Best Tankless Water Heaters – 2022 Reviews

| Last Updated: September 22, 2021

Gone are the days when you’d step in the shower and realize that you’ve run out of hot water. Such were the limitations of using a tank-based water heater, but this is the era of tankless water heaters. The hot water never runs out and you don’t have to wait for it to heat again. If that is what you want, then this article will guide you to pick the best unit for you.

Tankless water heaters or demand-type water heaters are an energy-efficient way of generating hot water in your household. Their instantaneous systems provide hot water only as needed, as opposed to tank systems that heat a large amount of water, regardless of how much you need.

Often seen as a more energy-efficient method, if you are looking to switch to a tankless water heater, here are some things to consider and a quick guide to the brands to look at.

Comparison of the Best Tankless Water Heaters

  • 9.5 GPM Indoor Natural Gas based water heater
  • Provides 94 percent energy-efficient performance
  • Designed with intelligent electronic controls for an enhanced experience
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  • Twin pipe indoor natural gas-based water heater
  • Comes with a choice between concentric and PVC venting
  • Features an energy factor of up to 0.96
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  • Best for the money
  • A 3 GPM indoors gas-based water heater
  • Activates only on demand and requires no pilot light
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  • Best Rheem Tankless Water Heater
  • Residential water heater that functions at 240 volts
  • Features an external adjustable digital thermostat with LED display
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  • Best AO Smith Tankless Water Heater
  • Electric Tankless Water Heater that functions at 240 volts with 32 kW
  • Compact design featuring 4 heating elements
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  • Best Navien Tankless Water Heater
  • High-efficiency unit with a field convertible gas system
  • Designed with an ultra condensing efficiency for enhanced results
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  • Best Rinnai Tankless Water Heater
  • Featuring from the V series, it comes in 7 variants for the users to choose from
  • Indoor high-efficiency natural gas-based water heater
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How to Choose a Tankless Water Heater

A tankless water heater is not something most people have invested in before. Therefore, picking out the right one may be hard for some users. If you are one of those, do not worry. Here are a few aspects that need to be considered before purchasing to make sure it is the right one for you.

Fuel Type

You want to ensure that the brand you are considering makes a heater that suits the fuel type you’re looking for. Two things are important to consider here. Firstly, which types of fuel do you have available in your home? While both natural gas and electricity are widely available in the United States, not all homes have the capacity for both. In the first instance, it is usually best to choose the type of fuel you have available to you, otherwise, you may face high installation costs to implement a whole new system.

Secondly, you want to consider the cost of running these systems, especially if you do have more than one fuel type available to you. You can run your tankless water heater on propane, natural gas, or electricity, but natural gas is generally the cheapest and cleanest type of fuel. That said, electric versions tend to use less water and therefore, have lower running costs.

GPM and Size

As mentioned above, picking the wrong size according to your house could result in an unsatisfactory experience. It is, therefore, necessary that the unit that you invest in is sized according to your house so you can get the best out of it.

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Think about the flow rate and size of the unit. Not all tankless water heaters can deal with the same demand for hot water. While some bigger models and brands are able to produce large quantities of hot water to a whole house, others are designed to work with smaller applications, such as a single sink or shower. With this in mind, consider how you’ll be using your water heater. If you want to be able to use it with various appliances at once, look for brands that offer bigger water heaters with a high flow rate or high gallons per minute (GPM) options that can serve the whole house. If, however, you want a water heater for an outside sink or a garage shower, you may just want a smaller unit with a low GPM.

Energy Efficiency

A tankless water heater is not like standard units which consume a large amount of electricity and, therefore, add to the electricity bill. These units are designed to save you not only energy but money on your bills, as well. While looking for a unit, look for one that provides the best of given efficiency. One way of ensuring this is investing in an Energy Star rated product.

Consider the energy efficiency of your water heater unit. If the energy efficiency is low, you will find yourself paying high power bills each month. You want to look for the Universal Efficiency Factor (UEF). The higher the number, the more efficient the system is, which represents how much of the energy is transferred into heat energy.

For gas water heaters only, you can look for the Energy Star. This is a seal that demonstrates a particular model or brand of water heater is exceptionally efficient. It is measured by five criteria: flow rate, efficiency, size, fuel, and the warranty.


It is easy to get fooled into thinking that large, well-known brands supply the best water heaters that are durable and have a long life while producing consistent service through their lifetime. However, it is not uncommon to find that some bigger brands don’t have the necessary reliability and would rather continuously replace a product than improve its longevity. As a customer, this would mean constantly reinstalling a product.

