Top 7 Best Tankless Water Heater (Reviews & Guide)

We provide details reviews and guide on water tankless heaters and our comparison table consists of 7 products with respective. You can pick according to your budget and demand. If you live in an area where the temperature plummets to freezing levels, it would be wise to invest in a water heater. It heats the water supply to your home and brings it up to a comfortable temperature for bathing and other forms of household utilities. You can choose between the storage tank water heater and the Tankless water heater. The major difference between the pair, one has a tank for storing water the while other water does not. There are plenty of reasons you might want to consider purchasing and installing a Tankless water heater. This article compares both types of heaters to help you assess your options and choose the one that is best for you. Also, finding the best tankless water heater can be difficult since there are plenty of brands and models to choose from. Read the guide below for some tips on how to find the best tankless water heaters. We have also reviewed some of the best options in the market to narrow down your choices and help you make the right decision.

Tankless Water Heater Comparison Table and Reviews

Listing Price
Rheem RTE 13 Electric
Flow rate: 4GPM
Point of use: 2 Max.
Power Source: Electric
Weight: 35 pounds
Product size: 7.2 x 7.2 x 7.2
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Takagi T-H3-DV-N Tankless
Takagi T-H3-DV-N Condensing Gas tankless water heater
Flow rate: 10GPM
Point of use: up to 5 Max.
Power Source: Natural Gas
Weight: 59 pounds
Product size: 11.2 x 17.8 x 24.9 inches
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EcoSmart ECO 11
EcoSmart ECO 11 Electric Tankless Water Heater
Flow rate: 2 GPM
Point of use: up to 3
Power Source: Electric
Weight: 6.5 pounds
Product: 3.8 x 8 x 11.5 inches
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Marey Tankless Water Heater
Marey ECO150 Tankless water heater
Flow rate: 2.5 GPM
Point of use: up to 2
Power Source: Electric
Weight: 10.1 pounds
Product size: 8.7 x 3.5 x 14.2 inches
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Rinnai RUC98iN Ultra Series
Rinnai RUC98iN Ultra Series Tankless Heater
Flow rate: 9.8 GPM
Point of use: up to 4
Power Source: Natural Gas
Weight: 82 pounds
Product size:10 x 18.5 x 26 inches
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Ecosmart POU 3.5
Ecosmart POU 3.5 Electric tankless water heater
Flow rate: 0.5 GPM
Point of use: 1 feature
Power Source: Electric
Weight: 4 pounds
Product size: 3 x 11 x 6 inches
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Stiebel Eltron Tempra
Stiebel Eltron Tempra Plus Electric Tankless water heater
Flow rate: 6 GPM
Point of use: up to 4 fixtures
Power Source: Electric
Weight: 19 pounds
Product size: 16.5 x 4.6 x 14.5 inches
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Reviews Of 7 Best Tankless Water Heater

Here are the list of best brand tankless heaters sorted out of 100 water tankless heaters. All formed into reviews along features, pros and cons as guide for you. Hope you pick the best in the end.

1. Rheem RTE 13 Electric Tankless Water Heater

The unit is capable of delivering up to 4GPM of water which makes it just ideal for point of use application and continuous delivery of hot water on demand. This highly versatile unit can fit into almost anywhere in your home. This works great especially when you have limited space to spare thanks to its compact design. The unit comes with the standard ½ inches water connection. It features temperature controls. There are also LEDs on the unit to indicate when it is active or in standby mode. This tankless water heater also features a rugged brass and copper heat exchanger with potentially high durability guaranteeing long term use.

  • It has a Compact size which makes it fit almost anywhere.
  • The unit has energy saving capability.
  • Single shower application makes it limited and not recommended for large household

2. Takagi T-H3-DV-N Condensing Gas Tankless

Takagi T-H3-DV-N Condensing tankless Gas water heater

This space-saving compact-sized water heater from Takagi is one of the best condensing tankless water heaters you can buy. With a gas input of around 200,000 BTUs, this efficient, energy saving unit can deliver enough hot water to conveniently serve 3 to 4 bathrooms depending on the climate in your area. The T-H3 delivers up to 10 Gallons of water per minutes which is quite ideal even for a large household. The unit comes with highly computerized safety features that help to keep the water temperature under check.  There are no pilot lights on this heater to worry about, and the unit is super silent while it operates.

