Best Tankless Water Heaters

automatic water heater isolated on white background

           Having hot water at discretion is a custom few people are willing to give up on so when there is no better way, a water heater is installed to provide hot water around the clock. Tankless water heaters are a practical solution that is also affordable, so the benefits are extended. Learn more about these water heating systems from the following lines and see how useful and efficient they are.

Top 5 Tankless Water Heaters Comparison

1. Rinnai RL94iN Natural Gas 2. Takagi T-K4-IN-NG Indoor Gas 3. EcoSmart ECO 27 Electric 4. Stiebel Eltron Tempra 24 Plus Electric 5. Eccotemp FVI-12-LP High Capacity Propane
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Product Specifications

Manufacturer Rinnai Takagi EcoSmart Stiebel Eltron Eccotemp Systems
Type Indoor Indoor Indoor Indoor Indoor
Use Residential & Commercial Residential & Commercial Residential & Commercial Residential & Commercial Residential & Commercial
Capacity Up to 5 Bathrooms 2-3 Bathrooms 1 Shower and 2 Sinks in Cool Climates and 3 Showers and Two-and-a-half Sinks in Warm Climates Up to 2 Bathrooms in Warm Climates and 1-2 Bathroom in Cool Climates 1-2 Bathrooms
Voltage 120 V 120 V 240 V 240 V 110 V
Dimensions 9.3 x 14 x 23 inches 20-1/4 x 13-3/4 x 9-1/2 inches 17 x 17 x 3.75 inches 16.6 x 14.5 x 4.6 inches 15 x 24 x 4 inches
Weight 50 lbs. 38 lbs. 13.75 lbs. 16.1 lbs. 33 lbs.
Color Silver White White Silver White or Silver


Power Source Natural Gas Natural Gas Electric Electric Liquid Propane
Minimum/ Maximum BTU 9,900 – 199,000 BTU 11,000 – 190,000 BTU 27 kW (92,000 BTU) N/A 25,000-74,500 BTU
Temperature Range 98°F – 140°F (residential)/98°F – 185°F (commercial) 98°F-167°F 80°F – 140°F 86-140°F 80°F – 140°F
Maximum Flow Rate 9.4 GPM 8.0 GPM 6.0 GPM 4.0 GPM 4.0 GPM
Flow Rate (45°F rise) 7.1 GPM N/A 4.1 GPM 3.64 GPM 4.0 GPM
PSI Range 20-150 PSI 15-150 PSI N/A 150 PSI 4.5 – 150 PSI
Water Connections 3/4″ MNPT 3/4″ NPT 3/4″ NPT 3/4″ NPT 1/2″ NPT
Vent Type Direct Vent Standard Vent No venting required No venting required Single Wall Vent
Energy Factor 0.82 0.82 0.998 0.99 0.79
Certifications ​AHRI, CSA, Energy Star Energy Star 1-UL Listed,CSA Listed,ETL Listed 4-UL Certified,CSA Listed,ETL Listed UL listed electrical components

Additional Specifications

Inlet Gas Pressure (min/max) 5,0 – 10,5 W.C. Inlet Gas Pressure (min/max) 4,0 – 10,5 W.C. Digital temperature control in 1-degree increments allows control of hot water Digital temperature control Digital temperature display with fully independent gas and water controls
Digital Temperature Control, Monitoring, and Troubleshooting Safety features: Freeze, Overheat, Surge Protection, and Troubleshooting Diagnostic Codes Patented Self-modulating Technology and Design Advanced flow control that provides consistent hot water temperatures even when demand exceeds capacity Precise temp / water-flow adjustment with independent controls
MC-91-1US Digital Controller with Error Code Indicator TK-RE02 Remote Temperature Controller Copper and stainless components Self-modulating control Manually controlled
Consistent with a pre-set temperature Exhaust & Water Temperature Safety Control Compact design Compact design Sleek modern design
Propane Convertible Preset Temperatures: 113F, 122F, 131F, 140F.
Sleek, modern design Fully modulating
Ultra-compact Design


Warranty 12 Years for Heat Exchanger; 5 Years for Parts; 1 Year for Labor 15 Years for Heat Exchanger, 5 Years for Parts Lifetime Warranty for Parts; No Labor Warranty 7 Years Against Leakage; 3 Years for Parts 2 Years for Parts
User Manual
Customer Support

Top Rated 2018 Tankless Water Heaters Reviews

           If you are convinced of the functionality of the tankless heater for water and you want to buy one for your home, you must know that there are some models for sale that are better and higher rated than others. To help you limit your choices, we have gathered information on the most reliable heaters you could choose from.

