Closeup on the bottom of a tankless water heater on a wall at left, with the article title at right

Tankless water heaters have become an increasingly sought-after option for many homeowners due to their instant water heating ability, excellent flow rates, and energy efficiency

But in a market saturated with choices, how do you know which one is the top option?

This comprehensive guide will go over the ten best tankless water heaters available. It’ll also provide a buyer’s guide at the end, which will help you choose the best model for your specific needs. So buckle up, and let’s get started!

Best Overall: Rinnai RL75IN 

The best and most readily-available tankless water heater for general use is the Rinnai RL75IN. Being a natural gas model, it provides an excellent combination of value and efficiency. It offers up to 7.5 GPM of hot water flow and can support a maximum of four different fixtures simultaneously.

The Rinnai RL75IN seen next to a window on the wall of a home
Courtesy of Ubuy

The Rinnai RL75IN is an excellent all-around unit with great value and top-of-the-line performance.

With its outstanding output of 7.5 GPM, this natural gas tankless water heater can support up to four fixtures at once. So if you live in an area with low temperatures, this model will supply endless hot water to at least three fixtures, provided the temperature at the cold water inlet is at least 57°F (13°C).

It is also equipped with Rianni’s Circ-Logic recirculation technology, allowing you to schedule it to automatically recirculate hot water in your pipes according to typical usage patterns. The Wi-Fi monitoring capability also enables you to keep track of your energy usage and troubleshoot any issues that may arise.

The model’s compact size reduces competition for storage space in your home and makes installation a breeze. These features come at a very reasonable price, making the Rinnai RL75IN the best overall tankless water heater.


  • Excellent hot water flow rate of up to 7.5 GPM
  • Supports up to four fixtures
  • Circ-Logic recirculation technology for efficient hot water delivery
  • Wi-Fi monitoring capability


  • You must purchase Rianni’s pump kit and control-R module to use Circ-Logic recirculation technology
  • Pricey

Runner-Up: Takagi T-H3-DV-N

If you’re after a high-end unit with all the bells and whistles, the Takagi T-H3-DV-N is your best bet.

This premium quality natural gas model can produce up to 10 GPM of hot water, making it one of the market’s most powerful tankless water heaters. It can supply enough hot water to four fixtures simultaneously in warm water climates and three in colder areas.

Promo photo of the Takagi T-H3-DV-N
Courtesy of Hebron Stores

Being Energy Star-certified, the Takagi T-H3-DV-N is also one of the most efficient models available. It has a 0.95 UEF rating, significantly higher than the standard 0.82 for natural gas tankless water heaters. The unit also has a built-in condensing technology that further improves efficiency.

Designed with commercial-grade copper alloy heat exchangers, the Takagi T-H3-DV-N can efficiently handle heavy residential use. It also comes with a self-diagnostic system and troubleshooting diagnostic codes that make it easy to identify and solve any issues that may come up.


  • Energy Star-certified
  • A high flow rate of up to 10 GPM
  • Self-diagnostic system for easy troubleshooting
  • No pilot light required


  • Expensive
  • Challenging to find qualified technicians for service and repairs
Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute, 199,000 BTU
189 Reviews
Takagi T-H3-DV-N Condensing High Efficiency Natural Gas Indoor Tankless Water Heater, 10-Gallon Per Minute, 199,000 BTU
  • Endless hot water, On-demand usage, Compact, Space saving, Energy conservation
  • Computerized safety features, No pilot light to have to worry about
  • Safety features include freeze, overheat, surge protection, and troubleshooting diagnostic codes
  • Satisfies the 2012 SCAQMD Rule 1146.2 for Ultra-Low NOx Emissions
  • Primary heat exchanger utilizes commercial-grade copper alloy for 25 times better heat transfer than stainless steel, Integrated controls and power cord as standard features

Best Budget-Friendly: EcoSmart ECO 18

Tankless water heaters are expensive, but the EcoSmart ECO 18 Electric Tankless Water Heater is a more budget-friendly option that doesn’t sacrifice quality or performance.

Promo photo of the EcoSmart ECO 18 electric tankless water heater
Courtesy of Drikes

This 18kW unit is designed for small to medium homes with up to two bathrooms. It has a flow rate of 3.51 GPM, which is sufficient for one or two fixtures in use simultaneously. With a stellar 99% efficiency rating, this unit will help you save up to 50% in water heating costs.

