Portable water heaters are more space and energy efficient than their tanked counterparts while also meeting your hot water needs on demand. The experts at This Old House scoured Amazon to discover the top-rated tankless water heaters and compiled their findings in this review.
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Tankless water heaters heat water on demand, rather than storing heated water in a reservoir. Read our breakdown of the top portable water heaters on Amazon if you’re in the market for a compact, low-energy model.
Our Top Picks
- 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
- Original Design: Tankless hot water heater only heats when necessary to conserve energy; For the latest in non-condensing technology and a cleaner layout that speeds up service and installation, check out our new RE180iN model
- Never Run Out of Hot Water with this Compact Tankless Gas 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 7.5 GPM (5 fixtures at once)
- Smart, Durable Design: Enhanced scale detection helps prevent serious, long-term damage to unit; Includes 15-, 5-, and 1-year residential guarantee 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
- Endless Hot Water: Enjoy unlimited hot water flow throughout the house; compact, durable, and easy to install; professional installation recommended
- Energy and Space Efficient: Space-saving design conserves energy as it heats only when necessary
- Optimal Water Pressure: High-performance up to 5.3 GPM hot water flow rate for a powerful, constant stream
- Enhanced scale detection lessens possibility of serious, long-term damage to unit
- Guaranteed to Last: 10-, 5-, and 1-year residential factory warranty for heat exchanger, labor, and parts, respectively
- 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
- 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.
- EcoSmart ECO 11 Sizing; 13-kilowatt tankless electric water heater ideal for providing hot water for a bathroom, small sink, office breakroom and other point-of-use or low-flow applications; provides between 1.3 and 3.1 gallons-per-minute depending on the inlet water temperature; refer to the sizing guide to select the proper solution
- ON/OFF Dial Control with adjustable digital temperature display
- Self-modulating power control
- 8kW Model Flow Rate: up to 1.95 GPM
- Side 1/2" NPT water connections
- On demand; continous hot water
Review
Best Electric Flow Rate: Stiebel Eltron Tankless Water Heater
- 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
For an electric tankless water heater, this model’s flow rate of 1.5-4.5 GPM is surprisingly strong. Energy savings are guaranteed on a continuous basis without the need for ventilation thanks to the smart self-modulating technology and small size of the device.
Pros
- Outfitted with memory settings
- Provides silent operation
- Has an advanced flow control function that keeps water temperature consistent while it’s in use
Cons
- Has a hefty restocking fee
- Has a larger footprint than other electric models
What Customers Are Saying
Consumers praised the hot water heater’s durability and dependability. For more than a decade, it served them well, they claimed. Customers who were unhappy with their purchases claimed that they had encountered difficulties when attempting to return them because of the product’s flaws.
Best Indoor Gas Model: Rinnai Indoor Tankless Hot Water Heater
- Original Design: Tankless hot water heater only heats when necessary to conserve energy; For the latest in non-condensing technology and a cleaner layout that speeds up service and installation, check out our new RE180iN model
- Never Run Out of Hot Water with this Compact Tankless Gas 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 7.5 GPM (5 fixtures at once)
- Smart, Durable Design: Enhanced scale detection helps prevent serious, long-term damage to unit; Includes 15-, 5-, and 1-year residential guarantee 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
In order to increase the water flow rate, this portable water heater operates on gas rather than electricity. Installing it indoors protects it from the elements and maximizes its thermal potential. Its 7.5 GPM discharge rate makes it a great choice for both larger and more average-sized residences.
Pros
- Built with enhanced scale detection to minimize long-term damage to the unit
- Can provide hot water to several appliances at once
- Equipped with a temperature lock that prevents accidental changes to water temperature
Cons
- Some customers said that the unit was difficult to install
- Most expensive option in this guide
What Customers Are Saying
Those who bought it raved about how simple it was to set up, how silent it ran, and how much money it cut off their energy bills. One unhappy customer even specifically mentioned a dent in the device after receiving the product.
