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Top 8 Best Tankless Water Heaters Reviews in 2020

Reviews of the Best Tankless Water Heaters

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If you’re looking for a way to save energy and cost each month, a tankless water heater can be a great investment. While the initial investment can be pricey (with installation costs considered), you will save money in the long-run compared to the cost of owning or renting a hot water tank.

This buying guide will cover gas powered tankless water heaters, which are suitable for providing hot water to multiple faucets in your home. We recently reviewed the best tankless electric water heaters, which might be a better choice if you’re trying to provide hot water to a single faucet.

This buying guide includes our expert tankless water heater reviews.

Here Is The List Of The Best Tankless Water Heaters With Our Expert Review:



Rinnai RL75IN Tankless Water Heater

If you have been looking for a compact water heater that has enough capacity to provide for the needs of the entire family, the Rinnai RL75IN tankless water heater would be a good machine to invest in. Featuring a well-oiled mechanism that boasts of high energy-efficiency, the product and its manufacturer have enjoyed a very good reputation for several years now. Despite being fairly small in size, it is a very powerful unit that can provide a medium-sized family with a regular supply of piping hot water.

Those who believe in using products that are built with the most advanced technology and have high-end features are bound to take an instant liking towards this product. It is a modern water heater that you can operate with your smartphone or an Alexa device. What is interesting is that the machine will drop a message to your registered mobile number (one that is linked to it) when it needs repair or maintenance. It features a digital control panel that lets you monitor its operations easily. On the same panel, you will find an error code indicator that will let you know when there is a problem with the machine and the steps you can take to troubleshoot it.

The water heater is Wi-Fi enabled, so you can easily connect it to your smartphone or any other device that supports Wi-Fi connectivity and control it remotely. The device is designed in such a way that it can be easily mounted to a wall. While you can set it up anywhere, mounting it to a wall will help you save on a large amount of space in your kitchen area or wherever you install it. Setting it up does not take a lot of time but professional help is needed for the assembly. With dimensions of 14 x 9.3 x 23 inches, it can be installed in any corner of the house. You get multiple venting options. It can be vented either through the wall or the roof. You also have the option to use a digital controller that can be programmed for 24 hours. It will keep you updated about your daily consumption of hot water and the amount of time you use the machine.



Wi-Fi enabled

Highly advanced features

Scale detection feature lets you know about contaminant build-up

Multiple venting options


Can be installed only by a licensed professional

Regular maintenance is required


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Rinnai V65eN Tankless Hot Water Heater

Many of the modern-day tankless water heaters have the kind of mechanism which many users, especially the ones who are not familiar with new-age technology, find complicated. The Rinnai V65eN tankless water heater has a simple mechanism that works towards providing you with an endless supply of hot water. The good news is that it does not have any controls or features that can leave you confused. This small-sized machine is often referred to as a ‘whole-house’ unit because of its capability to cater to the needs of a large-sized family.

Many large households tend to invest in multiple water heaters that they install in different corners of the house. This machine can produce 6.6 gallons of hot water per minute. The output may vary slightly based on the temperature outside. If you are living in an area that is characterized by a very warm climate, the heater will deliver optimum performance. If you are living in a cold area, it will register an efficiency of 4-6 gallons per minute. The machine needs around 150,000 BTUs to function efficiently. The power requirements are very similar to the kind most Rinnai models need. The device weighs around 48 pounds and is quite easy to be mounted anywhere in your house or office area.

It comprises a robust internal system of sensors, heat exchangers and burners, all of which contribute towards its smooth and efficient functioning. When the sensors detect the presence of cold water inside the pipes, the burners get fired up and the water creates a circle around the heat exchanger till the time it registers the same pre-set temperature that you have decided. As this water heater is a whole-house unit, members of the family can use hot water in the bathroom and the kitchen simultaneously. While the machine offers a pre-set temperature of 120 degree Fahrenheit, buying a remote control (sold separately) will help you choose a range between 98 degree Fahrenheit and 140 degree Fahrenheit.



Works as a whole-house unit

Easy to install and maintain

A good flow rate of water

Lightweight and easy to move around


Not recommended for very big residences

Can only be mounted in an outdoor space


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Stiebel Eltron Tankless Water Heater Tempra 24 Plus – Electric

Stiebel, a company based in Germany, has been manufacturing high-quality electrical appliances for several years. This tankless water heater features a bunch of high-end features and advanced controls that make it a must-have device for those who seek efficiency and modernity from their machines. This water heater was recently given a makeover by its manufacturer. The latest model has an upgraded look and features that make it all the more appealing. Its advanced temperature control and flow control allow you to customize the temperature and flow rate easily. Most traditional water heaters remain operational all the time but this machine functions only when you require hot water.

