Best Tankless Water Heater Reviews 2021

The most remarkable thing we can notice about the 21st century is its innovation. This comes into view when we look at the technology we have now in 2021. But when people say “technology,” they usually mean phones and laptops.

Well, the term also applies to water heaters. But with so many choices, how do you choose the best tankless water heater out there? It’s simple really, all you have to do is read this handy article.

It provides all the information you need to buy a tankless water heater for you and your family.
So without further ado, let’s see what makes tankless water heaters so great.

What is a Tankless Water Heater?

A tankless water heater is one of the best things you can buy to help yourself and the planet right now. These are water heaters that use a different heating system than regular tank water heaters. This system basically states that it’s pointless to keep water in one place and continually warm it up.

Instead of wasting time and energy like that, tankless water heaters heat up your water on demand. Thanks to this approach, one age-old problem is solved. You can never run out of hot water. Everyone in the family can shower right after each other. No one will have to wait for the water to heat up, as it is instantly hot.

Top 7 Tankless Water heater Compared

Even though all of these are the greatest tankless water heaters on the market right now, there are some differences.

This doesn’t mean that some of the water heaters are better or worse than the others, though. They simply have to be different because people don’t have the same needs.

Some will suit a small family better, while others are great for big households, and so on. In the table below, you will find the tankless water heaters and their differences. They were compared by their maximum flow rate and energy factor.

This is because these are two of the most important features to consider before buying your own tankless water heater. For further information, take a look at the article below.

Best Tankless Water Heater

EcoSmart ECO 27 Electric Tankless Water Heater

If you’re looking for a strong tankless heater that will work effortlessly even in the coldest weather, then you’ve found the right one. ECO 27 may just be the strongest heater EcoSmart has to offer. It’s so strong that it can even serve as the only heat source in the house. Bear in mind that this applies if you live in warmer climates.

But it’s just dandy for vacation houses, wood cabins, or lake houses. A medium-sized household would benefit from this product most, as that is the environment where the heater will reach its full potential without overworking itself. It just might be the best electric tankless water heater you’ll ever use.



  • Economic (saves up to 50% of water costs)
  • Compact size
  • You’re able to control the temperature of the water
  • Durable and highly efficient

What we liked

  • Great for households of 3-5 people
  • More consistent than some competitors
  • Automatic adjustment of power usage and pressure
  • Increased durability

What we didn’t like

  • Delivery takes a while
  • Unsuitable for anything big

This is a great product if you’re a small or medium family looking to save some cash. It works better in warmer climates but works well in colder areas, too. Though it isn’t very suitable for larger households, and the delivery times are a bit long, it’s a worthy companion.

Stiebel Eltron Tempra Plus 24 kW, Tankless Electric Water Heater

Tankless water heaters are the obvious choice if you want to save some money while still being warm and toasty in your home. But people tend to overlook one major perk they have- low noise. And that’s the first thing you’ll notice about this Stiebel model. The silent operation is possible thanks to high-grade electronic parts and the lack of mechanical switches.

The aforementioned parts don’t even vibrate. The issue with most heaters is that the heat will drop once the output increases, but that’s nowhere near true for this heater. The advanced technology prevents it and forms a sort of backbone.



  • Flow control technology
  • Silent
  • Made from high-grade materials to ensure durability
  • Temperature control option
  • Saves up to 20% on bills

What we liked

  • Consistent temperature no matter the flowrate
  • Temperature sensor ensuring no deviation of the setpoint
  • Automatic adjustment to temperature changes
  • High efficiency

What we didn’t like

  • Small warranty issues
  • Takes a little bit to heat up

Overall, this is a steady heater which will do its job properly. The issues it might have can be solved easily with better communication skills and some patience. It’s bound to save you some money and serve you for a long period of time.

Eccotemp L10 Portable Outdoor Tankless Water Heater

The Ecotemp L10 just might be the finest outdoor tankless water heater you can buy right now. This is because it’s the perfect middle between an inside water heater and an outside water heater. Essentially, it is portable, but it requires a firm installation. This makes it so much more than just a portable heater.