Being 90% smaller than traditional water heaters, the EcoSmart ECO 18 is also one of the most compact models available. Its sleek, wall-mounted design will free up valuable floor space in your home. 

It also features self-modulating technology that automatically regulates power based on water demand to improve efficiency further.


  • Affordable
  • Compact, space-saving design
  • High-efficiency rating of 99%
  • Self-modulating technology for improved efficiency
  • Easy to install
  • Digital temperature display for easy temperature control


  • Not well-suited for large homes or families
EcoSmart ECO 18 Electric Tankless Water Heater, 18 KW at 240 Volts with Patented Self Modulating Technology , 17 x 14 x 3.5
  • The product is highly durable
  • The product is easy to use
  • Manufactured in China
  • Amperage (amps): 75. Activation flow: 0. 3 GPM. Flow Rate @ 35 F Rise (gallons/min): 3. 51 gal (US)/min
  • The product works and is compatible with 2 X 40 AMP (DP) breakers and 2 X 8 AWG wire

Best Electric: Rheem RTEX-24

With its excellent performance and easy operation, the Rheem RTEX-24 scoops up our top spot for the best electric tankless water heater.

The Rheem RTEX-24 mounted on the wall of a garage next to the door
Courtesy of Amazon

This 240V unit is designed for small to medium homes with up to three bathrooms. It has a flow rate of 5.9 GPM and can provide an endless hot water supply for up to three fixtures in use simultaneously, depending on the groundwater temperature. 

Its digital temperature display allows you to easily adjust and monitor the water temperature and where it will be heated in your home.

Featuring a self-modulating power element, the Rheem RTEX-24 automatically adjusts its power output based on water flow to improve efficiency. This technology also makes it less likely to experience a sudden drop in water pressure, which is often an issue with tankless water heaters. 

With over 120,000 BTUs per hour of heating power, this unit can handle even the coldest groundwater temperatures. 

Rheem offers a five-year limited warranty on the RTEX-24 and a one-year warranty on parts, so you can be confident in its quality and performance.


  • Digital temperature display for easy temperature control
  • Self-modulating power element for improved efficiency
  • Five-year limited warranty


  • Some gas models provide higher GPM
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
677 Reviews
Rheem RTEX-24 24kW 240V Electric Tankless Water Heater, Gray
  • ON/OFF Dial Control with adjustable digital temperature display
  • Self-modulating power control
  • 24kW Model Flow Rate: up to 5.9 GPM for RTEX-24
  • Bottom 3/4" NPT water connections
  • On demand, consistent and continuous hot water

Best Value for Your Money: Stiebel Eltron 239222 Tempra Plus

With German engineering and a long history of quality craftsmanship, Stiebel Eltron is a trusted name in the water heater industry. The 239222 Tempra Plus is one of the company’s best models, packing many features and functionality in one affordable unit.

Featuring patented Advanced Flow Control, the Stiebel Eltron 239222 Tempra Plus can maintain a consistent temperature output of between 86-140˚F (30-60˚C) even when water flow varies. 

The Stiebel Eltron 239222 Tempra Plus pictured mounted on the wall in a garage next to the door
Courtesy of Amazon

This regulation is thanks to its self-compensating, flow-sensitive modulating power element that automatically adjusts power output to maintain desired water temperature.

With a 0.99 EF rating, it is the market’s most energy-efficient electric tankless water heater. Its small, sleek design also saves valuable space in your home. 

Stiebel Eltron offers a sever-year leakage and three-year parts warranties with the 239222 Tempra Plus, so you can be confident in its quality and performance.


  • Advanced Flow Control for a consistent temperature output
  • The most energy efficient with a 0.99 EF rating
  • Small, sleek design that saves valuable space
  • Reliable German engineering


