The 7 Best Tankless Water Heaters for 2023

Best Electric

Rheem Performance 7.03 GPM Tankless Electric Water Heater

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We recommend the Rheem RETEX-36 as the best electric water heater because it offers a generous flow rate, up to 7.03 GPM, and supports hot water for simultaneous multiple fixtures. Part of the Rheem Performance series, this tankless electric water heater saves on space without sacrificing effectiveness. It also has a 99.8 percent efficiency rating, according to the manufacturer. Installation requirements include space for the unit, which measures 18.25 x 21.625 x 3.5 inches, and wiring to four 40-amp double pole breakers.

This electric tankless water heater can supply water, simultaneously, to five showers and two sinks, at 105 degrees F, depending on your incoming water temperature. Most households should have no problem relying on this as a whole-house tankless water heater, since it can still supply two showers and two sink fixtures with hot water when the groundwater temperature is as low as 37 degrees F.

You can adjust the water temperature output to as high as 140 degrees F, but higher temperatures reduce the flow rate. In addition, Jones points out that most people should set the temperature between 110 and 120 degrees F for the sake of safety.

This model retails for about $650, which is a good value when you consider its performance and long-term savings from its energy efficiency.

Price at time of publish: $650

_{Fuel Type: Electric | Wattage: 36,000 | Flow Rate: Up to 7.03 GPM | Heating Power: Not listed}

Best Natural Gas

Rinnai RL75iN High-Efficiency Plus

4.2

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The Rinnai RL75iN is our pick for a natural gas tankless water heater since it offers reliable performance, impressive heating capabilities, and the ability to be installed in just about any indoor space, including an attic or crawl space. The Japanese manufacturer of water heaters is frequently praised for its reliability, and it doesn’t hurt that the heat exchanger on the RL75iN carries a 12-year warranty.

This model is capable of a maximum flow rate of 7.5 GPM and generates 180,000 BTU of heating power. For climates with groundwater temperatures from 47 to 67 degrees F, the RL75iN can keep water flowing to three or four fixtures at the same time.

While this model is compatible with Rinnai’s Re-Circ technology, you need to purchase additional components to take advantage of the hot water recirculation feature, which slowly and constantly circulates the water in the hot water pipes back into the water heater for reheating. It’s something to consider, since a common complaint about this model is it wastes a fair amount of water before sufficiently heating up sink or shower water.

Its compatibility with home Wi-Fi networks means it’s easier to control and monitor, even if you install it in an out-of-the-way location. If that feature is important to you, you need to purchase a separate control module.

Despite the prospects for adding to the listed price, we still recommend the Rinnai RL75iN as a top-performing natural gas tankless water heater and a worthwhile upgrade if you need to supply piping-hot water to multiple fixtures.

Price at time of publish: $1,130

_{Fuel Type: Natural gas | Wattage: Not applicable | Flow Rate: Up to 7.5 GPM | Heating Power: 180,000 BTU}

Best Budget

Ecosmart ECO 27 Electric Tankless Water Heater

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A tankless water heater can be a smart upgrade for your home, paying off in energy savings and convenience. You can maximize your savings while minimizing your spending if you shop for a budget option, which costs around $500 for a tankless electric model that can support an average household of three to four people. We recommend the EcoSmart ECO 27 as an affordable choice for an instant water heater.

This electric tankless water heater supports a flow up to 6.5 GPM and has self-modulating heating technology to keep water temperatures consistent. Instead of a flow switch, as you’d find on some tankless water heaters, the EcoSmart ECO 27 uses a sensor. This prevents a burst of cold water if water pressure drops while the unit is heating.

Temperature settings for this model range from 80 to 140 degrees F, which is plenty of heating power for most applications. But that falls short of the maximum 160 degrees F some tankless water heaters are capable of.

The EcoSmart is compact and doesn't take up much room when installed since it measures 17 inches tall and wide and only weighs 14 pounds.

If you’re looking for a space-saving alternative to a conventional water heater but need a tankless version that is easy on the wallet, the EcoSmart ECO 27 is a solid pick in terms of purchase price and long-term energy savings.

