Reviews of The Best Tankless Water Heaters of 2019

Published by Alexa Bartel on

Reviews of The Best Tankless Water Heaters of 2019

Switching from a traditional hot water tank to a tankless model is one of the best things you can do for your home and your water. A tankless water heater will heat your water without taking up too much room in your home or driving up your energy bills. That said, there are so many of these units on the market that it can be hard to identify the best tankless water heaters for your home.

We understand how intimidating it can be to pick the right tankless water system for your home, which is why we put together a guide of tankless water heater reviews to make your purchase decision easy.

IMAGEPRODUCT
  • Can meet any residential house’s need
  • Produced by an industry leader in water heaters
  • Hassle Free Warranty Process
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  • No Expansion Kit Required
  • Very Silent
  • Dual Pipe makes unit more efficient by using condensation water
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  • Best in class flow rates for electric tankless
  • Trusted by many verified online purchases and reviews
  • Great warranty for peace of mind
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  • Great value – flow rate and quality for the price
  • Trusted by many verified online purchases and reviews
  • Great warranty for peace of mind
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  • One of the best brands in water heaters
  • Standard 10 year warranty
  • Leading energy efficiency rate at 94% (Compared to other outdoor units)
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  • One of the best brands in water heaters
  • Strong flow rate at 8.6 GPM
  • Does not require any ventilation, since it is outdoor.
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  • One of the most powerful tankless heaters below $500 price mark
  • Built by a reputable brand name
  • Comes with a standard 10 year warranty
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  • One of the smallest units
  • Well reviewed by thousands of users
  • Industry leading warranty
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  • Maintenance free water heater
  • Well reviewed by thousands of users
  • Industry leading warranty
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  • Powerful unit capable of handling any incoming water temperature
  • Backed by one of the biggest names in water heaters
  • Industry leading warranty
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10 Best Tankless Water Heaters
Reviews of 2019

If you are looking for the best gas tankless water heater for your home, look no further than the Rinnai RUR98iN Ultra Series. This model is considered by many to be one of the best ever produced for residential use. Armed with an impressive 96% efficiency factor and the ability to provide 9.8 GPM ( gallons per minute ) of hot water flow at nearly any incoming water temperature, this tankless water system by Rinnai is capable of replacing traditional hot water heaters in nearly any climate.

A stand out feature that’s unique to this water heater is its Wifi Capabilities. This feature allows you to monitor and change your water heating settings over your home network. The system also boasts an innovative re-circulation line which allows this unit to produce an endless supply of hot water. It’s worth considering that very few tankless water heaters that offer these luxurious features — the investment will easily pay for itself in both savings and ease of use.

The Pros

  • Can meet any residential needs
  • Produced by an industry leader in water heaters
  • Hassle Free Warranty Process
  • No Expansion Kit Required
  • Quiet
  • A Dual Pipe makes the unit more efficient by using condensation water

The Cons

  • Most expensive unit you will find for residential use
  • Requires venting and does not come with a venting kit
  • Might be excessively powerful for smaller homes
Read the full in depth review: Rinnai RUR98iN 9.8 Max GPM Ultra Series

We can say with confidence that if you’re looking to provide on-demand hot water for your whole house, then the Rinnai RUC98iN Ultra Series is the unit for you.

With the ability to produce a staggering 9.8 GPM of hot water with a temperature rise of 50 Degrees Fahrenheit, this natural gas tankless water heater is perfect for nearly every home. Many of these tankless water systems aren’t capable of providing hot water for an entire house, due to the fact that most natural gas tankless models don’t have the same gallons per minute flow rate as this unit.

We recommend professional installation since this unit requires a natural gas hook up. It’s important to note, as with any tankless water heater, that it may take up to 20 seconds for the water to heat up from this heating unit to the faucet. That said, once it’s warmed up, this natural gas tankless water heater will provide an unlimited amount of hot water and slashed energy bills.

The Pros

  • Can meet nearly any capacity need
  • Produced by an industry leader
  • Hassle Free Warranty Process
  • No Expansion Kit Required
  • Quiet
  • Dual Pipe makes unit more efficient by using condensation water

The Cons

  • Most expensive unit you will find for residential use
  • Requires venting and does not come with a venting kit
  • Gas water heating might be excessively powerful for smaller homes

Read the full in-depth review: Rinnai RUC98iN Ultra Series

Electric based tankless water heaters have been making strides in recent years. For example, the Stiebel Eltron Tempra Plus has made waves as one of the best electric water heaters in the industry. It is, after all, Stiebel Eltron’s flagship product.

With capabilities to provide an impressive 4.0 Gallons Per Minute and attain incoming water temperatures of 72 Degrees Fahrenheit, this is truly one of the most powerful and efficient electric water systems available on the market today.