To look for a reliable brand, try to look at customer ratings. Take into account the durability or the product and its longevity, as well as the level of customer service that buyers experience. Try to find brands that are in excess of four out of five stars.


While you may find your ideal tankless water heater online, think about what happens if it breaks down. Sometimes you may have to find parts or someone who can service your unit. While you can sometimes call a service person from the brand’s manufacturer, this doesn’t happen all the time, which can require the additional cost of finding a service professional.

Before purchasing a water heater, consider if these are offered in your local area and whether someone in your near vicinity can help you if you need a repair.


Units come with a number of different features. Depending upon its features, a unit may range from being highly affordable to highly expensive. Before you invest in a unit, consider your budget, and invest in one that fits within it. If you do not, you might end up spending more on features that you simply do not need.

With all this in mind, the price can also be a determining factor. Unfortunately, the price of tankless water heaters does not always denote the quality. While cheaper models may save on upfront costs, usually they are less durable and need replacing sooner, while also being less energy efficient, increasing the running costs.

That said, more expensive products may also not be ideal for you. Expensive water heaters tend to be larger in size with higher flow rates. If this is not what you need, your money is going to waste. Always compare the price with the other factors and consider what you need first, as your application will determine whether the unit is of value or out of your price range.

Review of the Best Tankless Water Heaters

Now that you know what a tankless water heater is and which of its features need to be considered, you are ready to pick one for yourself. In order to help you out, we have listed and reviewed some of the best tankless water heaters you can find in the market. 

Best Overall


Rheem RTG-95DVLN-1 Water Heaters, Gray


Max Water Flow (GPM): 9.5

Energy Factor (EF): 0.94

Dimensions:‎ 18.5″ x 9.75″ x 27.5″

Water Temp Range: 85-185°F

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What Recent Buyers Report

Users that invested in this unit have been extremely surprised by how well it performed. They admitted to having a number of issues with their previous units that simply never hit the mark, but this one simply eliminated any issue that they had had previously, making it a fast favorite for them.

Why it Stands Out to Us

This option has a lot in store for its users, but of all those features, what really stands out to us is its electronic control and display. This electronic control allows users to not only use the unit with greater energy efficiency but with a greater level of ensured safety, too. With these features combined, this unit simply becomes unbeatable.

Who Will Use This Most

This tankless water heater by Rheem presents users with a very unique set of qualities. Such qualities make it ideal for a number of users. But this unit is specifically for all those users who want a natural gas water heater that allows them a safe functionality and efficient use, along with zero hassles that come with a tank.

Bottom Line

We find this unit to be a great one, not only in terms of its great number of features but also the great functioning, along with great user reviews. It will not only satisfy you with all the features it promises but also will impress you by providing a lot more than any other similar unit could.


Features a third party efficiency listing by HRI

Equipped with intuitive control for greater energy savings

Low NOx version designed to provide functioning like no other

Can be connected with 38 feet of 3-inch PVC or 5 feet of 2-inch PVC pipes

Stainless steel condensing heat exchanger allows a corrosion-resistant design


Installation process may take some time

Control system may give irrelevant errors

Warranty may not be applicable for a number of parts


Rinnai RUC98iN

Rinnai RUC98iN Ultra Series Indoor Natural Gas Tankless Water Heater, Twin Pipe


Max Water Flow (GPM): 9.8

Energy Factor (EF): 0.96

Dimensions: 10″ x 18.5″ x 26″

Water Temp Range: 98-185°F

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What Recent Buyers Report

Those that have invested in this unit will find a lot to say about it, but all of it would be in its favor. They say that it not only provides them with functionality and durability they expected but also comes with a sleek design that the users thought fit right in with their modern interior.

Why it Stands Out to Us

This unit provides an extensive list of features that we absolutely love, but what stands out to us particularly, is its compact size. It could easily replace a huge one, and it would take up less than half of the space and still provide greater functionality than the previous one.

Who Will Use This Most

A number of units will provide you with great functionality, but not all come with the ideal design like this one. If you are looking for a unit that will easily fit into the designated space and complement the aesthetics of your house, while maintaining its functionality, then this is the one for you.

Bottom Line

Some units are simply designed to excel in every aspect, and this unit is definitely one of those. It is designed with almost every feature a user looks for in a hybrid water heater, making it widely popular among users. If the top product doesn’t suit you, then this is the perfect substitute.


