Best On Demand Tankless Water Heater 2022- Hot Water With High GPM

Thinking of buying the best tankless water heater would be the smartest decision you have ever made. Yes! that’s true. As they are smart enough to provide a continuous supply of hot water, require less space because of their slim size, last but not least they have less energy usage than the storage tank water heaters, which results in saving $100 or more years on your utility bills, relying on the water use. 

Longevity is another big advantage of top-rated tankless water heaters. They last 20 years more than their conventional water heaters which have a maximum of 10 to 15 years of life span. 

I can’t promise you of giving the hot water on demand reviews of the perfect tankless water heater as nothing is perfect. But I assure you I am suggest the right type of water heater after thoroughly reviewing and testing the top ten tankless water heater that would meet your particular requirements of water usage. 

best tankless water heater

After thorough research and testing different models, I have listed down the reviews of the best and top tankless water heaters, including from hot sellers to economical choices. So, be wise while buying!

Top 10 Tankless Water Heater Reviews

Let’s explore tankless hot water heaters reviews in detail in order to pick the best one for your home. It took many days to research, analyze and test a few tankless heaters to suggest the different models depending on the requirement of hot water.  

Note: Best rated on-demand Tankless Heaters require special fitting, space and climate also affects its working. So, you must read the buyer’s guide in order to avoid having any bad experience.

Image Product Details   Price
ecosmart 27 electric tankless water heater EcoSmart ECO 27 Electric Tankless Water Heater Max GPM: 6.6
Item Weight: 10.98 pounds
Power Type: Electric
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Rinnai V65EN RV65eN Rinnai V65eN Tankless Hot Water Heater Max GPM: 6.5
Item Weight: 47.4 pounds
Power Type: Natural Gas
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Rinnai RU199iN RRU199iN, RU199in-Natural Gas Rinnai RU199iN Sensei Super High-Efficiency Tankless Water Heater Max GPM: 11
Item Weight: 64 pounds
Power Type: Natural Gas
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Rinnai RU180iN RRU180iN, RU180in-Natural Gas Rinnai RU180iN Sensei Super High-Efficiency Tankless Water Heater Max GPM: 10
Item Weight: 64pounds
Power Type: Natural Gas
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Stiebel Eltron Tempra Plus 29 kW, tankless electric water heater with Self-Modulating Power Technology Stiebel Eltron Tempra Plus 29 kW, tankless electric water heater Max GPM: 6
Item Weight: 10.37 pounds
Power Type: Electric
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Eemax EEM24013 Electric Tankless Water Heater Eemax EEM24013 Electric Tankless Water Heater Max GPM: 2.4
Item Weight: 8.08 pounds
Power Type: Natural Gas
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Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric Stiebel Eltron Tankless Water Heater Max GPM: 5
Item Weight: 1 pound
Power Type: Electric
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EcoSmart ECO 11 Electric Tankless Water Heater EcoSmart ECO 11 Electric Tankless Water Heater Max GPM: 3
Item Weight: 6.5 pounds
Power Type: Electric
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Rheem RTEX-18 18kW 240V Electric Tankless Water Heater Rheem RTEX-18 18kW 240V Electric Tankless Water Heater Max GPM: 4.4
Item Weight: 14.8 pounds
Power Type: Electric
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Rinnai RL 94IP Tankless Water Heater Rinnai RL Series HE+ Tankless Hot Water Heater Max GPM: 9.4
Item Weight: 44.2 pounds
Power Type: Propane
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Tankless Hot Water Heater Comparison Chart

Table Of Contents
  1. Top 10 Tankless Water Heater Reviews
  2. Tankless Hot Water Heater Comparison Chart
  3. How to Buy Tankless Water Heater – Complete Buying Guide
  4. What is a Tankless Water Heater?
  5. Indoor vs Outdoor Tankless Water Heater
  6. Tankless Water Heater vs. Tank
  7. How Does a Tankless Water Heater Work?
  8. What Size Tankless Water Heater do I Need?
  9.  What size tankless water heater do I need for a family of 5 members?
  10. Condensing vs. Non-condensing Tankless Water Heater
  11. Electric versus Gas Tankless Water Heaters
  12. Point of Use vs. the Whole House Water Heater
  13. Pros and Cons of Tankless Water Heaters
  14. What are the Advantages of a Tankless Water Heater?
  15. What is the Downside of a Tankless Water Heater?
  16. Conclusion
  17. FAQ

1. EcoSmart ECO 27 Electric Most Efficient Tankless Water Heater

EcoSmart ECO 27 Electric Tankless Water Heater
  • 50% saving on heating cost
  • 0.3GPM Activation flow
  • Efficient and durable
  • Sleek design fits anywhere

Ecosmart as a young company brought a revolutionary change in the race of top tankless water heaters. They introduced Patented Self Modulating Technology in tankless heaters to provide on-demand hot water even at the lowest temperature.

Are you living in an extremely cold temperature with the problem of having endless hot water in multiple fixtures at a time? But meanwhile, your budget is too tight… Then nothing to worry about, as EcoSmart Eco 27 is the right choice for you as this does not burdenize your pocket as well as space. This unit has more advanced features than its previous models of ECO 18 and ECO 24.

Patented Modulation System

Built-in Patented Modulation System helps reduce electric bills up to 50% makes it the best tankless electric water heater. This unit is up to 99.8% energy efficient and uses energy only when it is required. Precise Temperature Control is another super cool feature to set the target temperature. 

digital control helps saving upto 50% on water heating cost

The company claims that this unit has a generous and decent flow rate,  you can have three showers and a sink in use simultaneously without any delay in the supply of heated water. 

According to the US Energy Department, tankless heaters are 24 to 34% energy efficient and minimize annual energy consumption. Though ECO27 is not energy star certified, it is 99.8% energy efficient. 

Flow Rate

But the real experience says that the flow rate and optimum energy efficiency depend on the average inlet water temperature. If the temperature drops down to 37°F, this unit has the capacity to provide a flow rate of 3 gallons per minute for two showers at a time without running out of hot water. When the temperature gets a bit warmer, its flow rate and efficiency jump high to 6 GPM. Consequently, you can run 4 showers simultaneously. 

Its low activation flow rate of .03GPM is comparatively more amazing than others. Where other instant hot water heaters flick on at least at 0.5 GPM to heat water, this instant water heater stimulates quickly to low flow hot water requirements. 

EcoSmart Eco 27 is the ultimate economical choice for the inhabitants of the Northern United States where the temperature is too low but this is equally useful for the Southern United States where the temperature is relatively higher. 

Advance Features

Some advanced features make EcoSmart Eco 27 the best water heater tankless on the market. They are: 

  • EcoSmart Eco 27 has built-in precise technology that brings heating cost down. Its advanced mechanism heats water only on demand. 
  • Modern technology enables to display the exact water temperature passing through the pipes. 
  • Efficient and durable as copper and stainless components are used in manufacturing. Also replacement is easy.
  • Space saver by saving 12 cubic feet of storage space due to compactness  and sleek design. 
  • This on demand water heater needs 27kw, 240 volts and three 40 Amp double poles and draws 113 A.    
  • Digital Temperature Control ability allows to increase the water temperature by 1-degree increment.