1. Rinnai RL94iN

           In case you’re looking for a high-quality tankless water heater that will deliver hot water instantly, then the Rinnai RL94iN is surely one of the best possible choices. It’s designed for both residential and commercial use and is a great choice for larger homes because it can handle up to 5 bathrooms. The silver color offers it a modern look and the greatest thing is that you can convert it to propane in case you don’t want it to run on natural gas anymore. In what concerns the temperature range, we have different values for residential and commercial use, namely 90°F – 140°F and 90°F – 185°F. Also, Rinnai RL94iN can easily supply 9.4 gallons of hot water per minute, which makes it very efficient for those who need a greater water supply. Another significant advantage of this model is the fact that it can help you reduce the energy consumption up to 40%, thus being able to save more money. Moreover, the model features digital temperature control, monitoring, and troubleshooting and the MC-91-1US Digital Controller with Error Code Indicator will allow you to easily control it every time you need. In what regards the warranty, the product comes with a very generous one, making it one of the most reliable tankless heaters on the market. As for the installation, this has to be performed very carefully, so it’s wise to contact a certified Rinnai technician in order to install it for you.

2. Takagi T-K4-IN-NG

           The Takagi T-K4-IN-NG is built to last and due to its compact design, it can easily be mounted wherever you want inside the house. It is recommended for both residential and commercial use and due to the fact that it’s gas-powered, it’s also very powerful. This particular model can supply water for 2-3 bathrooms and it delivers great power and flow for basically any activity, the maximum flow rate being 8.00 gallons per minute. Moreover, with the help of the remote control, you can easily set the desired temperature between 98°F-167°F or you can use the preset temperatures. Another great thing about this model is the fact that in case there’s a problem, it will announce you through a blinking red LED or through an error code on the remote control. At the same time, the Takagi T-K4-IN-NG comes with safety features such as freeze, overheat or surge protection, so every time you shower you won’t be bothered by any water temperature fluctuations. In order to help you enjoy this powerful water heater for a longer period of time, the manufacturer offers a very long warranty on the market, namely 15 years on heat exchanger, and 5 years on parts for residential installation and 6 years on heat exchanger for commercial installation.

3. EcoSmart ECO 27

           The EcoSmart ECO 27 is an energy-efficient water heater that will easily offer you hot house water on demand every time you want. Also, this electric water heater is very easy to use and it will significantly reduce your energy bills by no less than 60%. In what regards the capacity of the heater, it can supply water for 1-3 shower and 2-2 ½ sinks, depending on the climate. Moreover, due to the fact that the model is a compact one, it will occupy less space in your house. The temperature range is 80°F – 140°F and the maximum flow rate is 6.0 GPM, making it the perfect choice for all those who want an efficient, yet affordable water heater. The new patented self-modulating technology is another great feature that places this model among the best on the market, being able to automatically adjust the amount of energy required to heat the water needed. Furthermore, it features a digital display that shows you the important data, allowing you to control the temperature in 1-degree increments. As for the warranty, the EcoSmart ECO 27 comes with a lifetime warranty on parts, while the labor isn’t covered by any warranty. However, we can surely say that this electric heater is one of the best options available because it provides instant hot water for your entire house.

