Best Tankless Water Heater Reviews 2021 and Buying guide

If you are thinking to buy the Best Tankless water heater, you landed at the right page. We made a comprehensive analysis of the various tankless water heaters available from the different manufacturers and shortlisted the best 5 for you. From our comprehensive buying guide to detailed product reviews, this article will help you in making the right decision.

Water heaters are expensive propositions; hence it is important to invest judicially in a quality product which could justify its pricing. Buying an expensive heater does qualify as the right choice. Sometimes, you end up spending on certain features which you never use.

Best tankless water heater reviews 2019

Rinnai RUC98iN Ultra Series Natural Gas Tankless Water Heater

The Rinnai RUC98IN Ultra Series is an indoor, tankless water heater suitable for both residential and commercial use. It is a gas powered heater weighing about 61.7 pounds and has a height of 26 inches. It has a control panel which features a digital display, water and gas control.

It also has a power button for easy on and off option. One unique feature of this unit is that you can lock the temperature button to prevent unauthorized access. It uses an electric ignition system thereby saving energy.

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The unit has a hot water flow rate which ranges from 0.26 to 9.8 GPM and it also has an extremely low activation flow rate. This makes it ideal for large households with simultaneous use of multiple facets.


  • The Rinnai RUC98IN has an energy factor of 0.95 which makes it one of the best Energy Star certified and energy-efficient water heaters.
  • It features automatic scale detection to ensure extended durability
  •  The heater uses approximately 95 % of its energy to heat water leaving only 5 % energy as waste.
  • The geyser has a sleek and compact build which makes it an easy fit for all spaces and also eases the installation process.
  • It can also be installed in close proximity to the point of use to facilitate faster delivery of hot water.
  • Being a tankless water heater, it provides hot water on the go without the need to store large volumes of hot water in reserve.
  • The advanced temperature control feature lets you set the desired water temperature as per your convenience.
  • It boasts a space saving design which makes it a perfect fit for smaller spaces.


  • Some user may find it on the expensive side.
  • It may be difficult to install and requires maintenance from Rinnai certified repair personnel.
  • The temperature of the water may drop for a few seconds when serving more than one outlets.


EcoSmart ECO 27 Electric Tankless Water Heater

 The EcoSmart Eco 27  is a tankless water heater which offers accurate temperature control. It is a highly energy-efficient model which suits single-family homes. It is self-modulating and its digital temperature control panel enables the users to precisely adjust the temperature of the water in 1-degree increments.

With the ability to provide an appropriate temperature range, it is perfect for really cold weathers. Adequate energy is drawn to heat the water as per the temperature.

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 It offers a wonderful self-modulating feature which enables it to adjust the amount of energy it draws based on how much water volume you’re using and the temperature at which it is set. This ensures optimum power usage and minimal wastage.

The unit is very easy to install, however, installation must be carried out by a licensed plumber to avail warranty in future.


  • The unit offers a maximum flow rate of 6.5 gpm which can support up to four showers and a sink simultaneously.
  •  The tankless water heater offers a sleek and compact design which can easily fit into small spaces.
  • Hot water is available instantly without the need to store gallons of water in a reservoir.
  •  The unit is low maintenance and easy to operate.
  •  The heater provides a remote control for separate heaters in the same home. This increases ease of use and convenience.
  •  It can easily handle large devices simultaneously.
  • The unit comes with a lifetime warranty period.
  •  Installation is easy as compared to traditional heaters.
  • The unit has received positive feedback from the majority of the users.
  • Extended durability comes with its stainless elements
  • The stylish design makes it an appealing piece to fall for


  • There have been a few complaints about hot water dribble.
  • The unit’s design sometimes causes water flow to restrict but that is limited to a few seconds.
  • Installation and maintenance may be tricky for some users.
  • The warranty policy is strict and adherent to rules.


Takagi T-KJr2-IN-LP Indoor Tankless Water Heater, Propane

Takagi T-KJr2-IN-LP Indoor Tankless Water Heater is a strong tankless water heater that is popular for being completely noiseless, getting the job done peacefully. It provides ultimate customer satisfaction as it suits multiple daily user needs. It tends to fulfil every user expectations without burning a hole in the pocket.

The unit has a power cord and remote control for ease of use. It enables you to control this product even without being close. The proximity of the remote control is limited to 6 meters. Therefore, it is possible to control your heater while washing your dishes or even having a shower.

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The safety system is well established in the unit.  The venting system is rooted in category III steel and the copper alloy allows high heating efficiency. Additional safety features like overheat surge protection are also embedded in the unit.