It’s meant to stay in place for longer periods of time, and then you can simply uninstall it and take it to your next destination. It’s also able to deliver large quantities of hot water in a short period of time, which means you can attach more than one shower to it.



  • CSA regulator for the propane tank included
  • Battery igniter instead of electricity
  • Safety shutoff
  • 2.6 gallons of hot water per minute

What we liked

  • Easy installation
  • Ideal for RVs, cottages, and cabins
  • Activates quickly
  • Efficient and long-lasting

What we didn’t like

  • Only 1/2″ npt to 3/4″ hose fitting
  • Fitting at the bottom should be further apart

This portable outdoor tankless water heater will be ideal for your summer residence. It’s meant to stay in place once you install it, but you can easily just install it on your next destination. The fitting makes the installation a bit inconvenient, but it’s nothing that a little effort can’t overcome.

Rinnai RUC98iN Ultra Series Natural Gas Tankless Water Heater

This here is a natural gas heater, but don’t let that fool you. Unlike most heaters of this kind that require impossible venting options, the Rinnai is not picky. You can either do your venting with concentric PVC pipes or double twin pipes, and it will work just fine. The installment is a fairly easy process, thanks to the aforementioned venting options.

What’s more, this heater is ideal for big houses and big families as it can emit steady heat without breaking a sweat. Yes, it’s true, it can supply hot water to multiple showers and faucets around the house.



  • Multiple venting options
  • Can be installed inside
  • No noise
  • Suitable for big houses

What we liked

  • Durability ensured by high-quality materials
  • Able to provide a high hot water flow rate
  • Can provide hot water to multiple faucets and showers
  • Very high energy rating (0.95)

What we didn’t like

  • A bit bulky
  • Not cheap

As you can see, this is an ideal tankless heater for a big household. Sure, you might have to invest some money into it, but it’s definitely worth it. Just think how much you’re going to save.

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

Are you looking for the best natural gas tankless water heater? Well, you might have just found it. If you’re a family of up to 5 five people, then you should definitely look into this product further. It’s able to keep everyone warm without putting too much power into the effort.

What’s more, it resists rather cold climates as well. It’s suitable for a household which has multiple showers and faucets and is bound to be a real money saver. What’s more, you won’t be experiencing any inconsistency in the hot water dispensing, as the heater is able to handle it all.



  • Consistent in tougher conditions
  • Extremely durable
  • Great energy rating (0.81-0.83)
  • Stainless steel venting

What we liked

  • Very reliable
  • Saves a lot of money because it’s a natural gas heater
  • The flow rate is consistent in both winter and summer
  • Remote control available

What we didn’t like

  • Not very cheap
  • Venting can be a hassle

This heater is ready to be your ideal hot water provider, but only if you’re ready to make the investment and time to install it. Good things come to those who work hard for them, and that’s especially true for this heater.

SioGreen IR260 POU Infrared Electric Hot Tankless Water Heater

When you think about tankless water heaters, what do most of them have as a common issue? Why, the buildup of lime-scale and calcium, of course. So, by that logic, the tankless hot water heater would have no issue with the buildup, right? Exactly! And that’s why the SioGreen IR260 makes the cut.

Furthermore, this heater is highly convenient for areas with well water or hard water. It’ll work best if you only apply it to one faucet or shower, though. The heater doesn’t quit, though, and will provide great quality for years to come.



  • Infrared water heater
  • No rust, limescale, or calcium buildup
  • Minimal chances of bacteria and algae
  • One shower tankless water heater

What we liked

  • Amazing value for the money
  • Provides just the right amount of hot water
  • Eye-pleasing design
  • Long-lasting if taken care of properly

What we didn’t like

  • Possible internal leaks
  • Unclear installation instructions

This water heater is perfect for anyone looking to save some cash with a tankless water heater that does its job. It doesn’t have all the bells and whistles, but it’s one of the greatest you can buy on the market right now.

Camplux 5L 1.32 GPM Outdoor Portable Propane Tankless Water Heater

There’s a common misconception that water heaters can only be installed into one wall and that they have to stay there for the end of time. But the thing is, some people require tankless water heaters for more than one house (vacation or lake houses, et cetera).