Robust And Long-Lasting

EcoSmart instantaneous warm water heaters don’t become rusty easily.  Its most advanced technique to combine copper and stainless steel reinforce its long-lasting and conduction ( ability to transmit heat from one side to others at high temperature).

It is proven by North American safety standards making it a reliable water heating solution and the best residential tankless water heater.

Adjustable Temperature

The modern digital interface allows showing the temperature which can be easily adjusted between 80°F – 140°F and enough for household use. Moreover, the 1-degree increment temperature option is an amazing but rather unfeasible attribute. 

To tackle the high demand for heated water, install a valve to throttle down the instant hot water flow rate.

Before buying the EcoSmart heater, one must sort out the heated water requirements and electrical fitting of the house units and the right size of the hot tankless water accordingly. Recommended electrical measurements are 27kw, 240 volts, 3 double pole 40A breakers, 112.5 AMP, 3 (8) require a wire and Amperage draw:113A

Technical Details

Voltage ‎240 Volts
Wattage ‎18000 watts
Amperage Capacity  2-50 amp
Item Weight ‎14.78 pounds
Maximum Pressure‎‎150 


  • 99.8% energy efficient, resulting in minimum energy loss i.e. 0.2%.
  • Generous flow rate regardless of the colder and warmer temperature.
  • The excellent flow rate in economical pricing.
  • Compactness and lightweight resolve the space shortage issue.
  • No regular maintenance is required but annual inspection is enough.
  • Eco-friendly, durable with a lifetime warranty.


  • Not energy star certified.
  • Temperature fluctuation is expected if valves are not installed and hot water demand increases in cold climates.
  • No industry Rinnai warranty will be given if the product is not registered within 30 days after purchase.

2. Rinnai V65eN Tankless Hot Water Heater, Large Best Outdoor Model

Rinnai V65eN Tankless Hot Water Heater, Large, White: tankless hot water heater
  • Max BTU’s 120,000
  • Max Energy Factor 0.82
  • Lightweight and Compact
  • Meets California and Texas NOx Emissions Standards

Rinnai is the name of trust providing reliable and durable tankless water heaters since 1912. That is why this company has become the number one seller of best on-demand water heaters in the United States and Canada.

Flow Rate

Rinnai V-Model is available in both indoor and outdoor models whereas Rinnai V65eN is featured to install outdoors only. It uses natural gas to work with a depth between 10,300 BTU (Minimum) to 150,000 BTU (Maximum). It provides a smooth flow rate of up to 6.5 GPM (gallon per minute) even for multiple fixtures simultaneously. It can run a single shower with dishwashing and laundry.

Energy Efficient

Though it is not Energy Star Qualified, still you can save on your utility bills as its Uniform Efficiency Energy Range is between 0.79 to 0.82. The Rinnai V65en series is an ultimate combination of High Efficiency and natural gas, which heats water on demand which saves energy from being wasted. 

Another key point is that watt consumption is fairly amazing, consumes 57 watts when being operated, 2 watts only on standby, and 104 watts when the anti-frost protection mode is on. 

Advance Features

Some of the special features are:

  • You can control the temperature range: The preset temperature range starts from 98°F to 120°F, but you can widen the range to a maximum of 140°F.
  • Error code indicator is integrated: makes it easy for you to sort out any possible issue and fix that accordingly. Moreover, the user manual contains all error codes along with their possible remedies. 
  • Temperature lock feature is amazing: as it keeps the water temperature constant in case of any unauthorized and sudden modifications in the water temperature.
  • Wi-Fi-capable tankless water heater.
  • Certified for installation in manufactured (Mobile) homes.
  • Complies with South Coast Air Quality Management District 14 ng/J or 20 ppm NOx emission levels: which is useful to keep the environment clean.
  • Compatible with the full line of Rinnai Digital Controllers: apart from the provided standard controller, this unit can sync with any Rinnai Digital Controller purchased separately
  • Offers decent residential warranty:  10-year warranty on copper heat exchanger, 5-year on parts, and 1-year warranty for the labor.

Durable And Reliable

The most compelling evidence is that this inline hot water heater has a robust structure, made of stainless steel which saves from rusty sediments and increases the lifespan. All these qualities make this unit named Rinnai V65eN the best on-demand tankless heater.

The most surprising fact is that it comes in the size of a suit briefcase with the dimensions of 9.6 x 14 x 24.3 inches and it weighs 47.4 pounds. 

Easy Installation

Undoubtedly, this is the easiest tankless water heater to install. The installation process for this unit is pretty simple and elaborated in detail in the user guide. As long as the user properly uses the provided instructions, this tankless hot water heater would act smartly. 

Rinnai V65eN as the best hot water heater has got the Amazon’s Choice badge because of the positive reviews given by happy and satisfied customers. No downside has been mentioned yet except this is suitable for small to medium homes or remodels. Moreover, 3 to 4 fixtures run smoothly with any shortage of warm water. 

Technical Details

Power Source ‎Gas Powered
Flow Rate ‎6.5 GPM
Style Outdoor Installation
Item Weight 47.4 pounds
Warranty 10-Year on Heat Exchanger, 5 Year Parts, 1 Year Labor


  • Endless hot water on demand.
  • Save valuable space because of the compact size.
  • Multiple fixtures simultaneously.
  • Temperature lock is included.
  • Sync with Wi-Fi monitoring.


  • Sometimes, it uses more amps than a standard 120 amps.
  • Not good for hard water.

3. Rinnai RU199iN Sensei Super High Efficiency Tankless Water Heater – Best For Large Families

best tankless water heater Rinnai RU 199iN
  • Circ-Logic technology
  •  Sensei SE+ Super High Efficiency
  • Up to 11 GPM hot water flow rate
  • Residential Factory Warranty

11 gpm Rinnai ru199in sensei super is a Sensei SE series with the most advanced techniques such as super high efficiency, energy star qualified, and voice activation command. The versatility of this unit is the availability for both commercial and residential usage and can be operated with both Natural Gas and Propane. Moreover, both indoor and outdoor versions are available to purchase as per users’ needs. 

High Flow Rate

One of the most outstanding features of this Rinnai ru199in tankless water heater is its highest GPM flow rate which is 11GPM hot water flow depending on the incoming water temperature. This robust flow rate is sure to provide instant hot water for a maximum of 7 fixtures at once. As a result, 2 or 3 persons can enjoy a hot shower, along with the dishwasher, and laundry activities are carried out on the other side. Therefore, it is wildly known as the best gas instant water heater.

The coolest fact to know is that its on-demand hot water flow rate varies from 0.26GPM to 11GPM. The minimum GPM capacity is ideal for the low demand needs of heated water such as shaving, and handwashing, etc. 