It features microprocessor technology which ensures that hot water is delivered at a constant temperature. If the temperature fluctuates while taking a hot shower, it will result in an unpleasant bathing experience. When you use this heater, you do not have to worry about such occurrences. The flow rate might fluctuate at times but there will never be any fluctuation in the temperature. The digital temperature control allows you to operate the machine at a temperature ranging from 86 degree Fahrenheit to 140 degree Fahrenheit. The temperature can be changed or adjusted by a simple turn of the knob.

This heater can produce 4 gallons of hot water per minute. When you draw a comparison with water heaters in a similar range, this device registers a medium-rated flow rate. It is capable of running multiple fixtures at any given point in time. It is one of the easiest tankless water heaters to set up. It can be installed conveniently without undergoing any venting process. The device is surrounded by a steel casing and boasts of a minimalistic and stylish design. It has been designed for both personal and commercial use. As it tends to consume a lot of power during its operations, it cannot be regarded as a very energy-efficient heater. The manufacturer offers a three-year limited warranty on the product and customer care support in case of any issue.



Three-year long warranty

Microprocessor technology ensures delivery of water at a constant temperature

Runs multiple fixtures simultaneously

Well-functional digital control box


Consumes a lot of energy

Not suitable for commercial use


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Ecosmart ECO 18 Electric Tankless Water Heater

If you have been looking for a medium-sized tankless water heater that is durable and efficient, you must consider buying the Ecosmart ECO 18 tankless water heater. Apart from its elaborate features, what makes this machine stand out is the ease with which it can be used. Even those who are not too comfortable with modern machines can operate it smoothly. It can produce 2.5 gallons of water per minute. The flow rate is relatively lower when compared to similar heaters but good enough for a hot shower. You can use this device to produce hot water from two different shower heads simultaneously. The installation process is quite simple but if you need professional help while setting it up, you can reach out to the customer support of the company.

It is an ideal water heater for those who have limited space in their home. Its compact structure also enables you to carry it or move it from one place to another easily. It is a self-modulating heater and therefore detects the flow rate and temperature on its own and adjusts the controls accordingly. The sensors are very effective at finding out if the water is being produced in the right temperature range. When the heater sets up the temperature initially, you might experience a 30-second delay. Certain water heaters work more efficiently when they are in an area that is characterized by warm weather conditions. This is one such water heater.

At a temperature of 15.56 degrees Celsius, this machine can produce 2.5 gallons of hot water. This heater is designed not to go beyond a particular temperature range while heating up. Because of this, you are ensured about the safety of the children in the home who might operate it accidentally. This water heater has been manufactured keeping the demands and preferences of large-sized families in mind. Even you have several members in the house, you will not be required to set up multiple heaters if you just install this one device. To install it, you need cables, a 60-ampere double pole breaker and a 125-ampere electrical panel.



Its compact design helps in conserving space

Heats up water very fast

Moderately priced

Temperature can be adjusted easily


Waiting time of 30 seconds while delivering water

Cannot be installed outdoors


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Rinnai RU199iN Sensei Super High Efficiency Tankless Water Heater

Sometimes, the thought of high electricity bills acts as a hindrance to buying a new electrical appliance. A lot of water heaters need a high amount of power to operate and that results in a significant increase in your monthly expenditure on electricity. The Rinnai RU199iN Sensei water heater lets you keep all these worries aside. It is a machine that is known to be highly energy-efficient and that is one of the reasons its popularity and demand has steadily increased over the years. It cannot be installed outdoors but if you are looking for good quality and energy-efficient water heater for your personal use, this is the one you should go for.

It is capable of providing a continuous supply of hot water for the entire household and therefore eliminates the need for installing multiple units at different points across the house. You will be able to have access to hot water at any hour of the day and out of any faucet you wish to. It features Circ-Logic technology that gives you the freedom to adjust the recirculation patterns in the machine. One of the biggest selling points of this heater is the fact that it has the kind of features and controls that help you customize your water consumption experience. It boasts of a sturdy build and is widely renowned as one of the most powerful water heaters offered by the manufacturer.