So instead of buying many and wasting money, they can now just buy a portable one. And that’s exactly what Camplux came up with. Not only may this be the best Propane tankless water heater out there, but it’s also the greatest tankless water heater for the money that you can find.



  • Lowest water pressure startup
  • Portable
  • Works well with a water pump from another model
  • Easy outdoor setup

What we liked

  • Compact and elegant design
  • Good price and value contrast
  • Flame failure device
  • Anti-freezing protection

What we didn’t like

  • Can leak at times
  • No on/off switch

As we have witnessed this is a great companion for your outdoor activities. It’s portable and very easy to set up wherever you go. As far as the cons are concerned, the on/off switch isn’t really an inconvenience as it will always be turned on, and there is always customer service.

Related: Best Propane Tankless Water Heater

Types of Tankless Water Heater

Tankless water heaters are one of the best innovations you have seen so far. Since they’ve become so popular, it’s no wonder that there are different types of this product. They exist because people have different needs.
And thanks to the various types of tankless water heaters, you’ll be able to choose just the right one, suitable for your everyday needs and wants.

There are some things that are common to all types, though. Of course, that’s the superior durability and high energy rating. What that essentially means is that you won’t have to buy another water heater for a long, long, long, long while. What’s more, thanks to the energy rating, you’ll save money.

What is the Advantage of a Tankless Water Heater?

In today’s day and age, all we keep seeing and thinking about is how to save our planet. This is because we tended to be a bit irresponsible in the past. Thankfully, there are many ways to amend our mistakes. That’s why it’s essential to use tankless water heaters.

They don’t store water in the tank and heat it up continually but instead heat water on demand. Thanks to this approach, a lot less water is wasted. What’s more, this is what preserves natural gasses. Don’t forget that this approach also saves you a ton of money on your bills at the end of the month.

It’s true. They are a bit more expensive than regular water heaters with tanks. This is nothing compared to the savings in the long run, though. Furthermore, we can say that tankless water heaters are by far superior to tank water heaters because of their durability.

You might be used to a certain lifespan of a tank water heater, and you might be thinking of how that can get better. Well, it can, since tankless water heaters last up to a decade more than regular tank water heaters.
To summarize, these are the advantages of tankless water heaters:

  • High energy rating
  • Save a lot of money
  • Extremely durable
  • Very eco-friendly
  • Save a lot of space
  • Unlimited hot water supply

How to Choose Tankless Water Heater – Features to Consider Before Buying

Before buying your ideal tankless water heater, it’s essential to know what you are actually buying. That means that you should be aware of some features which all tankless water heaters have.
Here is what you should pay special attention to:

The Fuel Source

There are different types of tankless water heaters, and that means they are fueled differently. Since there are electric and gas tankless water heaters, you’ll need to estimate which one you want. Heating on gas is less expensive, for example.

The Brand

There are numerous brands you can find which sell these products. You should opt for those which offer higher quality, though. You don’t want to end up unsatisfied. If you can, you should look for brands like EcoSmart, Takagi, SioGreen, Complex, and Stiebel Electron.

The Use

Do you need a tankless water heater for just one faucet or shower? Or do you need it for multiple showers and faucets? If you need it for the latter, you need to opt for a bigger tankless water heater so it can meet your needs. You can even use them as your primary source of hot water.

Related: Why Proper Maintenance of Tankless Water Heaters is Essential

Maximum Energy Efficiency

This neat little number is how much energy you’ll save by using a certain tankless water heater. The higher the number, the more you save. That means that the more money you’ll save too.

Final Verdict

Congratulations, you’ve reached the end of the article and now know which are some of the greatest tankless water heaters.

It’s been a long ride but hopefully an interesting one. To sum up, we’ve learned pretty much everything there is to learn about tankless water heaters. The only thing that’s left to do is actually buy one. The provided above features a type of water heater for everyone, from those looking for a single hot water source for the whole family to those just wanting a small and portable one.

I recommend glancing over the frequently asked questions segment once more than determining which your perfect match from the list is. This way, there’s no way you’ll make a mistake and end up dissatisfied with your purchase.

I’m confident you’ll make the right decision with the info you’ve just gained!