8 Best Tankless Water Heater Reviews-Buyer Guide 2021

By Jack Mash

best tankless water heaterThe devices used to quickly and frequently heat water in the home are some of the best invented in the past hundred years.

Whether or not you agree, it’s nice to acknowledge that, when it comes to warming water, you have different methods available to you – neither of which involve heating it over a fire.

The only problem is that heating water with a traditional, tanked water heater can get expensive.

Consider, then, a tankless water heater. These water heaters are also known as demand-type water heaters or instantaneous water heaters.

Instead of running at all hours of the day, liked tanked water heaters, these heaters only operate when you need them to. Sure, this means you may have to wait a few minutes for your shower water to warm up.

In the long run, though, tankless water heaters have proven to knock a fair chunk of change off of most people’s heating bills.

That doesn’t mean that tankless water heaters are perfect, of course, or that you should throw out your tanked water heater right away. Instead, take a look at some of the tankless water heater options.

You may be surprised to find that there’s a tankless water heater out there that’s perfect for you.

8 Best Tankless Water Heater Reviews

Ecosmart ECO 27 Review

EcoSmart ECO 27 Electric Tankless Water Heater

The Ecosmart ECO 27 is a fully featured tankless water heater distributing up to 6 gallons per minute.

The self modulating technology means the appliance can automatically adjust the power based on the actual amount of electricity needed to heat the water.

There is also a digital temperature control attached to the unit, allowing you to easily adjust the temperature with a simple 1-degree increment.

The best thing is that this water heater is covered by lifetime warranty on element, exchanger, and electronics.

Key features:

  • Copper and stainless steel parts
  • Patented self modulating technology
  • Digital temperature control
  • Compact size
  • 5 amps
  • 27 KW at 240 volts
  • Limited lifetime warranty


  • It is very easy to install
  • It is compact in size and will easily fit in various locations I your home
  • It is durably made with long lasting materials such as copper and stainless
  • Very easy to use with the digital temperature control
  • It is very eco-friendly as it saves a lot of energy
EcoSmart ECO 27 Electric Tankless Water Heater

Takagi T-H3S-DV-N Indoor Tankless Water Heater

The Takagi Indoor Tankless Water Heater is perfect if you want to save energy and money in your home.

If you want an smallest and effective water heater that will not take up much room then this particular model fits the bill.

It may be small, but it is extremely powerful.

The unit itself has gas inputs of around 140,000 BTU every hour.

The product is capable of meeting the requirements of small homes that need hot water regularly throughout the day.

It is best for homes with about 2 bathrooms to heat.

The water heater can be installed in both residential and commercial properties alike.

The heater is extremely compact meaning it can be installed and mounted pretty much anywhere you like around the home.


  • Easy to use with pre-set temperature.
  • 8-Gallon Per Minute
  • Controller to display water in temp, water out temp and flow rate.
  • Constant temperature monitoring by Inlet, outlet thermistors.


  • It is for small family 5 or less, it will be fine.
Natural Gas Indoor Tankless Water Heater

Stiebel Eltron Tempra 24 Plus Electric Tankless water heater

Stiebel Eltron 224199 240V, 1 Phase

For those interested in highly advanced tankless water heater models, the Stiebel Eltron Tempra 24 is the device to opt for.

As sleek as it appears, this device will help its user save on the electricity bill previously experienced with the traditional design and at the same time increase efficiency and convenience.

In addition, it comes with a digital temperature control that enables the user to change the temperature of the water with regard to the needs.

If you’ve been looking for a constant flow of hot water at a great rate, acquire this device and you will have a new experience in your home.

Key features:

  • Sleek design
  • Digital temperature control
  • 240 volts
  • Advanced flow control


  • It is very easy to set up
  • It comes at a very favorable cost
  • It is beautiful made with as leek design
  • It is durably made with heavy duty parts
 Stiebel Eltron Tempra 24 Plus Electric Tankless water heater

Eccotemp L5 Portable

Eccotemp L5 Portable Outdoor Tankless Water Heater

The Eccotemp L5 Portable is powered by propane gas, and the package includes the adapters for propane tank and standard hose nozzle.

This water heater is a compact unit weighing at only 13-pound. Its flame is ignited by two D-cell batteries.

In fact, the biggest selling point of this water heater is portability.

To work properly, it requires a minimum flow rate of 0.3 liters per minute and it can give a maximum flow of more than 1 gallon per minute.