The compact structure of this heater enables one to install it in places like a closet, attic or on the top of a cupboard where regular heaters would not fit. This device has a compact design which leads to saving a lot of energy. One of the many things this heater assures you of is providing hot water at a good flow rate. You also get the assurance of water being provided at a consistent temperature. When a water heater breaks down, you are mostly left with the option to replace it. That is not the case with this device. It is made of components that can be fixed or replaced easily.



Components can be easily repaired or replaced

Efficient recirculation system

Compact structure

High energy-efficiency


The installation process is a little complex

Customer support service could be better


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Rinnai RUR98iN Ultra Series Condensing Indoor Natural Gas Tankless Water Heater

With a capacity to produce 9.8 gallons of hot water per minute, Rinnai RUR98iN is one of the most powerful water heaters around. It is at its efficient best when the temperature is around 25 degree Fahrenheit. At 50 degree Fahrenheit, it can produce 7.5 gallons of water per minute. It features a dual ventilation system that ensures improved air treatment for the heater. The gas-fired pump that is manufactured in Japan is of very high quality and contributes towards the efficient functioning of the machine. It also features a thermal bypass technology that comprises an integrated pump, a thermal bypass valve and an internal bypass line. All these components work towards producing hot water at a consistent temperature.

It is one of the very few water heaters that feature Concentric Polypropylene or PVC/CPVC venting options. The venting configuration has been transfixed at the top which further helps in making the installation process more convenient. Concentric Polypropylene is known for its high-quality joint fit and ease of installation. It is the most suitable water heater for those who have multiple bathrooms at their home. It can support 4-5 shower heads simultaneously when the temperature is moderately cold. When the temperature is very cold, it can support 2 shower heads. Just like installing the device, maintaining it is a hassle-free process.

The remote control helps you adjust the temperature easily and the digital display screen keeps you updated with the operations of the heater. With a weight of 70 pounds and a dimension of 18.5 x 10.1 x 26.4 inches, it is a device that requires a lot of space to be installed or stored. Some of the components you would require to install this heater are weather-proofing equipment, ground lines, circuit breakers and exhaust pipes. This heater lives up to its title of being an ‘ultra-efficient’ device as it does a very good job of saving energy. It is Wi-Fi enabled and can be easily connected to any device which has Wi-Fi connectivity.



Made of strong and last-lasting components

Strong sensor system

Registers high energy efficiency

High-end safety features


The installation process is elaborate and expensive

Heavy structure


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Rinnai RUC98iN Ultra Series Indoor Natural Gas Tankless Water Heater

If you are planning to buy a new water heater but are not sure whether you will use it in your home or office area, you could go for this particular appliance. The Rinnai RUC98iN water heater has been designed for both personal and commercial use. The only thing you need to remember is that it is for indoor use only and cannot be installed in an outdoor space. It has a compact structure but at 61.7 pounds, it is not a lightweight machine. Its exterior boasts of a sleek design and that’s one thing that catches your attention instantly. The controls are placed at the lower end of the control panel. This panel consists of a power button, a digital display screen and water temperature and gas control buttons.

If you have children at home, this machine will not cause any harm to them. The temperature button can be locked easily to ensure that the children do not operate it in your absence. As far as venting options are concerned, you get a twin-pipe PVC. This device adheres to emission standards of nitrogen oxide set by authorized agencies. The water and gas supply inlets this device features are bigger than the ones you come across in most tankless water heaters. The electric ignition system it uses is quite energy-efficient and consumes only 2 watts of power in standby mode. When it is in operational mode, it draws 64 watts of power. During the winter season, it needs around 146 watts of power to prevent its components from freezing.

Its enormous size also reflects the large amount of power it contains. Regardless of whether you use propane or natural gas to run it, it will register an energy factor of 0.95. That is higher than the energy factor registered by an average gas-powered water heater. The device enjoys a high Energy Star rating. The water flow rate fluctuates at times but mostly remains steady. It can produce hot water out of multiple faucets or showerheads at the same time. It can heat water in a range between 95 to 140 degrees Fahrenheit. Since it is one of the heaviest and most powerful water heaters around, its price is also on the higher side.



Energy saver

Does not consume a lot of space

Adequate safety features

Dual-venting option



Cannot be installed in an outdoor location


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Rheem RTEX-18 18kW 240V Electric Tankless Water Heater

Many water heaters require you to follow an extensive process to install them. They may consume a lot of time and effort. If you call for professional help, it would cost you some money too. Sometimes, the tediousness involved with the installation process prevents a lot of people from investing in a new appliance. When you buy the Rheem RTEX-18 18kW 240V water heater, you would not have to face any such difficulty. It is a very easy-to-install device that can be set up in any corner of the house owing to its compact design. It has a sharp design that would complement the interiors of the area it is placed in.