4. Stiebel Eltron Tempra 24 Plus

           This tankless water heater has been redesigned by the manufacturer by using advanced technology in providing hot water to the people all around the world. The Stiebel Eltron Tempra 24 Plus is an electric version of a water heater that is capable of delivering instant hot water in up to 2 bathrooms. The maximum flow rate of 4,0 GPM and the temperature range of 86-140°F is more than enough to never again worry about the hot water supply from your house. The advanced flow control is an excellent feature because it provides consistent hot water temperatures even if you simultaneously use more fixtures at the same time. Also, other great things are the digital temperature control and the self-modulating control that make the Stiebel Eltron Tempra 24 a great addition to every home. However, we should also mention that the heater requires two 60-amp circuits, which is quite a lot of power, so make sure your home’s electrical system can safely handle the electrical requirements. As about the warranty, the manufacturer offers a 7-year warranty against any possible leakage and a 3-year warranty on parts, but the product has to be installed by licensed personnel in order to benefit from the warranty.

5. Eccotemp FVI-12-LP

           The Eccotemp FVI-12-LP will help you save up to 50% more energy in comparison with a traditions water heater, being the right choice if you want to start living a greener life. The heater runs on liquid propane and it can be installed wherever you want inside the house because it features a sleek and compact modern design. The maximum flow rate of 4.0 gallons per minute and the temperature range of 80°F – 140°F, making it good enough to handle 1-2 bathrooms with multiple appliances, although it’s not the most powerful model available. It comes with a digital interface and you can manually adjust the temperature, as well as the gas and water, having separate controls for each of them. Although this model doesn’t come with innovative features, you will surely be impressed by its popularity among many users and the affordable price that makes it among the first choices for those who want to receive good results at reasonable costs. However, one of the biggest disadvantages is the fact that the manufacturer covers the parts only for 2 years, which is less than all the other models reviewed. However, this shouldn’t worry you too much, because according to the general opinion, it is durable and reliable, so it should provide you hot water for a long period of time.

6. Marey Power Gas 10L

           This practical tank-free water heater is very economical and efficient as it doesn’t require any electricity to operate. You can choose from a natural gas and an LP model to best suit the supply of your house. The compact design that measures 24″ x 14″ x 7″ and weighs only 21 lbs makes it incredibly easy to install even in small corners. It turns on when the water is turned on so it will not waste any gas when not in use, so it’s even more environmentally-friendly. Moreover, you can set the water temperature with the adjustable knob, as well as the amount of gas it uses. Plus, you can adjust its operating according to the season so it will run more in winter and less in summer. The tank is turned on by an electric pulse ignition that requires 2 D-cell batteries. It’s 100% rust proof so any water leaks due to damage of the tank are excluded. For increased safety, it has Anti-combustion and gas pressure protections and it can function even when the water flow is as low as 3.6 psi so you shouldn’t worry about these details. It releases 3.1 gallons of hot water per minute and it is certified to operate perfectly or at an 87% performance during its entire lifespan.

Things You Should Know about these Heaters

           The tankless water heaters are cost-efficient alternatives to conventional heaters and they don’t require a storage tank in order to supply hot water. Due to the fact that they don’t need to reheat the stored water, the tankless models will significantly reduce your energy bill, this also being one of the main reasons why they’ve become so popular. These water heaters are widely used for both commercial and residential purposes and they work by quickly heating the water through a heat exchanger. They run on gas or propane or electricity and they come in different sizes, thus being able to supply hot water to one faucet or to the entire house. The temperature settings can be controlled manually or with the help of a remote control and every time you need hot water, it instantly heats the water until it reaches the desired temperature. Although the tankless system is more expensive than a storage tank one, it will eventually be more cost-efficient. Also, in comparison with the conventional tanks that store hot water, the tankless ones may need a longer time to warm your water.

The Differences Between Traditional and Tankless Heaters

           Most people have a traditional heater at home because this model is older and enjoys a larger popularity. However, the tankless model manages to score points from many aspects, as you are about to see. But first, let’s see which are the differences between the two types.