A simple and intuitive system that allows easy settings

Designed to provide users with a maximum BTU rating of 199,000

Features ultra-low NOx emissions that allow safer use of the system

A compact and sleek design that allows users to save a huge amount of space

Users can choose whether they want to go with a concentric venting or PVC option


Quite expensive compared to other tankless units

Some add-ons may be required for installation that are not included

Best for the Money

Eccotemp i12-NG

Eccotemp i12-NG Tankless Water Heater


Max Water Flow (GPM): 4

Energy Factor (EF): N/A

Dimensions: ‎17″ x 29″ x 11″

Water Temp Range: N/A

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What Recent Buyers Report

Investing in this unit, users admitted they did not have many expectations from its functionality, given its low price point. But in the end, they turned out to be greatly impressed by how well it performed and the continuous stream of hot water it provided, regardless of its compact size and affordable price.

Why it Stands Out to Us

The comparatively low price of this unit is a great incentive for users, but what really stood out to us was the child lock technology it features. Kids often like to push buttons, but with this unit, they can press all the buttons they want without messing up the settings or its functionality.

Who Will Use This Most

Tankless water heaters are the new norm when it comes to water heaters, not to mention their high cost efficiency. For those who want to try out these units without spending too much on them to see if they really perform up to the mark, this will function as the perfect trial unit. It will allow them to experience the ideal functionality of these units without spending too much.

Bottom Line

This item is one that will allow you not only to stay in your budget but also save more on your electricity bills, given the energy-efficient functioning that it offers. From its sleek design to its flawless operation, almost everything that it offers will simply impress you without any complaints at all.


Can be installed using the standard ½-inch NPT water fittings

Field-tested to provide optimal results at elevations up to 5500 feet

Horizontal venting allows a quick and convenient method of installation

Features a safe electronic ignition system that ensures safe use of the product

Designed with a fully automatic temperature control system and an energy-saving mode, along with a child lock technology


Using a different vent may void the warranty

Usage at a higher altitude may not be efficient

Installation may require a few items that are not included with the product

Best Rheem Tankless Water Heater

Rheem RTEX-13

Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater, GRAY


Max Water Flow (GPM): 4.8

Energy Factor (EF): N/A

Dimensions: 12.63″ x 8.25″ x 3.63″

Water Temp Range: 80-140°F

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What Recent Buyers Report

Rheem has been known for its high-quality products that come with uncompromised functioning. That is exactly what users expected to see while investing in this water heater by Rheem, and the brand has made sure not to disappoint them. Users admit that they got to experience the best of tankless water heaters with this unit, given the ideal features it provided them with.

Why it Stands Out to Us

As always, Rheem has designed this unit with a great number of features, but out of all these, the one that stands out to us most is its integrated LCD screen. Unlike that provided by most other standard units, this one is specifically designed to allow users to adjust the thermostat according to their own needs.

Who Will Use This Most

A number of users who have invested in Rheem in the past, prefer their subsequent products to be from the same brand, too. So, if you are looking for a tankless water heater manufactured by Rheem specifically for the best of functionality, then the unit is the best one for you.

Bottom Line

If you have used products by Rheem before, you know that it does not disappoint its users. And it doesn’t disappoint with this either. This specific unit has been designed with all the high-end features one could expect to find in a tankless water heater and the brand ensures that they all perform well.


Threaded for easy replacement, as well as simple installation

Allows a 99.8 percent energy-efficient functionality for great savings

Designed with self-modulating power control that allows high functionality

Equipped with not one but two durable copper immersion heating elements

Installation can be done using the standard-sized pipes with the ½-inch NPT adapters included


Not an Energy Star rated product

Installation may be easy, but takes time

Warranty given by the manufacturer is only some parts instead of the whole unit

Best A.O. Smith Tankless Water Heater

A.O. Smith R4MA-320E


Max Water Flow (GPM): N/A

Energy Factor (EF): 0.93

Dimensions: 6.13″ x 17″ x 18.13″

Water Temp Range: N/A

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What Recent Buyers Report

Users who have invested in this unit have found it to be one of their favorite investments, because of how well it pays back for the money that they have spent on it. For years, users have trusted A.O. Smith with their products, and after using this product, users have all the more reason to do so.

Why it Stands Out to Us

The one particular feature of this unit that greatly stands out to us is the use of four heating elements. Standard units come with only one, or at max, two heating elements. The addition of three extra heating elements provides the unit with an enhanced functioning that is better than any other you will get to experience.