The best feature of the Stiebel Eltron Tempra tankless model is its easy to use digital controls. Its small and sleek design allows you to install it nearly anywhere, from under the sink to behind a furnace or in a small utility closet. It uses solar as a power source, making it highly efficient — in fact, it can nearly match the utility costs of natural gas tankless water heaters or, in some cases, outperform them significantly.

Pros

  • Best in class water flow rate
  • Trusted by many verified online purchases and reviews
  • Great warranty for peace of mind
  • Industry leader

Cons

  • Slightly more expensive than other tankless models
  • Will require 2+ units to provide for an entire house

Read the full in-depth review: Stiebel Eltron Tempra Plus

If you are in need of a simple water heater to put under your sink or in a new powder room, then at 240-volts, the EcoSMART ECO model is the right unit for you. This unit is perfect even if your incoming water temperatures are quite cold, because it is able to provide a 1.5 GPM flow rate with a temperature rise of 50 degrees Fahrenheit.

Generally, this type of water system isn’t capable of handling high gallons per minute flow rate. For simple purposes, however, this unit from EcoSMART will be more than enough for nearly any home — regardless of its incoming water temperature.

EcoSMART is a highly trusted brand, and for good reason. Their system has been a best seller for three years straight, and as is known as one of the most efficient units on the market — it even has the reviews to back it up!

Pros

  • Great value, flow rate and quality for the price
  • Trusted by many verified online purchases and reviews
  • Great warranty for peace of mind

Cons

  • Somewhat unknown brand
  • Larger unit than expected
Read the full in-depth review: EcoSmart ECO 27

The Rheem RTGH-95XLN Prestige is one of the best outside tankless units you can find on the market. In addition to being high quality and well rated, it also boasts a high energy factor (94%) and one of the highest flow rates (9.5 GPM). The best part? The water heating system requires no ventilation and can meet the needs of most homeowners!

Pros:

  • One of the most trusted brands in the business
  • Standard 10 year warranty
  • Leading energy efficiency rate at 94% (Compared to -other outside units)
  • High energy factor & high flow rate at 9.5 Gallons Per Minute
  • Does not require any ventilation

Cons

  • While it seems expensive up-front, the high energy efficiency will make it cheaper over time.

Read the full in-depth review: Rheem RTGH-95XLN Prestige

If you’re considering a tankless water heater for outside to save a few dollars, then the Rheem RTG-84XLN is the right choice for you. With a strong flow rate of 8.4 GPM, which is satisfactory for most homeowners, this “middle of the road” unit with strong efficiency and low emissions is ideal.

One of this model’s best features is its remote control capabilities — this is best in the winter when you don’t have to go outside to adjust your settings. There’s a lot to love about the water heating system that boasts an environmentally conscious design to ensure efficiency and low emissions.

Compared with a hot water tank run on natural gas, this model will not only save you a ton of money, but save tons of carbon from being emitted into the atmosphere as well.

Pros:

  • From leading brand Rheem
  • Standard 10 year warranty
  • Leading energy efficiency rate at 84% (Compared to other units)
  • Strong flow rate at 8.6 Gallons Per Minute
  • Does not require any ventilation

Cons

  • May not last as long in harsher climates

Read the full in-depth review: Rheem RTGH-95XLN Prestige

If you are looking for that “middle of the road” tankless water system that is both high quality and affordable, then look no further than the Takagi T-KJr2-IN-NG Natural Gas Tankless water heater.

Takagi products are well known in the industry (although not as reputable as Rheem and Rinnai), and come highly rated on various online shopping websites. This model boasts the absolute best value in gallons per minute on the market today, thanks to its ability to generate a maximum of 6.6 GPM for under $500.00.

Pros:

  • One of the most powerful tankless water heaters below the $500 price mark
  • Built by a reputable brand name
  • Comes with a standard 10 year warranty
  • Very easy to maintain, comes apart easily

Cons

  • One of the louder units you can find
  • 6.6 GPM won’t meet the water heating needs of a medium-sized house
  • Only 81% energy efficient, so in some respects, it’s more expensive than high-efficiency counterparts.

Read the full in-depth review: Takagi T-KJr20-IN-NG

If you are looking for simple, affordable and easy to install tankless water heaters for smaller uses, the Bosch Electric Tankless Water Heater is perfect for your home. While it may not be suitable for larger uses such as a dishwasher or shower, this simple unit can provide unlimited hot water to your sink for under $200 — and it’s one of the few products on the market capable of achieving this.

