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Best Tankless Water Heater Reviews – A Complete Buying Guide

Unless you like the feeling of icy cold water cascading over your skin every time that you take a shower, you need a good water heater. Manufacturers now make tankless water heaters that do not have a large or bulky tank and instead offer warm and hot water almost instantly. Based on the power provided and gallon per minute rating, you may have enough hot water for each member of your family with water left over for doing dishes and laundry.

The most important thing to look at is whether the water heater uses gas or electric. We choose the best hot water heaters in both categories to help you find the one that will work best for your family and in your home. 

Top Electric Choice

Electric hot water heaters are great for homes that have electric lines already running through the house and homes that do not have any propane or natural gas hook ups, and the Eemax HA036240 240V 36 kW Electric (Check Price on Amazon.com) is easily the best of those hot water heaters. This hot water heater has approval from Energy Star and comes with a digital screen that lets you select the water temperature. You can spin the dial to adjust that temperature to a specific degree and to switch between Fahrenheit and Celsius too.

Top Gas Choice

The top tankless gas water heater is the Westinghouse WBRCNG140W 140K BTU Space Heating Boiler (Check Price on Amazon.com), which is available in a version that uses natural gas as well as one that uses propane to let you select which model will work in your home. It can help you utilize up to 95% of your home’s gas supply and run more efficiently with less gas wasted, and this is an Energy Star certified water heater. A large boiler inside helps heat the water faster and provides up to 7.1 gallons of hot water per minute on even the highest of settings.


Top Electric Choices

Rank Product Review Score
1 Eemax HA036240 240V 36 kW Electric
9.9 Buy on Amazon
2 Stiebel Eltron Tempra 36 Plus
9.8 Buy on Amazon
3 Stiebel Eltron 232886 Tempra 36B
9.8 Buy on Amazon

Top Gas Choices

Rank Product Review Score
1 Westinghouse WBRCNG140W 140K BTU Boiler
9.7 Buy on Amazon.com
2 Rinnai RUR98iN 9.8 Max GPM Ultra Series Condensing
9.6 Buy on Amazon.com
3 Rheem RTGH-95XLN Prestige Natural Gas
9.5 Buy on Amazon.com

Top 11 Electric Choices

Eemax HA036240 240V1. Eemax HA036240 240V 36 kW (Check Price on Amazon.com)

The Eemax HA036240 240V 36 kW landed in the top spot on our list of the best because it is one of the only water heaters that lets you adjust the temperature of your water to a specific degree, and you can even choose between using the water heater in Celsius or Fahrenheit. A control knob twists to pick the minimum or maximum temperature, but you can also press this knob down when you want to change between temperature options. It also comes with a digital screen that shows the current temperature setting, which can help you see when someone in your house changes your setting.

Inside this hot water heater are parts made from both brass and copper that do a good job of regulating heat, including a heat exchanger made from copper and a top on the exchanger made from brass. Designed for use and installation anywhere in your home, it takes up less than 90% of full hot water heaters but can still provide you with ample hot water. As this is an electric model, it does not require any special venting either because it will not release carbon monoxide or other dangerous vapors.

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Stiebel Eltron Tempra 362. Stiebel Eltron Tempra 36 Plus (Check Price on Amazon.com)

Stiebel Eltron makes our list of the top options, but the model that we rank the highest is the Tempra 36 Plus , which we think will do the best job in your home. This water heater has a great design that features a control knob that shows you the right temperature for different jobs like washing dishes or taking showers, which takes the guesswork out of deciding where to move the dial. It also has a digital screen that shows the degree of the current temperature and lights that tell you when the water heater is on and still operating or turned off.

Installing this hot water heater requires just two lines that allow water from your home’s system to enter the heater and come up to temperature before moving out through a second line. The manufacturer claims that you can save up to 20% on your electric bill with this model because it does such an efficient job of heating the water. It also features advanced flow control technology that ensures that water that comes out is at the temperature you selected and that it never comes out cooler or hotter.

Stiebel Eltron 2328863. Stiebel Eltron 232886 Tempra 36B  (Check Price on Amazon.com)

Though fairly similar to the Stiebel Eltron model ranked in the previous spot, this 232886 Tempra 36B is better suited for smaller homes but comes with all the same features that shoppers love about that model. It has two connections on the bottom that help you easily hook up your water input and output lines, which will provide your family with all the hot water that they need. This Tempra also has a sleeker and smaller design that makes it just a little more compact and lets it take up less space, and it’s up to 90% smaller than traditional gas water heaters.