Who Will Use This Most

A.O. Smith is a well-known brand in the industry, providing users with quality products for a number of years now. Users who trust A.O. Smith have been known to invest in its products time and again. If you are looking for a tankless water heater by A.O. Smith, this is the one for you.

Bottom Line

Regardless of your previous investments in products by A.O. Smith, or lack thereof, you will find this unit to be on par with your expectations. With its flawless design, high-end functioning, and enhanced features, you will find there are no aspects that would disappoint its users.


Digital interface of the system is intuitive and easy to use

With the compact size, it can be placed wherever you want

Unit requires no venting and replacement parts can be found easily

Four heating elements ensure a highly efficient heating process by the system

If the correct size is picked, it ensures a continuous stream of hot water, with no interruptions


Does not come with an Energy Star rating

Installation may require professional assistance

Considerably more expensive than other electric units

Best Navien Tankless Water Heater



Max Water Flow (GPM): N/A

Energy Factor (EF): 0.96

Dimensions: 13.2″ x 17.3″ x 27.4″

Water Temp Range: N/A

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What Recent Buyers Report

Users that have recently bought this unit for themselves have been very satisfied with their decision, as well as this hybrid water heater by Navien. Users have not only been impressed by its sleek design that gives a great first impression, but also the energy-efficient functionality that maintains that impression.

Why it Stands Out to Us

Of the number of features that Navien has provided this unit with, the one we like most is its heavy-duty anode. The high-quality part used here not only adds to the functionality of the heater, allowing for an efficient heating process, but also ensures greater durability of the product.

Who Will Use This Most

While some may perfer investing in a good old tank system that can store the heated water, others prefer a tankless unit that provides hot water immediately for use. If you plan on investing in one that is designed specifically by Navien, then this unit may be the best one in store for you.

Bottom Line

If you have been having a hard time choosing between a number of brands and have finally decided to invest in a unit by Navien, then allow us to solve the further issue of choosing the specific model. Of all the tankless water heaters the brand has to offer, this one is definitely the best.


Designed for higher level of functionality

Features very low NOx emissions that allow a safe use

Ultra-condensing efficiency allows it to function like no other

Dual stainless steel heat exchangers allow efficacy along with durability

Sleek design allows it to fit in with your interior while the compact size ensures you can install it wherever you want


Not an Energy Star rated product

A considerably expensive unit compared to the standard ones

Does not feature extra heating elements to compensate for the size 

Best Rinnai Tankless Water Heater

Rinnai V Series HE Tankless Hot Water Heater

Rinnai V65iN Tankless Hot Water Heater, 6.5 GPM, Natural Gas, Indoor Installation


Max Water Flow (GPM): 6.5

Energy Factor (EF): 0.82

Dimensions: 14.04″ x 9.27″ x 26.9″

Water Temp Range: 98-140°F

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What Recent Buyers Report

Users that have invested in this unit have all reported that they have benefited from it greatly. They claim that this unit has not only provided them with the best of tankless water heating technology but also allows great savings in terms of space, as well as money. To sum up, it is all they could ask for.

Why it Stands Out to Us

The one feature we think makes this unit worthy of being on this list is the great warranty terms it provides its users with. Users are provided with a great set of warranty terms that cover a number of aspects. This saves them from being hesitant about spending money on what they really need.

Who Will Use This Most

While an electric water heater may be quick and efficient with its functioning, the quality of performance provided by a natural gas water heater is simply unmatched. If you, too, are looking for a high performing natural gas water heater by Rinnai, then this unit is just the one for you.

Bottom Line

This natural gas tankless water heating system is designed to provide you with great-quality water heating, along with energy savings and durability. This unit is perhaps one of the best designed by Rinnai and provides users with all they need.


Allows users a hot water flow of up to 6.5 GPM

High-efficiency unit allows greater energy saving than standard products

Features a vacation mode that allows you to save energy while you are away

Compatible with the Control R 2.0 mobile app that allows remote control of the unit

Provides a residential factory warranty of 120 months for the heat exchanger, 12 months for the labor, and 60 months for the parts


Lag time is greater compared to other units

Installation may take longer and require assistance

Not ideal for use in smaller houses, as the energy consumption is optimized for heavier use

Best Richmond Tankless Water Heater

Encore RMTGH


Max Water Flow (GPM): 8.4

Energy Factor (EF): 0.93

Dimensions: 9.75″ x 18.5″ x 27.5″

Water Temp Range: 85-140°F

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What Recent Buyers Report

A number of users who invested in this unit did so due to their trust in products manufactured by Richmond. According to all those users, this product, too, displayed perfection of design and flawless functioning they are accustomed to in every other product by Richmond, and highly recommend it to others.