The digital temperature controls enable you to change the temperature very conveniently. It registers a very high percentage of 99.8 when it comes to energy efficiency. At an appropriate temperature, this heater can produce 4.4 gallons of hot water per minute. There is an external digital thermostatic control along with a digital display screen that helps you check and control the functioning of the heater. It supplies hot water throughout the day in a continuous manner. If you face some issues with the device, you can get any of its non-functioning components replaced easily.

One of the best and more convenient ways to install this heater is to mount it on a wall. It is made of premium quality stainless steel that is known to last for a very long period. The metallic gray color befits the solid build of the machine. It weighs just about 14.8 pounds and is compact. It needs a voltage of around 240 volts to function smoothly and is known to be fairly energy-efficient. Its self-modulation feature is very advanced and at par with some of the best tankless water heaters. It features two powerful heating elements that are bounded by strong copper wires from all corners. Despite being compact and moderately priced, it offers great power, efficiency and utility for a household that needs hot water on a regular basis.



A compact device which fits everywhere

Can be easily mounted to a wall

Highly energy efficient

Simple controls


No recirculation system

Might require a flow regulator


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Buying Guide: Best Tankless Water Heater

Tankless water heaters are designed to provide unlimited hot water and also maximum energy savings. However, not all products termed tankless water heater can offer these features.

So, how do you know the one that is right for you then? Consider the following. You can read more on the factors to consider when buying a tankless water heater here.

Size of the Household

The first thing to look for when buying a tankless water heater is the size of your household. The bigger the size of your household, the higher the quality of the unit you’ll need.

If you have a large household, your hot water needs will definitely be much. Therefore, you need to get a unit that will supply hot water to everyone in the house.

Price Tag

Consider the price tag. A small household does not necessarily need a higher heater that is expensive. A small tankless heater will provide enough hot water for the whole house if all faucets are not turned on at the same time. Price varies according to models and functionality. The more powerful the heater is, the more costly it will be.

Installation Cost

In addition, you need to consider the installation cost. The cost can be prohibitive or cheap – this depends on the manufacturer and the type of home you live in. For indoor heaters, ensure that proper venting is provided for it. This is one of the things that can significantly increase the cost of installation.

Again, some manufacturers insist on having their technician install the unit. If you do a DIY installation, you’ll void the warranty on your unit. Opt for a unit which doesn’t require professional installation.

Digital Display

Digital displays have become a standard feature in newer models of tankless water heaters. This helps in better monitoring and maintenance of the heater. It also helps you to keep an eye on the temperature of the water.

Warranty Period

If you see a water heater with a warranty of more than 3 years, this is a good deal, grab it with both hands. Anything below that is not advisable, in our opinion.

Drainage Valves

There are two types of drainage valves namely; brass and plastic. The brass is more durable than the plastic. When buying a water heater, consider the ones that have a brass drainage valve.

Antifreeze Protection

This feature helps to prevent the water from freezing when the temperature is low. This feature is most common in the outdoor water heater models while some indoor models also have the feature. This is good for places with low temperature.

Safety Features

Safety features are a must when it comes to buying tankless water heaters. One of the most important safety features is the flame protection which helps in detecting issues whenever the heater is malfunctioning.

There is also oxygen depletion. Most newer models of tankless water heaters have these safety features except the cheap ones.

Showerhead Capability

Some models of water heaters have showerhead capability whereby you can mount a showerhead to the water heater and take a bath directly. Anyways, this is not a common feature in most tankless water heaters.

About Gas Tankless Water Heaters

The gas tankless water heaters have been much around like their electric powered counterparts. There’s not much difference between both save for the fact that one is gas powered and the other, electrically powered.

Gas/propane tankless water heaters are believed to be much more powerful than the electric tankless water heaters. We, however, didn’t do any tests to compare the two. Two major things must be considered before going for gas/propane tankless water heaters.

  1. The first is to check if your gas supply is large enough to power the water heater.
  2. The second is to find a way to pass out the exhaust from the heat.
  3. Is the gas pipe long enough to reach the heater?
  4. What is the gas consumption rate of your home?

All of these will determine how much of the upgrades you will be needing to power your new gas tankless water heater. We explained these aforementioned factors and others in the buying guide below.