  • Traditional heaters heat a certain amount of water, between 30 and 50 gallons, and keep it in a tank for you to use it when bathing or washing the dishes. This means that the heater is continuously using power to bring the water to a certain temperature for you to use it, thus, increasing the electricity costs. Despite being more affordable and easier to install, the traditional heater has a shorter lifespan and can always run out of water, even when you most need it, which makes it less convenient to have at home. Also, you must make room for it as it takes more space than the tankless model.
  • Tankless heaters for water are more practical to have at home for various reasons and the first one is the instant water heating that ensures you will have hot water anytime you need it. It uses a power source, either electric or gas, in order to provide hot water on-demand, thus limiting the energy consumption. Also known as demand heaters, they are more compact and economical, being great for small homes that use around 40 gallons of hot water per day. The demand water heaters are more durable, with a lifespan of over 20 years, and a simpler operating mode that prevents energy waste. Their main drawback is the higher purchase and installation cost.

    The Advantages of Using a Tankless Model….

               There are many advantages of using this type of heater, so here we’ll present you the most important ones. Read them and see why a tankless unit is a better alternative to a traditional one.

    • Eco-friendly

                 Not only that it will reduce the energy costs, but this innovative product is much healthier for the environment. Most of the producers are highly aware of the need to protect the environment, so they use the latest technology in order to sell products that won’t harm the climate.

    • Convenience

                 A tankless water boiler offers great convenience to its users because it can supply continuous hot water for the entire family. Therefore, you won’t be forced to schedule your home chores or bathing times because the appropriate model for your needs will be able to successfully deliver great performance.

    • Durability

                 The tankless heaters are designed to be more durable, the average lifespan being more than 20 years, which is 5 to 10 years longer that the traditional heaters. This is possible due to the fact that they don’t corrode, thus being able to enjoy hot water for a longer period of time.

    • Less Bacteria Growth

                 Since the tankless heaters don’t have a tank to store the hot water, the bacteria growth will be significantly reduced. The result is that the chances to get an infection will be significantly reduced, so your entire family won’t be exposed to all sorts of health risks.

    • Safety

                 This heater is safer than a storage type because it operates only when you need hot water. At the same time, you won’t have to worry about the fact that the tank may break and flood your house causing serious damage to your home.

    • Space Saving

                 These models are compact and can be easily mounted wherever you want in the house. Therefore, having one of these and not a bulky tank will allow you to save more space and it will also look much better from the aesthetic point of view.


    ….and the Disadvantages

               Although they seem like heaven’s sent, it’s not all about advantages as there are some downsides to them as well. Before making a decision, it’s best to know both sides and decide only after a thorough analysis. Besides being money-saving and more convenient to use, they also require a large investment that is not always included in the budget.
               The main reason why people are skeptical is the increased energy cost brought by switching to a tankless model. It can bring costs up to three times depending on the type of fuel. The electric one, surprisingly, can be more money-saving while the gas-powered model can double or triple your electricity bill. Still, both types include higher operating costs which is something you will experience every month.
               The second reason is that not every home can handle tankless heaters because the electrical system might require an upgrade that can only be performed by a professional electrician. Rewiring your house can imply costs of $5,000 which is huge, added to the initial purchase cost of the heater. In short lines, these heaters are not only very expensive but also more money-consuming in the long run.

    How to Choose the Most Reliable Products

               In case you’ve decided to buy a tankless water heater and you want to know which are the most important aspects to consider, read the lines below and see what you have to do in order to choose the right model for your needs.

    • Decide the Fuel Type

    •            This is usually among the first things you have to take into account when you start looking for a water heater for your home. Therefore, before deciding whether to buy an electric or a gas or propane heater, you have to consider the utility available in your home. In case you have both gas and electric utility at your disposal, then you are lucky enough to compare the two options and pick the one that suits you best. The gas and propane tanks will offer you a higher flow rate and they are less expensive, while the electric ones are more durable and cheaper to purchase.

    • Determine the Flow Rate You Need

    •            In order to do determine the flow rate you need, you have to consider the appliances you usually use at one time. For example, if you have a big family, then you might have two showers running at once, a dishwasher and maybe a clothes washer. So, turn all of them on and calculate how much time each one takes to fill a 1-gallon container, then divide 60 seconds by the actual number of seconds it took to fill in the container and you will determine the flow rate of each fixture. After you find out, you just have to look for a model that will be able to supply you hot water at every time.