Why it Stands Out to Us

Of all the features this gas water heater has in store for us, what really makes it stand out from the rest are its water-saving settings. Most tankless water heaters are usually designed to save energy, but with this unit, you will find the option to save water, as well by limiting the water flow rate.

Who Will Use This Most

Products by Richmond are designed to provide users with a great number of features and conveniences. This unit serves to be ideal for all those users looking to invest in a tankless water heater that is not only impeccable in design, but also allows a high-end experience like no other unit.

Bottom Line

With this water heater, you may have to pay a great amount of money and it will require professional assistance for installation. But once you get past that, you will find that all the money and effort was definitely worth it. It provides you with a functionality that is better than what you’ll find in all other tankless water heaters.


Comes with a recirculation pump kit that heats up the water in the lines

With the leading low-flow activation, a minimum flow of 0.26 can be achieved

Exclusive water-saving setting allows users to save up to 1,100 gallons of water

Maintenance settings notify users the need for service after a certain amount of use

EcoNet-enabled unit allows users to connect to the EcoNet mobile app for a better experience and convenient use


Does not feature an Energy Star rating

High-end product that is not affordable for all

Installation requires professional assistance and takes a considerable amount of time

Best Lochinvar Tankless Water Heater

Residential Tankless Condensing With Built-In Pump Gas Water Heater


Max Water Flow (GPM): 10

Energy Factor (EF): 0.95

Dimensions: 11.25″ x 17.75″ x 23.63″

Water Temp Range: N/A

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What Recent Buyers Report

Those who have recently invested in this unit will tell you about the high functionality and flawless design that it features. According to those who have invested in products by Lochinvar before, this unit is absolutely up to the standards the brand has always provided for its users.

Why it Stands Out to Us

It is true that this unit comes with a great number of features, but the one we think makes it worthy of being on this list is its recirculation pump. This pump greatly reduces the lag time usually experienced with tankless units and brings it down to nil, since it recirculates the water in the lines and heats it, as well.

Who Will Use This Most

Products by Lochinvar may be a little more expensive compared to rest, but they also provide users with a lot more. So, if you want to experience the best by Lochinvar and can find a little extra money to spare, then this will be the perfect choice for you.

Bottom Line

All in all, this unit is one of those is designed to provide you with utter perfection. It not only provides you with the perfect aesthetics for your modern interiors but also provides functionality and a list of features second to none. With all that it has to offer, you can rest assured this unit will not disappoint you.


Features a sleek design that can fit in with any interior

Designed with a simple and intuitive control system that is extremely easy to use

Users can choose between two units that can be installed either indoors or outdoors

Level of NOx emission is less than that by any other, making it one of the safest to use

Comes with an integrated recirculation pump that allows heating of the water in the lines


Unit does not feature an Energy Star rating

Warranty only covers certain parts of the system

The compact size may not be suitable for a larger house

What is a Tankless Water Heater?

One can guess what a tankless water heater is, given the name itself. It is a unit that functions to heat water, but without the standard tank system seen in most water heaters where the water is heated and stored for use.

A tankless water heater is also called an on-demand water heater, which is exactly what it does, heat water on demand when needed by the user. Such water heaters are designed not only to ensure an endless stream of hot water but also to cut back on the energy consumption seen in a heater that constantly runs to heat and store water.

How Does a Tankless Water Heater Work?

A tankless water heater, as mentioned above, does not run all the time. It only begins its heating function when hot water is required. When you turn on the hot water tap, the water from your storage tank goes into the unit. Within the unit, the water gets heated, the process of which depends upon the type of water heater being used. The heating is usually done using an electric element or a gas burner. Once heated, the water further flows to the tap and may be utilized. 

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What Size Tankless Water Heater Do I Need?

One of the most commonly asked questions before buying a tankless water heater is in regards the size one should buy. The answer to this question depends upon the size of the house you live in. Investing in a heater that is too small for your house may not be satisfying, as it won’t perform as efficiently as these units are supposed to be.

On the other hand, buying a unit that is too big for the house will only result in spending unnecessary money and increased power consumption compared to what is really required. It is, therefore, important to consider the size of the house that the heater is intended for before investing in a unit.

What are The Advantages and Disadvantages of a Tankless Water Heater?

Just like every other unit, a tankless water heater also comes with its own advantages and disadvantages. If you haven’t been able to make up your mind about these units, then weighing its pros and cons may be able to help you out. Here are a few advantages and disadvantages.


