Best Tankless Water Heater

So you’re in the cold side of the country and you want to know the best tankless water heater.

Your search ends here ? this article is your one stop guide for the latest tankless water heater reviews as well as getting introduced with the tankless water heater on the market today.

A water heater is a device that significantly increases the temperature of tap water to make it more comfortable and convenient to use.

What Are The Types of Water Heaters?

There are actually several types of water heaters storage tank, tankless (on-demand), heat pump (hybrid), solar, and condensing water heater.

However, in this article, we will only compare the two primary types as used for most purposes.

1. Storage Tank Water Heater

Dubbed as the most common type of water heater, the storage tank type consists of a separate tank wherein the heated water is stored for the meantime until such time the user wants to use it. The tank is insulated but it doesn’t assure zero heat loss.

When the user desires to use the unit, the water will emerge from a pipe on top of the water heater. The unit also has a temperature and a pressure-relief valve. Either of them will open if the levels exceed the pre-set value.


The tank type water heater can typically supply you with high GPMs (gallons per minute) of water because hot water is already available in the tank.


You can expect significant heat loss even though the tank is insulated because heat in the tank naturally dissipates when the water is not in use. This means there are times you will not be getting your exact, desired hot temperature.

Other than that, the storage tank type has numerous similarities with a tankless variant because they typically have the same purpose. However, the tankless type basically wins on numerous aspects including efficiency.

2. Tankless (On-Demand) Water Heater

As opposed to the storing water principle of the previous type, the tankless water utilizes some heating coils that heat the water instantly when you turn the device on. It makes hot water on-demand, as the name suggests.

This type doesn?t require any tank to store the water because the water is heated and simultaneously delivered to its end-user.

Because of this concept, the tankless water heater is more energy efficient than a storage tank. However, it provides a somewhat limited flow of hot water per minute.

The tankless type is ideal for people who aren?t drawing too much water for consumption, but there are tankless models that can accommodate multiple showers and kitchen sinks at the same time.

Further, the tankless type is ideal for residential units using natural gas water. It?s also recommended for models running on electricity but this type may need a high-end upgrade on the house?s electrical capacity.


  • Tankless variants basically save you up the space which is supposed to be spent on the tank.
  • The tankless type also emits less emissions which is a big plus for environmental enthusiasts.
  • Tankless heaters gives you consistent hot water without the fear of heat loss.
  • This type is also cleaner because the water won?t be stagnant and prone to scales.


The only issue with a tankless variant is they usually have lesser GPMs compared to tanked variants. However, they sure can provide you with unlimited hot water.

Best Tankless Water Heater Reviews on the market

1. Marey Power Gas 10L Digital Panel Tankless Water Heater

Being a gas tankless water heater, this Marey does not require electricity to operate. For starters, this unit contains an auto ignition and is quite easy to install.


GPM – The output is at least 3.1 gallons per minute. Moreover, this one can heat water quite fast even at low pressure levels.

Auto cut-off – This Marey also boasts an auto cut-off protection feature should there be any unexpected absence of flame. It is shuts the gas supply off to save more energy, making the system more efficient.

Anti-freezing protection feature – This model is equipped with an anti-freezing protection feature. The water discharge valve is removed once the temperature drops beyond the freezing point. This mechanism will accumulate the standing water inside the internal pipes. Thanks to this feature, the water in the pipes will never freeze.

2D Cell Batteries – One thing that will surely impress you is the igniter used for this model 2D cell batteries. The unit doesn?t need any electricity to ignite the system. The double ignition device equipped in the unit provides sufficient heat to circulate the system. The ions sense the flame, making the system sensitive enough to give you an easy and convenient operation.


  • Safety Features
  • Easy to install
  • Auto-ignition
  • Highly convenient
  • Unlimited Hot Water
  • Clean and safe
  • Environmental-Friendly


  • The unit has a requirement for sufficient fresh air ? a clearance you need to adhere when mounting the unit.
  • Unsuitable for some apartments because it can only be installed outdoors

2. Stiebel Eltron Tempra Plus – Best Pick by Customers

Now make way for this German technology. The Stiebel Eltron Tempra Plus is a sleek water heater that requires no venting. The product has proven reliability and efficiency, making it an ideal must-have for every user who are fond of hot showers.


GPM – This one can deliver hot water up to 4 gallons per minute. The capacity makes it ideal for dual showers working at the same time.

Progressive Flow Control – One impressive thing about the Stiebel is consistency. Thanks to the advanced flow control technology, your shower will stay hot all throughout the operation. The Tempra Plus offers consistent comfort by maintaining the desired water temperature, all automatically!

