best tankless hot water heater

how does a hot water heater work

The best tankless hot water heater is a type of water heating system that does not use a traditional storage tank to hold hot water. Instead, it heats water on demand as it is needed, using a gas burner or electric element. This allows for a continuous supply of hot water and helps to save energy by only heating the water as it is needed, rather than constantly keeping a large tank of water hot. Tankless water heaters can be installed either inside or outside a home, and are often smaller and more compact than traditional water heaters. They also have a longer lifespan and can be more energy efficient, although they may have higher upfront costs.

our top picks of January 2023

EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with Patented Self Modulating Technology

The EcoSmart ECO 11 Electric Tankless Water Heater is a compact and efficient way to provide endless hot water on demand. Its patented self-modulating technology continuously monitors and adjusts the water temperature and flow rate to ensure consistent performance and efficiency.


This best tankless hot water heater is ideal for low-flow applications such as a bathroom, small sink, or office breakroom. It is 90% smaller than traditional tank heaters and can be installed on the wall or at the point of use. Additionally, it is 99% thermal energy efficient, only heating the water when it is needed, unlike a tank heater that maintains a constant temperature even when not in use.



Capacity: 2 Gallons


Power: Electric


Dimensions: 3.75 x 8 x 11.5 inches


Color: White


Wattage: 13,000 watts



Weight: 6.5 pounds


  1. Endless hot water on demand
  2. Compact size and easy installation
  3. Efficient and energy-saving
  4. Multiple applications


  1. Warranty only covers cost of heater, not labor or incidental damages
Rheem 11kW 240V Tankless hot Water Heater

The Rheem 11kW 240V, best Tankless hot Water Heater, is a reliable and efficient choice for homeowners in need of on-demand hot water. Its self-modulating power control and adjustable digital temperature display make it easy to use.


Its energy and cost saving capabilities can save you up to 50% on your energy bills when used in a point-of-use application. The compact, wall-mounted design is easy to install and fits easily in tight spaces, and the unit comes with a 5-year heating chamber warranty and 1-year parts limited warranty for added peace of mind.



Power Source: 240v Corded Electric


Dimensions: 12.63 x 8.25 x 3.63 inches


Color: Gray


Voltage: 240 Volts


Material: Stainless Steel


Weight: 7 pounds


Heat Output: 11 Kilowatts


Flow rate: upto 2.68 GPM


  1. On-demand hot water
  2. Energy and cost savings
  3. Easy to adjust electronic temperature control
  4. Reasonable warranty
  5. Compact
  6. Easy to install


  1. 240V electrical outlet may not be available in all homes
  2. May not be suitable for large households
  3. No venting or T&P valve required
.Rinnai CU160eP Propane Gas Condensing Tankless Hot Water Heater, 9 GPM

The Rinnai CU160eP Propane Gas Condensing Tankless Hot Water Heater is a powerfulenergy-efficient solution for providing hot water in demanding settings such as restaurants, educational institutions, and multi-family residential buildings.


With a flow rate of gallons per minute (GPM), this best tankless hot water heater is capable of supplying hot water to multiple fixtures at once, ensuring that you’ll never run out of hot water.

The Circ-Logic technology of this water heater enables recirculation patterns that coincide with your typical habits, while the Wi-Fi monitoring allows you to create hot water on demand.


While the compact, space-saving design of this best tankless hot water heater conserves energy and offers multiple venting options for installation flexibility, it may not be suitable for use in all climates and professional installation is recommended.The CU160eP also features instant heating technology and a long lifespan, but the warranty does not cover all components.



Capacity: 9 gallons


Power source: Natural gas


Dimensions: 22.05 x 33.86 x 14.76 inches


Weight: 70.8 pounds


  1. Energy and space efficient design
  2. High-performance flow rate
  3. Instant heating technology
  4. Long lifespan


  1. Professional installation recommended
  2. Not suitable for use in all climates
  3. Limited warranty coverage for some components
Rheem Indoor Liquid Propane Tankless hot Water Heater, 9.5 GPM

With a capacity of 100 gallons and a variety of energy-saving features, this tankless water heater is sure to meet your hot water needs. Some of the standout benefits of this product include its ability to adjust energy consumption, its easy and convenient temperature control.


This best tankless hot water heater comes with a digital remote control and a number of smart home features when connected to the EcoNet mobile app. The Rheem Tankless Indoor Liquid Propane Water Heater also has a variety of safety features, including a Guardian OFW overheat film wrap. And a 12-year heat exchanger warranty for residential use and a 5-year heat exchanger warranty for commercial use.