Let’s first look at the advantages. 

Cost Efficient

One of the greatest advantages of these units is that they are highly cost-efficient. Since they do not run all the time, and only when water is needed, they help save users a considerable amount of energy.

Never Run Out of Hot Water

These units function differently and faster than standard heaters. They serve to heat the water as it is passing through the unit. This functionality allows users to experience a stream of hot water that simply never ends.


By design and function, these units are designed to last longer than any other conventional water heater. And this difference is not just of a few years but almost doubles the number of years that a standard unit provides. Considering this, a tankless water heater would last a lot longer than a standard water heater would.


Meanwhile, the limitations of such units include:


While these units may last longer and help users save over a longer time, the initial cost paid for them is considerably more than that paid for other standard heaters. However, this cost can be recovered in a few months with the energy savings from its functioning.

Lag Time

While this unit may allow users to experience a continuous supply of hot water, before the hot water starts running, there is a slight lag time. This lag time does not signify the incompetence of the unit but is simply the time required to get rid of the cold water already present in the pipelines.

Tankless Water Heaters vs Hot Water Tanks

Conventional water heaters come with big tanks that are known to be reliable. Installers and plumbers are more than familiar with how these systems work, and therefore have a sense of trust in a system that they know as straightforward. Due to this, the upfront costs of these kinds of water heaters and the installation costs tend to be relatively inexpensive, in comparison to tankless water heaters. In fact, many people can install them by themselves. Often argued to be inefficient in terms of energy consumption, technology has improved to the point that there are now Energy Star rated conventional water heaters.

However, on the flipside, conventional tank water heaters are always on, meaning that despite their energy efficiency rating, they will always be using energy to keep the water hot, whether needed or not. Equally, their big, bulky size is inconvenient in small spaces and often produces far too much hot water for the average family. Moreover, many people tend to inherit the space for a tank from the previous owners. This means they are limited to the capacity they can have, meaning they may not be able to meet their demand if they cannot fit a big enough tank in.

The big, bulky tanks also mean that installation is less versatile, as the tanks cannot be hidden so easily in smaller spaces. And as it cannot be placed outside the home, there has to be an area dedicated to it.

Tankless water heaters, in contrast, only work when someone needs hot water, heating the water on demand. This can reduce energy costs by around 25% or more per year. While only heating water on demand increases the energy efficiency of tankless water heaters, the models are far more energy efficient by their operational design than tank versions. Some tankless units can have UEF values as high as 0.93 compared to an efficient tank water heater with a UEF of 0.65.

Being small in size allows for more options when it comes to the installation of tankless water heaters. Despite their small size, if correctly fitted, tankless models will generate continuous instantaneous hot water all around the house to meet your demands. You will also find that the long warranties on tankless water heaters demonstrate the durability of the products, with some lasting up to 20 years.

However, tankless models are expensive to buy and have a more complicated installation. This means you often have to pay for a professional to put it in. It is not easy to retrofit a tankless model, and venting materials and labor can be pricey.

How to Flush a Tankless Water Heater

Flushing a tankless water heater is an essential task for maintaining your unit, and a task which needs to be done regularly every 12 to 18 months. If your use is greater, it needs to be done more frequently to avoid any scale build-up. If you find yourself unfamiliar with this process, here is a quick guide on how to do it.

  1. Gather white vinegar, a five-gallon bucket, a hose set, and a submersible pump. This is what you will be using to flush out your tankless system. The brand or quality of the vinegar is not of great importance. Any standard three-gallon bottle of white vinegar will be good to use.

  2. Ensure that you have a flush kit installed. The flush kit, from the outside, just looks like two valves. For further explanation on where to find this flush kit, you may refer to the video linked below.

  3. Turn off the gas. If the gas valve is perpendicular to the pipe, it means it’s already off. If the valve is parallel to it, it means it’s on and has to be moved into a perpendicular position.

  4. Turn off the water valves on the system. There will be two valves that will have to be adjusted for this, one through which water comes into the system and the other through which it leaves.

  5. Remove the pre-filter to check for any deposits or blocks. Cleaning the pre-filter requires just a little amount of water. Once cleaned, put the filter back in place.

  6. Pour the vinegar into the bucket, place the pump on the bottom of the bucket, and connect the pump to the cold side of the water heater. Use a hose to connect the hot side on one end and place the other end in the bucket.