Best Outdoor Gas Model: Rinnai Outdoor Tankless Hot Water Heater
- Endless Hot Water: Enjoy unlimited hot water flow throughout the house; compact, durable, and easy to install; professional installation recommended
- Energy and Space Efficient: Space-saving design conserves energy as it heats only when necessary
- Optimal Water Pressure: High-performance up to 5.3 GPM hot water flow rate for a powerful, constant stream
- Enhanced scale detection lessens possibility of serious, long-term damage to unit
- Guaranteed to Last: 10-, 5-, and 1-year residential factory warranty for heat exchanger, labor, and parts, respectively
If you don’t have the room or the desire to add ventilation with your water heater, then this gas-powered model is the way to go. At only 33 pounds, this device is extremely portable.
Pros
- Lightweight for a gas model at 33 pounds
- Offers the option to use Wi-Fi technology for remote control
- Approved by the South Coast Air Quality Management District, which is responsible for regulating air pollution in California
Cons
- May not work with certain products, such as high-flow shower heads
- Doesn’t include a recess box to protect the unit from outdoor elements
What Customers Are Saying
In addition to its efficiency, simplicity of use, temperature regulation, and cost savings, buyers appreciated the product’s reputation for customer satisfaction. The product received mostly positive evaluations, but one reviewer mentioned problems with the flow switch.
Best Medium Capacity: EcoSmart ECO 18 Electric Tankless Water Heater
- 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
This electric tankless water heater has a flow rate of between 1.8 and 4.3 GPM, making it a medium capacity device. The water it produces can be adjusted in temperature from 80 to 140 degrees Fahrenheit via a dial that permits adjustments in 1-degree increments.
Pros
- Can help you save 60% on water-heating costs
- Offers point-of-use installation to limit the amount of time it takes hot water to get to you
- Has a wall-mounted design to free up floor space
Cons
- Some customers experienced poor customer service
- Must hire a plumber or electrician to install it to validate the warranty
What Customers Are Saying
Users who were satisfied with their acquisition of the water heater cited its low price, ease of installation, and dependability as reasons for their satisfaction. Customers who were unhappy with their purchases complained about the manufacturer’s customer support and the difficulties they encountered enforcing the warranty.
Best Small Capacity: EcoSmart ECO 11 Electric Tankless Water Heater
- 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.
- EcoSmart ECO 11 Sizing; 13-kilowatt tankless electric water heater ideal for providing hot water for a bathroom, small sink, office breakroom and other point-of-use or low-flow applications; provides between 1.3 and 3.1 gallons-per-minute depending on the inlet water temperature; refer to the sizing guide to select the proper solution
As its modest flow rate of 1.3-3.1 GPM suggests, this tankless water heater is best suited for single- or double-person households. It can maintain efficiency within one degree of the set temperature.
Pros
- Provides endless on-demand hot water at controlled flow rates
- Has a size that’s 90% smaller than traditional tank heaters
- Includes advanced self-modulating technology that only uses the precise amount of energy needed to heat the water
Cons
- The warranty doesn’t cover labor or accidental damages
- Can’t heat enough water for larger homes
What Customers Are Saying
Easy installation, reliable operation, and significant energy savings are just a few of the reasons why buyers praised this water heater. Dissatisfied customers typically cited unhelpful technical assistance and a failure to honor the product’s warranty as the root of their dissatisfaction.
Best Temperature Readout: Rheem Tankless Electric Water Heater
- ON/OFF Dial Control with adjustable digital temperature display
- Self-modulating power control
- 8kW Model Flow Rate: up to 1.95 GPM
- Side 1/2" NPT water connections
- On demand; continous hot water
The temperature readout on this compact, corded electric water warmer is both attractive and simple to read. Adjusting the water temperature is as simple as turning the handle beneath the screen. This burner is small enough to fit under a kitchen sink.
Pros
- Provides hot water on-demand
- Uses little electricity while saving homeowners on gas costs
- Doesn’t require any venting, allowing installation anywhere inside the home
Cons
- Some customers had longevity issues with their unit
- Has a limited capacity at only eight kilowatts
What Customers Are Saying
Overwhelmingly, satisfied customers have praised this portable water heater’s performance. They also mentioned that when they needed hot water, it heated it up fast, and when they didn’t, it turned off automatically to save energy. While many people love the convenience of a tankless water heater, some have voiced concerns about the size of the electrical cord required for such a setup.