Advance Features

Some of the most amazing features are:

  • Able to produce 11GPM hot water flow rate depends on the incoming water temperature.
  • BTU ranges from 15,000(mini) to 199,000(max) makes this unit super fast to fulfill instant warm water demand for the whole family simultaneously.
  • Up to 0.93% energy efficient, brings a drastic cut down in electric bills.
  • Provided with Circ-Logic technology, enables you to regulate recirculation patterns to supply heated water when you need it. 
  • Compact and wall-mounted design resolves space issues.

Advanced Circ-Logic Technology

Circ-logic technology is one of the advanced mechanisms that offer hot water instantly when you need it. This feature stops the water is cooled in the pipe and provides hot water immediately after turning on the taps without keeping you in waiting mode. So, you not only save water but your time also. To get benefit from this technology your house must have return line installation otherwise, thermal bypass valves are required.

Control-R Wi-Fi Module

Another key feature is Wi-Fi Ready, which gives you remote control to manage and monitor the unit. This Control-R Wi-Fi Module makes it easy to control the hot water supply from any corner of your home, and also you can activate recirculation if installed. Thus, it can be termed as the best tankless water heater.

Indoor Installation

Rinnai RU199iN is featured for natural gas: indoor installation. This is equipped with freeze protection down to 22°F. In like manner, to optimize the venting system, a valve is installed between the turbofan and combustion chamber to stop cold air from entering. 

RU199iN Indoor model offers flexible options makes it the best gas tankless water heater. It provides both concentric and PVC/CPVC venting. Through concentric venting, one pipe enters fresh air in and another sends the exhaust out. 

Before buying, must check the electric requirements of your house, must be compatible with the units’ requirements to get optimal performance. 

Technical Details

Power Source Gas Powered
Flow Rate ‎‎11 GPM
Style  Indoor Installation
Item Weight ‎74.1 pounds
Warranty 12-year residential for heat exchanger, 5 for parts, 1 for labor


  • Provides residential warranty: 10 years for heat exchanger, 5-year parts warranty, and 1 year for labor.
  • Circ-Logic Technology saves water and time.
  • Integrated with voice activation command and Control-R Wi-Fi Module Technology.
  • Temperature lock stops unwanted changes to water temperature.
  • Comes with the required valves such as 2 connection valves and 1 TP valve.
  • Energy star qualified.


  • A bit expensive unit.
  • Not certified for commercial use in Texas, or residential use in Utah.

4. Rinnai RU180iN Sensei Super High Efficiency – Best Instant Water Heater

Rinnai RU180iN Sensei Super High Efficiency Tankless Water Heater, 10 GPM - Natural Gas: Indoor Installation:tankless water heater reviews
  • ENERGY STAR Qualified
  • Uniform Energy Factor of .92
  • Equipped with Rinnai Circ-Logic
  • Simultaneous uses at multiple fixtures

Rinnai RU180iN is known for its best and optimal performance regarding the uninterrupted supply of hot water on demand. RU180iN employs SENSEI technology, which presents the easiest user experience and installation process with multiple locations options to enhance its performance. 

The self-compensate feature optimizes the performance of this unit by dealing with low and fluctuating gas pressure issues smartly and makes this best gas water heaters 2022. 

Excellent Flow Rate

Surprisingly, this RU 180iN SENSEI series boasts a maximum 10GPM flow rate which is pretty sufficient to entertain 5- 6 persons at the same time without running out of hot water. So, this electric tankless water heater 10 gpm is an ideal choice for medium to large families.

Flow rate requirements may be varied in different areas depending on the temperature of incoming water. The minimum flow rate is 0.26GPM sufficient for common tasks with low demand for hot water.  

Circ-Logic Technology

Coupled with a recirculating mechanism, Rinnai RU180iN delivers fast hot water whenever you need it and wherever you are. This Circ-Logic technology is designed to set the recirculation pattern to conform to your instant hot water needs. This saves your time and water.

In addition, if your recent plumbing configuration does not have the devoted return line to meet the circ-logic requirement, nothing to worry about.  A thermal bypass valve is the best alternative. 

NSF Certified

Moreover, this heater is not only energy-star qualified but also NSF certified and got approval for commercial applications. The 0.93% EF and condenser help reduce energy loss and boost saving.  

Longevity And Durability

The corrosion-resistant technique is another excellent feature that upgrades its longevity. The stainless steel heat exchanger resists corrosive nature and ensures durability and long-lasting functions. These features make this unit the most reliable water heater.

Slim design, wall-mounted and flexible venting features relieve you from the floor space issues.   

Technical Details  

Power Source Gas Powered
Flow Rate ‎‎10 GPM
Style  Indoor Installation
Item Weight ‎74.1 pounds
Warranty 12-year residential for heat exchanger, 5 for parts, 1 for labor


  • Wi-Fi compatible: to control and manage the unit remotely.
  • Uninterrupted hot water supply for up to 6 fixtures simultaneously.
  • Enhanced combustion design boosts optimal performance.
  • Easy installation process and serviceability.
  • Available in both natural gas and propane.
  • Amazing residential warranty: 10 years for heat exchanger, 5 years on parts damage, and year for labor.


  • Comparatively expensive.

5. Stiebel Eltron Tempra Plus 29 kW – Best Electric Tankless Model

Stiebel Eltron Tempra Plus 29 kW, tankless electric water heater with Self-Modulating Power Technology & Advanced Flow Control; instant hot water heater
  • Proven reliability
  • No venting required
  • Constant temperature output
  • Sleek design fits anywhere

State-of-the-art mechanisms like authentic operations, superior quality, and genuine functioning of Stiebel Eltron Tempra Plus have been successful to win the trust of its users. Tempra models are included in top-selling brands on Amazon on account of their optimal and reliable performance. 

Endless Supply Of Hot Water

Stiebel Eltron Plus 29kw is a powerful model for several outstanding features and provides an immediate solution to the demand for instant hot water to its users. This powerful 29kw electric tankless water heater is designed to fulfill the uninterrupted hot water demand for the whole house and commercial applications, especially in cold climates with temperature drops below 40°F.

It is suitable for dishwashing and does a load of laundry simultaneously.

Advanced Flow Control technology

Its built-in Advanced Flow Control technology provides a remarkable experience to the customers by providing consistent hot temperature water through various water fixtures simultaneously. Situationally, this automatic technique reduces the flow rate considerably if flow demand exceeds the heater’s capacity, and ensures consistency at temperature level regardless of exceeding water demands. 

As a result, you don’t experience an unpleasant temperature fluctuation with high flow demand occasionally. And the company claims that this feature is not found in other tankless water heater brands.