This unit is highly efficient at 98%, which means it requires little electricity to run. With power ranging from 3.2 KW to 12kW, you can adjust the model based on your needs and incoming water temperatures — all without breaking the bank or racking up your monthly energy bills. There is a lot to love about the unit itself that’s sleek, small, well designed, and won’t require you to sacrifice any much needed storage space.

Pros

  • One of the smallest models
  • Well reviewed by thousands of users
  • Industry leading warranty
  • Quiet unit 

Cons

  • Low flow rate, only useful for single sinks

Read the full in-depth review: Bosch Electric Tankless Water Heater

We recommend using the SioGreen IR260 Infrared model for your recreational vehicle because an RV is likely to be subjected to a variety of different water sources. This innovative model uses materials that resist the build-up of calcium and limescale, which means it requires minimal maintenance. You could even provide hot water for a shower with this small unit that’s able to produce up to 2.0 GPM.

One of the biggest drawbacks to these types of tankless water products is the fact that they are susceptible to a build-up of limescale and calcium — especially when the water source is hard. The reality is that when you are travelling in your RV, you will encounter hard water — even if you usually have a soft water source. For this reason, it’s imperative to use infrared water heaters instead of a traditional electric unit.

Pros

  • Maintenance free water heater
  • Well reviewed by thousands of users
  • Industry leading warranty
  • Relatively quiet unit

Cons

  • Low flow rate, doesn’t work well for high flow showers
  • Larger than expected

Read the full in-depth review: SioGreen IR260 Infrared

Whether you’re camping or roughing it at a cabin, there is nothing quite like a hot shower at the end of the day when you spend your day outside. The Eccotemp L10 Portable Outdoor Tankless Water heater is the best model for this purpose.

Powered by propane, this unit is able to heat nearly any incoming water temperature and provide refreshing hot water to your shower outside.

This model works with the standard 20lb propane tank and comes with the standard garden hose adapter. Simply buy it, hook up your gas line and garden hose, and you are off to the races! This unit is even capable of handling water temperatures below freezing (32 Degrees Fahrenheit).

Pros

  • Powerful unit capable of handling any incoming water temperature
  • Backed by one of the biggest brand names
  • Industry leading warranty
  • Works with standard garden hose and BBQ propane tanks

Cons

  • Water can take a while to heat up
  • Uses more propane than you would expect
  • The product doesn’t come with an external cover to keep it protected, so we suggest purchasing one

Read the full in-depth review: Eccotemp L10 Portable Outdoor

Tankless Water Heater Buying Guide

tankless water heater under sink

Why Go Tankless?

Tankless water heaters provide instant and on-demand hot water, whereas traditional tanks keep a fixed amount of water hot at all times [1] — this is an important distinction. Whether it is gas or electric, a traditional tank uses energy all day long.

The thing about tankless water heaters is that they only draw power when hot water is demanded — this makes them efficient and cost-effective. According to Energy.gov, tankless heaters can offer up to 37% energy savings [2].

We based our tankless water heaters ratings on their unique purposes, and which are best suited for particular needs.

Types of Tankless Water Heaters

There are various types of tankless water heaters; you can have one indoors or outdoors, fueled by gas or electricity.

It can be a challenge to identify the best unit for your home, which is why we’ve compiled a guide of water heater reviews. It’s crucial that you are aware of the advantages and disadvantages of your options.

Gas Tankless Water Heaters:

Gas tankless water heaters use gas to heat the water instead of electricity.

Advantages:

  • Much more powerful, able to heat multiple faucets at once
  • Lower cost than electricity in most cases
  • Able to heat water from cold incoming water temperatures

Disadvantages:

  • More expensive than electric heaters
  • Emit emissions directly from the unit
  • May require ventilation, depending on the unit and placement

Tankless Electric Water Heaters

This model uses electricity instead of gas to heat up the water in your tank. 

Electric tankless water heaters are typically smaller and more affordable than gas tankless water units.

Advantages:

  • Doesn’t directly emit CO2 (your electricity may come from a coal plant, however)
  • More affordable than a gas powered heater
  • Doesn’t require any ventilation

Disadvantages:

  • Most homes would require multiple units to produce the same amount of hot water as a gas powered unit
  • Require more maintenance due to limescale and calcium build-up
  • Electricity is generally more expensive than gas

Buying a single, large, gas powered tankless water heater or buying multiple tankless electric water heaters can produce the same hot water output for roughly the same initial cost.

Energy Star Certified Models

Products earn Energy Star certification if they are proven to be cost-effective, energy-efficient, and environmentally friendly. To be Energy Star certified, a product must be tested to ensure that it meets efficiency specifications [3].

What Size Unit Do I Need?

Of the many tankless water heaters on the market, which size is best suited for your home? For the purposes of this chart, we will assume that your home’s incoming water temperatures are 67 degrees Fahrenheit or above.

