The Best Tankless Water Heaters in 2021 (Reviewed & Compared)

Overview

The Rinnai RU199iN was marked as our best tankless water heater, to start, because it’s a compact, indoor unit that uses natural gas. It’s easy to use and install, and you can place it in several spots around the house. This can range from three to six fixtures.

Important Specs

Its BTU range goes from 15,000 to 199,000, meaning it can heat the water at a highly impressive rate. This model is Wi-Fi capable, so you can monitor the temperature remotely. The maximum water flow rate of 11 gallons per minute is more than enough for most households.

Durability

This is the best tankless water heater on gas power, it’s exceptionally durable, and it comes with excellent warranties. The residential heat exchanger has a 15-year warranty, the residential parts have a five-year warranty, and the residential labor comes with a one-year warranty.

Overview

One of the most trusted industry leaders, Stiebel Eltron, came up with its Tempra Plus design to revolutionize tankless water heating. The brand’s best electric tankless hot water heater never runs out of hot water, even when the demand is very high.

Important Specs

The GPM of 4.5 is more than enough to keep the entire household continuously supplied with hot water. This product has such a compact design that it can fit almost anywhere in the house. It’s also utterly silent, which is a nice bonus.

Durability

The installation is a cakewalk, the service life is very long, but the warranty still is more than fair. You get a seven-year warranty for leakage and a three-year warranty on materials and craft.

Standard Compliance

Finally, as the best tankless electric water heater, the Tempra Plus meets the ISO 9001, WQA, and UL standards, and it’s certified by each. These certificates are a huge plus because they assure customers of the product’s quality and safety.

The ISO 9001 is an international quality management standard by the International Organization for Standardization. A Water Quality Association certification stands out as the most trusted and reliable. And Underwriter Laboratories has been issuing third-party certifications for more than a century.

Overview

Takagi is one of the best tankless water heater brands in the industry, with more than 60 years of experience. It sells exclusively through contractors and wholesale plumbers. The company offers a wide selection of tankless water heaters, but the T-H3-OS-N is one of the best outdoor models.

It’s a powerful heater, with a serious GPM that makes you forget about ever running out of hot water. What sets this unit apart is the copper-alloy primary heat exchanger, which is up to 25 times better than stainless steel.

Important Specs

This is an ultra-low-emission option, nearly the best gas tankless hot water heater on our list, even though it uses natural gas.

Its maximum BTUs are up to 199,000. British Thermal Units represent the amount of energy required to elevate the temperature of a pound of water by one Fahrenheit—a high BTU rating equals more power. Tagaki’s model falls into the top end of the standard BTU range that most tankless water heaters offer.

Finally, there’s an Easy Link option that can support four units, but it goes up to a whopping 20 units via the remote control, which is always included. Last not least, there are safety features against surges, freezing, and overheating.

Durability

There’s a 15-year limited heat exchanger warranty and a five-year parts warranty. The secondary heat exchanger is 316L stainless steel, which is resistant to corrosion.

Overview

The Rheem RTGH-95DVLP-2 is an efficient condensing tankless gas water heater. It doesn’t run out of hot water, and it has a robust flow rate.

Even better, its water savings setting saves about 1,100 gallons of water annually when activated. It slowly decreases the water flow until the set temperature is reached.

Design Features

What’s excellent about Rheem’s best tankless hot water heaters is that they have low flow activation, perfect for low demand situations. There’s also a recirculation pump kit that saves up to 12,000 gallons of water a year.

Rheem even thought of temperature fluctuation, thus minimizing any cold water bursts by design. The installation is straightforward, and so is the service.

Important Specs

Finally, there’s a self-diagnostic system, maintenance notice settings for easier servicing, and a digital remote control. All of the best propane tankless water heaters from Rheem also come with EcoNet mobile app integration, available in the accessory kit.

Lastly, this unit can work even in high altitudes, up to 8,400 ft above sea level. The basic option can support up to six units, and the advanced control board supports up to 20 units.

Overview

Tankless water heater reviews highlight the smart controls the EcoSmart ESG-95 offers for increased security and performance. It’s a mid-efficiency tank that can conserve up to 1,100 gallons of water a year thanks to its reduced water flow.

The minimum flow rates are 0.26 GPM and 0.40 GPM for activation. This translates to a constant influx of hot water, even when the demand is low. The recirculation pump kit is there to give instant access to hot water.

Important Specs

There’s a maintenance notification setting that lets you know it’s time for a service check. Even the tankless water heater installation is intuitive, and you can set the unit up almost anywhere you want.

The concentric vent system has a built-in condensate collector. The smart design of this tankless water heater minimizes instances of blasts of cold water.

Combining Units and Safety

If you need to link up two tankless heaters, you can do that with the EZ Link cable. Finally, even though this is a gas unit, it has an ultra-low NOx burner that meets safety requirements. NOx stands for nitrogen oxides, which are reactive, toxic greenhouse gases.