  • High upfront cost
  • Requires a minimum electric service of 150 A
Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric, On Demand Hot Water, Eco, White, 20.2
  • CONTINUOUS FLOW – Advanced Flow Control patented technology invented by Stiebel Eltron, automatically maintains water temperature for constant comfort. It’ll reduce flow slightly if hot water demand exceeds capacity. Hot showers will never be interrupted again
  • SPACE & ENERGY SAVER – Its small, sleek white design saves space yet still provides endless hot water for your whole house, and no venting is required. Eco friendly unit saves energy with auto-modulation and the ability to electronically control water flow. Savings monitor even shows how much you save on energy costs
  • EASY OPERATION – Electronic switch activates the hot water heater and it’s noise free while in use. Has a digital temperature display and preset temperature and memory buttons, while the interior solid copper heating system does all the power work
  • TEMPRA 24 PLUS – This specific model is 24kW, 240V, requires a min recommended electric service of 150 A, and offers an output water temperature of 68° to 140°F. Check our guides below to compare features of our various Trend and Plus models, each available in different kW levels, Tempra Plus tankless water heaters can be set to limit the maximum hot water temperature to 109°F. This can be important in some installations to prevent the possibility of scalding.
  • WARRANTIES INCLUDED – Stiebel Eltron’s top-rated electric tankless water heaters perform with the highest standards for comfort and reliability. Our 7-Year Leakage and 3-Year Parts Warranties are included with purchase

Best Point-of-Use: Bosch Tronic 3000 T 4-Gallon (ES4)

Point-of-use tankless heaters are designed for smaller applications, such as providing hot water at a single sink or fixture. The Bosch Tronic 3000 T 4-Gallon (ES4) is one of the best point-of-use models on the market, perfect for compact homes, RVs, and boats.

The Bosch Tronic 3000 T 4-Gallon (ES4) installed under a bathroom sink
Courtesy of Amazon

It features a thermal efficiency of 98% and supplies up to four gallons (15 liters) of hot water per minute. If you already have a central water heating system, this heater will prevent water wastage by providing hot water only when and where you need it, cutting long wait times for hot water at the tap.

And you don’t have to worry about installation, as this unit doesn’t require professional help. Mount it to a wall, shelf, or floor with the provided bracket, then connect it to a standard 120V electrical outlet, and you’re good to go!


  • Thermal efficiency of 98%
  • Supplies up to 4 gallons per minute
  • Prevents water wastage
  • Easy installation; no professional help required


  • Limited to small applications as a point-of-use heater
Bosch Electric Mini-Tank Water Heater Tronic 3000 T 4-Gallon (ES4) - Eliminate Time for Hot Water - Shelf, Wall or Floor Mounted
10,479 Reviews
Bosch Electric Mini-Tank Water Heater Tronic 3000 T 4-Gallon (ES4) - Eliminate Time for Hot Water - Shelf, Wall or Floor Mounted
  • CONVENIENT HOT WATER HEATER: 4 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 13.5 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
  • FAST RECOVERY RATE: Eliminates long waits for hot water at your sink, get on demand hot water at your every need (supplies up to 2 sinks at a time)
  • EASILY MOUNTED: Can be shelf, wall or floor mounted (bracket included); simply tap into the cold water line and install the water heater directly at the sink to provide hot water

Best Portable: Camplux AY132

If you’re an outdoor enthusiast or often find yourself away from home, you’ll want to take a portable tankless water heater with you. The Camplux AY132 is one of the best mobile models on the market and is perfect for camping, bathing pets and animals, and washing dishes while on the go.

A couple sitting outside a tent on their campsite, as the man plays guitar and the Camplux AY132 sits on the ground next to them
Courtesy of Amazon

This tankless water heater is powered by liquid propane and delivers up to 1.32 GPM hot water. It also features a battery-powered ignition system, so you don’t have to worry about matches or a lighter to start it. 

The model features a gas regulator and showerhead for easy setup, and the compact design means you can take it almost anywhere.

Its easy operation makes it a perfect choice for off-grid living, as you can have hot water at the push of a button. However, you must ensure you have water pressure of at least 30 PSI for the Camplux AY132 to do its thing adequately.


  • Light-weight and easy to set up
  • Battery-powered ignition system
  • Freeze protection
  • Ideal for camping, fishing, and road trips


  • Must have water pressure of at least 30 PSI
  • Ideal for small applications only
Camplux Tankless Water Heater, 1.32 GPM Portable Propane Outdoor Camping Water Heater, 5L, AY132, White
  • Lightweight, Compact & Portable Design: The 10 pounds lightweight portable water heater's folding handle keeps it out of the way and enables easy setup outside.
  • Flow Rate & Temperature Specification: The temperature raise is 114.8℉ (46℃) at its highest point and 46.4℉ (8℃) is at its lowest point of 1.32 GPM. Also, 1.32 gallons of hot water can be produced per minute at the flow rate of 1.32 GPM.
  • Versatile Applications: The lowest water pressure at beginning for the water heater is 3.0 PSI. For off-grid and rural areas, this hot water generator powered by two size D batteries is ideal. No more chilly outdoor shower anymore.
  • 6-in-1 Protection & CSA Safety Approved: This tankless water heater is CSA Approved with anti-freezing protection, over-heating protection, low water flow protection, dry combustion protection, high water pressure protection and flame failure device.
  • Installation Instruction & Package Content: This Camplux AY132 heater comes with 1-year guarantee, 5 feet premium on/off shower head, 5 feet gas regulator, 1 set US-standard garden hose, and 1 installation hardware pack. Setting up this propane water heater simply takes 10 minutes.

