The Ultimate Guide to Purchasing a Tankless Water Heater

With so many of the best tankless water heater reviews on the internet, it’s no wonder that interested customers are left in such a daze. There are so many brands, and not to mention, there are so many tankless models, each claiming that they are the best. The competition does not end here. What with the electric, natural gas, and propane models? It seems like they (the different brands) are trying to confuse the customers.

latest water heater models

Now, this is the reason this site is solely created. Its existence is devoted to assisting consumers in purchasing tankless models, be it Electric or Natural Gas (NG) models. On this site, we guide you through the top tankless models of the most popular brands.

So, the question is electric or gas?

To be frank, each and every model referred to in this site is unanimously efficient. Nevertheless, here are a few tips to give you some ideas for making the right purchase.

The 3 Best Tankless Water Heaters of 2023

  1. Stiebel Eltron Tempra 36 Plus
  2. Rinnai RL Series HE+
  3. EcoSmart ECO 27

Dive Deep, Not Wide!

In the vast ocean of tankless water heater reviews, it’s easy to drown in information overload. But what if you didn’t need to wade through endless pages of opinions to find the best of the best?

You’re just three models away from making an informed decision. Our top three recommendations are to reduce the noise, save time, and potential confusion. Because sometimes, less is more. Delving deeper into countless reviews might muddle the waters instead of clearing them.

So, skip the marathon reading session. Stick to our trio of excellence, and equip your home with a heater that’s tried, tested, and truly top-tier!

Stiebel Eltron Tempra 36 Plus: Best Electric Tankless Water Heater

Stiebel Eltron Tempra 36 Plus

Among the top eco-friendly tankless heaters we’ve come across, the Stiebel Eltron Tempra 36 Plus ensures optimized electricity consumption, adapting to your heating needs. With a base heating level set at 68°F, there’s no fear of unexpected burns during a swift hand wash.

This smart device, standing at just 14.5 inches, operates silently and offers an impressive flow rate of up to 7.5 GPM and a power of 36,000 watts.

Its innovative tech slightly adjusts the water flow during peak hot water use, ensuring you won’t be jolted by sudden cold bursts. The user-friendly buttons and dial let you set the desired temperature effortlessly, complemented by a memory function. Its energy-efficient modulation is displayed on a clear digital screen.

With this non-condensing model, external venting is unnecessary. Moreover, the Advanced Flow Control ensures a steady temperature delivery. It’s one of the top indoor units, exuding a sleek, understated aesthetic. Its compact size is perfect for tucked-away installations, yet it remains appealing when in view.

For installation, seeking an electrician’s expertise is advised since it draws 300 amps, potentially necessitating an electrical service panel update. The Stiebel Eltron Tempra 36 Plus comes with a seven-year leak warranty and a three-year parts warranty.

CategoryElectric, Indoor
Size14.5 x 4.63 x 16.63 inches
Flow CapacityUp to 7.5 GPM
Total BTUNot provided
Power36,000 watts

Rinnai RL Series HE+ Best Gas Tankless Water Heater

Rinnai RL Series HE+ Tankless Water Heater

Boasting a noteworthy performance, including a rapid 7.5 GPM flow capacity and a commanding 180,000 BTU, the Rinnai RL75iN High-Efficiency Plus stands out despite its relatively compact stature, measuring 31 inches tall. Its robust nature is ideal for indoor setups and can supply hot water to multiple points simultaneously. Though this variant utilizes natural gas, an analogous model supporting propane is also on offer.

While its price point leans towards the premium, the assurance of a 12-year warranty can certainly sway any hesitant minds. Owing to its intricate design, professional fitting is advisable.

A standout feature is its ability to sync with Wi-Fi. However, acquiring the Control-R Wi-Fi Module is a separate affair.

CategoryNatural gas, Indoor
Size31 x 17.5 x 13 inches
Water Flow7.5 GPM
BTU Rating180,000

EcoSmart ECO 27: A Leading Choice in Tankless Water Heating

EcoSmart ECO 27

Topping our recommendations for the most efficient tankless water heaters, the EcoSmart ECO 27 stands out with its user-friendly interface, enhancing energy conservation and contributing noticeable savings on your electric charges. With a flow capacity of 5.27 GPM, it has the muscle to promptly heat water for a medium-sized household, maintaining consistent warmth. Its 27,000-watt machinery has unique self-modulating technology, calibrating energy use according to your precise hot water demands.

The unit houses a smart sensor to detect any decrease in water pressure, ensuring you aren’t subjected to unexpected cold bursts—a prevalent issue termed the “cold water sandwich” in many tankless systems. The heater’s temperature span ranges from 80°F to 140°F. It’s further complemented by an intuitive digital thermostat, enabling precise single-degree adjustments. Though it might not attain the peak temperatures of some competitors, it unquestionably delivers satisfactory warmth for daily tasks.

Purposely crafted for point-of-use mounting, its compact design ensures minimal space occupancy. Weighing in at a mere 14 pounds, its portability is notable. Intended for indoor utilization, it’s compatible with 3 x 40 AMP double pole breakers for setup.

The EcoSmart ECO 27 tankless water heater comes with a commendable limited lifetime warranty. While including Wi-Fi capabilities could be the cherry on top, this unit remains a stellar mid-tier tankless heater that’s dependable, efficient, and economically priced.

CategoryElectric, Indoor
Size17 x 3.7 x 17 inches
Flow Capacity5.27 GPM
BTU RatingNot provided
Power27,000 watts

Factors to Consider When Buying a Tankless Water Heater

After researching with our expert team, we found some points you can follow to find the best tankless heater.

Fuel Type

If you are searching for a tankless model that will be ideal for a whole-house purpose, I recommend choosing either a gas-fired or propane-fired model. The electric tankless models are ideal for simultaneously running one or even two applications.