While it doesn’t have a digital temperature screen, it does have a dial on the front with temperature markings around the edges that still let you pick a specific temperature, and those markings make it clear which temperatures are suitable for commercial use, residential use and basic water needs like washing your hands. A small light beneath this knob changes colors to reflect when the water heater has power, which causes this light to blink rapidly, when it’s in standby mode but still has power and when the water heater is completely off.

Stiebel Eltron Tempra 204. Stiebel Eltron Tempra 20 Plus (Check Price on Amazon.com)

Another option from the same manufacturer is the Stiebel Eltron Tempra 20, which is a hot water heated designed to provide enough hot water for every room in your house as well as every user. Whether you want the scalding hot water associated with commercial use, water hot enough for your daily shower or warmer water for doing dishes and washing your hands, this water heater will let you pick the right temperature setting, and it even included a sticker around the control knob that shows you which temperature is best for each application. The power light will turn bright red when the water heater has power and fade to a dull red color when it does not have power.

Installation of this model is easy because it does not require any vents and comes with connections already attached to the bottom for hooking up to the water lines. You can adjust the flow rate of the water heater based on what you need to use it for too, and it has a flow range of 0.58 to 4.5 gallons of water per minute. It requires a circuit breaker of just two times 50 amps to run.

SioGreen IR8000 Infrared5. SioGreen IR8000 Infrared Electric (Check Price on Amazon.com)

SioGreen designed this IR8000 for those who wanted a more powerful commercial hot water heater that they could use in their homes because it packs all the top features of commercial models into a water heater designed for residential use. It requires 80 amps of your circuit breaker to run but can provide enough hot water for all the rooms in your home, including your kitchen and multiple bathrooms. Instead of using the old metal coils that some heaters do this water heater uses infrared technology that will never require any maintenance like your old hot water heater did.

A unique feature of this hot water heater is that it only heats the exact amount of water that you need and will not leave water sitting around on the inside, which can leave that water with a metallic odor or taste. As it does not heat and then waste large amounts of water, this model can help you save up to 60% on the cost of heating hot water for your home. This is also a hybrid hot water heater that has solar cells that absorb heat from the sun to provide you with hot water if your electric goes out.

Rheem RTE 27 Electric6. Rheem RTE 27 Electric (Check Price on Amazon.com)

With a flow rate of five gallons of water per minute, this Rheem RTE 27  moves so quickly and smoothly that you’ll never run out of water, even if you hop in the shower right after a loved one climbs out. A temperature control located right on the front of the unit lets you move a knob to the left to turn the heater to its lowest setting or all the way to the right to use it at its highest setting, and while it doesn’t have a digital screen, it still offers plenty of temperature options. Finding out whether the unit is on is as easy as looking at the lights on the front, which shows you when it’s in standby or operational mode.

The heat exchanger inside features a combination of both brass and copper to keep the water at the temperature you want, and it has connections that allow water to flow from one hose, inside the water heater and out the opposite end to reach your tub, sink or shower. In addition to its maximum flow rate, this water heater also has a minimum flow rate that lets you use just 0.4 gallons per minute.

BOSCH Tronic 6000 C7. BOSCH Tronic 6000 C (WH27) (Check Price on Amazon.com)

Designed to take up as little space as possible, this Tronic 6000 C from BOSCH is so compact that you can install it anywhere you need it, including in your laundry room, kitchen or basement, and it takes up 90% less space than a standard hot water heater would. BOSCH guarantees that the Tronic will provide you with an endless stream of water at a temperature high enough for bathing, and flow sensors built into the unit will regulate the water to keep it hot. Though it has a standby mode, it can actually keep water hot when turned to this mode, which ensures that water will still come out hot, even after it shuts down.

The front of the unit features a small screen and a knob below the screen, but plus (+) and minus (-) symbols on either side of the knob let you know which way to turn it to increase and decrease the water temperature. You can then see the exact temperature on the screen. The Tronic also comes with built-in scale protection that keeps mineral residue left behind by hard water from leaving behind scale inside the water heater.

EcoSmart ECO 36 36kw8. EcoSmart ECO 36 36kw 240V (Check Price on Amazon.com)

One of the most popular hot water heaters around is the EcoSmart ECO 36 , which is perfect for those who want to protect the environment and reduce their water and heating bills. EcoSmart claims that you can slash your water heating bills in half once you install this model and that it can keep you from wasting water too. This is an on demand model that provides you with hot water anytime you need it, and though it’s a little on the small side, this water heater can heat water in seconds after you turn on the tap.