Is the best tankless water heater for everyone?

The answer is yes and no.

Yes: If you can afford the unit and the installation costs, please go ahead and install one for your self.

No: If you’re tight on a budget or you already have a means of getting hot water. However, you should have in mind that the benefits of installing the best tankless water heaters are endless in the long run.

Unlike the traditional water heater that can only contain a limited amount of water, a tankless water heater does not have any limited amount of water it can contain. So, every member of your family has uninterrupted access to hot water.

Gas Tankless Water Heater vs Electric Water Heater, which is best?

The truth is there is no best choice between the two. They are both very good. If you’re looking to replace your existing unit, we suggest buying the same type. That is, if you have been using the gas type and you need a replacement, simply replace it with a gas tankless heater.

Switching from electric tankless water heater to gas tankless water heater or vice versa will require additional cost for fittings and installation. But, if you do not mind the cost, either of the two is best.

How to care for your Tankless Water Heater

Tankless water heaters tend to store up minerals after a long while. The minerals in water which cause its hardness are the sole culprits. We strongly advise installing a water softener as well as a whole house water filter in your home. This will greatly reduce the number of impurities in your water thus prolonging the lives of your appliances that use water.

To keep your tankless water heater in good shape, always flush it at least once every 6 months. It is not tasking to flush the heater although you’ll need to screw and unscrew. You can hire experts to do the flushing if you don’t want to get your hands dirty.

Here’s a video tutorial showing how to flush a tankless water heater.

Video 1

Video 2

Frequently Asked Questions About Tankless Water Heaters:

1) What is a Tankless Water Heater?

These are water heaters that are devoid of a tank and provide a continuous supply of hot water on demand. Tankless water heaters work on a very simple but effective mechanism. Inside the tankless unit, cold water flows through a pipe and gets heated by the heating elements present inside the device. Unlike traditional water heaters which conserve water inside them, it does not feature a storage system. It heats the water coming from the pipes as and when you require it.

2) How quickly does a tankless water heater heat water?

When you switch on a faucet, the heater gets turned on because of the pressure coming in from the flow of water. If you use gas, the gas burners will work towards heating the water. If you opt for heating elements, the water will receive heat when it flows through the unit. The water gets heated very quickly. The time it takes to receive hot water depends on the distance between the water heater and where water is supposed to be used. 

3) What are the advantages of using a tankless water heater?

There are several advantages associated with using a tankless water heater. Most of the tankless water heaters are compact-sized and can be easily mounted on a wall. Their ease of use and installation makes a lot of people prefer them over other kinds of water heaters. When you buy it, you do not have to worry about making space for it in your kitchen. Because of its size, it can be set up almost anywhere. Most of its parts are easily replaceable and recyclable. Apart from being cost-effective, they are environment-friendly too. Storage tank water heaters suffer from leakage issues at some point. That is one thing you would not have to worry about while buying a tankless water heater. 

4) Is it difficult to maintain a tankless water heater?

No, maintaining a tankless water heater is an almost hassle-free process for two primary reasons. One, it does not feature a storage tank which needs to be cleaned regularly and two, it is very small and compact. Since it is an electrical appliance, it is advisable to get it serviced once every 12 months. That is pretty much all you need to do to keep it in good shape. 

5) Does weather affect the functioning of the tankless water heater?

Yes, the weather does affect the temperature of the water that comes out of the water heater. These days, most tankless water heaters come equipped with an in-built freeze protection system that ensures that it remains protected from the freezing temperature outside. The pipes inside the heater are also insulated to protect them from the effects of extreme cold.


Going tankless is a great decision. The units on we reviewed above are here because they met our criteria. Which would you go for – the gas or the electric tankless water heater?

Share your thoughts in the comment section below.


Leave a Reply to Walt Anderson Cancel reply

  • Hey Walt, I’m curious why Takagi was selected as the best tankless water heater, why not a more popular brand like Rinnai or Rheem?

    • Hey Victor, thanks for your question. In my experience, the Takagi units perform just as well, heat water to the same temperature, require the same maintenance and use the same power as the more expensive brands, like Rinnai and Rheem. After installing these units for many customers over the years, I haven’t heard of the Takagi units breaking down or otherwise missing the mark on performance. Given that they are cheaper than the name brands, and have the same performance, it justified selected it as the best. Basically you can the same performance for less money, and this guide is all about helping you find the best bang for your buck. Hope that helps! — Walt