Energy Saver – Another astonishing aspect of the Tempra Plus is the integrated self-modulating technology. This smart feature constantly monitors the system and ensures the unit is using the least amount of energy possible. This results in a significant energy saving scheme that guarantees up to 99 percent energy efficiency.

Quiet – If you treat your bath as your personal space for Zen and peace, then the Stiebel Eltron could be your best buddy. The unit works in total silence; you will have an easy time achieving your silent sanctuary.

Compact – The Tempra Plus is a small unit that packs great power inside. Moreover, it requires no venting at all.

Digital Display – The unit has a digital temperature display for you to easily monitor and input your desired preference. This also puts a high-end touch to the overall look of the unit.

Solid copper heating chambers – The internals of the unit is composed of sturdy copper heating chambers that are always up to the task. The materials inside is what makes the unit durable and truly reliable ? something you can easily find in a German product. It makes you more confident and satisfied when using the product.


  • Medium GPM: Up to 4 gallons per minute
  • Energy saver
  • Compact and quiet
  • With solid copper
  • Comes from a great brand
  • Guaranteed unlimited water
  • Cost saver


  • It’s risky to do-it-yourself the installation. Get an expert electrician and a good plumber to work together to achieve the right installation.

3. Rinnai RL75iN Natural Gas Tankless Water Heater – Best Choice

While this model comes from the higher end tier, its features make the investment truly worth it.

If you are searching for a company that constantly integrates the latest in technology in their products, then Rinnai is an ideal bet. Their line up can easily compete for the title, best tankless water heater.


Efficiency – With an efficiency factor of 0.82, the Rinnai RL75iN is an Energy-Star qualified product. This gives you confidence that your unit is highly efficient and up to the task.

Scale Detection Feature – The most impressive thing about this Rinnai is the advanced scale detection feature that gives you a piece of mind. Scheduling a regular maintenance is one of the tasks of owning a tankless water heater. The heating elements are easily damaged by the build-up of minerals in the water. The scale detection feature helps you prevent a severe, chronic damage to your unit.

High Capacity – When you are in a warmer climate, you can expect elevated capacity that can go as high as 7.5 gallons per minute of water flow. Make sure your gas lines are properly set up; you don?t want to end up complaining when you can?t achieve those GPMs.

Natural Gas Heater – This one is an indoor unit. That feature makes this model ideal for people living in a cold climate who can?t install outdoors but really need the power of a natural gas heater.


  • Very high GPM: Up to 7.5 gallons per minute
  • Highly efficient
  • Energy Star qualified
  • Good looking device; sleek
  • Advanced scale detection feature
  • Comes from a good brand
  • Less emissions


  • There are claims from numerous sources this item has a slight half-minute flow delay at the tap.
  • The system is also complicated to install.

4. Noritz NRC661-DV-NG Indoor Condensing Direct Tankless Hot Water Heater

Noritz has been in the industry for more than 60 years. Matter of fact, Noritz is the first to introduce the electronically controlled tankless water heater way back in 1981.

Up to this date, this brand is still one of the leaders in superior hot water technology.


GPM – This one can heat water up to 6.5 gallons per minute ? highly adequate to support multiple bathrooms and a kitchen sink.

Digital Display – The digital display acts like your assistant in operating with your water heater. It shows you the current temperatures and flow rates. The digital display also helps you in troubleshooting your unit.

Standard Input – The unit consumes gas in a range of 15,000 BTU per hour up to 120,000 BTU per hour. The manufacturer ensures this one is built with extreme engineering precision. The unit can last up to 15 years ? which is actually double the typical lifespan of a conventional tank type water heater.

Efficiency – This Noritz can easily compete when it comes to efficiency. The NRC661 is rated at 93 percent efficiency. The higher the efficiency, the friendlier it is both for your pocket and the environment.


The Noritz is packed with all essential features dedicated for safety. It has an overheat prevention device, flame sensor, condensate overfill, lightning protection, fan rotation detector, and freeze protection. Furthermore, it has high elevation adjustment feature and temperature lockout. What more could you ask for?

Clean Water

Another thing that makes the Noritz quite appealing is clean water assurance. The unit will only work once turned on ? this means the water is not stored with some rusty scale. Bottom line: you have a clean and fresh water right when you need it.


  • Very high GPM: 6.5 gallons per minute
  • Comes with safety features
  • Guaranteed clean water for consumption
  • Highly efficient at 93%
  • Can last for 15 years


  • Cold water sandwich sensation.

5. EcoSmart ECO 27 Electric Tankless Water Heater

The ECO 27 is one of EcoSmart?s largest electric tankless water heaters. The brand boasts to have a patented self-modulating technology, giving its users exclusive features that one can never find on other brands. This one runs 112.5 Amps and at 27 KW on 240 volts.