The product comes with only 1-year limited warranty on parts.

Key features:

  • Liquid propane fuel
  • Minimum flow rate of 0.3 liters per minute
  • 4 gallon per minute
  • Portable tankless water heater
  • 2 D cell battery ignition
  • One year limited warranty


  • It is very easy to install and operate
  • It is lightweight and really suitable to travel with while camping or hiking
  • It is powered by battery and just needs replacement if they run out
Eccotemp L5 Portable Outdoor Tankless Water Heater

Rinnai RUC98iN Ultra Series Natural Gas Tankless water heater

Ultra Series Indoor Natural Gas Tankless Water Heater

This is one of the simple looking but versatile tankless water heater that performs outstandingly in offering hot water for your entire household.

This excellently designed unit is powered by propane or natural gas which is stronger than electricity and ideal for use in cold regions such as in the northern American.

It as well comes with a simple control unit for adjusting the temperature as required.

Other great features include; maximum of 96 energy factor and ultra low NOx emissions. Purchase this gadget today and lower your utility bills by almost or more than half.

Key features:

  • Ultra low NOx emissions
  • Concentric or PVC venting choice
  • Powered by natural gas or propane
  • Control unit
  • Maximum of 96 energy factor
  • 12 year warranty


  • It is durably constructed to last long
  • It is highly reliable for use in very cold environments as it utilizes natural gas as its source of power.
  • It is compact in design for easy and quick installation


  • You will have to pay a little bit more for gas per month.
Ultra Series Indoor Natural Gas Tankless Water Heater

Ecosmart ECO 18 Electric Tankless Water Heater

Ecosmart ECO 18 Electric Tankless Water Heater

The Ecosmart Eco 18 is an electric tankless water heater that is designed to provide instant hot water for your house, without the hassle of storing a large tank water heater in your cupboard.

Ecosmart have become one of the leading tankless water heater manufacturers on the market, consistently producing durable, reliable water heaters that last for years.

One of their latest offerings is the Ecosmart Eco 18 which has been released to rave reviews, this review will show whether this electric water heater is deserving of all the praise.


  • Capable of heating 2.5 Gallons of water per minute which is enough for a small to medium sized home.
  • This water heater was easy to install and I only needed a bit of help from a plumber but the device was set up in a matter of hours.
  • This electric tankless water heater to be very reliable, providing hot water only when you requested it.
  • Save up to 60% on your water heating cost which is a considerable amount especially throughout the winter months where demand for hot water may be significantly higher.


After reviewing the Ecosmart Eco 18 for just over a week I didn’t come across any issues or problems. I only thing i would say is that as good looking the casing may be, it does feel a flimsy which to some may not give the impression of quality, however this would be nitpicking.

Also to some this may be a bit difficult to install by themselves so be prepared to request the help from a plumber but this is the case with most tankless water heaters.

Ecosmart ECO 18 Electric Tankless Water Heater

Eccotemp L10 Portable Outdoor Tankless Water Heater

GPM Portable Outdoor Tankless Water Heater

The Eccotemp L10 Portable Outdoor Tankless Water Heater would be ideal for people who need a high capacity tankless outdoor water heater to use with cabins, lodges, barns, garages, potting sheds, campers, RV’s, hunting camps, horse washing stalls, summer homes, or wherever a supply of hot water is required on a more permanent basis.

This outdoor water heater delivers plenty of hot water, from 80 degrees Fahrenheit up to 165 degrees Fahrenheit, which is adjustable upon installation.

In fact, the unit is rated to provide a supply of hot water of as much as 2.65 gallons per minute, which is enough for one or two hot water applications running simultaneously, such as a kitchen sink and a shower.


  • The unit includes a stainless steel rain hood to help with the venting of the flue gases and also to protect it from the outdoor elements.
  • It features an auto-cut-off protection that will instantly shut off the gas supply in case of a flameout, in order to minimize the danger of a gas leakage.
  • The unit incorporates an automatic safety shut-off timer which will operate after 20 minutes of continual usage.
  • The heater will automatically shut off the gas supply in case water ceases to flow through it.


  • May cause problem on adjusting the water temperature, when there is low water pressure.
Portable Outdoor Tankless Water Heater

Rinnai RL75iN

Rinnai RL75IN Tankless Water Heater

The highlights of this product include Energy Star certification and the fact that it delivers 7.5 gallons per minute.