Capacity: 100 gallons


Power Source: Natural Gas


Dimensions: 9.88 x 13.88 x 25.63 inches


Color: Gray


Voltage: 120 volts


Material: Stainless Steel


Weight: 62 pounds


Flow rate: up to 9.5 GPM


  1. Continuous hot water
  2. Energy efficient and cost-saving
  3. Adjusts energy consumption
  4. Easy and convenient temperature control
  5. High-altitude capability
  6. Digital remote control


  1. For indoor use only
  2. Requires 120V power supply
.Stiebel Eltron Tempra 29 Plus Tankless hot Water Heater

This model provides an on-demand, continuous supply of hot water, and its sleek design means it won’t take up much space in your home. Plus, it doesn’t require venting, which is a huge plus.


However, it should be noted that this water heater does require hard-wired 240 or 208-volt electric service, with a maximum draw of 28,800 watts at 240 volts or 21,600 watts at 208 volts. It also requires three separate dedicated 40 amp breakers with 8 gauge copper wiring, and a minimum of 200 amp total service to the residence.



Capacity: 0.39 Gallons


Power: Electric


Dimensions: 4.63 x 16.63 x 14.5 inches


Color: White


Wattage: 28.8 KW


Material: Copper


Weight: 1 pound


  1. On-demand hot water
  2. Space-saving design
  3. Energy efficient
  4. Multiple certifications


  1. Requires hard-wired electrical service
EcoSmart ECO 8 Tankless Water Heater, Electric, 8-kW - Quantity 1

The EcoSmart ECO 8 Tankless Water Heater is a highly efficient and cost-effective solution for those in need of a reliable source of hot water. With a capacity of 2 gallons and a heating output of 8 kilowatts, this electric tankless water heater is perfect for small to medium households. It features a digital temperature control that allows you to set your desired temperature in increments of 1 degree, ensuring that you always have the perfect water temperature for your needs.


One of the major benefits of this Best Tankless Hot Water Heater is its energy efficiency. It has a high energy factor of 0.82, meaning that it uses less energy to produce hot water than traditional tank water heaters. This not only saves you money on your energy bills, but it is also better for the environment. The EcoSmart ECO 8 Tankless Water Heater is also highly durable, with durable heating elements that are threaded for easy replacement.



Capacity: 2 gallons


Power: Electric


Dimensions: 9.75 x 3.75 x 12 inches


Color: White


Wattage: 8000 watts


Weight: 4.75 pounds


  1. Highly energy efficient
  2. Digital temperature control
  3. Highly durable
  4. Easy to use


  1. Warranty only covers the cost of the heater, not labor or incidental damages

Factors to consider When purchasing the Best Tankless HOT Water Heater


Tankless water heaters come in a range of sizes, and it’s important to choose one that is appropriately sized for your household. A unit that is too small will not be able to keep up with demand, while a unit that is too large will be less efficient and more expensive to operate.


Fuel type:

Tankless water heaters can be powered by electricity, natural gas, or propane. Each fuel type has its own pros and cons, so you should consider which one is most suitable for your home and budget.


Natural gas: Tankless hot water heaters that use natural gas are generally the most cost-effective option, as natural gas is typically less expensive than electricity. They are also relatively efficient, with some models having energy efficiency ratings as high as 98%.


Propane: Tankless water heaters that run on propane are a good choice for areas where natural gas is not available. They are generally more expensive to operate than natural gas models, but still more cost-effective than electric tankless water heaters.


Electric: Tankless water heaters that use electricity are the most expensive to operate, but they have the advantage of being able to be used in any location since they do not require a gas line. They are also relatively efficient, with some models having energy efficiency ratings of up to 99%.



Look for a tankless water heater that has a high energy factor (EF) rating, as this will indicate how efficiently the unit converts fuel into heat.

Warranty: Make sure to choose a tankless water heater that comes with a good warranty, as this will provide you with protection in case anything goes wrong with the unit.



Tankless water heaters can vary significantly in price, so it’s important to set a budget and look for a unit that fits within it.


Flow rate:


The flow rate of a water heater refers to the amount of water that the heater can heat and deliver to a plumbing fixture, such as a showerhead or faucet, in a given amount of time. It is usually measured in gallons per minute (GPM).


For example, if a water heater has a flow rate of 4 GPM and you are using a showerhead that has a flow rate of 2.5 GPM, the water heater will be able to fully heat the water for the shower. However, if you were using a showerhead with a flow rate of 5 GPM, the water heater would not be able to fully heat all the water, and you would experience a decrease in the temperature of the water as you shower.


The flow rate of a water heater can be affected by a variety of factors, such as the size of the heater, the type of fuel it uses, and the efficiency of the heating element. In general, larger water heaters and those with more efficient heating elements will have higher flow rates.
Enable registration in settings - general