Ideal Flow Rate

Being the most efficient on-demand water heater, its three heating modules provide a smooth transition of heating power from a minimum of 21.6kw to a maximum of 28.8kw on 240 volts. This unit supplies 3.1GPM water flow at 42°F (2 fixtures running at a time), and maximum flow is 6GPM at 72°F (4 fixtures functioning simultaneously) temperature, sufficient for the home with 3 bathrooms in warmer areas, 2.5 baths in moderate climates and 1.5 baths for colder areas respectively. 

Self-modulating Technology

Self-modulating technology in Tempra 29kw ensures that the minimum amount of energy is used to heat water. So, this unit is 99.5% efficient and saves 15- 20% when compared to electric tank heaters. 

True Thermostatic Temperature Control, an intelligent feature, in collaboration with full power-modulation automatically adjusts its power output to accommodate the variation in inlet water temperature and flow rate, consequently desired output temperature of hot water is available.

For efficient and optimal performance, an anti-scale filter is suggested to save this unit from pre-mature failures produced due to minerals present in hard water. 

True microprocessor mechanism maintains steady output temperature regardless of the variations in flow rate whereas other tankless heaters do not provide steady temperature if the flow changes.

Smart Digital Temperature Display

The smart digital display and appropriate dial selector allow you to adjust the required output water temperature such as 64°F for hand washing, 107°F for a hot shower, and up to 140°F for commercial applications. 

Tempura Eltron requires 208 – 240volts with 21,600 – 28,800 watts respectively, draw 150Amps, 3x 40 Amp double-pole breakers, and 3 x 8 gauge copper wiring, and ¾ NPT Pipe fittings. 

So, identify your hot water needs and recognize your electric panels if you are interested in buying this unit.

Technical Details

Voltage ‎240 Volts
Wattage ‎18000 watts
Amperage Capacity  2-50 amp
Item Weight ‎14.78 pounds
Maximum Pressure‎‎150 


  • The sensor detects flow demand automatically.
  • Most precise temperature control.
  • Equipped with Advanced Control Flow to provide the constant temperature.
  • The self-modulation feature adjusts electrical usage and saves energy.
  • Uninterrupted supply of hot water.
  • Warranty: 7 years for leakage, 3 years parts and workmanship.
  • Easy to install and use.


  • A bit expensive.
  • Water filter required for optimal performance.

6. Eemax EEM24013 Electric – Best Point-Of-Use Tankless Water Heater

Eemax EEM24013 Electric Tankless Water Heater, Blue; instant water heater
  • Compact size
  • Self-modulating technology
  • Sleek design fits anywhere
  • Continuous Supply of hot water

Eemax EEM24013 tankless water heater electric is specially designed to fulfill the instant hot water demands of small families requiring minimal flow rate and point-of-use applications. 

To get the terrific performance, you must know your water demand and the capacity of this unit, as this unit does not allow water for multiple showers simultaneously with an ideal flow rate. 

Flow Rate Of Water

This unit is capable of delivering endless hot water for one sink only in colder climates depending on the average inlet water temperature. Sufficient to provide continuous hot water for 1 sink and shower at the same time in relatively warmer climates. The flow rate of this unit is 0.3GPM.

instant, consistent endless hot water

Thermal Energy Efficiency

Eemax 24013 is certified to 99% Thermal Energy Efficiency, helping save on energy. Price is economical and you save up to 50% on water heating costs. 

Self-modulating technology adjusts power consumption according to hot water requirements smartly. And this energy-efficient feature reduces the electric costs up to 20% as a whole. 

self-modulating technology

Moreover, 90% are smaller than the traditional water tank, and can even be placed in a kitchen cabinet. It is also fairly easy to reset the tankless via the eemax eem24013 reset button, which can be found next to the thermostat.

Corrosion Free

Insulating materials like Copper and brass are involved in manufacturing, so nothing to worry about leakage and sediment. 

The sad thing to know is that this unit is unable to fill a shallow tub but good for showers. Makes annoying noise when it cycles on. 

To have an amazing experience with this instant water heater, you must know your hot water demands and electric panel requirements which are 1 x 60 Amp breaker, 1 x 6 AWG wires, and 240 volts. 

Technical Details

Voltage ‎240 Volts
Wattage 13kwatts
Amperage Capacity  57 amp maximum
Item Weight ‎‎4.99 pounds
Warranty ‎5 years for leaks and 1 year for parts


  • Instant, constant, and endless hot water is available all the time.
  • Insulated material avoids water leakage.
  • 5-year leakage and 1-year parts warranty included.
  • Energy-saving and money-saving.
  • Simple installation and electric cables, connectors, and NPT adapters are included.


  • Irritating voices when switches.
  • Can’t fill large bathtubs.
  • Slowly adjusts the temperature.

7. Stiebel Eltron Temra 24 Plus – Inline Water Heater

Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco, White; best water heater
  • Noise-free
  • Eco-friendly unit
  • Advanced Flow Control
  • powerful copper interior heating system 

Living in areas with cold temperatures is very challenging in many ways. An uninterrupted supply of hot waters for showers and other house chores feels like shooting in extreme cold.

Robust Tankless Heater

Then, Tempra 24 plus is one of the robust electric tankless water heaters, a perfect choice to fulfill instant hot water demand for whole-house applications in the Northern USA, Canada, and the areas with frigid temperatures. 

This unit allows you to operate 2 hot showers, including tub filling, which is a really super cool function of this model. 

Flow Rate Sensor

Integrated with a flow rate sensor, which regularly sends important data to the microprocessor. And this microprocessor-controlled feature heats the water according to the set temperature. So, you can save 15- 20% on electricity. 

Flow Rate Measurement

This model provides 2.6GPM at 42°F (1.5 fixtures)  and 5GPM at 72°F allowing you to run 3 water applications at the same time. The sizing chart of Stiebel Heaters helps you to choose the right model.

Electric Requirement

To get the maximum benefit of this model, your house has the recommended electrical service which is 24 kw, 240 volts, max. Amperage draws 100 A, min. required breakers 2 x 50 A DP, required wire size 2 x 6/2 AWG and min. recommended electric service 150A. 

Advanced Flow Control Technology

Advanced Control Flow German Patented Technology is an exclusive feature of the Tempra series. As the unit’s sensor detects that hot water demand is increasing more than the heater’s capacity, this Control Flow automation adjusts the flow to maintain comfort. It slightly reduces the flow to carry on steady and uninterrupted hot showers. 

automatically reduce the flow of water


This is an Eco-friendly unit. Its auto-modulation feature along with the ability to electronically measure water flow helps savings 15 – 20 % energy. Interestingly, the saving monitor displays how much you save on energy costs. 

The sleek design with wall mounting feature saves space, as well as no venting, is required. This model has earned the Amazon choice badge because of its outstanding functionality.

sleek design fits anywhere

Technical Details

Voltage ‎240 Volts
Wattage ‎18000 watts
Amperage Capacity  2-50 amp
Item Weight ‎14.78 pounds
Maximum Pressure‎‎150 


  • No annoying sounds, totally silent operations.
  • Up to 99.5% energy rating.
  • Sleek design and no expensive venting required.
  • Safety proven: Shut down automatically in case of overheating.
  • Smart self-modulating energy saves energy.