GPM in Northern US – The ECO 27 is able to heat as much as 3 gallons per minute of incoming water having low temperature (37 degrees Fahrenheit). This ability makes this water heater ideal for people living in the northern parts of the United States. It never runs out of hot of water, giving you the opportunity to run up to two (2) showers simultaneously.

GPM in Southern US – If you are living somewhere in the southern United States, the ECO 27 is capable of handling up to 6 gallons of incoming water per minute, offering you unlimited hot water access for up to three sources (or a little more)! You can use it on three showers working at the same time plus a sink. You can easily consider this one as the best tankless water heater.

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Settings – You can set your desired temperature (increments of 1 degree) through the digital temperature. The available settings ranges between 80 degrees Fahrenheit and negative (-) 140 degrees Fahrenheit.

Endless Hot Water – Tank type water heater stores hot water for you to use later. Contrary to that, the tankless type does a much better job ? it heats the water as it passes through the unit! It?s like giving you a real-time hot water right when you need it.


  • High GPM: Up to 6 gallons per minute on select areas
  • Guaranteed endless hot water
  • Compact
  • Space saver
  • Energy saver
  • Cost saver
  • Comes with great warranty

6. Takagi T-KJr2-IN-NG Indoor Tankless Water Heater, Natural Gas

This Takagi indoor tankless water heater is another great product that brings a lot of promise. Specifications include a 6.6 GPM max flow rate and a heating power of 140,000 BTU.

Unlike the previous product, this one can handle almost seven (7) gallons of incoming water per minute. It implies higher capacity for a more simultaneous use. Further, it has an energy factor range between 0.81 and 0.83, giving obvious hints of its power.


Thermistors– This one has both inlet and outlet thermistors for consistent temperature monitoring. This feature gives the unit real-time monitoring of the water temperature so the unit can also simultaneously heat the water to the desired temperature.

Tankless – Being tankless means you don?t have to worry about freeing any floor space just to accommodate the unit. Conventional tank heaters will require the owner to dedicate some square meters to install the heating unit. On the other hand, tankless variants give you the convenience to just mount the unit on the wall, and that?s it!

Flow rate – This one has an amazing capacity ? up to 6.6 gallons per minute. Living in the southern states and considering the average water temperature there, the unit can handle up to two (2) showers working concurrently. You can even include additional one (1) sink into the equation.


  • Very high GPM: Up to 6.6 GPM
  • Higher capacity for more simultaneous use
  • Low operational cost
  • Advanced thermistors


  • Expensive installation

7 Eccotemp FVI-12-LP High Capacity Propane Tankless Water Heater

The Eccotemp is another exceptional propane tankless water heater having enough capacity for home use. This one has a sleek modern design that you?ll surely love. It has the looks that doesn?t look cheap, making it easy to trust.

Main specifications include a heating capacity of up to 4.8 gallons per minute, enough to tackle your bathroom shower. Moreover, it runs on 74,500 BTU and this one offers an accurate temperature and water-flow adjustment.


GPM – This is good for small homes: 4.8 gallons per minute.

Propane – The main thing this product boasts is it utilizes a strong propane flame to instantly heat the water that flows through its tube. That way, you can have a hot shower without ever storing the hot water in a separate tank first. The product heats the water spontaneously while you use it. Now you can say goodbye to cold showers forever! As long as water is flowing from your source, hot water will come out.

Sufficient heat – At 2.3 gallons per minute, the unit can heat the water up to 77 degrees Fahrenheit. Moreover, it can make the water hot up to 45 degrees Fahrenheit at 3.6 gallons per minute. This one delivers water with precise temperature at a pressure of 30 to 80 psi.

Power ventilation – Efficiency and safety are two things that must go together and the FVI-12 has got what it takes to deliver the two. It comes with power ventilation.

NPT fittings – The model is equipped with true ?-inch NPT fittings to accommodate most applications. You will not have a hard time installing this one.

Digital Temperature Displays – Who still uses analog these days? The Eccotemp has designed this one with a digital temperature display to give you real-time, accurate reading of the degree the unit is currently working on. The digital display primarily shows the independent gas and water controls.


  • Medium GPM: Up to 4.8 gallons per minute
  • Sufficient heat
  • Comes with power ventilation
  • Strong propane flame
  • Easy to install
  • Good for small homes
  • Promotes huge savings
  • Very safe to use


  • Apparent bad customer service.
  • Company refused to award some customers with warranty service.