  7. Turn on the pump. The hose connections will have made a loop that will allow the vinegar to go into the cold side, then into the hot and then flow out. Allow this to go on for an hour and the flushing process will be over.

  8. Remove the flushing apparatus and hook the unit to your water lines, going in reverse with the steps that you initially did. Your system is now flushed and good as new.

Make sure to refer to the video below before flushing to be sure of the whole process. 

How to Install Tankless Water Heater

While some tankless water heaters require professional assistance for their complex installation methods, though the same isn’t true for all. Most units can be installed by the users themselves, requiring very few to almost no efforts. If you, too, wish to install your tankless unit yourself, here’s how to do it.

  1. Uninstall your previous unit. This unit may require a varying number of steps, depending upon the type of unit previously used. Before removing the old unit from its place, ensure that the water has been drained and all electrical and water connections have been shut down.

  2. Add a one-inch gas pipe to the system and make one hole in a wall. Then connect it to the outside for an exhaust vent. 

  3. Mount the unit on the wall, attaching it to the exhaust vents on one side and copper pipes on the other side for water intake and output.

  4. Make the required electrical connections for digital control and display. This may require safety measures such as turning off the breaker beforehand and using safety gloves.

  5. The water valves and the electric breaker can finally be turned on and the tankless water heater is now ready for use.


With these tankless water heaters, we can finally say goodbye to running out of hot water when needed. If you want to experience a stream of hot water without any interruptions at all, then a tankless water heater is designed just for you. With the consideration of all the mentioned aspects, you will be sure to find a unit that’s perfect for you.

A Look at the Key Brands 

Take a look at some of these brands offering high-quality tankless water heaters. Each specializing in different ways, these brands offer top products with good added extras.


A German company that started in Stuttgart in 1886, Bosch is a leader in a variety of technologies, from the automotive industry to industrial technology. Bosch now has factories and branches worldwide, with a particular dedication to improving everyday life with innovative technology.

They are known for their thermotechnology and provide sound water heater units that have a long life and work very efficiently. Bosch has a special focus on environmental stewardship and preserving the planet. In this sense, they have made it their aim to develop ultra-efficient products to reduce fuel consumption, including their tankless water heaters. Both tankless water heaters, the Therm and the Greentherm have up to 98% efficiency, making them super-efficient compared to competitive models. Their condensing models are more efficient than their non-condensing models, but all of them are compact in size, making them ideal to fit into a residential-sized space.

Bosch has dedicated their time to producing energy-efficient products that fall in line with the idea of a smart home. Their concept is to provide a series of integrated systems in the home that are easy-to-install, use, and maintain. For this reason, Bosch is one of the best brands for cutting-edge technology and innovation.

Stiebel Eltron

Founded in Berlin, Germany, in 1924, Stiebel Eltron is a very trusted brand with a focus toward customer care and service. They have a mission to provide products that are energy efficient, extremely safe, and provide comfort to the user.

In terms of energy efficiency, all of their products are highly insulated in order to prevent loss of heat while in use. However, their energy efficiency does not compromise their performance, as each tankless water heater includes smart microprocessor technology to enable a steady rate of flow regardless of whether the demand varies on the water heater.

As Stiebel Eltron focuses on customer comfort, they have a varying range of water heater sizes in order to make sure you have the correct size for your home. Easy to figure out and install, their range is user-friendly and enables you to have the most efficient unit for your usage pattern. When it comes to installation, because they are small in size, they can be stored closer to the water source and do not cause a disturbance in the house. They have a long lifespan, as hot water is not being stored within them and because the unit automatically senses the temperature of incoming water and adjusts accordingly.


EcoSmart specializes in designing high-quality environmentally-friendly products. Unlike other manufacturers with diverse ranges, EcoSmart only makes tankless water heaters, as they feel these are more environmentally-friendly and energy efficient than older models, such as stored hot water tanks. They offer both gas and electric tankless water heaters, as well as condensing water heaters.

EcoSmart has a patented technology incorporated in all their models called Self-Modulating Technology. Each model is equipped with a flow sensor that monitors the demand on the water heater. This modulates the energy consumption to the demand on the water heater, which results in up to 50% savings on your water heating bills.

As EcoSmart focus on energy efficiency and savings, they aim to make it as easy as possible for customers to save energy when using their water heater. Each model is fitted with a digital display, which makes it simple to lower the temperature and save energy.

The heaters are also designed to be easily maintained and serviced. For example, if the element burns out, the whole unit must usually be removed and replaced. With EcoSmart models, the element is easy to unscrew and replace, making the whole process user-friendly and making EcoSmart one of the most eco-friendly and waste-reductive brands.