  • The unit has a compact design which makes it easy to carry around the house and appropriate for residential areas.
  • With this unit, there is no need to worry about altitude limitations as it has a resistance of approximated 6000 ft. above sea level. The deep switch setting enables it to function at the different altitude levels.
  • The unit offers easily adjustable temperature and flow settings with dual thermostat
  • The company offers a warranty of 15 years.
  • Revolutionary sensors to minimize emissions and monitor the efficiency
  • Internal components do not freeze under extreme cold weather
  • Built-in surge protector to turn of automatically when overheated
  • Excellent water heating range from 99 degrees F to 167 degrees F
  • Long lasting design at affordable pricing
  • A compact and lightweight unit with reliable performance
  • Overall, the unit has received a very good response from its users.


  • The installation needs to be done by a certified professional company in order to avail the warranty.
  • This product may not be suitable for very large houses.
  • The product may face flow issues with excessive usage.
  • The product works only with propane.


Stiebel Eltron Tempra Plus 

Stiebel EltronTempra 36 plus is a high capacity, electric Tankless Water Heater. It is suitable for medium to big size homes and for both warm and  cold environments. The product saves money, space and energy with its efficient operations.

It is one of the highest rated electrical tankless water heaters which can provide a consistent stream of hot water even in larger households.  The device has a weight of 20.5 pounds and measures 4.6 x 16.6 x 14.5 inches. 

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Its modulating function keeps the temperature steady at all times. The heating elements facilitate the heating of  water gradually from the minimum to maximum. Its compact and sleek design is appealing to the eyes and also easy on space. Its lightness enables it to easily fit in any location with ease.


  • It offers precise temperature control enabling it to work with both cold incoming water and preheated water.
  • The product can give hot water at a rate of 5.5 gallons per minute which makes it suitable for a home with two bathrooms.
  • The copper sheathed heating element enhances the heating capacity of the product.
  • The product comes with a detailed manual to guide the users on installation and maintenance.
  • The lack of mechanical switches makes the device noiseless.
  • The product comes with a 7 years warranty for any leakage and 3 years on the unit’s parts. 
  • The heavy duty material and components provide durability to the product.
  • The product is capable of providing hot water in an instant.
  • Advanced flow technology to adjust the flow of water with demand
  • Intuitive temperature display with an easy-to-read digital format
  • This unit has bagged the five-star performance for its energy efficiency


  • The device requires enormous power to keep going.
  • The highest capacity of the product may not be achievable at very cold temperatures.
  • Some users complain that the product is not able to maintain hot water for long durations.
  • It is relatively expensive when compared to its counterparts


Rheem RTGH-95DVLN 9.5 GPM Indoor Direct Vent Tankless

This tankless natural gas heater projects the features to comply with the interest of common user. It is one of the cost-efficient, flexible and energy saving heater which can also be used for commercial purpose. Regulatory bodies have ranked this prouct higher in terms of safety.

Built-in-blower with LED display allows measuring the temperature settings. It is a remote controlled device. It comes with an intelligent electronic system which makes it 110% safer for the children. It is considered as 94% energy efficient and comes with stainless-steel condensing exchanger.

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Rheem is an established brand which is known for its dedication in achieving the consumer satisfaction. Most of the water heaters from this brand have an expected life span of 8 to 12 years.


  • An energy efficient heater which saves on your utility bills
  • It possess intelligent control system
  • Built-in blower with digital LED display
  • Reliability of the device does not get affected with the pace of installation you choose
  • AHRI certification to ensure high-quality
  • Free protection of up to -30F
  • Easy installation
  • Very safe to use and ideal for the families with kids
  • Low Nox Version makes it environment-friendly


  • No eligible for international shipping
  • Valves are not included


Rinnai V65EP 6.6 GPM Outdoor Low NOx Tankless Propane Water Heater

With a flow rate of 6.6 gpm, this tankless water heater supports up to 2 bathrooms easily along with the kitchen facuets. It has a high thermal efficiency of 0.82. It facilitates easy installation. As it is provided with 1 or 2-inch gas line, you are not required to buy any extra line.

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While sitting inside your house you can easily adjust the temperature with its remote thermostat. Very compact in size, it can fit any congestion location easily.  It is an environment-friendly unit which complies with South Coast Air Quality Management.

It is an energy efficient unit which saves on your utility bills. If you are located in hard water area, it is recommended to go for vinegar flush periodically as maintenance regime. Overall, it offers a quality construction, reliability, and ease of use.


