The 7 Best Tankless Water Heater for 2021

tankless water heater

The name ‘tankless’ is the commonly used term for an instantaneous water heater. Tankless water heaters are not new appliances. They’ve been around for many years.

Designed and equipped initially for industries where storage space was limited but huge quantities of endless hot water were needed. For the same reasons these units are also used in large multi-unit residential complexes and mid-sized businesses. Instantaneous water heaters are also used as residential pool and spa water heaters.

Over the years, the design and applications have been modified and changed, becoming much smaller. This smaller size requires less space, and able the unit to be placed closer to the point of use. This benefit of the smaller size instantaneous water heaters appeals to the broader residential retailer market.

Best Tankless Water Heater


1. Bosch Electric Mini-Tank Water Heater

⭐ Best Overall

Bosch Electric Mini-Tank Water Heater Tronic 3000 T...
  • CONVENIENT HOT WATER HEATER: 2.5 gallon point-of-use mini-tank fits under your sink to provide hot water right where you need it. Thermal efficiency is 98%. Dimensions : 13.75 W x 13.75 H x 10.75 D Inches
  • LONG LASTING QUALITY: This electric water heater is easy to maintain and has premium glass-lined material for a long service life. (Amps 12A, Volts (VAC) 120)
  • INDEPENDENT INSTALLATION: 36-37" cord plugs into a 120 volt outlet for independent installation or in-line with a large hot water source

2. EcoSmart ECO 11 Electric Tankless Hot Water

⭐ Best Runner Up

EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at...
  • Endless On-Demand Hot Water; Consistent hot water when you need it that never runs out; Continuously monitored water temperature and controlled flow rates ensure efficiency and consistent performance within 1 degree of selected temperature
  • Save Space; EcoSmart tankless electric water heaters are 90% smaller than traditional tank heaters; may be installed on wall or at point of use; Dimensions 11.5 x 8 x 3.75 inches
  • Save Energy; EcoSmart tankless electric water heaters are 99% thermal energy efficient; Only heats water when called unlike a tank heater that maintains water temperature even when not being used.

3. Tankless Water Heater Electric 5.5kw 240V

⭐ Best Low Cost

Tankless Water Heater Electric 5.5kw 240V, ECOTOUCH...
  • 【INSTANT & SUFFICIENT HOT WATER】Applied with 5.5KW heating system, the electric water heater supplies instant, consistent and endless hot water of 116℉or higher temp shortly, no waiting for preheat nor terrible temp up & down, perfect companion for sinks. Time to get rid of those "lukewarm" toys.
  • 【SMART SELF ADJUSTMENT】The hot water heater adjusts power input based on flow rate and temp setting in real time. For example, less power will be applied by the system when waterflow reduced, thus you still get ideal temperature instead of scalding hot water, which means comfortable experience. Optimal energy efficiency of 98% saves considerable electric charge.
  • 【CONVENIENT USE】The tankless water heater comes with digital display & touch control panel so temp setting is easy job. Now turn on the tap and let the smart unit do the rest, you needn’t go through hard lesson about temp setting by a mixer tap without any hint. The Black model comes with Remote control, useful for installation under sink.

4. Ecosmart ECO 18 Electric Tankless Water Heater

⭐ Best Rolling Towel Storage

ecosmart ECO 18 Electric Tankless Water Heater, 18 KW...
  • The product is highly durable
  • The product is easy to use
  • Manufactured in China

5. Rinnai RL75IP RRL75iP, Medium, Natural Gas

⭐ Best Wall Mounted Towel Rack

Rinnai RL75iP Propane Gas Tankless Hot Water Heater,...
  • Optimal Water Pressure: High-performance 7.5 GPM hot water flow rate for a powerful, constant stream
  • Guaranteed to Last: 12-, 5-, and 1-year residential and 5-, 5-, and 1-year commercial factory warranty for heat exchanger, parts, and labor respectively

6. Stiebel Eltron Tankless Heater

Stiebel Eltron Tankless Heater – Tempra 36 Plus –...
  • On-demand, continuous and unlimited supply of hot water
  • Sleek design saves space and no venting required
  • Electronic switch activated for virtually silent operation. Phase- single 60 Hz. Voltage- 208 V. Wattage- 27 kW

7. Rheem RTE 13 Electric Tankless Water Heater

⭐ Best Rheem Tankless Water Heater

Rheem RTE 13 Electric Tankless Water Heater, 4 GPM
  • On-unit temperature control, LEDs indicate active element and standby mode
  • Standard 1/2" water connection
  • Rugged brass/copper heat exchanger

8. Rinnai V65iP Propane Tankless Hot Water Heater

⭐ Best Propane Tankless Water Heater

Rinnai V65iP Propane Tankless Hot Water Heater, 6.5 GPM
  • Energy and Space Efficient: Space-saving design conserves energy as it heats only when necessary
  • Optimal Water Pressure: High-performance up to 6.5 GPM hot water flow rate for a powerful, constant stream
  • Enhanced scale detection lessens possibility of serious, long-term damage to unit