Rinnai also gives a digital controller that gives error notification in case something goes wrong.

The error codes and possible remedies are listed in the manual instruction that comes with the product.

The RL75iN is covered by 12-year warranty on heat exchanger, 1-year warranty on installation (residential), and 5-year on parts.

Benefits of tankless water heater

  1. They occupy very little space when compared to traditional water heaters. This is because they don’t come with tanks and are compactly designed to take up very little space.
  2. This type of water heater is highly efficient and will enable you save a lot on your energy bills. The tankless water heater is shut off when not in use unlike the traditional water heater where it uses power all the time to keep the water warm and ready for use.
  3. Though the initial cost of acquiring a tankless water heater is on the high, it last longer than the traditional water heater with a lifespan of around 20 years while that of its counterpart is 13 years.
  4. If you use a tankless water heater, you will never run out of hot water as long as you don’t go beyond the recommended capacity.
Rinnai RL75IN Tankless Water Heater

Factors to consider when selecting the best tankless water heater


Days are gone where you required enough space to install a traditional water heater with a big tank. The best tankless water heaters are very compact with some measuring to a size of a briefcase.

These are very simple to install and can fit easily in various areas in your home. As well, look for a size that will heat your water well.

Energy source 

There are three main energy sources used to power a tankless water heater. These include; gas, propane, and electricity.

Depending on the area that you live in, you may need a tankless water heater this is powered by one of the three sources.

If you live in extreme cold temperatures like in the northern part of U.S and Canada, you will need a gas powered tankless heater as it’s more powerful. For those who live in the south or at least not very cold regions can use an electric powered tankless water heater.

Always get the right tankless water heater that is compatible with the power source in your house be t gas, propane or electricity.


Consider choosing a very efficient water heater so that you can save on the cost of electricity or gas bills. The tankless water heater is very energy efficient and will save on your costs a great deal. This is because it can be powered off when not in use.


These tankless water heaters are very reliable as they have low maintenance costs in case a problem emanates.

In addition, they are very easy to repair and will only costs a few bucks in such scenarios. As well, they assure you of warm or hot water throughout unlike the traditional water heater.

Environmentally friendly

Since these devices are on stand-by mode all the time, they utilize very little energy which is a great thing for the environment. The electric models are regarded as 100% eco-friendly. Pick a model that is very eco-friendly.

Gallon per minute 

As you look for the best tankless water heater for your home, consider checking out the gallon per minute that it is able to offer.

Gallon per minute is the amount of water your unit can heat. Most of the devices come with a gallon per minute that ranges between 0.3 gpm to 0.9 gpm.

If you live in very cold areas, you need a device with a higher gpm such as 0.6 and above.

Another thing to note is that when your water pressure surpasses the gallon per minute indicated, the temperature of the water will start to fall.

Flow activation

Each and every tankless water heater functions by electronically measuring the flow of the water. This means that if the water flows quickly, the temperature of the water will reduce drastically and if it flows slowly, the temperature will rise. Thus, you should always use the recommended flow rate of water to ensure you get a certain level of hot water.

Clean and safe 

One of the greatest advantages of using tankless water heaters is that they are very safe and clean as they don’t build up rust like traditional tanks do.

Thus, they ensure that you receive clean and fresh water to use in the house for different activities.


Consider the capacity of a tankless water heater before buying one. You should ensure it meets all your warm water needs at home such as washing dishes, showering or even washing.


If you want a tankless water heater to travel with is as well available. These are powered by batteries which are mostly rechargeable.

Look for a lightweight and compact design so that you can carry it with much ease as you go camping or hiking.

Temperature range 

Most of the devices come with temperature ranges indicated on it for various uses. Make sure the temperatures indicated meet all your different water uses.


Does the device you are opting to purchase have a warranty?

Not all products are high quality and even so, you need a warranty to be fully secure in case the tankless water heater comes with a defect or requires the attention of a specialist. Ensure you buy from notable brands which normally offer quality products with warranties.


Price shouldn’t be a big determine of the device you choose. Electric tankless water heaters are the cheapest while those powered by gas are the most expensive.

Depending on your location, select a tankless water heater that will perform well without letting you down in the hour of need.

Choose a gas or propane operated tankless water heater if you stay in cold areas.

For more in depth review of tankless water heaters here.

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