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  • With a 10GPM output, this heater is suitable for large household
  • High efficiency and energy conservation
  • Eco-friendly low emission unit
  • The temperature may drop during every use

3. EcoSmart ECO 11 Electric Tankless Water Heater

EcoSmart ECO 11 Electric Tankless Water Heater

With an output of 2GPM, this unit might not be your favorite if you are looking for a high output water heater. But there are still plenty of features that will potentially endear you to this powerful tankless water heater. First, it’s sleek and modern design makes the unit quite attractive. It is small and light-weight which makes it suitable even when you are short of space.In-built with smart technology, Eco 11 is can raise water temperatures by up to 38°F. There is a digital control which allows you to set the temperature according to your preference with increments of 1 degree. This unit is configured to be a whole-home unit and can operate a shower head and a sink at the same time or any equivalent configuration. Self-modulatory technology ensures safe and convenient use of this heater in any and every climate.

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  • This unit is portable and can be easily mounted on a wall
  • Smart temperature control
    Energy saving
    Self-modulatory technology
  • Installation can be quite expensive

4. Marey ECO150 Tankless water heater

Marey ECO150 water tankless heater

Easy and simple management along with full control are few of the top features of this heater. The ECO150 features an LCD panel with controls that makes it possible to program the unit. With this you can set it to your desired temperature. This ensures efficient energy consumption while promoting ease of use. This unit is also touted to be quite durable. The patented heating element is German-designed. It is built with stainless steel which makes it resistant to corrosion and reduces mineral buildup that may cause damage to the unit. An output of 2.5GPM means it can be used simultaneously at two points in the house. It has a flow switch activation system which means the heater is triggered by water pressure and needs no additional switch or button to work. It can raise incoming water temperature by up to 41°F using just 14.6kW of electricity.

  • Durable stainless steel heating elements
  • Efficient flow switch activation
  • Simple and compact
  • LCD display and controls
  • The installation process is a bit complicated

5. Rinnai RUC98iN Ultra Series Tankless Heater

Rinnai RUC98iN Tankless water heater features a save-spacing design which makes it ideal for those with limited space to spare. With a BTU rating of 199,000, this gas powered unit is highly efficient. It has an energy factor of 0.95 and can potentially deliver up 9.8 Gallons of water per minute which is sufficient enough for multiple water outlets simultaneously.

Installation of this unit is convenient thanks to a twin piping option. This allows you to choose between concentric or PVC venting options depending on your existing venting system. The inlet and outlet pipes are also bigger than many of the other tankless heaters in its category. The unit operates silently and gives you complete control over the temperature of water it delivers.

  • Space saving design
  • With an efficiency of about 95% this unit is highly energy efficient
  • Advanced control features
  • It might take a while to reach optimum temperature especially if it hasn’t been used for a long time

6. Ecosmart POU 3.5 Electric tankless water heater

Ecosmart POU 3.5 Electric tankless heater

This point-of-use tankless heater from EcoSmart is a simple and portable solution for those with minimal water needs. The heater is designed for under-the-sink installation thanks to its sleek and portable build.  It has a flow rate of 0.5-GPM which makes it suitable for single point applications.

With this heater’s compact design, installation is simple and easy. An under-the-sink fitting eliminates the needs for long piping and makes instant delivery of hot water possible. There are digital temperature control and monitoring and the unit is built to save up to 60% energy during use.

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  • High efficiency
  • Simple installation
  • Compact design
  • Just one output point can be used at a time.

7. Stiebel Eltron Tempra Plus Electric Tankless water heater

Stiebel Eltron Tempra Plus Electric Tankless water heater

]This highly reliable and energy efficient unit conserves enough energy to save up to 20% on your electricity bills. The heating elements in this unit are copper sheated which further contributes to the unit’s energy efficiency. This water heater delivers water at a flow rate of up to 5.5 GPM which makes it one of the best electric tankless water heaters with high output.