8. Rheem RTG-64XLN Outdoor Natural Gas Tankless Water Heater

The Rheem RTG-64XLN is yet another remarkable water heater powered by natural gas. This is one of those ideal models you would like to have as your first tankless water heater.

This unit is typically longer-lasting than most electronic models while having numerous similarities to a traditional tanked water system.


GPM – This one packs a great capacity. The Rheem RTG-64XLN can deliver hot water at 6.4 gallons per minute (GPM). The capacity is enough to cater multiple showers plus sinks simultaneously ? which is a good thing to have.

Efficiency – It has an energy efficiency rating of 82 percent. This Rheem packs a power of 150,000 BTUs to deliver the required heating power. This level of power is actually on par with most natural gas tankless water heaters today.

Natural Gas – If you can notice from other Rheem products, you may figure out the similarities between this unit and their propane variants. While both natural and propane do have similar features and functions, the difference between the two is that the former is a methane unit. This means less emissions.


The unit doesn?t need a complicated installation process. This Rheem won?t require you to have the expensive, fancy category III stainless steel vent as it only needs a cheaper PVC variety.

Flow rate
The minimum flow rate requirement for the RTG-64XLN to work is 0.26 GPM. That means the heater won?t start unless the water achieves that flow rate. In terms of temperature, the exact rate actually depends on where you live and the corresponding temperature outside. When it comes to controlling the unit, you have the option to either use the remote or adjust it manually.


  • High GPM: 6.4 gallons per minute
  • Uses Natural Gas
  • Longer lasting
  • Less emissions
  • Easy Installation


  • Can only be installed outdoors.
  • Indoor installation causes fumes to build up

9. Camplux Outdoor Propane Gas Tankless Water Heater

This Camplux is an outdoor propane gas tankless water heater with 4.22 gallons per minute capacity. It has a digital temperature display to give you an intuitive access to the unit.


Automatic safety device – This unit has got all the essential safety features you could want. For starters, it has a 20-minute automatic safety device. Additionally, it has an anti-freezing protection and flame failure feature.

High Efficiency – One impressive thing about the Camplux Water Heater is it integrates a simple design with a high output structure. The thermal efficiency is rated at 88.5 percent high. With a high rating like that, it means you have an instant hot water whenever you need it. The best part is it?s endless and will remain hot as long as you need it.

Shower Head – Another thing you?ll surely like is the shower head. The multi-functional unit allows you to modify the settings to your desired preference. Now you can enjoy your hot water the way you want it.

Package-Ready – This water heater package comes with all the necessities you might need. Camplux comes with the required adapters and a CSA approved gas regulator. But it doesn?t come with a manual though.


  • Medium GPM: Up to 4.22 gallons per minute
  • Automatic safety feature
  • Hot shower the way you want it
  • Ideal for outdoor installation
  • Smart drain plug
  • Highly efficient for a natural gas
  • Excellent customer service


  • The thing doesn?t come with some manual so installing by yourself is not recommended.
  • The device turns itself off after 20 minutes and you may have to start it again.

10. BOSCH WH17 Tronic 6000 Tankless Water Heater

Now this one comes more affordable than it actually looks. This Bosch is something you?ll think to be a thousand-dollar water heater only to find out it’s way less expensive than you first thought it would be which is pretty much a good news.


Efficiency – This Bosch has a staggering 97 percent of thermal efficiency ? one of the highest in our list. The Tronic 6000 is designed to accommodate your entire house and deliver hot water wherever needed. The thermal capacity is so high that you don?t have any stand-by water loss.

Powerful – The Tronic is actually the most powerful group among the Bosch water heaters. Group because Tronic actually comes in two series ? the 5000C and the 6000C. The former comes with one but the largest while the latter comes in two smaller but still pretty powerful ? the WH27 and WH17. The one in our list is the 6000C WH17 where 17 stands for the kilowatts.

Compact – An astonishing thing about this Bosch is it?s lightweight and small, yet it packs superior thermal efficiency. Thanks to being compact, this unit is easy to handle and install anywhere indoors.

Whole house capacity

The manufacturer emphasized the Tronic 6000C can supply your entire house. It has sufficient power to heat and deliver water to a single or even multiple fixtures.

Modulating Power

This feature comes in handy when operating because it makes the unit prepared to whatever your hot water demand is. Another factor is the temperature fluctuation which drives the unit to either use less or more power to give you the comfort you deserve.


  • Powerful water heater
  • Has modulating power
  • Highly efficient at 97 percent
  • Can work for your whole house
  • Compact design in a lightweight package
  • Less Scale; no mineral build-up to worry about


  • The minimum flow rate required by the unit is 0.75 gallons per minute.
  • This stream is a little bit too much if you are in the bathroom and you just want to trickle for a while.