  • It is perfect for the medium family size
  • It comes with temperature lock and remote control
  • It is certified with safety installation
  • It comes with enhanced scale detection
  • Very low working noise
  • Low NOX design


  • Once you turn the tap off, water gets cold again


Rheem RTG-64DVLN Tankless Natural Gas Water Heater

Rheem RTG-64DVLN is a tankless mid efficiency water heater designed to supply continuous hot water.  It comes with very easy installation and also offers support from the Rheem Tankless support team in case you need assistance.

The product comes with a remote control that allows you to remotely manage the water temperature. The range of the remote is up to 10 feet. You can connect the heater to your thermostat with the help of a spool of 10 foot of wire which comes with the unit.

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This unit works best for small homes where one or two showers are required. Like many other tankless water heaters, you do not require any adapter for ventilation.


  • It frees up a lot of space as it takes up very less storage space due to its compact design.
  • It has a maximum flow rate of 6.8 gallons when used with warmer ground-water and 5.3 gallons per minute when used with water at a lower temperature.
  • The higher rating of the product enables you to use hot water in two or more rooms at the same time. 
  •  The minimum activation rate of the product is 0.4 gallons per minute which are lower than many of its competitors.
  • Rheem RTG -64DVLN heater can work at higher altitudes and homes more than 9000 feet above the sea level.
  • The product has an easy installation without the need to hook up any vents or extra pipes.
  • The user gets the super hot water in a few seconds
  • Concentric venting with an integrated condensate collector to ensure hassle-free ventilation
  • Thermostat wire is included
  • Ez-link cable is provided along with the unit


  • When water flow increases, the performance of the unit dips.
  • Maintenance may require assistance from certified personnel.
  • It can only be used with propane and not natural gas.
  • The water pressure may vary depending upon the source of water.


What are the various types of water heaters?

There are mainly five types of water heaters:

  • Conventional storage tanked water heaters

A water heater with a tank which determines how much hot water you can avail at once. The insulated water tank ensures to keep the water warm until required. These conventional heaters restrict the amount of water. In case you need excessive water, you need to wait for some time until the refilled tank heats up.

  • Tankless Water heaters

These water heaters have a super-heated coil which can heat the water quickly. These heaters cater to the uninterrupted supply of water to cater to your excessive hot water needs. The models which use natural gas to heat up the water works well for homes. You should choose the size of the tankless heater depending upon your water requirements.  These water heaters are energy efficient as well.

  • Heat Pump water heater

These water heaters consume 60% less electricity compared to the conventional ones as it used the heat in the ground to heat water or in the air. But these water heaters require space for its installation and not meant for the congested places. Although, these water heaters are highly efficient but do not work well under the adverse cold climatic conditions.

  • Solar Powered Water heater

By drawing the energy from the sun, these are the most energy efficient water heaters. From roof-mounted solar panels, solar energy is transferred to the heat-conductive material places in a closed-loop system. But these heaters are ideal for the places with abundant sunshine. These are environment-friendly and super energy efficient water heaters but incredibly expensive as well.

  • Condensing power water heater

By using the unused gas fumes of your house, these water heaters are best to use for the houses using the natural gas primarily as its source. It is a tank style water heater but only available in the large models. If your requirements are less than 55 gallons, this is not judicial to invest in these water heaters.

What are the benefits of tankless water heaters over its counterparts?

To cut down the energy bills, tankless water heaters are an ideal choice. If you choose the best tankless water heater, it will help you to cut down your utility bill by 30-40%. No just energy efficient, these heaters bring you a plethora of benefits to allure you as a user as follows:

  1. These are on-demand heaters which ensure a consistent supply of hot water. Just press a button and enjoy the hot water.
  2. The compact design of the tankless water heater makes them an ideal choice for any set-up or smallest spaces.
  3. There is no standby heat loss involved and they require energy just to heat-up your water at a mentioned temperature
  4. As tankless heaters have close to zero emissions with NOx technology, they are environment-friendly
  5. As there are no chances of rupturing of tanks, there will be no hassles of flooding, making them safe for household use.
  6. These heaters last up to 5 to 10 years  when compared with the tanked water heaters. Hence, you can justify the high-price of tankless water heaters with their extended durability.
  7. Few tankless models bear the internal fault warning system integrated with them to advise the user at the event of some fault
  8. Tankless water heaters are very easy to operate. There are remote-operated models available which facilitate hands-free operations

Buying Tip: Before shortlisting a tankless water heater, it is important to consider its flow rate. A heater with a lower flow rate than required will not be able to suffice your hot water needs.

Factors to be considered for choosing the best tankless water heater:

Each water heater boasting a unique feature makes it difficult for you to determine which one shall e ideal for you.  Underlining your requirements and choosing a one which can suffice most of your requirements is a must. But, there are certain selective features which must be available in any water heater to make it an ideal choice:


To ensure proper functioning, a tankless water heater needs venting. Venting is only required for indoor tankless water heaters. A unit supporting the category III venting offers better combustion.

