The Most Comprehensive Guide For The Best Tankless Water Heater: 5 Top Models Tested And Reviewed

Tankless water heaters are not a new thing, but they have been more and more popular during the last several years. Reasons are simple. These water heaters are more sophisticated and they offer more benefits than conventional heaters. The best tankless water heater will provide you hot water at any given moment, without any losses or issues. In addition, there are lot of facts you should know about these water heaters.

16.1 pounds
25 x 15 x 15 inches
7 Years
4.6 Star Rating
16.9 Pounds
17 x 17 x 3.5 Inch
4.1 Star Rating
38 Pounds
6 x 13 x 20 inch
10 Years
4.3 Star Rating
79 Pounds
18 x 9 x 27 inch
7 Years
4.3 Star Rating
10.8 Pounds
11 x 5.5 x 14 inch
10 Years
4.2 Star Rating

Click here to see our top 5 picks of the Best Tankless Water Heater on the market today.

Advantages of tankless water heaters

There are so many benefits of tankless water heaters so we are going to need some time to list all of them. First of all, they are much smaller, so they occupy less space than any other type. As a matter of fact, most of these units can be installed under a sink. For small apartments, this is the main advantage and probably the main reason why so many people use them nowadays. Of course, the actual size depends on the model and the specifications, but in general, all of them, are small.

They also eliminate waste of water. Basically, they heat only the water which is going to be used, so they will reduce your energy bill. Of course, don’t expect some massive savings, but keep in mind that your household will use less water than equivalent one with a conventional water heater.

Energy will be saved as well. As you can understand, there is no need to heat the water which will cool down and then heat it again, due to the fact only water which will be used immediately is heated. This saving will be determined by several factors including the water use, the size of a water heater, the number of people inside a house and etc. Nevertheless, expect massive savings here. If we combine the last two benefits, we can deduce that we don’t have to turn on the water and then wait for the hot water to reach the final destination. In a case with tankless water heaters, hot water is immediately available. Interesting: You can expect savings up to 15% for average household on electricity and water.

However if you’re looking a corded one, you can look at our article about the best electric tankless water heater.

These water heaters are capable of providing unlimited amounts of hot water as long as they are used according to their specifications or better said a gallon per a minute. This is actually one reason to consider when looking for a new tankless water heater, which we will explain in the next sections.

The last but not least, these water heaters last longer than conventional models. They will stay fully operational for 20-30 years, while most, conventional units can withstand 15 years.

By now you should understand that tankless water heaters are probably the best choice you can make. They are easy to install as well, they are durable and they can meet most of your demands. Also, they are considered as eco-friendly alternatives, so if you are trying to protect the environment, the best tankless hot water heater is the only alternative.

An interesting addition can be associated with the way how tankless water heaters work. Obviously, they don’t have a tank, so the water is immediately heated in a small compartment inside a water tank. The heaters themselves are very powerful, so they are capable of heating the water as it passes by near them. This technology means that there are no losses in the heat, water or anything else and it is the most sophisticated at the moment. It is believed that in the near future, tankless water heaters will completely replace other types, something which we will explain next.

Different types of water heaters

Different types of Water HeatersBelieve or not, there are so many different types of water heaters. Of course, you have one in your home right now and you have been using it forever, but which type you have? It is essential to know something about different types in order to realize why tankless water heaters are so preferable.

  • Storage tank water heaters

They are the oldest, the most primitive and the most common water heaters in the world. As the name suggests, they have a tank where the water is kept. Inside there is a heating element or a heater which will heat up the water. Now, there are plenty of varieties here. Early models were made from ordinary metal, so their lifespan was short. New ones are made from advanced metals so they can last up to 15 years. In addition, the heaters inside them are prone to malfunction, so they will have to be replaced on a regular basis. We should add that the installation process is simple, but it involves lifting a massive tank in the air to attach it to the brackets located on the wall. Interesting: Some people believe that turning on the water heater only when they need hot water will save energy, but this isn’t the truth! In that case scenario, a water heater will use more energy, so this is an ineffective way.

  • Natural gas storage tank water heaters

This type is commonly associated with a modified version of the conventional storage water heaters we have explained earlier. They use natural gas in order to heat up water and they are extremely economical. As a matter of fact, they are some of the most efficient water heaters ever developed. On the other side, we have an installation which is complicated and a time-consuming process. You definitely won’t be able to install it all by yourself and you will have to hire professional staff, which is expensive as well. Still, these water heaters are popular and they are used for massive houses with large families.