  • Water filter required to deal with hard water.
  • Not suitable for old houses as electrical panel upgrade is required.
  • A sediment filter and regular flushing are required regularly.

8. EcoSmart ECO 11 Electric – Small On Demand Water Heater

EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology; on demand hot water heater
  • Lifetime warranty
  • Uniform Energy Factor:0.98
  •  60% on your water heating cost
  • Patented self-modulating technology

Eco 11 electric tankless water heater is the hot seller on amazon. This model is suitable for a small sink, low flow showerhead, toilet, and office breakroom, and other low flow applications.

This on-demand water heater has dual functions: it can be used as a point of use water heater in areas with pretty cold climates and can be configured as a whole house tankless heater in warmer areas.

Flow Rate in GPM

Climatic condition matters a lot for the optimal performance of this model. Eco 11 is the ultimate choice for inhabitants living in locations with temperatures 67°F or above. The water heating capacity of this model is 2 gallons per minute which is sufficient for one shower head with a 1.5 GPM flow and two sinks running simultaneously while the incoming water temperature is 67°F and the output temperature setting is 105°F. 

In cold climates, this on-demand hot water heater works great when used as a point of use with a sink or other low-flow appliances. Interestingly there is a direct relationship between water flow and temperature rise. So, when a high-temperature rise is required in extreme cold, it will be restricted in the number of fixtures. You can run only 2 sinks with the low flow at a time.

 Like other models of EcoSmart, this unit also ensures the frugal use of the required amount of power to heat the water through its amazing self-modulation technology. So, you save a handsome amount on energy and water heating costs yearly. 

equipped with self-modulation technology

Exact Temperature Display

This unit displays the exact temperature of running water. Also, the desired temperature can be easily reset through a convenient dial on the front part of this unit. 

The convenient size of this unit saves up to 12 cubic feet of space. This Eco-friendly model 99.8% is energy efficient. 

Suitable Electric Fitting

This unit requires 13 kW, 240 volts, max Amperage 57, required breaker 1 x 60 Amp, and 1 x 6 AWG wire gauge. 1/2 NPT adapters are also included.

To consider the suitable electric fitting required for the particular unit is essential for the optimal performance of the unit. 

Technical Details

Voltage ‎240 Volts
Wattage ‎18000 watts
Amperage Capacity  2-50 amp
Item Weight ‎14.78 pounds
Maximum Pressure‎‎150 


  • Equipped with a self-modulating mechanism that intelligently adjusts the required energy based on the hot water need.
  • Digital temperature Controller with increments of 1-degree.
  • Stainless steel heat exchange.
  • Thermal auto safety.
  • Durable heating elements that are subject to easy replacements.
  • Lifetime warranty for electronic, exchanger, and elements.
  • Convenient size frees up the huge space as the tankless heater is 90% smaller than the storage tank.


  • Warranty does not cover the cost of labor or any incidental damage.
  • The limited flow rate in cold climates.
  • Require regular maintenance.

9. Rheem RTEX-18 18kW 240V High Capacity Tankless Water Heater

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater, small, Gray; best hot water heater
  •  LED display (+/1 degree accuracy)
  • Adjust power automatically
  • Durable Copper immersion
  • Threaded for easy replacement

Everyone does not need a large amount of hot water, not even simultaneous use of instant hot water. Rheem RTEX-18 as a mid-range model is the ideal choice for small families, apartments, and medium-sized homes with up to 2 to 3 persons. 

Flow Rate in GPM

This is the best seller electric tankless heater as it provides a 4.4 GPM flow rate but at a low price. This unit supplies endless hot water for points of use or other multiple applications depending on your preferences. 

In cold climates, it has the ability to deliver an adequate water flow rate of up to 2.5 GPM for a shower and a sink. Whereas in a warm climate, this unit provides up to a 4.4 GPM flow rate sufficient for 2 showers and 2 sinks

Advanced Self-Modulation Technology

The advanced self-modulation feature intelligently adjusts the required power after sensing the hot water demand. Subsequently, you save on energy bills. 

Coupled with two heating elements, this unit ensures a regular and quick supply of hot water continuously. As two heating elements heat water more rapidly as compared to one heating element. So, you don’t have to wait for long to have hot showers.

Durable And Reliable

Made with copper immersion, these two heating elements are resistant to high temperature and corrosion. So, this unit is durable and lasts long. 

The installation of this unit is pretty simple. You don’t need any licensed professional installation which is pretty expensive. The cool thing to know is that the package contains all the required hardware. 

LED Display

Integrated with external thermostatic control, it has a digital LED display with a 1-degree increment. So, you can set your desired water temperature as per your demand.   

Eco18 is the best choice for indoor use as its operations are noise-free.

This RTEX=18 requires 18 kW, 240 Volts, 2 x 40 amp breakers, and 8 AWG wires. Must upgrade your electric panel accordingly for the primal performance of the heater.

Technical Details

Voltage ‎240 Volts
Wattage ‎18000 watts
Amperage Capacity  2-50 amp
Item Weight ‎14.78 pounds
Maximum Pressure‎‎150 


  • Save energy, space, and water.
  • All switches operate silently.
  • Robust unit, resistant to high temperature and corrosion.
  • Ideal choice with a tight budget
  • Threaded for trouble-free replacements.
  • Energy-efficient, no more use of energy but as needed.


  • Can’t handle the high flow.
  • Not suitable for large families.
  • The wiring guide is not easy to understand.

10. Rinnai RL Series HE+ – Best Whole-House Tankless Hot Water Heater

Rinnai RL Series HE+ Tankless Hot Water Heater: Indoor Installation, Large, Silver; inline water heater
  • Sustainable reliability
  • Affordable, efficient savings
  • Endless hot water on demand
  • Up to 9.4 GPM hot water flow rate

To buy a best high volume tankless water heater that saves both your time and money is not an easy task. You have to consider many parameters like gallons per minute, energy-efficient, simultaneous use of multiple water applications providing instant hot water: in case of large families, indoor & outdoor installation if you have space issues. If stuck between rinnai condensing vs non condensing heaters, Tankless Rinnai water heaters with condensing technology provide the same efficiency and benefits as their non-condensing counterparts.

Non-Condensing Water Heater

Rinnai RL94iP HE is part of Rinnai’s non-condensing propane tankless water heater. The liquid propane acts as a fuel to operate this model and produces more units of energy to heat water much faster than others. So, the saving period starts immediately. 

Being an efficient-burning fuel, propane models allow the use of multiple fixtures simultaneously without disturbing the consistency of the water flow rate. 

Excellent Water Flow Rate In GPM

If we talk about the capacity of this unit, this model offers a pretty amazing flow rate up to 9.4 GPM making it a powerful model. You can run almost 4 to 5 water appliances at the same time without running out of hot water even if you are last in the shower taking line. You can run the dishwasher, do a load of laundry and enjoy a hot shower at the same time.

