Best Tankless Water Heater

The best tankless water heater is the preferred choice of today’s household, whether it’s for small-scale usage or for multipurpose needs to be fulfilled. As compared to the old-styled tank water heater, the tankless version is more efficient. Here we have researched and made a list of the best tankless water heater

Electric Tankless Water heater

Image Product Details   Price
eco smart eco 27 Eco Smart Eco 27 Capacity: 6.5 GPM
Color: white
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Stiebel-Eltron-Tankless-water-Tempra-36-plus-1 Stiebel Eltron Tankless water-Tempra 36 plus Capacity: 7.5 GPM
Color: White
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EEmax-EEm24027-Electric-Tankless-Water-Heater-1 EEmax EEm24027 Electric Tankless Water Heater Capacity: 7.4 GPM
Color: Blue
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Rheem Rtex-18 Electric tankless water heater Rheem Rtex-18 Electric tankless water heater
Capacity: 4.4 GPM
Color: Grey
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Stiebel-Eltronb-Tankless-Water-Heater-Tempra-24-Plus-1 Stiebel Eltron Tankless Water Heater-Tempra 24 Plus
Capacity: 4.5 GPM
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Bosch Electri Mini-Tank Water Heater Tronic 3000T 4Gallons(ES4) Bosch Electri Mini-Tank Water Heater Tronic 3000T 4Gallons(ES4) Capacity: 4 Liters
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Moreover, tankless heaters last longer in terms of life cycle as compared to the old tank counterpart. For instance, the traditional tank heater lasts for 10 to 12 years, whereas the tankless heater has a life cycle of more than 20 years. That’s indeed a win-win product to go for even if the cost of the latest tankless heaters is a bit higher.

Tankless water heaters are money savers in terms of energy and, therefore, money savings. As per research, tankless heaters save more than 25% to 35% energy consumption than traditional tank heaters. Therefore the best tankless water heater will be valuable for us.

So here we have brought for you the best available products in the market that are based on technical evaluation and ratings from satisfied consumers. These products will definitely fulfill the needs which people want to avail at best available prices.

Therefore we have arranged out two categories of best tankless heaters i.e. gas tankless heaters and electric tankless heaters. 

Here we go!

(1) EcoSmart ECO 27 Electric Tankless Water Heater

EcoSmart is part of the Reheem family of brands. It is well known for manufacturing and supplying innovative and life-enhancing tankless electric heaters for homes and businesses.

Technical Specs:

ECO 27 is a 27 Kilowatt electric water heater having a delivery capacity of 2.7 to 6.5 gallons per minute (depending on the inlet water temperature). It has to be fixed with 240V source, 3 phase, 40A double pole breakers.

The ECO 27 saves you a lot with 50% of water heating costs.  The digital temperature control allows efficient temperature control with a range between 80-140 F. It’s also equipped with durable and efficient components made with copper and stainless steel with easy replacement.

The self-modulating technology allows it better control of temperature based on the inlet water temperature and efficient flow rate sensor, thus ensuring endless hot water supply for its user.

Other Features:

This product has the dimensions of 17Hx17x3.625D with a lightweight of 13.75lbs. It comes with a fittings size of 3/4” NPT. With its sleek design, it saves up to 12 cubic feet of storage space.

This product has gained 74% 5 stars and 11% 4 star satisfied customer reviews, thus ensuring its customer trust. The recommended electrical panel should be of 200Amp capacity. With the lifetime warranty on electronics, exchanger, and element, it’s the best buy for a good cost being offered.


  • Self-modulating technology
  • Durable components with easy replacement
  • Digital temperature control


  • Only available in white color

2. Stiebel Eltron Tankless Heater – Tempra 36 Plus

Stiebel Electron Tempra 36 plus is the top-rated made in Germany product designed for whole-house electric tankless water heater solutions.

Specifications :

The tempra 36 plus model offers a maximum of 7.5 GPM flow rate which can be counted for the whole family setup to get heated water on demand. It is a single-phase device with 60hz, 208 V supply required, and required ¾” NPT connection.

Digital Displays:

This model provides you with user-friendly digital display functions which empower the user to keep an eye on the temperature situation for the heated water being delivered. Moreover, the Plus models are also equipped with temperature memory settings.

Advanced Flow Control:

The industry-exclusive feature maintains the automatic temperature control thus maintaining hot water supply despite various fluctuations in water output. So the user has to remain carefree for running out of hot water. 