Best for Outdoor Use: Rinnai V53DeN

While most tankless water heaters are designed for indoor installation, the Rinnai V53DeN is a great option for those who need hot water outdoors or want to save space indoors. This whole-house natural gas-powered unit provides 5.3 GPM hot water, ensuring a steady water supply for multiple uses.

The Rinnai V53DeN pictured mounted on a brick home's exterior wall
Courtesy of ItCare

Its enhanced scale detection system with a built-in descaling feature helps prolong the unit’s life and maintain its performance. In addition, the model’s energy-efficient and space-saving design mean it can be installed almost anywhere, even in tight spaces.

With a ten, five, and one-year residential warranty on heat exchange, parts, and labor, the Rinnai V53DeN is a superb choice for those needing a reliable and durable tankless water heater.


  • 5.3 GPM hot water output
  • Energy-efficient and space-saving design
  • Enhanced scale detection system with a built-in descaling feature


  • Heavy
Rinnai V53DeN Tankless Hot Water Heater, 5.3 GPM, Natural Gas, Outdoor Installation
  • Endless Hot Water: Our tankless hot water heaters let you enjoy unlimited hot water flow throughout the house with a compact and durable design that fits your home and lifestyle
  • Energy and Space Efficient Tankless Gas Water Heater: This small hot water heater conserves energy, only heating when necessary; Enhanced scale detection lessens possibility of serious, long-term damage to unit
  • Optimal Water Pressure: This tankless water heater offers a high-performance hot water flow rate up to 5.3 GPM for a powerful, constant stream that serves up to 4 appliances at once
  • Professional Installation Recommended: Visit the Find a Rinnai PRO page on our website to locate a qualified technician in your area to install your tankless water heater; We do not recommend installing a water heater without a technician
  • Guaranteed to Last: 10-, 5-, and 1-year residential factory warranty for heat exchanger, labor, and parts, respectively

Best for Big Homes: Rinnai RL94iP

For big homes with multiple bathrooms and high demand for hot water, the Rinnai RL94iP is the best-suited tankless water heater. With a maximum hot water output of 9.8 GPM, this whole-house propane gas unit provides an endless and constant hot water supply throughout your home.

The Rinnai RL94iP shown mounted on the wall of a laundry room
Courtesy of Anderson Propane

The unit is equipped with Circ-Logic technology that enables water recirculation based on your schedule and needs, so you’re never without hot water. Being a gas-powered model, it ensures optimal performance and energy efficiency. Its self-diagnostic system alerts you of any issues making maintenance a breeze.

To ensure your safety, the RL94iP comes with a freeze protection system that kicks in when temperatures drop below freezing. 

It also has a guaranteed twelve, five, and one-year residential warranty and five, five, and one-year commercial factory warranty for heat exchangers, parts, and labor, respectively.


  • Excellent 9.8 GPM hot water output
  • Circ-Logic technology for recirculation of water
  • Self-diagnostic system
  • Freeze protection features


  • Expensive
Rinnai RL94iP Tankless Hot Water Heater, 9.8 GPM, Propane, Indoor Installation
  • Original Design: Tankless hot water heater's Circ-Logic technology offers recirculation patterns that match your habits; For the latest in non-condensing technology that speeds up service and installation, check out our new RE180iP model
  • Never Run Out of Hot Water with this Compact Propane Water Heater: Non-condensing tankless hot water heater from Rinnai is only the size of a small suitcase and fits in a wide variety of spaces, but provides up to 9.8 GPM (6 fixtures at once)
  • Smart, Durable Design: Includes 12-, 5-, and 1-year residential guarantee and 5-, 5-, and 1-year commercial factory warranty for heat exchanger, labor, and parts, respectively; See Controlr module for WiFi control (not included)
  • Professional Installation Recommended: Visit the Find a Rinnai PRO page on our website to locate a qualified technician in your area to install your tankless water heater; We do not recommend installing a water heater without a technician
  • Find Your Rinnai: See our product guides, manuals, energy guide, warranty information, videos, and tables to find the right tankless water heater for your home; Check our Ground Water Temperature Map to see if this heater is optimal for your region

Best for Small Homes: Rheem RTEX-13

Petite homes with limited demand for hot water will find the Rheem RTEX-13 a perfect choice. This electric tankless water heater provides up to 3.17 GPM hot water and is 99.8% energy efficient. In addition, its compact, sleek design makes it perfect for installation in tight spaces.