Buyer’s Guide
If you’re looking to purchase a tankless water heater, then you should read our purchasing guide to learn about the various factors, such as power source and flow rate, that you should consider.
Power Source
Tankless water heaters use electricity or gas for power.
- Electric: Those who prefer an electric water warmer can easily hook it up to their existing electrical network. A sensor in the heating element activates the burner and a thermostat begins working to bring the water to the desired temperature as it flows through the device. Electric water heaters are less expensive to purchase than their gas-powered counterparts, but they also produce cooler water.
- Gas: Water heaters that operate on gas are more effective and can provide hot water for multiple appliances at once. Based on whether or not they have two heat exchangers, they can be further classified as condensing or non-condensing.
- Non-condensing: One heat exchanger is used in a non-condensing device. The device loses a lot of heat that could be used to heat more water in the exhaust, which is around 300 degrees Fahrenheit. This gas heater model, however, is less expensive than its condensing version. Because it uses the same venting as your old gas-powered tank water heater, you can save money on both the device and the installation.
- Condensing: Condensing water heaters use the hot exhaust from the primary heating device to heat even more water. Although purchasing a condensing water heater will cost more than purchasing a non-condensing device, you will save money in the long run due to the water heater’s lower energy consumption.
Flow Rate (GPM)
The GPM, or gallon per minute, is a common measurement of tankless water heater performance. The discharge rate of electric water heaters is lower than that of non-condensing gas heaters, which is lower than that of condensing gas heaters. Think about how many items you want to use simultaneously and how much water they each need to determine the appropriate flow rate. To give you an idea, a standard shower head uses 2.5 gallons per minute of water, while a dishwasher needs only one and a laundry machine needs 1.5 gallons per minute. At least three gallons per minute (GPM) of flow rate is required to simultaneously operate a washing and a shower.
Indoor vs. Outdoor
If you don’t have the room for a gas-powered water heater or the ability to install the air necessary to operate one safely, an outdoor water heater may be the best option for you. In the winter, when they are open to the elements, they are less effective at their job of heating the water passing through them.
Installation
There is less of a learning curve involved when installing an electric water heater as opposed to a gas one. They are more flexible in terms of placement than gas-powered water warmers because of their compact size. After deciding where to put it, you’ll need to hook up the water heater to the house’s plumbing and power supply. A gas water heater installed indoors must have adequate airflow to prevent the accumulation of combustion byproducts that could be harmful to human health. Since the unit, vents, and ducts all need room, this not only lengthens the installation process but also restricts placement options.
Maintenance and Warranty
A professional should service your tankless water heater once or twice annually, depending on the brand and type. Many local water sources contain minerals (also known as “hard” water), which can cause your tankless water heater to clog or become less efficient. You should also consider hiring an expert plumber to install your tankless water heater if you want to maintain the warranty offered by the manufacturer.
Frequently Asked Questions
Will I save money with a tankless water heater?
Yes. Tankless units are more costly than traditional ones. However, it is more cost-effective than traditional water heaters in the long term.
How long will it take my tankless water heater to heat my water?
When using a portable water heater, the water is typically hot within a few seconds. The distance between the heater and the faucet is probably to blame for the temporary delay.
Will my tankless water heater still work if the power goes out?
A power failure won’t affect gas water heaters because they aren’t wired into your home’s electrical system. Water can still pass through electric heaters, but they won’t boil the water unless you have a battery backup.
What are the drawbacks of a tankless water heater?
There are a few disadvantages to tankless water heaters, including the fact that you have to wait longer for hot water, that they are expensive to install initially, and that you can’t easily get water to a comfortable lukewarm temperature. It’s also possible that electric portable water heaters won’t function if the power goes out.
Last update on 2023-03-24 / Affiliate links / Images from Amazon Product Advertising API