The manufacturer provides 7 years of leakage and 3 years of parts complete warranty.

Other Features:

The Tempra 36 plus is a sleek designed product with offered dimensions as 4.63×16.63×14.5 inches. As compared to gas heaters, it doesn’t require the vent for flu gas release.

Tempra 36 has the following certifications: ANSI/UL Std. 499, CSA Std C22.2 No. 88, ISO 9001 WQA tested and certified against NSF/ANSI 372 which ensures its protection and operational capability.

Moreover, the satisfied customers are giving 79% 5 stars and 11% 4-star reviews thus expressing their satisfaction in this product.


  • Great for big household
  • Advance flow control
  • Offers high efficiency


  • A bit expensive in good features

(3) Eemax EEM24027 Electric Tankless Water Heater

The Eemax electric tankless electric heater ensures the hot water supply with its instant supply system. It’s a 240V, 27KW unit.  Its delivery capacity is up to 7.4 GPM for hot water.

It’s the best choice to provide heated water of up to 1 shower and 2 sinks in colder climates. While in warmer climates, its capacity is up to 4 showers.



The advanced self-modulation mechanism makes it possible to provide instant heated water.

Other Features:

The Eemax EEM24027 has dimensions of 17x17x3.75 inches and it weighs about 13.75 pounds.

It banks 75% 5 stars and 10% 4 stars satisfaction reviews from its users.

Eemax provides 5 years leak warranty and a 1-year warranty for its parts.


  • Equipped with self-modulation technology
  • Highly efficient
  • Less space is required.


  • Not found as such.

(4) Rheem RTEX-18 Electric Tankless Water Heater

RTEX-18 model from Rheem is recommended for medium family needs which offers efficiency and continuous supply of heater water for its users.


The Rheem RTEX-18 is cable to deliver a flow rate of 4.4 GPM which makes it a quite good option for medium-level housing and offices.  It requires 18KW maximum power with a 240 V supply.

Quality make :

This model is made up of robust copper immersion elements with a brass top that increases its longevity. The element is also threaded to make easy replacement.

Advanced Self Modulation:

The self-modulation feature makes it possible to meet the hot water requirement based on programmed logic to deliver better.

External Digital Control:

It is installed with an external digital thermostatic control with LED Display (+/- 1-degree accuracy). It makes it easy for the user to watch and adjust the hot water according to their needs.

Other Features :

The RTEX-18 has dimensions of 18.25×3.5×14.5 inches and it weighs about 14.8 pounds.

It is easy to fit with its ¾ inch NPT water connections.

Based on user reviews, the satisfied customers have given this product 74% 5 stars and 11% 4 stars. At a good price, this product is definitely a first buy option.


  • Advanced self-modulation
  • Calm working
  • Durable with easy instalment


  • Difficult for medium houses in colder regions.

(5) Stiebel Eltron Tankless Water Heater – Tempra 24 Plus

The Tempra series with 24 plus model is a 24kW, 240V water heater which required a current supply of 150A. Its heated water flow rate is up to 4.5 GPM and its offered temperature range is from 68 to 140 F.


Digital Display and Pre-Set Temperature buttons:

The Germany-made model is a symbol of reliability and good service to its customers. It is added with a digital display because of which the user remains updated for the temperature information.

Moreover, the pre-set temperature buttons are there along with the temperature memory settings.

Advanced Flow Control:

The Tempra 24 has the patented technology of advanced Flow Control. It helps to maintain a constant supply of heater water. Therefore hot showers are never going to be interrupted.

Other Features:

The model has dimensions of 4.63 x 16.63 x 14.5 inches. It comes with water connection fittings of ¾” NPT.

This model is provided with 7 year leakage and 3 years parts warranties.

Based on customer reviews, 79% satisfied customers have shown their content in the product performance with 5 star ratings  and 11% with 4 star ratings. 


  • Energy Saver
  • Advanced Flow Control.
  • Silent Operation


  • Pricy for good household solution

(6) Bosch Electric Mini-Tank Water Heater Tronic 3000 T 4-Gallon (ES4)

The Bosche brand is considered a sleek designed product that is useful for small to medium usage.


The ES4 version has a delivery capacity of 4 liters that ensures the hot water supply at near points, below the sink, kitchen, and offices. The Temperature range varies from 65-145 F. It has 1440 watts that it carries on 120 V.

