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We purchase every product we review with our own funds — we never accept anything from product manufacturers.

  • 111 Models Considered
  • 34 Hours Spent
  • 1 Experts Interviewed
  • 211 Consumers Consulted
  • Zero products received from manufacturers.

    We purchase every product we review with our own funds — we never accept anything from product manufacturers.

    Shopping Guide for Best Tankless Water Heaters

    Traditional water heaters are fickle friends in many ways. During heavy use, the 40- or 80-gallon reservoir can be emptied faster than it refills and heats, leaving someone in a cold shower. Heating and maintaining that much water at once isn’t very energy efficient, and if the heater suffers a catastrophic failure — that’s a lot of water pouring into your attic or garage.

    While water heaters have been a staple in homes for decades, their inefficiencies have led to a new breed of home hot water systems — the tankless water heater. The tankless water heater is a mega-sized version of an electric tea kettle. There is no tank of standing water. Hot water is supplied through an element that heats the water just before it’s used by a cook who needs hot water for making the evening meal, or when it’s time for the kids to take a bath before bed.

    At BestReviews, we take great pride in our thorough research and objectivity. To gain insight into the areas we cover, we perform detailed research on the top products, and conduct surveys with consumers to learn about their likes and dislikes. We never accept freebies or samples from product manufacturers, which allows us to remain unbiased in our work.

    If you’re ready to buy a tankless water heater, please consult the matrix above to learn more about our five top selections. If you’d like to know more about what makes tankless water heaters so special, we invite you to read on and take advantage of our shopping guide.

    Do an inventory of the points in the home where hot water is likely to be needed simultaneously, and choose a tankless water heater with adequate capacity.

    How Does A Tankless Water Heater Work?

    Tankless water heaters only heat water when you need it, so minimal energy is wasted.

    The beauty of a tankless water heater is its ability to provide a continuous supply of hot water. Compared to a traditional water heater, a tankless option is more efficient in its delivery, and is a big energy saver. A tankless water heater is a heating element (either gas or electric) that connects directly to the home’s water pipes. When a hot water tap is turned on, water flows through the element and is sent to its destination.

    Electric heating elements provide a slower flow rate than gas-powered models. A sensor in the heating element turns on the burner and as water enters the unit, a thermostat springs into action to get the water quickly to the desired temperature.

    Gas-driven tankless water heaters need to ventilate through the ceiling and outside the house. Larger tankless systems, called gas condensing units, are armed with a second heating system. These provide more hot water to homes wanting to simultaneously use a dishwater, shower and kitchen sink.

    The first electric tankless water heater was invented in 1929 by Stiebel-Elton.

    Tankless Water Heaters Considerations

    Several factors go into deciding whether a gas-powered or electric-powered tankless water heater is right for you. The most important is the availability of a gas line at the installation point. If you don’t already have a gas feed in the house, you’ll have to have the appropriate type of service installed. It may be simpler and most cost effective to just go with an electric heater.



    Electric water heaters are less expensive. In some cases, they can cost as little as $500. Base prices don’t usually include installation, however, so be sure to factor that in.

    Product in Depth

    Product in Depth

    EcoSmart ECO 27 Electric


    The Ecosmart ECO 27 Electric Tankless Water Heater is easier to install than a gas unit, but running costs depend on local supplier rates. Homeowners and professionals alike give the Ecosmart high ratings. Comments like “I've saved a lot of money on my energy bills!” and “I never run out of hot water!” are common.



    Gas models are easily more efficient than traditional tank-based units. However their efficiency peaks somewhere near 85%,while electric models are more than 90% efficient. Even though fuel is general less expensive than electric energy, many select the electric model because they last longer, and are cheaper to install.


    A water heater is the second most energy-sapping appliance in the house, after climate control systems.



    When installing a gas-powered tankless water heater, new vents and air supply ducts must be put in place to ventilate the byproducts of burning gas. If placed in a tight space, installation can be more rigorous, due to the need of alternative venting, such as side-wall venting.

    Electric models are often smaller and can be placed in smaller spaces where a gas tankless might not fit. An electric unit can be put closer to the area where hot water is needed, which adds to efficiency and customer satisfaction. The only additional cost for an electrical tankless unit would be if a house’s electric service would need to be updated or remodeled.


