Best Tankless Water Heater for Whole House Reviews 2022

While conventional water heaters remain the best choice for some, tankless models save room and can help lower your heating bill.
If you’re considering for best tankless water heater, your first decision will be to pick a gas or electric model. While high-end gas models may be more effective than electric ones, they are also considerably more costly and hard to install. Also, tankless water heaters save gallons of water per minute as compared to storage water heaters. Because one has to wait in the shower until hot water starts flowing in.
There are also some other safety concerns to consider. Some homeowners would not prefer using gas. Gas tankless hot water heaters are typically not efficient compared to the electric tankless water heater, so there are many reasons to select an electric tankless water heater.
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2 | 4.5/5 | |||
3 | 4.5/5 | |||
4 | 4.5/5 | |||
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7 | 4.5/5 | |||
8 | 4.5/5 |
Stiebel Eltron has a great experience with best electric tankless water heaters. The high-quality Tempra 29 plus is rated for up to 4.5 GPM. In addition, it can raise the water temperature for one or two showers well by 90 degrees Fahrenheit level, making it an impressive yet economical choice for homes. This model is equipped with exclusive Electronic Temperature Control that ensures steady output temperature even with varying flow rates.
It is easy to install. Operation is simple, with an Exclusive design that prevents dry firing and an Electronic switch activated for virtually silent operation. In addition, the tankless design prevents Legionella bacteria growth. This model has a 28.8kW unit requiring a 240V supply and 3 x 40 DP breakers.
PROS
- Sleek design
- saves space
- no venting required
CONS
- Tempra 29 will only handle approx. 2.6 GPM flow rate
Rheem also has a great experience with gas tankless water heaters. The high-efficiency indoor natural gas tankless water heater is rated for up to 9.5 GPM.
In addition, it can raise the water temperature for up to four bathrooms to 120 Degrees Fahrenheit, making it an impressive yet economical choice for homes. Furthermore, this model has an exclusive Digital Remote Thermostat that ensures steady output temperature even with varying flow rates.
Based on Department of Energy (DOE) test procedures, Rheem gas tankless water heaters have a Water Savings Setting. When this setting is enabled, water waste is reduced by up to 1,100 gallons per year.
Rheem indoor tankless gas water heaters are small & compact – saving you valuable space in your home. They can easily be wall-mounted in tight spaces – like in a utility closet, attic, or storage room – and only need ½” clearance on both sides. Hence, it is another best tankless water heater.
PROS
- Low operating cost
- Water & Gas Leak Detection will shut down unit
- automatically adjust the amount of energy required to heat the water
CONS
- Relatively Expensive.
Another best tankless water heater is Tempra 12 Plus. With its Electronic switch that activates the hot water heater, Stiebel Eltron Electric Tankless Water Heater Tempra 12 plus has a digital temperature display, preset temperature, and memory buttons, while the internal solid copper heating system does all the energy work.
This unit is 12kW, 240V requires a min recommended electric service of 100A, and delivers an output temperature of water from 68° to 140°F.
It reduces the flow of hot water when demand surpasses the capacity to ensure that hot showers will never be interrupted. Tempra 12 Plus will typically consume 15-20% less energy compared to conventional electric tankless water heaters
Its small, sleek design saves space and no venting is required.
PROS
- Continuous Flow
- Noise free
- Excellent warranty
- Space saver
CONS
- Not recommended for large households
With its advanced technology, comfort, and value, this Rinnai’s model is another best tankless water heater. Its models offer a compact tankless water heater that has a longer lifespan. Unlike tank heaters that accumulate rusty sediments, this model heats water on demand only, saving energy costs. The flow rate of this is unit up to 5.3 GPM.
It also comes with safety features that include Flame Failure -Flame Rod, Boiling Protection, Combustion Fan RPM Check, Over Current-Glass Fuse, Remaining Flame (OHS), Automatic Frost Protection, and Thermal Fuse
PROS
- Endless Hot Water
- Space-saving design
- Value for money
CONS
- No Temperature Controller
- Indoor installation requires an exhaust
Another best tankless water heater is Rheem RTEX-24. If you want continuous hot water quickly, then this 99.8% Energy efficient tankless electric water heater is perfect for a single point of use or multiple application.
It is Compact and stylish, with digital temperature control in increments of 1°F ranging from 80°F to 140°F. Its flow rate for the whole home is up to 6GPM.
It is a 24.0Kw unit, and a breaker of (3×40)AMP is recommended by the company.
PROS
- Simple Installation.
- Digital temperature display.
- External controls to adjust temperature in increments of 1°F.
CONS
- No reserve water when power goes out.
- Installation requires knowledge of installing breakers.
This eco 8 tankless water heater only turns on when you need hot water. As a result, it cuts down on heat loss, saving you up to 50% in water heating costs, according to the DOE. Also, instead of storing hot water like a traditional tank water heater, it heats water as it passes through the unit.