Energy efficient

Buying a water heater comes with a worry about electricity bills. Hence, it makes sense to choose a 5 star rated water heater which ensures lesser energy bills. With a temperature rise of 70 degrees, a gas-powered water heater gives a flow rate of 5 gallons while an electronic model can provide only 2 gallons as flow rate.

Gas heaters are not just cheaper but they also require a low annual operating cost.


Broadly three types of ignition systems are available with the tankless water heaters. The complex the ignition, more energy-efficient it would be. Most of the expensive models come with complex ignition system to cut down your utility bills.

Size of the heater

Especially, when you have limited space, it is very important to consider the size of the heater which can suitably fit. A water heater delivering a flow-rate between 2 to 5 gallons every minute is an ideal choice.  If you are choosing a gas variant, the flow rate of water should be 8 gallons as a high flow rate is provided by gas heaters over the electric ones.

Robust design

Especially, if you are choosing an outdoor tankless water heater, it is important that is should have a robust design to withstand the adverse climatic conditions. There are models which come with anti-freeze kit which saves the internal part of your unit from freezing under extreme cold weather conditions.

Fuel type

A perfect balance between the energy efficiency and consistent flow rate makes an ideal tankless water heater. From the three types – Propane, electricity and gas, you can choose the one depending upon the fuel available in your region as well as its cost.

Frequently Asked Questions

Can I install my tankless water heater on my own?

As per the local plumbing code, there are many manufacturers who does not provide the warranty if you install your tankless water heater on your own. Any plumbing defect also leads to serious consequences of damage. Hence, we recommend seeking plumbing help from a qualified plumber.

Most of the tanked gas heaters come with the venting requirements. 240-volt wiring is also required to install as a configuration for safety and best performance.

Can I replace my existing tanked water heater with a tankless one?

Yes, it is possible if you comply with certain conditions as follows:

  • A special vent pipe for gas heaters
  • You should have access to the stable gas supply
  • Bigger gauge wire required for electric water heater installation

After meeting the aforesaid requirements, you can easily replace your tanked water heater with a tankless one.

How much does a tankless water heater save?

If you are using a restricted quantity of hot water and the cost of propane or natural gas is reasonable, you are expected to save 30% over the tanked water heaters. As there is no stand-by heating time involved with tankless water heaters, it largely impacts in lowering your energy bills.

Why first-hour rating is missing in tankless heaters?

First-hour rating is only available in the tanked heaters because the full tank can determine the amount of hot water it can generate in an hour. For tankless heaters, gallon per hour rating is applicable which shows the number of gallons per hour generated by the heater on raising the temperature of incoming water. So, the flow rate is determined for the tankless heaters.

What is the ideal temperature to heat the incoming underground water?

You need to consider the two things to answer this question rightly. Firstly, the temperature you’re required as output. Secondly, the temperature of underground water goes as input. Now deduct the former temperature with the latter one to derive the ideal temperature set up.

A temperature between 90-110 degree F is considered ideal for a shower while for washing hands, people prefer the temperature of water equivalent to the body temperature.

What is the life expectancy of a tankless water heater?

Most of the models come with a life expectancy between 15 to 25 years depending on the installation and water quality. These models appropriately return their high value if maintained regularly. Maintenance plays a key role in extending the life of your water heater.

It is important to remove the scales deposits regularly. There are few models available in the market which comes with descaling warning to notify the user.  If you install your outdoor tankless unit at a place safe for adverse climatic conditions, it will also contribute to the durability of the water heater.

There are models with a self-regulating internal mechanism which intimate the users about any malfunctioning.

Are tankless water heaters restricted to install in certain regions?

Yes, installation of specific tankless water heater models is restricted in certain cities and states. Hence it is important to check with the local authorities before finalizing a tankless water heater. There are certain models as de-ionized and 3-phase which do not cover under the return policy. It is recommended to take the necessary precautions in choosing a tankless water heater when you belong to a restricted territory.


Tankless water heaters are a revolutionary proposition with their compliance with sustainable energy. From heating up water fast to cutting down your energy bills, these heaters are matchless in every aspect. When it comes to a price point, the long term durability and energy efficiency of these heaters absolutely justify the intensive investment and gradually maximizes your return on investment (ROI).

As each feature comes at a certain price, choose a model which offers the feature which you are going to use. Fix up your budget and preferences and narrow down the list accordingly. The advantages of a tankless water heater cannot be undermined over its counterparts. Always look for a brand which offer the customer service in your vicinity to avoid after-sales servicing hassles.