Better Insulation :

The glass-lined tank provides better insulation and durability, providing better efficiency, and that is in a small amount of time. Its also equipped with a Temperature/Pressure relief valve as an added feature.

Other Features:

The ES4 model dimensions are 13.75×13.5×13.75 inches and it weighs 17.3 pounds.

For water fittings, it is provided with 1/2” Male NPT which can be used for fittings.

With its sleek design, it can be floor, shelf, or wall-mounted easily. It has a limited 6-year parts warranty also.


  • Sleek Design.
  • Best for small hot water needs
  • Temperature control knob


  • Not suitable for larger household

Gas Tankless water Heater

Image Product Details   Price
Takagi T-H3-DV-N Takagi T-H3-DV-N GPM:  10 GPM
Colour: White
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Rinnai Rur98 iN Rinnai Rur98 iN GPM: 9.8
Color: silver
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Rinnai V75 IN Rinnai V75 IN GPM: 7.5
Color: white
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Noritz NRC66DVNG Noritz NRC66DVNG GPM: 6.6
Color: white
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Rinnai V65EN Rinnai V65EN GPM:  6.3
Colour:  white
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Ecco i12 NG Ecco i12 NG GPM: 3
Colour:  Black
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(1) Takagi T-H3-DV-N Condensing Natural Gas Tankless Water Heater

The Japanese-made Takagi T-H3-DV-N model is amongst the better available indoor models. It’s suitable for both houses and small commercial applications. It has a 10 GPM delivery capacity and can provide continuously heated water for almost 4 bathrooms. It has a heating range from 100-185 degrees Celsius.


High-Quality Heat Exchanger:

The primary heat exchanger uses commercial-grade copper to allow for much higher efficiency and better heat transfer compared to steel.

The efficient condensing system utilizes the flue gases for additional heating, adding 15-17% additional heating efficiency.

The 199,000 BTU gas input makes it sure to keep supplying hot water for its users.

Safety Features:

The Takagi model is integrated with computerized safety features. These features include freeze, overheat, surge protection, and troubleshooting diagnostic codes. Through the codes, one can easily find out the problem being faced.

Moreover, it satisfies the 2012 SCAQMD Rule 1146.2 to comply with the ultra-low Nox emissions.

Other Features:

It is free from the pilot requirement, therefore not to worry about keeping the pilot on.

This model has dimensions of 10.75 x 17.75 x 22.5 inches and it weighs 59 pounds. 

It has Energy Star certification and the sound level it produces is a maximum 55 dB, which is quite satisfactorily least noisy.

The bulb voltage required is 120 V.


  • Suitable for up to four showers
  • Computerized safety features
  • Certified up to 10,000 ft altitude performance


  • A bit noisy as compared to electric counterpart.

(2) Rinnai RUR98iN Condensing Indoor Natural Gas Tankless Water heater

The RUR90IN model is amongst the top performers in the series. It’s the best suitable for larger houses with a delivery capacity of up to 9.8 GPM. It’s an indoor condensing natural gas-operated machine.


High Efficiency:

With Rinnai’s condensing technology, dual heat exchangers offer higher-end efficiency. It carries an efficiency of about 96%. Such high-end performance ensures an endless supply of hot water.

The heating input that Rinnai RUR98IN can take in is 199,000 BTU/Hour. The heating range is from 98F to 140F.

Integrated Recirculation Pump:

This model comprises the best feature of the recirculation pump. The pump within the tank along with a crossover device permits the cold water in the pipe to be recirculated back to the water heater. This makes it possible to provide a dedicated hot loop line.

Electrical Parameters :

The model has a direct ignition system, so no need to consider pilot problems.

The AC input to be attached to the unit is 120V AC.

The different power consumptions are as follows:

  • Normal Operations: 205 watts
  • Standby : 3 watts
  • Anti Frost protection: 150 watts

Safety integrations:

This beast machine is equipped with the following safety features:

  • Boiling protection
  • Over current protection
  • Automatic frost protection
  • Thermal Fuse
  • Remaining Flame (OHS)
  • Combustion fan rpm check

Moreover, the tankless heater complies with the South Coast Air Quality emission levels.

Other Features:

It has dimensions of 12.5 x 10 x 26 inches with a weight of about 73 pounds.  

The product offers 2 tier warranty i.e: For residential ones: 12-year limited warranty on heat exchangers, 5 years on parts, and 1 year on labor. For Commercial ones, it offers a limited 5-year warranty on heat exchanger, 5 years on parts, and 1 year on labor.