The Stiebel Eltron Tempra features an ergonomic design which makes installation quite convenient anywhere you want the unit to be mounted. It can be conveniently mounted on the wall and has an appealing design that will make it look good on your interior décor.

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  • Ergonomic design
  • Energy efficient unit
  • Installation is easy and convenient
  • It might not be ideal for homes with less than 60-amp power.

Read This: Before Purchasing A Tankless Water Heater

If you have made the decision to go tankless, there are a lot of factors to put into consideration before making your final choice of what to buy.  You don’t want to waste money on a unit that wouldn’t work for you. Since there are plenty of options to choose from, you need to be as informed as possible. Here are some important things you should know before making a purchase:

Be sure you really want a Tankless water heater: While a tankless water heater is a great option for delivering hot water to your bathroom and kitchen faucet, the fact is, not everyone can install tankless water heaters.  First it is expensive to purchase and install. Also, you will need to make a lot of modification to your home to get it installed. Thus if you don’t think installing a water heater is worth all that stress and money you can still settle for the traditional tank storage unit.

2. Check the Energy Factor rating: Since efficiency is one of the main motivations for switching to a tankless unit, it is important that you choose a tankless heater that energy efficient. The metric used to measure this is the Energy Factor rating. This measures the overall efficiency of a unit. You should compare this value for every tankless water heater you are considering. Generally, you want the water heater with the highest EF rating. The higher the rating, the more efficient the unit will be compared to others.

3. Choose the right size: One of the major things you should get right when it comes to buying tankless water heaters is the size. This has little to do with the size of the unit itself. Instead, choosing the right heater size depends on these factors:

  • Required temperature rise
  • Flow rate

The temperature rise is a measure of the difference between how hot you want the output water to be and the temperature of the groundwater supplied to your home. This depends largely on where you live and varies from one location to the other. The flow rate, on the other hand, is a measure of how much water the heater is able to heat per time. It is usually measured in Gallons per Minutes or GPM. This value depends on how much water you will use simultaneously from various outlets. To find the right size of water heater for your home, you should calculate both of these factors and find a heater whose temperature rise and flow rate matches that of your home perfectly. Generally, Gas powered heaters tend to perform better here than electricity powered type.

4. Warranty: Like every other household appliance you should consider the warranty on your water heater. Compare the terms of the warranty for the various units as well as the conditions needed to activate or void the warranty.

5.Fuel type: The major things to keep in mind here is that gas units are more complex and cost more to buy, install and maintain. As far for the operating costs of both units, it varies from one location to the other since the cost of electricity and gas aren’t stable and their availability and price varies from one region to the other. However, gas units are generally more efficient than electric powered units in terms of energy consumption.

6. Safety Issues: Before you make a purchase check the safety features on your unit. In all cases, it is always recommended that you hire a professional to handle the installation of your unit rather than handling it yourself.

Gas Vs electric tankless water heater

Choosing a tankless water heater to purchase is a critical decision. A lot goes into selecting a good one including your choice of fueling options. Basically, you have to choose between a heater powered by electricity or gas. It’s hard to simply say which one wins between these two, but your choice at the end of the day depends largely on your budget, hot water demand of your household, installation and personal preferences. Here is a comparison between both options

Cost of purchase: An electric tankless water heater costs a lot less than a gas powered unit. You can get a good quality electric tankless unit for as low as $500 while a quality gas unit of similar capabilities can cost as much as $1000. The price can get even higher depending on how which type you purchase.

Installation: Gas units are more complicated and quite expensive to install. The non-condensing types require complex venting systems to ensure air-flow. Most of them also require extensive modifications to your existing venting systems and gas lines for them to work effectively. Electric units are simpler to install with little or no modifications required.

