electric powered models, this should be easy since not venting is required. For a gas powered unit, install venting. Since it can be expensive and complicated, don’t shy away from asking a technician to help you vent for your gas water heater.

  3. Step 3: Connecting the power source

    With venting done and the unit on the wall, connect the cables serving the electrical source. Let the manufacturer’s manual guide you on how to connect each cable. Note that you will need a circuit breaker or two for your water heater. They should be installed next to the heater itself.

  4. Step 4: Run water through the unit

    Run water through the water heater and head on to your shower to enjoy.

Tankless Water heater Maintenance

tankless water heater maintenanceTankless water heaters rarely develop problems when well maintained. However, once in a while you will experience the heater dropping temperatures or delivering water at a slower rate. If this happens severally, it is time you geared up for some maintenance exercise.

Gas Heater Maintenance

The biggest problem you will experience with a gas heater is the burner getting clogged. When this happens, the water temperatures in your shower will reduce dramatically. To confirm that the burner is really clogged up, you will observe that some of its parts don’t produce flames. Remove it and clean the apertures properly. Return it and check if all apertures burn correctly. If the problem still exists, replace the burner.

Cleaning the water Heater

  1. Turn off the cold water source that leads to your water heater. Turn off the power sources and relief the lines’ pressure by pulling out the silver tab from the pressure relief valve.
  2. You will need vinegar and a bucket for this exercise. In fact, place the sump pump in a bucket containing vinegar.
  3. Connect a hose from the heater’s inlet to the sump pump. Connect another hose from the bucket to the pressure relief valve.
  4. Turn on the pump to scale the water heater. Scaling is the process for removing hard water sediments from the heater.
  5. Remove the inline filter and other filters in the heater and clean them. Replace any worn out filters.
  6. Eject vinegar and replace the bucket with clean water. Turn on the pump and let it run clean water through the system for a few minutes.
  7. Replace the heating elements from your electric model if they are ineffective.

Tankless Water Heater Brands

The first water heater was invented in 1889. As time moved on, technology kicked in and companies began to produce their own water heaters. By the late 1950s, leading water heater manufacturers had already invented tankless water heaters. They were uncommon in the US, but in Europe and Asia, tankless water heaters have been popular for quite many years. Today, the following companies lead in producing respected and quality tankless water heaters.


Rheem is a popular name in the water heater industry. Based in California since 1925, the company has produced some of the best water heaters we have today. As of date, Rheem is also the largest manufacturer of water heaters in the US. Some of its most popular tankless water heaters include Rheem RTGH-95DVLN.


EcoSmart is a popular tankless water heater brand among those who only look for the most energy efficient models. The company advertises itself as making product s that will save you money in energy expenses. The company’ major specialization is with tankless water heaters. According to online reviewers, the company has a great customer service department.


If you love gas powered water heaters, you better go for a Rinnai. The Japanese company has been manufacturing tankless, gas powered water heaters for almost 100 years. The company has several best-selling products such as Rinnai RL 75iN and Rinnai RL 94Rinnai is also common for designing energy efficient gas water heaters, something that most of its competitors are poor at.

Stiebel Eltron

If you love European designed products, you may want to get your next tankless water heater from Stiebel. The German company is popular both in Europe and in North America as a whole. They are known for producing high quality heaters and for infusing technology to make the heaters user-friendly.

Bottom Line

There are over a dozen popular tankless water heater manufacturers. You have tons of water heaters to choose from. But there is always the best tankless water heater for each family. Take your time to research on various heaters before you can decide if it meets your needs. Evaluate your home’s needs, installation, and budget before you can conclusively settle on a particular water heater. If you already know what kind of heater you are looking for, however, head straight to our tankless water heater reviews above and you will find one that meets your needs.