(3) Rinnai Indoor Tankless Hot Water Heater V75IN

Rinnai V75IN is another natural gas-based indoor water heater with an immensely satisfying customer experience for medium-sized homes.


This indoor model has a hot water capacity of delivery up to 7.5 GPM. It can provide a temperature range from 98F to 140F. It is approved for higher altitudes operation up to 10,200 feet.

The BTU consumption in the device is up to 180,000 BTU/H.

Electrical Parameters:

It is equipped with a Direct electronic ignition system. The electrical connection of 120V AC is to be provided.

Mobile App Integrations:

The V75IN also has wifi connectivity along with a mobile app connection. Through this feature, you can monitor timers and schedules and remotely put the system into vacation mode.


Following safety protections are provided with the device:

  • Flame failure, flame rod, boiling protection
  • Over-current protection and thermal fuse
  • Automatic frost protection

Other Features:

The V75IN has dimensions of 14.04 x 9.27 x 26.9 inches and it weighs 45.6 pounds.

In terms of warranty support, V75IN provides a 10-year heat exchanger warranty, 5 years for all other parts, and 1 year of reasonable labor.

The sound level produces is up to 55 DB which is quite silent.

The device has controlled Nox emission levels as devised by District 14 ng/J or 20 ppm.


  • Low Nox levels
  • WIFI Connectivity
  • Least noisy


  • Quick access isolation valves need to be bought separately

(4) Noritz NRC66DVNG Indoor Condensing  Tankless Water Heater

The Noritz NRC66DV is an indoor tankless water heater with natural gas as fuel. Its makers claim to be the innovators in the water heating industry for over 60 years.


The NRC66DVNG model has a delivery capacity of 6.6 GPM with a sustained heater water supply.

It has to be supplied with 120V AC and it takes less than 4 amperes of current for its operations and safety features working. The amperages of different functioning are:

NG: 43 watt

Freeze prevention: 139 Watters.


The efficiency energy factor for this heater is 0.91 on NG and 0.93 on LP. Its condensing feature makes it possible to tank its thermal efficiency to 93%.

Its temperature gauges up to 140 F. 

Safety Features:

The Safety devices being provided include:

– Flame sensor

– Overheat prevention device

Lightning protection device

  • Freeze protection
  • Condensate overfill
  • Fan rotation detector

Other Features:

The NRC661DV-NG model has dimensions of 6.7 x 13.8 x 23.6 inches and it weighs only 11.42 pounds which is quite lightweight.

The valve kit required for installation shall be sold separately.

In terms of warranty, Noritz gives a 12-year heat exchanger, 5-year parts, and 1 labor warranty which is quite a good one.

(5) Rinnai V65EN Natural Gas Outdoor Tankless Hot Water Heater

The Rinnai V65EN is the outdoor tankless hot water heater with a delivery capacity of 6.3 GPM suitable for mid sizes families. It can cope with hot water needs for up to 2 and a half bathrooms. 



As compared to conventional water heaters, the tankless version and especially Rinnai products offer a bigger life cycle of expectancy of about 20 years as compared to 8-10 years of traditional ones and reasonable labor of 1 year.

Every part of the Rinnai water tank is replicable so the replacement of the component will never be an issue.


The maximum BTU’s Rinnai uses is 120,000 with an energy factor of 0.82 which is very good efficiency for gas heating tankless heaters.

It offers a temperature range ranging from 98F to 140F.

This model also meets the California and Texas Nox Emission standards for customer safety.

Wifi Monitoring:

The Rinnai family is always a step ahead with technological advancements integration in its products. With Wifi monitory you can easily monitor the heating service of the water heater.  

Other Features :

The V65EN model gives you a 10-year warranty on the heat exchanger, 5-year parts warranty.

Its dimensions are 9.6 x 14 x 24.3 inches and weigh 47.4 pounds.

More than 80% of satisfied customers have given 5-star reviews and 10% with 4-star reviews, showing customer satisfaction in the product.  

(6) Eccotemp i12-NG Tankless Water Heater

With the capacity of 3 GPM eccotemp i12 LG is good for a small house or for use of water in small quantity without any doubt. It comes in dimensions of 16 x 16 x 11 inches and as far as its color is concerned it comes in black color.


It comes with a sleek design with easy to use led display controls


  • It comes with child lock technology
  • No pilot light needs and starts only without a pilot.