How Does A Tankless Water Heater Works?

Evident to its name, this type doesn?t use any tank or any similar thing of some sort. When you turn the tap water on, the cold water (or water with it corresponding default temperature from the source) travels through the pipe and into the water heating unit.

There are two types of tankless water heater ? electric and gas. When the cold water reaches the unit, either an electric element or a gas burner heats the said water. The hot water will then be delivered to the user.

Depending on the type and some other important factors, a tankless water heater can give you hot water at a rate of 2-6 gallons per minute. That?s 7.6 to 22.7 liters of hot water per minute, and sometimes a little bit more.

The primary advantage of the tankless type is you don?t need to wait for any tank to fill up with sufficient water for you to use. Once turned on, a tankless water heater gives you instant hot water.

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Electric VS Gas Tankless Water Heater: Which One Is Better?

This serves as your buying guide whether you?ll choose a tankless water heater powered by gas or something electric.

There is actually no concrete answer as to which of the two types is better electric or gas? Here are some factors to consider when selecting between them.

1. Initial cost

Let’s give this one to the electric variants. Gas-powered counterparts are more expensive than the electric type in terms of initial product cost.

Gas tankless water heaters generally cost around a $1000 (more or less) ? even higher if you choose those with electronic ignition systems. On the flipside, whole house electric tankless water heaters cost around $400 to $1000.

2. Installation Cost

Another point goes to the electric variants. Electric tankless water heaters are commonly smaller in size; around 25 percent smaller than most gas types. Moreover, electric variants don?t emit exhaust gases consequently eliminating the need for ventilation.

Because of that two factors, electric heaters can be installed in more possible locations compared to a gas variant.

A gas-powered tankless water heater requires a complicated process because you need to address venting and combustion supply needs. This makes the installation quite expensive.

3. Operating Cost

Now this one goes to the gas-powered variants. Natural gas is undeniably a much cheaper input fuel when compared to the electricity per BTU necessary to power the other type. When you use a gas-powered water heater, you won?t need to add significant electricity into the equation. This saves you a lot of cash especially in the long term.

4. Efficiency

Electric tankless water heaters are generally more efficient with a rating peaking at 95 percent and more. On the other hand gas variants can only go as high as 80 to 85 percent of efficiency.

At the end of the day, you will benefit most if you weigh-in your own needs and not necessarily follow who?s beating who in a particular factor. For instance, the type of tankless water you choose depends on the availability of the source you intend to use.

If you have adequate electrical supply to support this high-output device, then go for electric. On the flipside, if you have a convenient source of propane or gas, then go for that variant.

If you have abundant resources then that?s the time you?ll consider other factors into the equation:

  • The difference in their cost to achieve the proper size for your home/commercial use
  • Your budget for installationYour own specific preference (probably from experience or friend?s testimony)
  • Water demand (your needs, habits, and usage)
  • Desired installation area

How To Ensure Consistent Hot Water?

Gas-fired tankless water heaters generally can produce higher GPMs compared to electric ones. However, even a massive gas-powered tankless water heater won?t do well if used in a large household.

For instance, using three showers and some sinks instantaneously can really push your tankless water heater beyond its limit. You might end up with cooler-than-expected water.

The most recommended action to beat this problem is to purchase more than one tankless water heater and install them in parallel. This significantly elevates the capacity of your system.

Best Tankless Water Heater 2021 Buying Guide

So you?ve been introduced to the top 10 best tankless water heaters, now it all boils down to the specific item you?ll purchase for your needs. To help you select in a wiser manner, here are some factors you can consider.

1. Compact design

Not everyone has the convenience to provide space. For instance, if you live in an apartment where space is extremely limited, a compact and sleek water heater will do well with what?s available.

This is also your opportunity to achieve an easy maintenance scheme. Not to mention that sleek units look good.

2. Long service life

Basically, tankless water heaters in general last longer than conventional tank water heaters. It would be wise to have a tankless water heater that can serve you for extended years.

3. Low cost

Fortunately, being tankless alone already gives you significant savings when compared to a tank-variant. You can even save more when you choose the right type.

For instance, an electric type is less expensive in terms of initial cost and installation cost. But when it comes to operational costs, a gas-powered variant can easily win this aspect.

4. Eco-friendly

You should consider the environmental factor as much as possible. Choose those that emit less NOx and are friendly to our planet.


There are a lot of tankless water heater reviews around but you can rarely find an article as elaborated and comprehensive as this.

The top 10 candidates for the best tankless water heater has already been introduced to you. Now it all boils down to selecting an item or two for your needs ? be it residential or commercial.

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