The front of the unit features a solid black face with a bright and shiny knob in the center that you can turn when raising and lowering the temperature of your water. EcoSmart added words on each side to tell which way to turn the knob based on the temperature that you want, and thanks to its bright digital screen, you can actually view the accurate temperature of the water too. Depending on the temp you choose, this water heater can heat and provide you with between 3.5 and six gallons of hot water every minute.

IHeart Tankless Electric Water9. IHeart (Check Price on Amazon.com)

This iHeart Heater is a good choice for those living in the southern half of the United States because the ground water in those regions is naturally warmer, which allows the water heater to bring that water up to temperature even faster, and depending on where you live, you may find that it can provide enough hot waters for up to three people to take a shower right after one another. Sensors inside the water heater monitor the water passing through up to 50 times each second to ensure that the water is always at the right temperature. It also comes with a standard inlet and outlet for hooking it up to your system.

As long as you have a memory stick, you’re only seconds away from doing a full diagnostic scan on the unit because it lets you connect that memory stick to your laptop or desktop to see when the unit needs maintenance or repairs. A touchscreen display shows you both the temperature of the water coming in and the temperature of the water going out. When you need to adjust that temperature, you can simply use the up and down arrows on this screen.

EcoSmart 24 24 KW10. EcoSmart 24 24 KW at 240-Volt (Check Price on Amazon.com)

Another EcoSmart hot water heater that would do well in your home is its 24 24 KW at 240-Volt, which requires a three double pole of 40 amps to run, which is standard in many of the modern homes built today, and it will work with most 200 amp circuit breakers. Designed for homes located in both warmer and lower climates, it can heat water that comes from the ground of a temperature as low as 37 degrees Fahrenheit. Though it heats nearly three gallons of water per minute, you should compare this model to the needs of your home to determine if it can supply enough hot water for your whole family.

Like the other EcoSmart hot water heater we included on our list, this one has a digital screen on the front that both lets you know the temperature of the water and also shows any temperature changes made by you or another user. The bright blue color of the numbers is easy to see against the darker background, and the unit itself has a dark background all across the front. Using the silver knob lets you adjust the temperature one degree at a time.

Eemax HA018240 240V11. Eemax HA018240 240V 18 kW (Check Price on Amazon.com)

This Eemax HA018240 240V 18 kW combines elements of smart hot water heaters with traditional heaters, and you may notice that it looks pretty similar to the EcoSmart line of water heaters. Though it looks like a simple metal box, it features a compact design that you can install anywhere and lots of features tucked inside like a copper heat exchanger with a brass piece on top that monitors and regulates the water passing through. As it requires a standard 240V circuit breaker to run, this water heater is suitable for use in most residential buildings.

If you want to turn this water heater off, you can press down on the dial on the front until you hear a click, but this dial also rotates in both directions to turn the water temperature up and down. The digital screen that this water heater has on its front shows you the current temperature, which you can adjust based on your preferences or how much energy you want to save. Though it has a wide temperature range, it also comes with a built-in scald prevention feature that keeps the water from scalding any users.

Top 11 Gas Choices

Westinghouse WBRCNG140W 140K1. Westinghouse WBRCNG140W 140K BTU Space (Check Price on Amazon.com)

No matter how many people live in your home, this Westinghouse WBRCNG140W 140K BTU  will ensure that you always have more than enough hot water on hand because it has a flow rate of 7.1 gallons of water per minute. Certified by Energy Star, this Westinghouse hot water heater has a modulating boiler inside that uses natural gas and produces up to 140,000 British Thermal Units, which ensures that the water always comes out at the perfect temperature. With an efficiency rating of 95, installing this model in your home can help you save significantly on the cost of hot water.

The heat exchanger inside uses stainless steel, which is just as durable and long-lasting as copper and also does an adequate job of regulating heat. It comes with a warranty directly from Westinghouse that covers all the parts inside for a period of five years and the water heater itself for a full 10 years, though the warranty only covers residential use and not commercial use. Another feature that you will appreciate is a built-in detector that monitors the water heater for signs of leaks, and this feature will alert you of any gas leaks it finds.

Rinnai RUR98iN 9.82. Rinnai RUR98iN 9.8 Max GPM Ultra Series Condensing Indoor NG (Check Price on Amazon.com)

The Rinnai RUR98iN 9.8 Max GPM Ultra is one of the best gas hot water heaters for those who prefer the look of electric models but do not want to change their hook ups and connections. It features a digital screen on the bottom that shows the temperature you selected and nearby buttons that let you turn the water heater on and adjust the temperature up and down by a single degree at a time. The recirculation technology that it uses keeps you from running out of hot water because this feature allows warm water to keep moving through the lines to have hot water ready the moment you turn on the faucet.