Operating costs: you can consider operating costs in terms of cost of fueling and the efficiency of the unit. Right now, gas is a cheaper fuel compared to electricity in most places. This makes gas a more economical option compared to electricity based on cost alone. The situation is reversed in some regions of the world with electricity being the cheaper option. Also, electric tankless heaters are more energy efficient compared to gas-powered units. This compensates for the higher price in the long run.

Output: Generally, Gas tankless water heaters can deliver more hot water than electric powered units.  This might not be an issue if your household water requirement isn’t high. But it is a major factor to consider if you use a lot of hot water and the groundwater temperature in your area is quite low.

Maintenance: electric units require less maintenance compared to the gas powered units. Also, because of the simplicity of its design and electric tankless water heaters are easier to repair and will typically last longer than gas powered units.

Check for the Top 5 Best Electric Tankless Water Heater on the market

Brands of Best Tankless Water Heaters

Meet the various tankless water heaters brands popular among users. Although there are other brands but these are the only one that made it up our list in after market researched:

1. Rheem: Rheem is a producer of residential water heating products. The company has a complete line of water heaters offering a combination of high water output and low energy consumption. Rheem has been around for close to a century and is the largest maker of water heating products in all of North America.

2. Ecosmart: EcoSmart is one of the leading brands that produce and distribute tankless water heaters. EcoSmart has a reputation for producing green-energy water heaters that are economical and energy efficient. The company has a complete line of tankless technology which is suitable for both residential and commercial applications.

3. Rinnai: Rinnai is one of the most reliable manufacturers of tankless water heaters in the world. The99 year-old brand makes both gas and electric tankless water heater and a long list of other household appliances.

4. Takagi: Takagi specializes in making tankless water heaters and their accessories. The brand has been in the business of delivering innovative water heating solution for more than 7 decades. Takagi tankless water heaters are sold exclusively by contractors and wholesalers.

5. Noritz: Noritz is a leader in smart tankless water heater technology. The company was the first to introduce electronically controlled tankless water heaters and still remains one of the top producers of smart, easy to control, and energy efficient tankless water heaters.

Bosch: Bosch has a complete line of Gas powered condensing and non-condensing water heaters. Bosch offers both points of use and heat pump electric heaters along with controls and other related accessories.

The Tankless vs Tank Unit

When it comes to choosing water heaters for your home, your options are either Tankless or Tank storage water heater. Making a decision between both options can be tough especially if you are not familiar with both options. It is important that you know how both types of water heaters work and how they compare against each other.

How Do They Work?

Tank water heater: as the name implies, a Tank water heater has a storage tank which is able to store between 20 to 80 gallons of water depending on the type you purchase. This water is heated to about 120 degrees Fahrenheit and stored in the tank until you are ready to use it.

Tankless water heater:  A tankless water heater, on the other hand, doesn’t have a tank for storing water. Instead, it has a high-powered burner which is able to heat up cold water quite rapidly as it is passed through a heat exchanger in the heater.  The heated water is then delivered directly to your shower or any other faucet in the home.  They are also known as on-demand water heaters.

Comparison of Tankless and Tank Water Heater Units

Efficiency: generally, tankless water heaters are considered to be more energy efficient compared to the tanked varieties. Homes that use tankless water heaters that supply less than 41 gallons of water per day will enjoy 24-34% more efficiency than those who use tank water heaters of similar capacity. Efficiency increases, even more as daily water use increases. Homes that use up to 86 gallons per day may enjoy up to 40% or greater efficiency.

Costs: We can compare costs for Tank and Tankless water units from two perspectives i.e. the cost of purchasing and installing the unit and the running cost of the unit.

Cost of purchase and installation: Tank water heaters are cheaper to purchase and install compared to tankless units. A good tank water heater will cost between $500 to $800 to purchase and install while you will have to spend around $2,000 – $4,500 on a tankless water heater.

Running cost of the unit: Although tankless water heaters are more expensive to purchase, it compensates for its high cost by helping homeowners save some money in the long run. Since they are more energy efficient, experts say gas-powered water heaters can help homeowners save as much as $100 per year while those powered by electricity can help you save up to $44 annually.