  • Tankless water heaters

Of course, we must include tankless water heaters on the list. But, we have explained them already so there is no need to repeat the explanation. Just keep in mind that they are small, compact and obviously they don’t use tanks. They heat water as it passes through them. But, there are so many factors which must be taken into consideration when looking for the best tankless hot water heater. Installation is relatively simple and chances are high that every single homeowner can install it all by himself.

  • Heat pump

Here we have a special type of water heaters. They are rare, very efficient and they operate in an interesting way. In essence, the pump will capture the heat from the air or from the ground and use it to heat up water. In general, they are 60% more economical than conventional models. But, the pump will need up to 7-foot of clearance in order to be installed and these water heaters don’t work well when the temperature is low. That’s why they are rarely used in areas where temperatures may get very low at some part of a year. Installation is also complicated and expensive, so these units should be used only if you want something special and you live in an area where temperatures don’t go below zero.

  • Solar water heaters

Do you want something futuristic in your house? If you do, then solar water heaters are a great choice. They have solar panels which are mounted on the roof and they will absorb solar energy and transfer it to the special fluid which is used to heat up the water in a tank. It is the most affordable type of water heaters and based on the latest technology. However, most of these systems require a backup option, such as gas heating or use of electricity. Also, they are expensive and they will require up to 30 years to repay themselves! Yes, this technology is becoming more and more affordable, but at the moment it is still expensive for most people.

  • Condensing

Probably most of you have never heard of this type of a water heater. Let us explain how they work. Basically, they use exhaust gasses from the gas heating of a house to heat up the water. They are designed to be used for tanks which have a capacity 55 gallons or more and they are very affordable to install and they will repay themselves very soon. But, families which don’t need this amount of water don’t need these water heaters either. They are simply not needed for most small families.

As you can see, there are so many different types of water heaters. Each type comes with advantages and disadvantages, so keep in mind that perfection doesn’t exist here. On the other hand, we have tankless water heaters which are appealing due to the fact they have much more benefits than drawbacks.

Factors which must be taken into consideration

Different Designs of Water HeatersNow you are ready to look for the best tankless water heater. Before you decide to buy a model which looks nice, there are a variety of factors which must be taken into account. They can make a massive difference and they are something that each homeowner must pay attention to. We will explain all of them in order to assist you when it comes to choosing the best model for your needs.

  • Energy factor or EF

You will definitely have to take into consideration this factor. EF stands for how effective a tankless water heater is in heating the water. The higher the number, the better. Usually, the values range between 92 and 96, meaning that a particular unit is 92% efficient. This factor is also important due to the fact it literally reduces the energy bill. As such, we can say that it is the top factor to consider if you are looking for a way to make your energy bill lower. We must add that there are some units with very low energy factor values. They are not great and they should be avoided!

  • Warranty

Because tankless water heaters are time-consuming to install and they are not very cheap, you will want to pay attention to the warranty. The longer the warranty it, the better, because you will feel safer in purchasing that model. Now, this factor cannot be generalized, but there are some values we must mention. In the recent months, most manufacturers offer a warranty which is up to 15 years on heat exchanger and 2-5 years on other parts. This is great warranty and it should be targeted if you are looking for the best tankless water heater. It also tells you that all the components are high-quality units and that all elements are made to last.

  • Flow rate

And here is one of the most important factors of them all. For conventional water heaters it refers to the capacity, so 80 gallons tank is recommended. But, tankless water heaters don’t have tanks, so their capacity is measured in water flow. It is presented as gallons per minute. Most households require between 5 and 8 gallons per minute (GLP) in order to stay fully functional. The higher the flow rate is, the better, but the price is higher as well.

  • Temperature rise

Here we have an interesting factor. Temperature rise can be calculated using a simple formula. You will have to subtract the water temperature before it reaches to the heater from the desired temperature. If you want hot water with 120 degrees temperature but it enters your home with 50 degrees, the temperature rise is 70 degrees.

  • Fuel type

All tankless water heaters use some type of fuel to operate. Most common units use electricity and they are the simplest of them all. However, we have units which use natural gas or propane in order to heat up the water. This is a crucial factor to consider before purchasing the unit you want. Changing the fuel type is very expensive and almost impossible in some cases. The most efficient units will use natural gas, but they are also very expensive. The simplest of them all are those which use electricity. They are also the most affordable of them all.