9. Noritz EZTR40NG 40 gal Tank Replacement Indoor Tankless Water Heater

⭐ Best Noritz Tankless Water Heater

Noritz EZTR40NG 40 gal Tank Replacement Indoor Tankless...
  • Endless hot water
  • Direct replacement for existing 40 gal tank water heater
  • High Efficiency

10. RINKMO Electric Tankless Water Heater

RINKMO Electric Tankless Water Heater - 24KW 240V...
  • 💧 INSTANT ENDLESS HOT WATER: RINKMO 18KW tankless water heater requires 3 x 40 AMP breakers and 3 x 8 AWG wire, the Water Flow is 0.66GPM/2.5L/min. You aren't limited to the amount a storage tank heater can hold, tankless water heater technology will instantly supply the hot water your lifestyle demands.
  • 💧 MONEY & TIME SAVING EXPERT: Units are designed to be highly efficient by heating water only when it's needed, no need to preheat, giving you hot water in seconds, not minutes, saving up to 40% energy.
  • 💧 10 TIMES SAFE PROTECTIONS: A Safer water heater, designed for point-of-use especially living with babies. Inner water and electricity lines separate technology prevents from building up rust and scale inside the tank, you'll always experience fresh, clean water that's heated on demand.


Recap: The Best Tankless Water Heater

  • Bosch Electric Mini-Tank Water Heater
  • EcoSmart ECO 11 Electric Tankless Hot Water
  • Tankless Water Heater Electric 5.5kw 240V
  • Ecosmart ECO 18 Electric Tankless Water Heater
  • Rinnai RL75IP RRL75iP, Medium, Natural Gas
  • Stiebel Eltron Tankless Heater
  • Rheem RTE 13 Electric Tankless Water Heater
  • Rinnai V65iP Propane Tankless Hot Water Heater
  • Noritz EZTR40NG 40 gal Tank Replacement Indoor Tankless Water Heater
  • RINKMO Electric Tankless Water Heater


Should I Purchase a Tankless Water Heater?

Bathroom renovators over the years have debated whether or not tankless water heaters are a good remodelling choice and do these tankless units really save you money? The answer however is never cut and dry.

Well its kind of like one of those questions when your spouse comes up to you and asks, does this dress make me look fat? You know no matter what you say you’re going to get in trouble anyway because she is just trying to pick a fight…The same thing applies to the question, are tankless water heaters really the right choice?

Most advocates have already made up their minds on the issue and are just looking for examples to justify their point of view. We however will look at purchasing a tankless water heater with an unbiased eye.

Yes, tankless water heaters are great because they provide hot water on demand as compared to regular tank storage heaters which will eventually run out of hot water if you use them for too long and too often.

Also regular storage heaters can waste energy if they have a constantly burning pilot light. We know that gas tankless water heaters use high-efficiency burners to rapidly heat water as it runs through a heat exchanger. This could result in a sixty to ninety dollar savings per year on your energy costs depending upon your water usage, which is good.

Cost Of a water Heater

The average cost of a tankless water heater is between seven-hundred-fifty and two thousand dollars, while the average cost of a regular water storage tank is between three and five hundred dollars.

As you can see, tankless water heaters cost substantially more than tank storage water heaters and despite the fact that they are twenty-five more efficient than regular tank storage water heaters.

If we were to spread the cost savings out versus the cost of the unit it would take approximately twenty years to recover your cost, unfortunately most tankless water heaters only have a twenty year life span.


To install a tankless water heater you will probably need new electrical outlets to run the cooling fan, you will most likely need to upgrade your ventilation system and possibly your gas pipes which could really increase your installation cost, not to mention the inconvenience of getting these upgrades done.

A Yearly Servicing Schedule to Prevent Calcium Buildup

Maintenance could also be costly as calcium has a tendency of building up within the units over time. Most manufactures recommend a yearly maintenance servicing by a qualified technician which if not followed could potentially shorten or void your warranty.

Installing a water softener could help to alleviate some of the problems associated with calcium build up and scaling.

Flow rate of hot water from a tankless system will be affected by the temperature of your groundwater. The warmer your groundwater, the faster the hot water flow rate, so homes located in colder climates will potentially need a larger system to get sufficient hot-water flow speed.

Another problem with tankless water heaters is the quickness of getting the hot water to the tap that it is need. There is normally cold water in the pipes that has to be pushed out by the incoming hot water before it reaches you.

If you are brushing your teeth or shaving, there is the potential of the heated water not getting to you in time before you are done those simple rudimentary tasks.

So the question still remains, should you run out and get a tankless water heater today? The answer is no if you are servicing a large household. However there are tankless water heater systems that work at the point of use, such as under your kitchen or bathroom sink and can be integrated into your shower system.

And while there are larger units that serve multiple plumbing fixtures around your entire house, if you have a large family and use a lot of hot water, the most efficient use of a tankless water heater is to be used as a booster system for your bathroom water needs.

However it should be noted here, you can still get by quite nicely if you are single or are couple with minimal water needs by purchasing a tankless water system. The bottom line is to look at your water usage and then decide if a tankless water heater is the right fit for you and your lifestyle.

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