Without losing the consistency in flow, either 3 to 4 hot showers run smoothly or one shower with multiple faucets.  So, Rinnai RL94iP HE is the convenient choice for a family with 4 to 5 people with regular demand for instant hot water.

As compared to previous RLiP model, this model helps conserve both energy and water, being featured with PVC pipes, which have the capacity to save heat for a long.  All rinnai tankless water heater reviews are based on real testing and usage.

Circ-Logic Technology

Circ-logic technology provides you peace of mind by allowing quick access to instant hot water through the recirculation process. This circ-logic feature not only provides instant hot water but also preserves the hot water for future use. So, you don’t waste your time and water. 

This unit is robust and durable as stainless steel is involved in its manufacturing, also minimizing the danger of debris and limestone formation inside the pipes. So the heater works efficiently and lasts long.

How Rinnai’s ThermaCirc360™ Recirculation Works

Digital Temperature Control

You Can control the temperature ranges from 98 to 140°F through digital control. Wi-Fi monitoring mechanism gives you remote control to manage this unit from anywhere in the house.  

This is the biggest tankless hot water heater with an indoor installation model, and vents directly by utilizing concentric venting systems. This model requires 115 volts.

Technical Details

Power Source Gas Powered
Flow Rate ‎‎9.8 GPM
Voltage‎115 Volts
Item Weight ‎44.2 pounds
Warranty 12-year residential for heat exchanger, 5 for parts, 1 for labor


  • Highly efficient and preserves both water and energy.
  • Isolation and Pressure Relief valves are included.
  • Energy-star certified.
  • Allows consistent flow rate for multiple fixtures.
  • Easy preventive maintenance.


  • Advanced safety features are not included.
  • Has some noise issues.
  • Warranty is not applicable in some cases.

How to Buy Tankless Water Heater – Complete Buying Guide

tankless water heater buying guide

Instant hot water heaters are the basic need of the winter season for most of us, but when the market comes with a diverse variety of products. Then the right choice of purchasing on-demand hot water heaters becomes pretty difficult.

On increasing demand for hot water heaters, we have gathered all the factors one should consider before buying a tankless water heater. So, without wasting any time, let’s dive in.

What is a Tankless Water Heater?

As the name implies, tankless water heaters provide people hot water when they need it. Being most efficient in saving money, these tankless heaters are also free from any energy loss.

These tankless heaters are diversified into several categories depending on fuel, budget, power capability, and much more. The most basic tankless water heaters’ most basic division is based on the energy they consume for their efficient activity.

Types of Tankless Water Heaters

The fuel category for the tankless hot water heater depends on many factors, but most probably, the typical fuel types for tankless water heaters are natural gas, propane, and electricity. Every fuel has its pros and cons, and they also affect the productivity of the heater.

Natural gas tankless water heaters offer higher power output as compared to those of electrical models. Also, they can provide an ideal temperature in heating the water at a very affordable rate.

Though natural gas is ideally low in budget, gas tankless heaters are pretty expensive because of the technology used to make the units. Also, their initial setup upfront costs more( up to &1000) than that of an electric heater with tackling installation.

Buying a tankless water heater with the right choice of fuel is a deliberate decision. It’s time to have a look at the description of each fuel source.

Natural Gas   

Natural gas is one of the cheapest sources, and in most cases, the connections are direct. But these heaters offer you long-time use. Also, people with high household demands prefer natural gas as they are within the budget.

But the downside of tankless heaters having natural gas as a fuel source is storing natural gas which is not at all. Therefore, these appliances are not the right choice for RV use.

You have to spend more money on completely installing the natural gas heater if your house does not own an existing natural gas hookup.

 Propane Gas  

Propane gas is one of the most expensive fuels, and most people cannot fit this in the house. For a tankless water heater with propane, gas is used as fuel. So, a portable fuel tank is an integral part of the tanks.  

These portable propane tankless water heaters allow you to change the tanks when they have gotten empty, but this feature acts as the downside of the instant gas hot water heater as they are not appropriate for houses. But you can use them in recreational vehicles. Propane water heaters are more efficient but cost more than electric water heaters.

 Electric Supply   

Another fuel used in tankless heaters is electricity. Most of the time, people go with electric tankless water heaters, which are an affordable choice, whether about installation or initial purchase. But the increased electricity budget can add up to the cost.

The tankless electric water heaters have special electric specifications, depending on the model. Therefore, an expensive upgrade to the current electric system would be necessary to meet the unit’s specifications.

Indoor vs Outdoor Tankless Water Heater

Best of all, these tankless water heaters are also available in indoor and outdoor models. So, it is important to understand their pros and cons, including their installation process, their lack of space, and their venting concerns, before choosing an indoor vs outdoor tankless water heater.

Tankless Water Heater vs. Tank

tankless water heater vs tank

Converting to the tankless water heater is trending now, but even this cannot justify the current reach and importance of tankless water heaters. Tankless water heater dimensions make it efficient according to the choice of need.

 But for instant and continuous hot water delivery, tankless water heaters are usually preferred by the majority.

 Tank-type water heaters offer a higher flow rate as the water flows from the faucet freely without any water heating system obstacle that can slow down the water pace.

From the budget perspective, tankless water heaters are beneficial as there is no need to preheat the water or maintain its temperature that saves energy and time too to a considerable extent, and is thus easily affordable.

Initial installation of tankless water heaters is a bit pricey, but it will not be a bad deal when you enjoy a lifetime service.

Tankless water heaters are long-lasting but take time to install. On the other hand, tank-type water heaters are easy to install.

Storage tanks occupy a sufficient space whereas tankless heaters are slim and compact with a wall-mounting facility that can be fit easily on the wall anywhere in the house. 

How Does a Tankless Water Heater Work?

Tankless heaters help deliver the right amount of water. The working of tankless water heaters is genuinely excellent with a step-by-step heat process.

The water passes through a series of burners in natural gas and electric coils in electric heaters in every round. After passing these heaters, the water reaches the water fixtures from where you can use the required hot water for everyday use.

How does a tankless water heater work?

These tankless heaters are costly to install but think wisely; a one-time investment with long time usage is not a bad deal. Also, they do not run a water shortage due to fixed connections.

The temperature heat depends on the water flow and temperature coming from the direct links that vary concerning your place’s ties and geographical distribution.

How much water a tankless heater can handle depends merely on the increases in temperature degrees of the flowing water in the pipelines, and this is known as gallons per minute (GPM).

What Size Tankless Water Heater do I Need?

The next question that arises in any person’s mind when choosing a tankless water heater is the size that best suits your household and family’s demand for hot water. For this, one should know how to size a tankless water heater.

A few years back, tankless water heater sizing was a major point of interest, but now people do not look for tankless water heater sizes. Instead, they look for the type and quantity of faucets the tankless water heater will serve.

It is typically called GPM (Gallons Per Minute) or flow rate.