Rinnai gives you two venting options: PVC and concentric to let you pick the type of venting that will work best for your home, but both types allow any gas to move outside of your house and away from your family. Though it has an Energy Factor rating of 96, it’s no larger than a small suitcase to help it save on space. Other features that cut down on the wait time for hot water include a thermal bypass valve and integrated pump.

Rheem RTGH-95XLN3. Rheem RTGH-95XLN Prestige NG (Check Price on Amazon.com)

This Rheem RTGH-95XLN Prestige has an energy efficiency rating of 94, which not only earned it an Energy Star seal of approval but also lets you know that it will use less of your natural gas when heating water for showers and other uses. The Prestige has a venting system that requires the use of two PVC pipes and keeps any natural gas from leaking out of the unit, and you can use this unit will both longer and shorter pipes based on the size of your home. It has a minimum flow rating of 0.26 gallons per minute, which is the lowest in the industry and suitable for smaller cleaning and washing jobs.

Rheem includes an EZ-Link cable that you can use for connecting this water heater with a second heater, which creates a dependable system designed to meet the needs of even the largest of homes. Unlike other water heaters that require a chip for use in homes in a high altitude area, this one will compensate for that altitude without any other parts. The Prestige is also one of the only natural gas tankless water heaters to come with its own remote control for changing the settings without opening or using the unit.

Navien NPE-240A Premium4. Navien NPE-240A Premium Condensing (Check Price on Amazon.com)

A common issue that some have with gas tankless water heaters is that the exchanger inside isn’t strong enough to keep up with the demands of all users, but this Navien NPE-240A Premium  actually has two heat exchangers inside that work together to keep the hot water flowing, and both use stainless steel to ensure that the exchangers last longer. Designed for use with a 1/2-inch gas line, this Navien water heater will easily connect to the existing gas line in your home. It meets all low emissions standards and comes ready for installation with a venting system to move any gas produced out of your home.

As an Energy Star certified water heater, this one uses less natural gas to help you save on gas costs and features a condensing design to use even less gas. The water heater also has a small screen that sits on the bottom front of the unit and shows you the current water temperature. It uses an intelligent preheating system that actually helps heat the water up as soon as it comes out of the ground to reduce the time that you spend waiting for hot water.

Reliance TS-540-GIH5. Reliance TS-540-GIH 199K Indoor NG (Check Price on Amazon.com)

The Reliance TS-540-GIH 199K is one of the most reliable gas water heaters designed for use in homes with existing natural gas lines, and it has a 95 efficiency rating, which helped it obtain Energy Star certification. Built-in condensing technology allows the water that flows through the unit to come up to temperature faster without using as much natural gas as other heaters do, and it is a 199,000 BTU unit that can use as much gas as necessary to heat all the water your house needs. This also earns our recommendation because it has a higher flow rate of 10 gallons per minute, which is higher than all the other water heaters we saw.

Though it requires vents of three-inches or four-inches, Reliance designed this gas water heater to work with vents made from different materials to ensure that those vents offer the protection that you need for your family and that the vents will not clash with the decor of your home. When you choose the right size unit for your home, you may even earn a credit good when you file taxes next year. This tankless heater has a digital screen that shows the input and output water temperatures and gives you access to additional settings.

Noritz EZTR40-NG6. Noritz EZTR40-NG Indoor NG(Check Price on Amazon.com)

If you want to replace an old and clunky water heater that takes up a lot of space, you’ll like the Noritz EZTR40-NG Indoor, which the manufacturer designed specifically for use as a replacement for a standard gas water heater with up to a 40 gallon capacity. Though it’s larger than some of the other units on our list, it still takes up significantly less space than traditional gas water heaters do and features a design that provides you with an almost endless supply of hot water. It comes with both a flexible venting kit for creating a venting system that works with your home and an isolation valve kit.

Connections on the top of the water heater let you hook up both your water lines and the venting, and those connections allow both cooler water to come through and warmer water to come out. As it has an Energy Star listing, this water heater can help lower your water heating bills by 10% or more. It also has a maximum flow rating of more than six gallons per water and a durable metal door that protects the inside of the heater but opens to give you full access to the heater’s settings.