Flow Rate

We show a comparison chart regarding tankless water heater flow and GPM and their effects on ultimate service. Before buying a water heater, you must remember that the minimum flow rate is much more important than the maximum flow rate.

FixtureAverage Flow Rate GPMAverage Temp. (°F)
SHOWER2.5 to 3.0 GPM104°F

Following this flow rate chart lets you easily understand how to find the foremost tankless water heater for your home. This chart shows that the flow rate completely depends on your living location temperature. So, that’s a very important thing to know about your living location temperature before buying a tankless water heater. When the temperature is 70 degrees Fahrenheit, a typical tankless water heater can give 5 GPM hot water. And this amount easily covers the regular home use of hot water. Remember that a terrific tankless water heater can control output temperature based on inlet temperature and current water flow rate.


This basically depends on your in-house family’s demand. To better understand, we put a worksheet to enrich your knowledge regarding size things to consider before buying a tankless water heater.

According to your family member number, you can find the best-performing tankless water heater by analyzing this water heater sizing guide:

Residential water heater sizing guide

Then, by analyzing this worksheet, which actually shows the estimation of peak hour demand by first-hour rating:

USEAverage Gallons of Hot Water Per UseUsed Time Per HourHourly Gallons use in 1 Hour
Shower10X1 Hour=10
Shaving (0.05 gallon per
2X1 Hour=2
Dishwashing or food
prep (2 gallons per minute)
4X1 Hour=4
Automatic dishwasher6X1 Hour=6
Washing Machine7X1 Hour=7
Total Peak Hour Demand=29

When you analyze this chart and put your chosen water heater data on the chart, you can find the best combination of Fahrenheit and flow rate, which you are looking for the best tankless water heater.


This is one of the most important points to be noted before buying a tankless water heater. Because for the campaign and residential use, the space-saving dimension is much more important. Buy a water heater with a longer dimension. Setting in bathrooms or under the cabinet space may not be suitable. On the other hand, if you want to go for a campaign, longer dimensional water heaters create transportation difficulties. Let’s see how you can compare the dimensional size between two tankless water heaters. Let’s look at Tank versus Tankless water heaters to find the best-performing water heater for your family or commercial use.

Dimension of tank water heaterTankless water heater dimension
ForGallonSIZE(MODEL:ENT 308-6,408-6,508-6)WEIGHT
2 person3051″ X 50.5″ X 42.4″10812″ X 9.75″ X 3.75″6.75
4 person4064.5″ X 63″ X 55.5″11918″ x 14″ x 3.75″13.75
5-6 person5051.625″ X 50″ X 42″14918″ x 17″ x3.75″13.75

After a long time researching, we found that people were always searching for a high-efficiency electronic device with more energy efficiency. Whether it is an electric or gas-fired tankless water heater, if it consumes more power, your electricity bills or gas bills will be higher, becoming a burden for you. So, this is another important point to consider before buying a tankless water or another technological device.

Basically, the tankless water heater is more energy efficient in 3 ways:

  • No standby Loss: when traditional tankless water is switched off, it does not consume energy. This tankless water heater consumes energy from the moment you turn it on. For example, a house needing 41 gallons of water each day can consistently appreciate 24 percent to 34 percent vitality productivity. A home with 86 gallons need of hot water can appreciate productivity up to 51 percent.
  • Water Heater with Copper Heat Exchanger: You may ask why a tankless water heater is more energy efficient. It is only because of a tankless heater built with copper heat exchangers like aluminum nickel, and these materials heat water faster, so they consume less energy to heat the water hot.
  • EnergyStar Certification: this is one of the easiest ways to find an energy-efficient tankless water heater. If they have the EnergyStart certification.


Compared to even the best electric tankless models, the gas models are expensive. This does not mean that the electric models are cheap. Moreover, you will also get higher utility rebates and other available tax credits regarding the electric models. Yet, there are similar facilities for the gas models, which are of advanced technology.

Who wouldn’t fall for an intriguing feature if it makes your life more comfortable? After all, the tankless models are for-your-sake-of-comfort products, and you must take as many advantages as possible.

So, another important factor to consider is the features & technologies that your tankless model will be packaged with. You are justified in buying the model with advanced technologies, whether electric or gas. Besides these, you should also observe the relation between flow rate, temperature rise, and other additional factors like warranty and Energy Star certification.

It’s wise to be thorough since someone once said, “Little knowledge is dangerous!

As a side note, you may find our natural gas tankless water heater reviews helpful regarding this subject, where you will get acquainted with the best natural gas models. Unless they don’t fulfill your requirement, there are also the electric tankless water heater reviews, which will catch your attention if you are one of those who thinks or believes that electricity is the future!

Final Verdict

In the extensive landscape of water heater brands, discerning the exceptional from the merely good is pivotal. Regarding premier tankless models, three names consistently top the charts: Stiebel EltronRinnai, and EcoSmart. Their unmatched dedication to technological advancement and their dependable durability position them as the industry’s frontrunners. On the other hand, brands like BoschNavienRichmondNoritz, and Rheem also earn noteworthy mentions for their quality.

As homeowners navigate the intricate avenues of water heating solutions, these brands emerge as options and trusted beacons of excellence.

As a consumer, you should review the reviews, consumer ratings, etc., of the particular tankless model you are interested in before buying it. Look over the issues like repair and maintenance, portable features, plumbing, useful accessories, etc. The is an ideal platform to find invaluable information from consumers and experts.

The best tankless water heater is the one that is ideal for your use from every aspect. So, take your time and consider the criteria mentioned above when purchasing a tankless water heater for your home. The ultimate decision is yours, so make it a wise one!