Established in 1988, Eemax started out as a line of commercial water heating products. In 2000, they expanded into producing residential products. They are now part of the same family as Rheem and EcoSmart, a large Japanese company called Paloma Group. Eemax is definitely not as well known as some of the other brands on the market, as they entered the market somewhat later than their counterparts.

However, despite a late arrival, Eemax offers some of the most durable tankless water heaters out there. They tend to last well over 20 years, while being far cheaper than many of the other products offered by the competition.

Their tankless water heaters are also hugely energy efficient. They tend to have an energy efficiency rating of 99%, which puts them ahead of many of the big brands, as they only lose 1% of their energy when converting it to heat.

In terms of being user-friendly, Eemax products are easy to install. They are compact and able to fit into small spaces, meaning you don’t need to find a separate storage space for them. Not only that, they work on low  water pressure so you don’t need to install any complicated parts to get Eemax water heaters going. With low prices, high efficiency, great durability, and user-friendly installation, Eemax offers a lot to rival their long-standing competition.

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As Eccotemp wants to provide their clients with the best option for their home, their range of tankless water heaters is extensive. You’ll find different fuel types, installation types, applications, and so on to suit whatever application you need in your home or on the go. Eccotemp clearly has the customer in mind and proves itself as a customer-friendly supplier at every turn.


The largest manufacturer of water heating devices in the U.S.A., Rheem was founded in California in 1928. Having won a myriad of awards for their energy efficiency measures and forward-thinking designs, Rheem is a household favorite across the country. They are now part of the Paloma Group in Japan and sit as a subsidiary with other brands like Ruud and EcoSmart.

Rheem offers high-efficiency condensing tanks with efficiency ratings of up to 96%. Their models can be fueled by gas or electricity, and all come with electric controls to help monitor the temperature more effectively, to harness the energy efficiency of the unit.

One notable thing about Rheem tankless water heaters is the performance value. Their products are highly rated for providing a consistent temperature, even during high demand. The Hot Start Programming prevents a fluctuation in the temperature while the unit is working, while most of their water heaters tend to have very high flow rates. In this sense, they work well in households with multiple bathrooms and hot water appliances.

One downside to Rheem products is that they generally have a higher price tag than their competitors. Despite this, they have a great warranty, and their customer service is very highly praised, making them a worthwhile investment.


A tankless water heater could be your first step toward a more energy-efficient home. Aside from being more ecologically friendly, tankless water heaters tend to save you money, while also being a little easier to install. The prices of different brands can vary wildly, and this is usually due to their reputation and service. Always make sure to consider customer reviews before taking the plunge.

People Also Ask

It is essential to have all your doubts cleared before using one of these tankless water heaters so you can experience the best of them. In order to ensure that you, too, have no doubts about these products left, here are a few questions that users frequently ask regarding these units.

Do Tankless Water Heaters Run Out of Hot Water?

They are designed to function differently from the standard tank-based water heaters, which is why these units never let you run out of hot water. Instead of heating water and storing it for use, these units are designed to heat water on demand, allowing a continuous stream of hot water.

What Size Tankless Water Heater Do I Need for My Home?

The right size depends upon the size of the house it is needed for. The bigger the house is, the bigger the ti needs to be and vice versa. If not, users may not be able to experience the optimal results these units can provide.

Do You Need a Water Softener With a Tankless Water Heater?

If it isn’t maintained properly, regular users may start noticing deposits of mineral. These deposits may block the pipe, cause corrosion or even increase the number of bacteria. In order to avoid this, using a water softener may help by preventing mineral build-up.

Does a Tankless Water Heater Increase Home Value?

They cost a considerable amount, while its installation may cost a bit more, too. But all these expenses combined will be worth it in the end since they increase the home value. With the installation you can expect your home value to rise by up to four percent.

Are Tankless Water Heaters Safe for Mobile Homes?

Yes. They can be used in mobile homes with great ease, without any safety concerns. The few things that need to be considered are the on-site electric or gas changes that might have to be made, as well as the local climate of your area.

Other Related Tankless Water Heater Guides

Here are some related guides we have that you may be interested in:

My name is Bob Wells and I am a retired HVAC tech from Washington state. I am currently retired and no longer do much with HVAC, however, I feel like I have a lot of knowledge in the subject and I wanted to create a website where I could talk about what I've learned and help upcoming HVAC techs. Find more info about me and HVAC Training 101.