    Some tankless water heaters allow you to set the desired water temperature very precisely, with a digital display.

    Staff  | BestReviews

    Flow Rate

    It’s important to buy a tankless water heater with enough capacity to meet all your simultaneous hot water demands. A small model won’t be able to supply a clothes washer, shower, and kitchen sink all at the same time. Before you purchase, create a list of hot water uses in your home, and try to anticipate scenarios where multiple locations will need hot water. Check the manufacturer ratings and customer reviews to determine whether a model you’re considering will provide enough water at the most high-demand times.


    A point-of-use tankless water heater (such as one for a utility sink in the garage) is a variation on a standard model that is installed to serve one use case.


    Indoor vs. Outdoor

    No convenient space inside the house for a tankless water heater? Some models are designed for mounting on the outside of the house, taking up space that you otherwise might not be using.

    Product in Depth

    Product in Depth

    MareyGas 10L Tankless Water Heater

    Compact, easy-install.

    The Marey Gas 10L Tankless Water Heater is one of the more easily installed gas models on the market. Most customers purchase this unit for smaller homes, such as vacation cabins, and like the fact it can run in areas with frequent power outages. Some comment that the unit changes temperatures without warning, which can lead to going from scorching hot to cold in a matter of seconds.

    Maintaining Your Tankless Water Heater

    If it’s low maintenance you want, an electric tankless water heater is your best bet. All that is required is the need to periodically change the unit’s screen filter. The safety and efficiency of a gas-powered model’s operation should be inspected once a year.


    Tankless water heaters can last up to 20 years, which is about twice that of a standard hot water heater.


    • Under $100: While there are models in this low price band, they come with some limitations — some are only powered by propane (which adds complexity to the installation and ongoing use) while others are geared for only warmer climates or for instances where only one usage (such as a sink) is needed.

    • Under $150: In this slightly higher price range, again there are models that use propane fuel or built for a single purpose such as an outdoor shower. However, for under $150, you begin to find some electric tankless models, albeit at a lower wattage, which translates to less power.

    • Under $250: Electric models in this range deliver better performance, such as greater efficiency and more water flow on demand. Some of these models do require installation close (within 50 feet) of the point of use, but that is offset by the fact most claim to be easy self-installs.

    • Under $500: To move up to gas-powered tankless models, the price jumps significantly. These models will provide greater flow capacity, and they’re more likely to offer additional features, such as digital temperature setting.

    • Under $2,000: If you want a unit that will provide a lot of hot water on demand with a strong flow to multiple points of use, it will cost you. Along with the everyday excellent performance, these premium models typically have longer warranties, top-tier customer service, and great durability.
    Tankless water heaters are relatively new, and local installation codes may have changed recently. Check with a professional or your municipal offices to ensure yours meets code requirements.


    Q. Does a tankless water heater change the way I use the shower?
    For best results, manufacturers recommend that you turn the hot water tap on full, allow the water to heat, then cool the delivered water by opening the cold water tap. This allows the tankless water heater to run at top efficiency, while you make fine adjustments via the amount of cold water being mixed in.

    Q. How long does it take for the water to actually get hot?
    Most tankless water heaters reach their peak temperature and start heating the water within seconds of the tap being activated. The slight lag you experience in receiving hot water depends mostly on the distance between the heater and the tap.


    In many cases, replacing an existing water heater with a tankless model will require a permit and inspection.

    Staff  | BestReviews

    Q. If the power is out, will my electric unit still work?
    Most electric tankless water heaters will still allow the water to flow when your power is out, but the heating element won’t warm unless you have a battery backup, or some other source of electricity.

    Q. Are tankless water heaters impacted by altitude?
    Altitude matters for tankless units. At 4,000 feet, a gas unit begins to lose its efficiency at a rate of 4% per 1,000 feet. Electric models are not effected.

    The team that worked on this review
    • Alice
      Web Producer
    • Allen
    • Bob
    • Eliza
      Production Manager
    • Jeff
    • Melissa
      Senior Editor

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