The complexity of installation: Tankless water heaters are quite difficult to install. They have special venting requirements and installation is best handled by an expert. On the other hand, storage tank units are simpler to install. However, tank water heaters are bogus and require you to have sufficient space for a successful installation. But tankless units can be installed in homes with little installation space which makes installation convenient even when you are short of space.

Convenience: there is a reason why tankless units are called on-demand water heaters. They can be fired up and ready right when you need them. Tank water heaters, on the other hand, might take a while to reach optimum temperature. However, the output is one area where you might have an issue with a tankless unit depending on the type of unit you purchase. A small unit might only be able to handle one faucet at a time which means you might have challenges using it in a home where more than one shower will be running at the same time.

Pros and Cons of Tankless Water Heaters

Everything has its good and bad side. Here are the upward and drawback of tankless hot water heater. With this, you can know how to use your heater properly whenever you purchase one.


It saves costs: Although tankless water heaters are typically expensive, they help you save money in the long run since they are more energy convenient compared to tanked heaters.

Longer lifespan: With regular maintenance, tankless water heaters can potentially last up to 20 to 30 years and operate at optimum performance.

Small space is not a problem: Tankless water heaters can be installed in homes that are short of space. Some types can even be installed outside your home compared to heaters with a tank that requires a lot of space for a successful installation.

Instant use: tankless water heaters can deliver hot water instantly. Since they heat a small volume of water at once, it takes less time to heat up the water.


  • It is more quite expensive to purchase
  • The installation cost of tankless water heater units is high
  • There might be output issues for homes that make use of a lot of hot water. (Using multiple showers at the same time might be a challenge).

Tankless Water Heater Maintenance Guide  

Most good quality tankless water heaters can operate at full capacity for 20 years or more. However, like every other household appliance, it might require routine maintenance to keep it in perfect working condition. The dissolved minerals in water can accumulate within the heating chamber of the water heater. This may lead to corrosion of the heating surface if the mineral build up is not removed. Thus it is important to occasionally purge your Tankless water heater to keep it in great shape. You can follow these simple tips as a guide.

A. Turn off the power: Whether your unit is powered by electricity or gas, the very first thing to do before you begin maintenance is to turn off the electricity source or shut off the gas supply as the case may be. This is an important safety precaution that must be followed.

B. Close the water valves: You should turn off both the valve that brings cold water into your tankless water heater and the one that takes hot water out of it. In some cases, you might also have a third pipe which is the primary pipe that brings water into your home. You should close off all these pipes before you proceed.

C. Remove the cap to the purge valves: The next step will be to remove the valve caps located on hot and cold water valves. However, you should be very careful when you do this. But before you proceed, be sure to close the valves completely first as this will ensure that all the water pressure within the heater is relieved first. Once this is done, slowly remove the valves and keep them clean and dry while you proceed with the rest of the steps.

D. Attach the hosing lines: Typically, these come with your unit. You might have to purchase new ones compatible with your unit if no hosing line comes with it. Check the user manual for a more detailed guide for correctly attaching the lines.

E. Open the purge port valves: you will have to turn the valves to a position perpendicular to that of the hot and cold water valves

F. Clean the unit: after purging your tankless water heater, you can then proceed to clean the unit. You need about 3 gallons of vinegar to get your unit completely cleaned up. Avoid using chemical cleaners to clean your water heater as this can adversely affect your health. Once you are done cleaning with vinegar follow the flushing and draining procedure as specified in the manufacturer’s manual

G. Close the purge port valves and replace the cap

H. Restart the unit. The procedure for this differs depending on whether you use an electric or gas powered heater.

How often should you carry out maintenance on your tankless water heater?

There is really no fixed answer to this question. Most homeowners carry out routine maintenance on their unit once in a year. Some manufacturers also have specific guidelines and specifications as to how often maintenance should be carried out. Typically, the hardness of the water in your region is one of the major criteria that affect how often your unit should be maintained.


Choosing the best tankless water heater is a tough decision. But with the right information, you will find the decision a lot easier to make. By following this detailed guide and product, you should find it easier to choose the tankless water heater that works best for your household.