If not, you will generally want to play it safe and invest in one the best tankless water heaters reviewed in our guide.

Demand TypeSize
Bathroom Sink0.5 GPM
Standard Shower2.5 GPM
Low-Flow Shower1.5 GPM
Dishwasher1.0 GPM
Washing Machine1.5 GPM
Kitchen Sink0.5 GPM
Laundry Sink1.0 GPM
DwellingBathroomsGPM
Apartment / Condo13.0 GPM
Small House (<1000 sq. ft.)14.0 GPM
Average House (<1600 sq. ft)27.5 GPM
Large House (1600+ sq. ft)3+10+ GPM

1 bedroom 1 bathroom apartment with appliances:
A normal apartment with a bathroom sink, shower, kitchen sink and dishwasher (but no washing machine), you would need a 4.0 GPM flow rate to run everything simultaneously. One option would be to buy two electric systems — one for the restroom and one for the kitchen.

2 bedroom 2 bathrooms
A 2 bedroom 2 bathroom house will generally have 2 showers, 2 restroom sinks, a kitchen sink and dishwasher as well as a washing machine. In order to run everything at once, you will need at least 8.5 GPM of flow rate. A homeowner typically won’t need to run everything at once, in which case they could get away with 7.5 GPM. Keep in mind, however, that you need more power in the winter for higher temperatures to rise.

4 bedroom 3 bathrooms, in-law suite
A large home with 3 showers and restroom sinks, and 2 kitchens with 2 dishwashers and 2 washing machines would require flow rate over 15 GPM to provide hot water to all faucets at the same time. While this is an unlikely scenario, it is a good idea to have at least two gas-powered tankless water heaters to provide sufficient demand to the entire house.

Indoor vs Outdoor Systems

Even though we typically recommend buying an indoor system, you have to consider two important factors before ruling out investing in an outside heater.

Space: If space is a constraint for you, you can save space by placing your system outside. Proportionally speaking, a small cabin or cottage, or a multi-unit building that requires multiple units, can save a lot of indoor square footage using this kind of system.

Sound: Some water heaters make more noise than others, although all of them make some noise. In a small enclosed space, this can be irritating and can be avoided by placing the unit outside.

Ventilation: If for any reason you foresee your system’s ventilation being overly complicated or constrained, you may want to place it outside to avoid all ventilation concerns. The truth of the matter is that sometimes ventilation for tankless water heaters takes up more space than is available.

lathering hands under faucet running hard water

Incoming Water: Hardness and Temperature

Temperature:

If your incoming water temperature is below 50 degrees Fahrenheit, that’s an indicator that you’re better off with a gas-powered tankless water heater.

Other water heaters are simply not powerful enough to raise the temperature more than 30 degrees Fahrenheit. Unless you are willing to give up hot water during the winter, you’re likely better off going with a gas-powered unit.

On the other hand, if you have a cottage or cabin that is only used in the summer, then you may want to consider a different model for heating your water.

Map of incoming water temperatures in the United States [4]

 

Hardness:

If your water is particularly hard (i.e. you need to use a softener), then you will need to either maintain your tankless water heater more regularly or use additional equipment to soften the water before it enters the hot water heater. Limescale and calcium build up can destroy your unit if it’s not cleaned regularly.

Map of water hardness in the United States [5]

electrical wiring of EcoSmart ECO 27 Tankless Water Heater at 240 Volts

How do Tankless Water Heaters Work?

All tankless water heaters work more or less the same way. They heat water directly without the use of a storage tank. When a hot water tap is used, the incoming cold water enters a heating chamber and is then heated by a powerful heat exchanger.

For those not familiar, a heat exchanger is a tool that allows heat to transfer between sources. You’d also find a heat exchanger in your other household appliances i.e. your refrigerators and air conditioners [6].

The best tankless water heaters on the market are made with different materials and are used for varying purposes. It’s important to do your research to ensure that you get the right model for your unique needs.

Cleaning & Maintenance for Tankless Water Heaters

If you invest in one of the best tankless water heaters on the market, you are going to want to take care of it.

If you are a handy person who’s familiar with water heater maintenance, check out these quick refresher videos on how to flush your water heater:

It’s also important to clean out the filter, which can accumulate some sediment as well. This video quickly explains how to do this:

If you are a beginner and have never performed maintenance before, don’t be nervous about maintaining your tankless water heater. This 8 minute video takes you through the process step by step.

It’s important that you don’t use store-bought descaling products, as they contain harmful chemicals that can run off in your tap water. As mentioned in the video below, use all-natural, pure white vinegar. Vinegar is completely safe for humans to consume, so no need to worry if you don’t flush 100% of the vinegar out of the system.