Also, this ecosmart electric tankless water heater comes with Advanced self-modulating technology, this unit has digital temperature control that raises water temperatures from 80 – 140° F. Likewise, this eco 8 water heater is an 8-kilowatt tankless electric water heater ideal for providing hot water for a bathroom, small sink, and office breakroom.
For installation, this electric ecosmart tankless water heater requires a breaker of (1 x 40)AMP and Water Connections of 1/2″ CF.
PROS
- Save up to 50% on your water heating costs.
- Compact design.
- Advanced self-modulating technology.
CONS
- EcoSmart would not honor the warranty if the unit is not registered within 30 days.
- Not recommended for more than 1 bathroom.
Designed for continuous hot water, Rheem RTG-84XLN-1 is an outdoor natural gas tankless water heater. With a minimum flow rate of .26GPM and a minimum activation flow rate of .40GPM, it ensures hot water is received even in low-demand situations. Also, it gives a maximum flow rate of 8.4GPM
It comes with a Digital Remote Thermostat. Furthermore, no venting is required as this unit is for use outdoors. And this unit is best if used with up to 3 bathrooms.
Item Dimensions are LxWxH8.88 x 13.88 x 23.63 inches, and Water/Gas Connections required for installation are 3/4″.
PROS
- Value for money
- Easy to install
- Tech Support
CONS
- Compared to electric ones, gas water heaters take little time to heat.
This 8kW model provides up to 1.95 gallons of hot water per minute (GPM), enough for 1 shower.
The Digital temperature control on the front of this model allows easy set point adjustment. It does not require venting, so it can be installed anywhere inside your home.
It is pertinent to mention the installation process. This unit’s Dimensions are LxWxH 12.6 x 8.25 x 3.63 inches. The Breakers required for this unit are (1 x 40)AMP and side 1/2″ NPT water connections. Therefore, this best tankless water heater should be considered for a small household.
PROS
- On demand continuous hot water
- Self-modulating power control
- Dial Control with adjustable digital temperature display
CONS
- Only works with 1 shower.
Check out how tankless water heater works.
Q: What is a tankless water heater?
A tankless water heater is a device that heats water on demand without storing it in a tank. It uses gas or electricity to heat the water as it flows through a heat exchanger. Tankless water heaters can provide hot water faster and more efficiently than traditional tank models.
Q: What are the benefits of a tankless water heater?
Some of the benefits of a tankless water heater are:
- It saves energy and money by only heating water when needed.
- It provides endless hot water without running out or waiting for reheating.
- It saves space and reduces maintenance by eliminating the need for a bulky tank.
- It lasts longer and has lower operating costs than a tank model.
- It has lower risk of explosions, burns, or exposure to toxic metals than a tank model.
Q: How do I choose the best tankless water heater for my home?
To choose the best tankless water heater for your home, you need to consider several factors, such as:
- Your hot water demand and usage patterns. You need to calculate how many gallons per minute (GPM) of hot water you need at peak times and how many appliances or fixtures you want to run simultaneously.
- Your fuel type and availability. You need to decide whether you want a gas or electric model and check if you have adequate gas supply or electrical capacity for your chosen unit.
- Your installation location and requirements. You need to determine where you want to install your tankless water heater and what kind of venting, piping, wiring, or permits you may need.
Q: What are some of the best brands and models of tankless water heaters?
Some of the best brands and models of tankless water heaters are:
- Rinnai: A leading manufacturer of gas-powered tankless water heaters that offer high performance, reliability, and efficiency. Some of their popular models include Rinnai RL75iN, Rinnai RU Sensei Super, Rinnai Outdoor Tankless Hot Water Heater, etc.
- Stiebel Eltron: A German company that specializes in electric-powered tankless water heaters that feature advanced technology, design, and quality. Some of their popular models include Stiebel Eltron Tankless Tempra 24 Plus, Stiebel Eltron Mini 6 Electric Tankless Water Heater, Stiebel Eltron Tempra 36 Plus, etc.
- EcoSmart: An American company that produces eco-friendly electric-powered tankless water heaters that use self-modulating technology to adjust energy consumption based on demand. Some of their popular models include EcoSmart ECO 18 Electric Tankless Water Heater, EcoSmart ECO 11 Electric Tankless Water Heater, EcoSmart ECO 8 Tankless Water Heater, etc.
Q: How do I maintain my tankless water heater?
To maintain your tankless water heater, you should follow these steps:
- Flush your unit regularly with vinegar or a special descaling solution to remove mineral deposits that can affect its performance and efficiency.
- Replace your filter screen or cartridge periodically to prevent clogging or damage from debris or sediment.
- Check your venting system for any leaks, blockages, or corrosion that can cause safety hazards or reduce efficiency.
- Consult your owner’s manual for specific instructions on how to troubleshoot any problems or issues with your unit.


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