The best tankless water heaters will often have ultra-low NOx units like this one, which emit only 7–15 parts per million. In other words, ultra-low NOx technology is two times safer, if not even more. Not only that, but it’s also more efficient.

Overview

The Eemax HA018240 water heater is labeled for residential use—for multiple or single points of use. It provides steady, never-ending, on-demand hot water. It has excellent temperature control with a 60° F leeway.

Durability

The materials used for this unit are very sturdy. The cover material is stainless steel, and so is the color. The element material is copper. The minimum operating pressure is 35 pounds per square inch, and it goes up to 150 PSI.

Important Specs and Standard Compliance

Overall, the design of this best-rated electric tankless water heater is simplistic and functional. It serves its purpose but lacks many of the fancy add-ons you get from top-tier units—which are significantly more expensive than this one.

This Eemax electric heater has an adjustable thermostat. It’s UL listed and certified. It complies with low-lead UL standards and the Uniform Plumbing Code, which governs the inspection and installation of plumbing systems to improve the public’s health, welfare, and safety.

Overview

In the point of use category, the SioGreen IR 288 is one of the best tankless water heaters on the market. It has a good flow rate at a 30° F temperature rise. Plus, it reduces energy costs by up to 65%, so it’s well worth the buy.

Durability

Put simply, it’s durable, lasting over 10 years. It is corrosion-free and self-maintaining. The setup is intuitive and straightforward. Even though it provides a sustainable flow, it uses low amperage—the voltage is 220 volts, and the wattage is 8.8 kW, while the amperage is 37 Amperes.

Important Specs

This model comes with a thermostatic intelligent temperature controller, fully modulating power control, and an LED temperature display. For all these reasons, it’s one of the best electric tankless water heaters on the market.

You’ll save energy and space with this product. It’s also very safe, with overheat thermal cut-off fuses, anti-scald protection, and residual current leakage detection.

Overview

The Bosch Greentherm 9000 is one of the best tankless water heaters with gas heating. It has an extraordinary design with integrated drain ports and top connections for water. Additionally, it has an auto-calibrating sensor, which makes its operation seamless.

Important Specs

Not only is this heater functional, but it’s also very stylish and sleek. This model comes with integrated Wi-Fi controls and a glass front. You can even install its app on your smartphone or tablet to wirelessly control the temperature and recirculation pump.

Durability

The heat exchanger warranty is for a whopping 15 years, while other parts have a five-year warranty, and the reasonable labor warranty is for one year. In terms of the warranty, this is the best tankless natural gas water heater.

Special Notice

There are different iterations of the Greentherm 9000 for residential or commercial use, so make sure to consult a contractor about your needs so they can suggest the right fit.

Overview

The Titan N-120 made our list of the best tankless water heater choices in 2021 because it’s truly the best buy option. Even considering its fair price, the company offers a month-long return warranty. There’s a free USPS shipping special included with the purchase, meaning the product will only take up to three business days to reach you.

Durability

You get a 10-year warranty for the casing and a one-year warranty for the parts. In terms of protection, you’ll also get a dual Microtemp thermal fuse and a manual resettable thermostat.

Important Specs

Other electric tankless water heater reviews note that the temperature rise decreases drastically as the flow increases, going from an 81° F rise at 1 GPM to 20° F at 4 GPM. This is actually a positive feature—it means the water heater is conserving energy while providing a sufficient GPM for a smaller household, or separate unit needs.

Its available voltage goes from 220 to 240 Volts, the maximum wattage is 11.8 kW, and the max amperage is 54. Neither the voltage nor the amperage should be an issue in an average household. But these specifications are there to let you make any necessary adjustments. However, it’s advisable to put an electric tankless water heater on its own circuit or circuits.

It’s the best RV tankless water heater, but you can also install it in a house or condo. This model is what an average home needs—it’s incredibly popular, cheap, and useful. Its energy efficiency is 0.99, which is exceptionally high for this price range.

Overview

Eco Touch isn’t necessarily the best tankless water heater brand. However, it’s worth considering for smaller households and those with limited hot water needs.

The Eco Touch ECO90 is a perfect point of use water heater for kitchen or bathroom sinks. Its modern design fits into any stylish home, whether you choose the black or white model.

Important Specs

The optimal energy efficiency of this device is a whopping 99.8%. The electricity bill reduction alone is worth this investment. It’s so effective because of the smart power adjustments, which decrease with the water flow.

Speaking of this powerful element, it can heat water at 1.5 GPM, from 67° F to 106° F. The device’s voltage is 240 V, the wattage is 9 kW, and the maximum amperage is 37.5 Amperes.

Durability

This final entry on our best tankless hot water heater list provides perfect hot water, but not too hot, and of course, it’s designed to avoid flashes of cold water. The lifespan of this point of use tankless water heater is extended with the anti-corrosion build in the heating element.