  • Only suitable for small use

Buyer’s Guide

Buying the best tankless water heater is definitely a one-time job and a long-term decision to be made.  Selecting the right water heater based on the exact needs is always the point of consideration before selecting tons of available options.

We will let you know a better approach to avail the best practice, based on technical parameters before you finalize your in-budget tankless water heater. So let’s hop in!

Proper Sizing of the Water heater:

Following are the steps to do the good calculation for deciding your best tankless water heater:

  1. Required Flow Rate
  2. Ground water temperature
  3. Counting the GPM required at a time

One of the first points to start with a selection of the best tankless water heater is the required water for households or in any commercial place. Different water needs are to be considered, which we call the required flow rate. Following are the household water requirements:

  • Shower ranges from 1.5 – 2.5 GPM (gallons per minute)
  • Kitchen Sink ranges from 1 – 2.2 GPM
  • Bathroom Sink ranges from 0.5 – 1 GPM

The second important factor in the best tankless water heater is for sizing calculation is the available water that is to be fed to the heater for heating, the groundwater temperature. The hotter the water, the higher will be the hot water output and vice versa.

For example,  Tempra 24 plus model offers a 2.6 GPM flow rate at 42 F inlet water, while at 72 F inlet water feed, the hot water flow rate is 5GPM. Of course, this difference in performance is because of the temperature difference that takes time to heat the water to the required heated level.

Now coming to the third step is the calculation of the best tankless water heater how many total taps are to be operated at a time with hot water. For example, a house has two washrooms, your shower flow rate is 1.5 GPM, so your tap need will be 3 GPM. Add a kitchen sink of 2 GPM. So you can get a heater which can guarantee you a hot water supply of 5 GPM.

Fuel Input for heating

Certain heating sources for heater water are available. Among famous sources are Electric and Natural Gas/propane. As compared to the traditional tank water heaters, the tankless versions are more efficient as mentioned in Wikipedia.

Tankless water heaters are both available in Electric and Natural Gas modes. Both have their Pros and cons. We have narrated both

  • Electric Tankless water heaters:

Electric heaters are lightweight, compact, and provide a noise-free environment. It gives quick operations in heating service.

  • Gas Tankless water heaters:

Natural gas as fuel input for heating is definitely the cheaper option for heating. Moreover, the gas heating elements are a bit faster in heating water.

However, natural gas water heaters have a high upfront cost as compared to electric counterparts. Moreover, the indoor version of gas heaters must be provided with proper vents to expel flue gases. The additional hardware required for venting can raise the installation cost.

Energy Efficiency

A tankless heater needs to be energy efficient. Why? The answer is higher the energy efficiency, the higher is the cost savings in terms of money.

Electric tankless heaters are in fact highly efficient ranging from more than 95% energy efficient.

Natural gas tankless heaters are available in two modes :

  • One without condensation system
  • One with the Condensation System

The condensation system utilizes the flue gases from the heater and provides additional heating to water, thereby increasing the efficiency to about above 90%. On the other hand, the gas tankless heaters without condensation systems are up to 15% less efficient as they don’t have a mechanism to tap the flue gases.

However, the gas heaters with condensation systems are higher in cost. But putting a higher upfront cost to gain more efficiency with cheap gas fuel is definitely a good combination.

Go Thru Technical Specification

The technical specification sheet is the most important document that depicts the users’ right and accurate information. The buyer must go through the technical data sheet to ensure the product manufacturer’s technical details.

Safety Features:

The buyer is searching best available option in the market to fulfill his requirement for hot water. Electric and Gas-based tankless heaters offer certain protection features that ensure the user’s safety and product reliability. The user must ensure the basic availability of safety features before making the decision.


Concluding Remarks:

The tankless water heaters are the futuristic approach towards comfort for household and commercial purposes. They provide you with a better outcome with an optimized solution of cost-saving and efficient methodology.

With the passage of time, innovation keeps coming with added features for user comfort. We have selected the best available options for our readers and provided our best efforts to guide them with better information.

All the information is providedin our article is based solely on the datasheets, user guides of the selected products. Therefore feel free for product authenticity in case of its features.

We are confident to give pure information about the product to our readers. However, in case of any queries, do let us know. We are for sure open to suggestions and guidance from our valuable readers.

Related Topics:

Propane Tankless Water Heater

Point of use water heater

Electric Tankless Water Heater

Gas Tankless Water Heater