Determination of Power Source 

Power source ultimately depends on the user’s preferences and the current circumstances. Electric tankless water heaters are generally a better option for houses where the water demands are not too much.

Electric heaters are less expensive as compared to gas tankless heaters. But they do require a huge amount of energy to be functional. So, you have to upgrade the electric panel system of your house to get optimal performance, which is an expensive process notably. 

Moreover, they are a good choice to be used as point-of-use tankless water heaters but normally avoided to be used as whole house water heaters due to costly electric upgrades. 

Whereas gas tankless water heaters are the smart choice if your location has the availability of natural gas or propane. They also provide fast response time and high heat output to fulfill user’s demands efficiently.  

They are generally suitable to be used as whole-house tankless, but they require expensive venting. The good thing to know is that they are available in both outdoor and indoor installation. The outdoor installation is vent-free. 

 What size tankless water heater do I need for a family of 5 members?

Similarly, a family with five members looking for hot water on demand systems will have different priorities with some of the general extra appliances including an extra half-bathroom, one more shower, an additional washing machine, a dishwasher, and a half bathroom faucet.

The overall GPMs of the appliances, as mentioned earlier, will be about 10 gpm electric tankless water heater or 28 kW electric water heaters will be required, if your location is in the northern parts of the USA where the inlet water temperature is relatively low.

For the southern part of the USA, only 7 GPM or 18 kW on-demand hot water heaters would be convenient to fulfill hot water demand for a family of 5 members, depending on the inlet water temperature which is usually between 60°F to 80°F.

Calculation of Water Flow Rate

Tankless water pressure and water flow rate are directly related to each other. The water flow rate in the tank, whether it is a storage tank or tankless water heating system, aids you in how to choose a tankless water heater for you.

The water flow rate means the amount of water that can pass through the tankless heater when the heating system is working. Generally, we calculate the water flow rate in gallons per minute (GPM). 

There are two extremes of water flow rate, i.e., minimum flow rate (activation) and maximum flow rate. It ranges between 0.1 – 0.9 GPM.

 Minimum/Activation Flow Rate means the minimum amount of water required for activating the heating system of a tankless unit.

While the Maximum Flow Rate is the maximum amount of water that can flow smoothly in the water heating appliance. The water flow rate and temperature rise are directly related.  

How many GPM of hot water heater do I need? You can easily understand this with an example. For using two showers at a time, approximately 5 gallons of hot water per minute is required.

If you are using a shower faucet and washing machine, 4.5 gallons per minute will be enough. In short, the GPM for tankless models will depend on the number of appliances.

 For instance, how many gallons per minute does a shower use? The average shower GPM is 2.5 gallons, which means 20 gallons of water for the average shower.

The following table will represent the general flow rate. The flow rate varies at different temperatures.

Bath Tub4.0 GPM102°F
Shower3.0 GPM104°F
Clothes Washer2.0 GPM120°F
Dish Washer1.5 GPM110°F
Kitchen Sink1.5 GPM110°F

Temperature Rise

Temperature rise means the increase in temperature level needed for heating the incoming water according to your choice. If the heating system cannot maintain the water flow rate, you will start having cold water in the faucets.  

 Temperature rises can be calculated as:

Expected shower temperature – incoming water temperature = required heater temperature rise

 The difference between the incoming and outgoing water temperature is termed as temperature rise; for instance: the incoming and outgoing temperatures are 50 °F and 105 °F, respectively; the approximate temperature rise will be 55 °F.

Temperature rise and water flow rate have an inverse relationship that means if there is a more incredible temperature rise, the water flow rate will be low and vice versa. The temperature rise required for tankless water is also affected by the local water supply.

chart showing the relation between flow rate and incoming water temperature

The local water supply temperature varies in the regions of even the same country, like in the North U.S, the temperature rise is merely 35 degrees Fahrenheit. Also, it depends on the time that the tankless unit will take to heat the water for usage.

Power Unit, measured in British thermal units abbreviated as BTU, is termed as the energy required to heat the water to a targeted temperature. The amount of energy needed to raise one pound of water temperature by one degree Fahrenheit is one BTU.

Power Input (BTU)

The basic formula to calculate the power unit is:

(500 x GPM x Temperature Change = Required Power Input in BTU per Hour)

Efficiency Percentage

Condensing vs. Non-condensing Tankless Water Heater

Tankless units are also categorized into condensing and non-condensing water heaters in case of gas used as a fuel because whenever some gas is used in any procedure, water vapor or steam always forms due to the fuel burning and serves as the byproduct.

The pipes and ducts collect this steam and drain it out. Condensing and non-condensing tankless units are separate from each other due to the change in steam release duration in the ventilation process.

Condensing Tankless Water Heater

In a condensing water heater, a particular unit is referred to as a condensing unit where residual exhaust heat is captured and reused. After this, it passes through a cooling system and gets released through ventilation with 98 percent efficiency.

Non-condensing Tankless Water Heater

There is a direct and immediate vent steam system in the non-condensing tankless units that can bear up the high temperatures as premium quality materials are used in their construction.

Their initial installation costs much, but as a whole, they are okay to buy. Due to the immediate ventilation system, these tankless water heaters come with an 80-85 percent efficiency rating.

Electric versus Gas Tankless Water Heaters

One can buy an electrically heated or tankless gas unit, but people prioritize their choices based on the benefits they offer. Tankless gas water comes with more extensive gas lines, but their installation is a bit hectic and expensive compared to electricity.

Gas tankless water heaters can heat water faster and supply water with a higher pressure.

Different aspects make the tankless heaters top picks based on fuel choice. Some of them are:

  • Electric models are more efficient than gas tankless heaters, with an EF reach of 0.98. For gas-powered water heaters, the EF reach is 0.9. The minimum water capacity is a 40-gallon tankless water heater, and in some cases, it elevates up to a 75-gallon tankless water heater.
  • Prices of natural and propane units generally cost higher than electric models.
  • As for the initial cost, electric water heaters are affordable, costing between $500 to $1,000.
  • Electricity is the basic need and thus available everywhere; therefore, the electric heater is easy to install. Whereas gas heaters, you must have access to natural gas or propane that is not possible in some places. 220-volt tankless water heaters are common in the market as far as the power source is concerned.
  • The maintenance is easy. You just have to clean the inlet screen filter regularly. But for gas water heaters, one must have a trained technician to check them properly, and it can be expensive.
  • They ensure the least energy consumption which results in lowering the energy bills.
  • Gas units are heavier than electric units.

Point of Use vs. the Whole House Water Heater

Any house requirements decide what type of installation the users should go with either a point of use heater or whole house tankless.

The whole house gas tankless water heater usually fulfills large demand for instant hot water and has a different installation setup where all the appliances are connected with the tankless water heater. Now you can enjoy hot water from any of the house water inlets with the residential tankless water heater.

Whereas point-of-use tankless water heaters are designed to fulfill the low demand for hot water, and installation refers to only one appliance closer to the tankless water heater. These small water heaters are the best for a small family with two to three persons.