Rinnai RUC98iP Ultra7. Rinnai RUC98iP Ultra Series Propane NG (Check Price on Amazon.com)

Though some tankless water heaters have a bland look with plastic components and light colors, this Rinnai RUC98iP Ultra Series Propane has a more modern look that includes a rugged case that protects the internal components and a matching metal front with all the buttons that you need right on the front. Instead of fumbling with the door to change the water temperature, you can just use the buttons on the front. You can press one button to view the output water temperature and another to view the input water temperature, or you can use the arrow buttons to increase and decrease the water temperature as it comes out.

Designed to meet all emissions standards, this water heater has a low emissions rating that makes it suitable for use in regions with emissions regulations, but it will also work with a vent system to ensure that no emissions or fumes every reach your family. With a 96 energy factor, this is one of the most efficient water heaters that rely on propane around. It comes with everything necessary for installation inside the box and features connections that will work with two different types of vents: concentric and PVC.

Bosch 830 ES LP Therm8. Bosch 830 ES LP Therm NG (Check Price on Amazon.com)

Standard water heaters feature a large tank that keeps the water stored inside at a warmer or higher temperature, but this Bosch 830 ES LP Therm has a tankless design that still provides you with ample water for bathing and other uses. It has a max BTU output of 175,000, which is a little lower than some of the others on our list and one of the reasons why we ranked it lower. Despite being smaller in size, it still has an overall energy efficiency rating of 83, which lets you know that it will still use less gas than your old water heater did.

Capable of working with four-inch or three-inch vents, this water heater uses those vents to ensure that the fumes and emissions produced safely vent outside your home and that those fumes will never disrupt your family. Its electronic ignition is more effective than other types of ignitions and ensures that the water heater comes on quickly, and the ignition works with a burner designed and patented by Bosch for regular use. The water heater also has a digital display on the front that shows the water temperature and a maximum flow rating of 8.3 gallons of water per minute.

Rinnai RU98EN 9.89. Rinnai RU98EN 9.8 GPM Outdoor Ultra-NOx Condensing NG (Check Price on Amazon.com)

Low emissions water heaters like this Rinnai RU98EN 9.8 GPM are mandatory in certain parts of the country like California and other regions that have laws in place to protect the environment. This one meets the standards in place in both Texas and California because it releases fewer emissions and will do less damage to the environment while also ensuring that those fumes don’t make your family or pets sick. Rinnai also designed this as one of the only gas water heaters designed for outdoor installation, which means that you don’t need to find space in your home for it.

With a maximum flow rating of 9.8 gallons of water per minute, this condensing tankless water heater ensures that hot water comes out of any faucet almost as soon as you turn it on. It has an energy factor rating of 95 and comes set at a temperature of 120 degrees Fahrenheit, which is suitable for most residential uses, but you can adjust that temperature up and down as needed. You’ll also like that this water heater is compatible with the line of digital controllers available from Rinnai and that it has a condensing design to help you save on energy costs.

Rheem RTGH-95XLP10. Rheem RTGH-95XLP Prestige Propane (Check Price on Amazon.com)

If you live in a larger home, or you have a number of people who need hot water, you need a larger hot water heater that can accommodate the needs of your household like this Rheem RTGH-95XLP , which has a higher flow rate that provides up to 9.5 gallons of perfect hot water every minute. It features a direct venting system that lets you connect two vents to the water heater, which it turns ensures that any of the fumes produced will enter into those vents and move away from your home. This system also allows Rheem to market this as a low emissions water heater and ensures that it meets the emissions standards found in most states.

A condensing heat exchanger inside does a more effective job of heating the water without using as much propane as other water heaters will, and it has an energy efficiency rating of 94, which earned it certification from Energy Star. Its activation flow rate, which refers to the rate used when the unit is on a higher setting, has a minimum flow rate of .40, but you can change this flow rate based on your specific needs.

Rinnai RUC90iN Ultra Series11. Rinnai RUC90iN Ultra Series Condensing Indoor NG (Check Price on Amazon.com)

This Rinnai RUC90iN Ultra is another good choice for use in homes with more people as well as homes with multiple bathrooms because it has a maximum flow rate of nine gallons of water per minute, and no matter what temperature you set that water to, it will always come out quickly at that temperature. Though it doesn’t have a tank that stores hot water, it uses condensing technology to quickly heat the water and to store hot water inside the pipes. You can use this model with either PVC or concentric options, and it can work with vents of different types of keep fumes out of your home.

Up and down arrows near the bottom of the water heater let you adjust the temperature in one degree increments, and you can see the temperature as it changes via the digital screen nearby. This tankless water heater will show you the temperature of the ground water when you press the input button, which can help you decide how high to raise it, and you can also click the output button to view the temperature of the water coming out of the heater.