The model comes with self-modulating power control that adjusts the heater’s output to match the amount of water flow, so you never use more energy than necessary. In addition, its external adjustable digital thermostatic control with an LED display makes setting the perfect water temperature easy.

The Rheem RTEX-13 installed on a wall
Courtesy of Rick Merryman

With its simple installation and easy operation, you won’t need to hire professional help, saving you even more money. It’s threaded for 1/2″ (1.27 cm) NPT adapters and has 1/2″ compression water connections.


  • Compact, light-weight design
  • 3.17 GPM hot water output
  • 99.8% energy efficient
  • Self-modulating power control
  • External adjustable digital thermostatic control


  • Not suited for high-demand applications
Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater, GRAY
  • External adjustable digital thermostatic control with LED display (+/1 degree accuracy
  • Durable Copper immersion two heating elements, field Serviceable.Self-modulating power control
  • Simple installation – 1/2 NPT adapters included; side 1/2 inch Compression water connections
  • 99.8% energy efficient. External controls to adjust temperature in increments of 1°f. Water-Saver Shower Head – 1.5 GPM
  • Threaded for easy replacement, simple installation, digital temperature display 54 A. 13kW Model Flow Rate: up to 3.17 GPM

Factors to Consider When Purchasing a Tankless Water Heater

Tankless water heaters are 24-34% more energy-efficient than traditional tank storage water heaters making them an excellent choice for those looking to save on their energy bills. And since they’re usually a significant investment, you must choose a suitable model for your home.

To help you decide, here are a few factors to consider:

GPM Rating

Gallons per minute (GPM) or water flow rate measures how much hot water the unit can deliver in a minute. Choosing a model with a GPM rating that meets or exceeds your peak demand is important. 

Calculate the GPM rating by adding up all the appliances and fixtures that will be using hot water simultaneously. For example, a standard shower uses about two GPM, while a dishwasher uses about three. 

This figure means you will need a tankless water heater with a GPM of at least five to meet the demands of a shower and dishwasher running simultaneously.

Energy Efficiency Rating

While tankless water heaters are more energy efficient than traditional storage tank water heaters, there’s still a big difference in the efficiency of different models. 

A tankless water heater installed on a wall

The energy efficiency rating measures how much power the unit uses is converted into heat. The higher the rating, the higher the efficiency. Look for models with an Energy Star rating, as these are the most efficient.


The climate you live in will also affect your decision. For example, if you live in an area with cold winters, you’ll want to choose a model with a freeze protection feature to ensure the unit doesn’t freeze and burst in the colder months. 

Groundwater temperature will also affect how many gallons per minute your tankless water heater can deliver. You can get away with a lower GPM rating in warmer climates as the groundwater temperature will be higher.

Fuel Type

Tankless water heaters models are available in:

  • Electric
  • Natural gas
  • Propane

Natural gas models offer the highest GPM ratings and efficiency, making them the best choice for high-demand applications. 

Electric tankless water heaters are the most popular choice as they’re more affordable and can be used in most climates. 

Propane models offer an excellent middle ground between electric and natural gas models. In addition, their portability makes them a good choice for those who want to use them in RVs or cabins.


Of course, the cost is always a factor to consider. Tankless water heaters are more expensive than traditional storage tank water heaters, but they last much longer, have a higher energy efficiency rating and will save you money in the long run. 

Determine your hot water needs and set a budget to avoid overspending. The best unit for you should tick all the boxes on your list and fit within your budget.

Key Takeaways

Considering GPM rating, energy efficiency, and cost, we have found the Rinnai RL75IN to be the best tankless water heater for most people. It’s a natural gas model with a 7.5 GPM flow rate and is Energy Star-rated. 

Compared to the other models on this list, it offers the best value for the price, ensuring optimal performance and long-term savings.

Check out the Rinnai RL75IN on Amazon today!


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