Pros and Cons of Tankless Water Heaters

Many questions arise when we think about buying a tankless water heater. Some of the questions are:

We have jotted down all the answers in detail for your ease.

What are the Advantages of a Tankless Water Heater?

The benefits of a tankless water heater do not limit to a known extent. Every instantaneous water heater comes with a variety of advantages. Some general plus points of endless hot water heater are:

benefits of tankless water heater

Saves Energy

Tankless heaters provide hot water on the spot. In addition, there is no heat loss by heating and re-heating water as the tankless heater will only process it whenever hot water is required.


Above all, tankless water heaters are famous for their life span that is amazing with long service life. If a user uses the tankless water heater with proper care and maintenance, the average life of the tankless heater is about 20 years.

Replaceable Parts 

Electric tankless water heater pros and cons are noticed at a large level as they come with the facility of replaceable parts. Manufacturers have adequately taken all the facts under consideration, and with proper dedication, they have designed the heaters so that if it happens to break or leak at some point, it can be repaired and even replaced.  

Compact Design 

They come with a compact and robust design for easy and quick installation. You can mount these tankless water heaters on the wall both outside and inside the house. And no need to worry about space consumption as compared to tank storage.

Unlimited Supply of Hot Water

The capability of tankless heaters to supply hot water is fantastic, and every tankless heater offers heating services according to the requirements of the place. If you have the right size for your house, your family will enjoy the tankless heater’s long-lasting benefits.

Tankless water heater benefits the users in providing fresh water. There is no scene of water sitting in the tank in storage water heaters. You will be served with freshwater as the connections are made directly with the pipelines.

Fresh Water Availability

Resultantly, your hygiene will also be okay because there will be zero chance of rusting when there is no water sitting. The tankless heater performs its duty well whenever hot water is needed, and as the demand is fulfilled, the tankless heater immediately stops the water heating process.  

Mind Relaxation

As there is no storage tank with a tankless water heater so there will be no chance of any leakage until or unless you face a significant crack in the pipelines but not directly related to the tankless heaters. They are efficient in their activity, and it rarely happens that they are having issues before the guaranteed time.

What is the Downside of a Tankless Water Heater?

Sad to know that tankless water heaters have some drawbacks. Let’s check them out:

what is the downside of a tankless water heater?

Initial Costs

Though tankless water heaters are not too costly, they demand a handsome amount of money for the initial setup. But except for the initial costs, they are easy to manage in the budget. 

Capacity Issues

As far as the demand is concerned, every house has its own specific water demands, and here it comes when most people are stuck. It may happen you have to install two large tankless appliances according to the requirements of our house.

But your apartment or house does not seem enough to compensate for two tankless heaters, so as an alternative, you can also add a small point of use for bathroom services.

Upgrading Power Resource

Upgrading power resources for the electric tankless water heaters is a must. One has to implement water heating systems with recommended electricity for delivering a larger quantity of hot water, especially in older places.

Expensive Venting

Expensive venting is required for a non-condensing gas-fueled model.

Output Limitations 

The system’s capability should match the household’s hot water demands; otherwise, the tankless heater will not deliver hot water of expected demands. Yeah, if your tankless heater comes with a storage tank, it can manage the water demands to some extent in emergency cases.

types of tankless water heaters


This buying guide describes thoroughly all features of top tankless water heater brands.

Now, it is easier for you to choose the best instant tankless heater to provide you with in-line hot water, ideally fulfilling all your household demands of instant hot water.


What is the best tankless water heater on the market?

The best tankless hot water heaters must have the following features to be the best. They must have a maximum of 6GPM. They must be energy star certified. As they are eco-friendly and energy-efficient and almost save 50% on electric bills. 

Furthermore, robust materials like stainless steel and copper are used in manufacturing which increases durability and long-lasting. 

The best tankless water heaters come with a convenient warranty. Some of the models of popular brands fulfill the above-mentioned criteria. 

They are EcoSmart 27, Rinnai RL series, Stiebel Eltron Tempra series, and Rheem 240kw are some of them.

Is a tankless water heater worth it?

Tankless hot water heaters come with multiple benefits like they provide endless hot water for household demands but never run out of it when installed properly. 

They do not waste energy by heating and reheating water as they heat water instantly when it is required. 

They terminate standby loss. Being most energy efficient, they use less energy, only when hot water is required. Consumer reports state tankless heaters help you save $100 yearly as they are 22% more efficient than conventional tanks. 

Surprisingly, tankless water heaters have slim and compact designs with wall-mounting features that do not require huge space to be placed. They fit easily anywhere on the wall in the house.

Also, they are available in electric or gas models. So, choose wisely which is in your budget. They are robust and have decent warranties. With regular maintenance, they can run up to 20 years.

Damage parts are easily available and replaceable. 

What is the disadvantage of a tankless water heater?

Sadly, instant hot water heaters have some disadvantages too. For instance, they have a limited flow rate. If you need multiple water applications with instant hot waters at the same time, you will face a low flow rate or even cold water accidentally. Unless you install either a whole house tankless heater system or many point-of-use water heaters near each water source self-modulating power control. And definitely, this solution is costly.

An on-demand water heater is three times more expensive than a traditional water heater. You have to spend sufficiently on electric upgrades in the case of electric tankless heaters. 

Not only gas models are expensive but their initial cost is also high. As you spend a huge amount on installation and venting. 

If your location has hard water, then water softener installation is a must to run the tankless heater properly. Otherwise, the tankless water heater will die soon. Regular maintenance is compulsory for the longer life span of a water heater.

What size tankless water heater do I need for a family of 5?

The family with 5 people has a high demand for instant hot water. As many household tasks like hand washing, dishwashing, hot showers,  and laundry might be carried out simultaneously. 

So, it would not be a wrong estimation if we say that 10 gpm tankless water heater electric is the considerable flow rate for the family with five persons. And the incoming water temperature is low. 

And 7 GPM is adequate for this 5 memeber family if the inlet water temperature is high. 

How long does a tankless water heater last?

Fortunately, top rated tankless water heaters last long. But their long life is dependent on various factors which are regular maintenance, decent usage, and incoming water quality. 

Tankless water heaters last about 20 years, whereas storage tanks have a shorter life span, generally 8 to 12 years. 

They are robust and made with stainless steel which is corrosion resistant. Further, their parts are easily available and can be replaced easily. These features also extend their life span.

What is the average cost of tankless water heater?

It depends on the size of the tankless heater and the demand for hot water. Generally, you need to spend $400 to $700 for a medium-sized tankless unit. If you go for larger tankless models, it may cost around $ 1000 to $1800 apart from the installation cost.

Daniel Adley is an experienced and skillful plumber having more than 20 years of experience. He is a skillful plumber who passionately repaired and optimized water appliances of large buildings, offices and homes. He would efficiently identify plumbing and maintenance issues.

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