  • Size

Size of a tankless water heater isn’t very important for the flow rate, but it is crucial due to the fact where you want to install that particular unit. Some models are very small, so they can be installed under a sink. Others are much bigger, so they must be installed in a basement or some other place. New models are usually smaller than the older ones and they are made from high-quality materials. Keep in mind that in some cases, the flow rate may be linked to the size of the water heater.

  • Maintenance

All tankless water heaters must be properly maintained. There are a lot of factors which must be taken into consideration here. For example, which fuel type the tankless water heater uses, what is the flow rate and which technology it uses. The main thing to know is that all tankless water heaters can be clogged inside due to minerals found in water. Hard water is a huge enemy of these water heaters, so regular maintenance is mandatory. The more frequently you maintain your unit, the longer it will last.

  • Climate

Maybe this factor doesn’t sound relevant but it is more important than you can imagine. Users who live in areas with a lower temperature so where the climate is cooler will have to consider only units with a high flow rate. They are capable of reaching the desired temperature and meeting the requirements of the owner. On the other hand, if you live in a sunny state, models with a low flow rate are ideal as well.

  • Indoor or outdoor tankless water heater

Another factor to consider is where your tankless water heater will be installed? We have indoor and outdoor models. Obviously, indoor models can be installed inside the house, while outdoor units are designed to be installed outdoors. This is an important factor to consider because it determined the fuel type, the specifications and it is simply something that depends on each house owner independently.

  • Digital control

Digital temperature control allows you to adjust the water temperature precisely as you want or better said as you need it. Most new models have 1-degree accuracy, meaning that the hot water will be as hot as you want it to be. Always pay attention to this factor because it is crucial and it is a game changer. Most new models come with it, so this matter can be generalized.

    • Ventilation

Ventilation is mandatory for some models but not for all of them. It is up to you to decide do you want a tankless water heater which requires ventilation or no. Keep in mind that electric models don’t require it, meaning that the installation is much simpler. On the other side, we have natural gas models which do require ventilation, which makes their installation more complicated and requires more time. Always check this factor in the instructions before purchasing a unit, because if you make a mistake, you will have a huge issue.

5 Best Tankless Water Heaters

Stiebel Eltron Tempra 15 Plus Electric Tankless Whole House Water Heater, 240 V, 14.4 kW

This model is the best tankless water heater available on the market today. It is based on the latest technology and it comes in different versions. The one we have here is 14kW, but they start from 12 and reach 37kW. The more kW, the more powerful the unit is, so this model is suitable for all of you. It is also elegant and comes with all features you are going to need. Let’s start with the digital control system. It is very accurate and it is more than just appealing to the users. It makes the entire water heater even more desirable.

When it comes to reducing the water bill, you can expect up to 20% reduction, which isn’t bad at all. But, the main advantage of this model is the Seismic Proof Construction which made it so reliable and so popular. The unit we tested can replace a standard 50-gallon tank without any issue. As such, we will recommend it for most of you and you are going to be perfectly satisfied with the overall results. Value for money is decent as well, especially if you know that the warranty is 7 years on leakage and 3 years on parts.

In a nutshell, this tankless water heater has it all. It is well-made, it is durable and all owners are satisfied with it. Yes, the price is a bit higher than we expected, but it is definitely a worthy investment.


  • Seismic Proof Construction
  • Digital temperature control
  • Modern design
  • Doesn’t require ventilation
  • 20% reduction in water bill cost


  • Bigger versions are expensive
  • Instructions may be confusing

EcoSmart ECO 27 Electric Tankless Water Heater, 27 KW at 240 Volts, 112.5 Amps with Patented Self Modulating Technology

And here is a tankless water heater which will make sure you save more money on water and electricity than ever before. First and foremost, the unit comes with the ability to save up to 50% on heating cost. The main reason for that is in the self-modulating technology, which uses only the amount of energy which is needed. As such, there is no waste of energy and it truly makes a huge difference in the long run. The digital control system is accurate and very appealing as well.

We liked the fact this is a compact model, allowing you to install it literally anywhere you want. In addition, it is made from high-quality materials, so it is going to last for many years to come. Maybe it is small and compact, but it can heat water within 80°F – 140°F range. It also offers 6 gallons per minute of water flow and comes with the latest systems and the all-new design of the inner parts.

The best part is warranty and value for money. We can even say that it is an affordable model. Warranty is a lifetime on all electronics and the heating element, which is superb. But, the price is still more affordable than most other models available on the market right now.