    • Measure the Temperature Rise

    •            Another important thing you have to do in order to determine which one will offer you great results is to measure the temperature rise. The incoming water temperature usually depends on the outside temperatures that may vary according to the area you live. So, for measuring the incoming water temperature you have to turn on a cold water faucet, wait several minutes and then measure the temperature of the water. The difference between the incoming water temperature and the desired outlet water temperature is the temperature rise. Since most people shower with water that ranges between 100°F and 105°F degrees, the difference between your incoming water temperature and 105°F degrees will be the temperature rise that you’ll need.

    • Choose a Reliable Brand

    •            This is also very important because since there are numerous models on the market, you have to invest in a reliable brand. In order to do this, you have to learn more about the company, the materials, and technology they use, the warranty they offer, how committed they are to helping their clients and so on. A good brand usually receives good reviews from customers, so a great idea would be to do a little research before you decide upon a certain brand.

    How Easy Is to Install a Heater?

    Installing a tankless water heater is neither too complicated, nor too simple. You can install it by yourself or you can get the help of a professional, so it’s basically up to you to decide. Here are some important details about each option.

    In case you opt for the first option, namely to install it by yourself, there are some things you have to know. Firstly, you have to read carefully the instructions provided by the manufacturer and begin the installation only after you know what you have to do. Secondly, make sure you have all the necessary tools in order to accomplish the installation process. Also, if you want, you can get the help of a friend. Finally, after you perform all the steps it’s recommended that you test the water heater to be sure it works properly.

    If you don’t want to install it yourself, then you should ask for professional help. Some companies sell the unit with the installation fees included, while others require an extra charge for performing it. At the same time, you can ask a professional to help you with the installation, but you have to make sure you don’t lose the product’s warranty.

    Top Brands On the Market

    • Rinnai

                 A reliable brand is the guarantee of remarkable products that offer great results and performance to all its users. Such is the case with Rinnai company that is specialized in manufacturing and selling residential and commercial tankless water heaters and home heating solutions all over the world. The company has been committed to developing high-efficient products for almost 100 years and it’s present in 13 countries, being among the world’s top leaders in this industry. All the company’s employees are dedicated in all they do and this is why all their products are rigorously tested before being sold to the customers. The Rinnai products are present in many homes and institutions and their superior quality and innovation have easily passed the test of time, being very durable and user-friendly.

    • Takagi

                 Another trustful brand in this industry is Takagi and there are many reasons why it has become so popular. First of all, the company is present in the industry since 1952 and its excellent products are a proof of commitment and innovation. The company offers energy-efficient residential and commercial tankless water heating systems, being constantly concerned about the protection of the environment. Although the main office is based in Canada, there are also subsidiaries in California, New Jersey and Tennessee and the products are sold only by contractors and plumbing wholesalers.

    • EcoSmart

                 Another popular brand in the water heating industry is known under the name of Ecosmart and the company main’s goal is to produce environmental-friendly products that can help you save up to 50% more energy. This is mainly possible due to the patented self-modulating technology that is a great innovation in this industry. The EcoSmart company manufactures both residential and commercial versions that are made by using the best materials and technology.

    • Stiebel Eltron

                 There are many things to be said about the Stiebel Eltron company, but in some simple lines, we will tell you that the company has been established since 1924 and now it’s one of the biggest manufacturers in the hot water and renewable energy industry. The brand has gained more and more experience over the years and now, we can truly say that it’s one of the best on the market when it comes to delivering high-quality products. Their water heaters are very popular among the many users and for good reason, the Stiebel Eltron brand has always been among the top water heater’s brands all over the world.

    • Eccotemp Systems

                 The Eccotem Systems company is relatively new, being founded in 2004, but ever since then, it was truly committed to producing practical tankless heaters that can be purchased at reasonable prices. The company is always looking for researching and developing state of art products that can be used by a wide range of people who need hot water for their homes. Also, the brand is known for products that are both ecological and cost-efficient, being definitely a great choice for many users.