  • Value for money
  • Warranty
  • Self-modulating technology
  • Compact design
  • 50% savings


  • 6 gallons per minute of water flow may be an issue
  • Obsolete design

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

All of you who are looking for the best natural gas water heater should consider this model. It is the best due to a variety of reasons. First of all, it provides 140.000 BTU, which is one of the highest values today. It also offers 6.6 gallons per minute of hot water. Overall, it is suitable for smaller houses and families who have a constant need for hot water. The design is modern and all components are made to last, which is actually the main advantage of the unit we have here. The warranty is the next best thing. It is 10 years for the heating elements and 5 years on the parts, which made it one of the best warranties out there. In addition, the price is lower than usual.

So what you can expect from this water heater? It is well-made, it comes with everything you need and it is reliable. Most owners claim that the durability is actually impressive and all of them are satisfied with this unit. On our tests, the water heater performed well and we didn’t have any complications. Installation is relatively easy to complete and it is possible to do it all by yourself. An additional fact you should know is that this model requires stainless steel ventilation (level III).

At the end, we only can say that this is a great water heater which has it all. It is easy to install, offers great features and it is reliable. Furthermore, it looks great and it is made by one of the best manufacturers on the planet. You will definitely be perfectly satisfied with it and you are going to use it for a long period of time.


  • Modern design
  • Easy installation
  • Long warranty
  • Affordable


  • Requires installation
  • Lack of advanced features

Rheem RTGH-95DVLN 9.5 GPM Indoor Direct Vent Tankless Natural Gas Water Heater

Do you want the best tankless hot water heater when it comes to energy efficiency? Of course, you do. In that case scenario, you will definitely want to consider the model we have here. It is the latest generation unit which comes with an energy efficiency of 94%. Furthermore, it provides 9.5 gallons per minute and it is based on all-new technology. We were able to see that this particular model is more than just popular right now and it has a high satisfaction rate. In general, it offers all a water heater must provide and something extra. Of course, all of this comes at a price, but the unit in question is suitable for heavy-duty demands, so it is more advanced than the other two models we have on the list. In addition, the electronic controls have been updated, so now they are intelligent which maximizes the energy efficiency.

Keep in mind that this is an indoor water heater, so it must be installed accordingly. One, interesting thing you should know about it is that it comes with the self-diagnosing system, so it is more than just appealing for those who seek perfection. Installation is generally simple and the manufacturer offers a great user manual in the package, which will help you install this powerful water heater.

At the end of a day, this is a powerful, high-end tankless water heater designed for those who need a high water flow and who must have hot water at any given moment. We should add the fact that this unit is one of the best we have tested in the recent past.


  • 5 gallons per minute
  • 94 energy efficiency
  • Modern and sophisticated
  • User manual


  • Expensive
  • Requires plenty of maintenance

Camplux 5L 1.32 GPM Outdoor Portable Propane Tankless Water Heater

This is truly an interesting water heater. It is a portable model for outdoor use. This means that you can use it in different locations any time you want. In general, it is a high-quality model which offers a low water flow and comes with a shower hear. Yes, we did say it is special. The water flow is actually 1.32 gallons per minute, which is sufficient for a single user and there won’t be any complications. Other facts you should know is that this model comes with 20 min automatic safety feature and anti-freezing system, which will make sure it is fully operational even when the outdoor temperatures are very low.

There are additional features as well. It saves water and it is designed to use as low natural gas as possible, all in order to stay fully economical. The main reason why we included it on the list is in the pressure it requires. As a matter of fact, it requires only 2.5PSI in order to operate, while all other models require more pressure, which makes them less effective and impractical for some users.

In essence, the model we have here will do all the things it is designed for. It is a great portable model which is small and compact, so you are going to be able to use it all the time and you are going to be satisfied with it.


  • Portable design
  • Anti-freeze technology
  • Safety features
  • Economical
  • Requires less pressure than any other model on the market


  • Better water flow would be more desirable
  • Showerhead quality


The best tankless water heater is right here on the list. It is up to you to decide which version you want and which one you actually need. In general, all 5 models are high-end versions and they are designed for owners who wants the most. Regardless of the fact which model you choose, you are going to be perfectly satisfied with it and you will use it for a long period of time, but we have to be honest. If we had to pick one out of these 5, it would be the Rheem RTGH-95DVLN.