    What’s Behind Our Ratings

               Our selected models are the best ones on the market and all of them are a perfect choice for those who want to receive endless hot water in their homes. However, in order to better understand the main aspect of a tankless heater, here we’ll present you our selection criteria.

    • Capacity

                 Since every tankless water heater has a different capacity, it’s very important to know this aspect about every one of them. Usually, for a small house, a water heater that can handle 1-2 bathrooms it should be enough, but in case you live in a bigger house, then you surely need a heater that will be able to deliver hot water for more than 2-3 bathrooms. All our models are whole-house water filters and they are designed for both big and small houses. However, you should know that you can always link more tanks together if the model you want is not capable of handling more bathrooms.

    • Power Source

                 There are three types in terms of fuel: electric, gas and propane. All of these options are effective for delivering hot water, but there are some differences between them that are worth to mention. The first type, namely the electric models are more affordable and cheaper to operate and install, they don’t require maintenance and they are much safer for the environment. On the other hand, the gas and propane models cost with an average of 500-600$ more than electric models, they need a more complicated and expensive installation, they require annual maintenance and they usually produce greenhouse gasses. However, since the electricity takes longer to heat the water, the gas water heaters are still considered to be a greater choice in this department.

    • Temperature Range

                 The temperature range represents the minimum and maximum temperatures that can be set for a particular heater. Usually, you will never set the heater at the lowest or highest temperature, but still, it’s highly important to know this aspect. Usually, for warm water, a 90-110°F range will be more than sufficient, while for receiving hot water you will need a 140-150°F range in most cases.

    • Maximum Flow Rate

                 The maximum flow rate represents the maximum amount of hot water it is able to heat within a minute and it’s measured in gallons per minute. In order to determine the maximum amount of hot water you need, you have to run simultaneously more fixtures you usually use. In general, a shower head, a dishwasher, and a clothes washer will need a flow rate between 3.5 and 7.5 GPM.

    • Energy Factor

                 The energy factor is the energy efficiency of home appliances or equipment, such as water heaters, clothes washers, and dryers or dishwashers. Therefore, an appliance that has a higher energy factor is more energy efficient.

    • Additional Specifications

                 The additional specifications show you important particularities of every model presented in our comparison chart in order to find out more information about it. They are mostly features or other technical specifications that differentiate one product from another.

    • Warranty

                 The warranty is highly significant, especially when we refer to water heaters. Such is the case with our units because it’s important to know what and for how much time the manufacturer will cover it in case of any defects or malfunctions.

               After comparing the best models on the market and offering you all the information you need to know about them, you only have to decide which heater is the best for you. If you live in a larger home, you definitely need a heater with a greater capacity, such as the Rinnai RL94iN Natural Gas or Takagi T-K4-IN-NG Indoor Gas. However, if you live in a smaller house and you look for an electric heater, then you can confidently go with the EcoSmart ECO 27 Electric which is also our choice. No matter what you choose, you can be sure you won’t be dissapinted because, in comparison to the traditional heaters, the tankless ones are much more practical and easier to use.

    Frequently Asked Questions

    ?Where Is the Best Place to Install the Heater?
    All the selected models are made for indoor use and you can install them wherever you want. Most people prefer to hide the heater, so they prefer the kitchen, the bathroom, or any other hidden place. As long as you strictly follow all the installation instructions, you can put the heater in whatever place you want.

    ?How to Choose the Right Heater Size?
    This may seem difficult but in fact, it isn’t. In order to properly size the heater for your house, you simply have to pay attention to the specifications it comes with. Look for the capacity of the heater and see how many showers and sinks it can handle. Some units are appropriate for 1 or 2 bathrooms while others can easily provide hot water for 5 bathrooms.

    ?Are These Units Expensive?
    The price of the heaters depends on many aspects, including the fuel, capacity, brand, and so on. Some units can cost up to $1500 while others are much less expensive. However, the most expensive models usually come with more features and are built for larger houses, so the price is justified.

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