Price at time of publish: $407

_{Fuel Type: Electric | Wattage: 27,000 watts | Flow Rate: Up to 6.5 GPM | Heating Power: Not listed}

Best Point-of-Use

Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater

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A point-of-use tankless water heater is a good choice if you need to ensure that a specific fixture in your home has a ready supply of hot water at all times. This type of water heater is usually installed close to the fixture it supports, such as under a sink cabinet or near the primary shower. For that type of tankless water heater, the Rheem RTEX-13 is a popular pick that provides instant hot water.

This small tankless water heater delivers up to 3.17 GPM, which is more than sufficient to supply a single fixture. It measures 12 inches high and 8.25 inches wide, so it’s compact enough to be installed inside a bathroom vanity or closet. Its electronic temperature control gives you the option to set the water temperature in 1-degree increments, from 80 to 140 degrees F.

The only downside to this affordable, electric point-of-use instant water heater is its 5-year warranty on the heat exchanger, which isn’t as long as the warranty period on some other models. Also, this unit only requires wiring to a single 60-amp double pole breaker. But we strongly recommend that you secure professional installation.

Price at time of publish: $330

_{Fuel Type: Electric | Wattage: 13,000 watts | Flow Rate: Up to 3.17 GPM | Heating Power: Not listed}

Best Propane

Rinnai V53DeN Outdoor Tankless Water Heater

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While most tankless water heaters are installed inside your home, installing one outdoors avoids having to rip out drywall, reroute gas lines, and vent the unit. Also, some basements are just too small to accommodate an installation. If you want to go the outdoor route, you should only purchase a tankless water heater designed for outdoor installation.

We recommend the Rinnai V53DeP, a whole-house tankless water heater that has the features and durability needed for outdoor installation. It’s not as powerful as some other tankless water heaters but is sized right for small to medium homes. The unit's maximum flow rate is 5.3 GPM, and it can support two showers simultaneously in most conditions.

This model uses liquid propane as a fuel source but can be converted to natural gas. (If your home lacks a natural gas line, you need to have one installed.) In either case, venting is usually required, according to Jones, and for this reason, these types of units are often installed outside the house.

Another key feature that qualifies the Rinnai V53DeP for use as an outdoor tankless water heater is its anti-freeze protection. The unit should continue to function in cold weather conditions, even as low as minus-4 degrees F.

The manufacturer recommends that for cold-weather climates, you also install an optional drain-down system to ensure that water inside the unit can drain if there’s a power failure, gas outage, or component failure. You also should ensure that it is protected from direct wind exposure.

Price at time of publish: $620

_{Fuel Type: Natural Gas | Wattage: Not applicable | Flow Rate: 5.3 GPM | Heating Power: 120,000 BTU}

Best Energy Saving

Stiebel Eltron Tempra 36 Plus Whole House Electric Tankless Water Heater

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Tankless water heaters offer significant savings on energy costs when compared with conventional water heaters, Jones says. “Rather than slowly heating and then storing water for use, a tankless water heater heats very quickly and only when there is a demand for hot water,” he explains.

While you can expect to see energy savings with any tankless water heater, Stiebel Eltron rates its Tempra 36 Plus as one of its most energy-efficient units. (This is a manufacturer estimation: Energy Star doesn’t issue energy factor ratings for electric tankless water heaters.) It offers up to 7.5 GPM of hot water to three or more fixtures, and operates with virtually none of the noise associated with water heaters, according to the manufacturer.

Some tankless water heaters are known for reducing the temperature when another tap is turned on. The Tempra 36 Plus eliminates this "cold water sandwich" with an advanced flow control feature that reduces the flow of water by a marginal amount if the demand for hot water increases. This allows the heater to maintain the output temperature, so you don’t wind up with a cold burst of water in your shower, sink, or anywhere else the tap is turned on.

A frequent complaint of instant hot water heaters is the water gets too hot, too soon. However, with a minimum temperature setting of 68 degrees F, this Stiebel Eltron model has one of the lowest temperature thresholds of tankless water heaters.

Installing this unit requires 300 amp electrical service; consult an electrician to see if your home’s electrical panel is properly equipped before purchasing this powerful electric tankless water heater.

Price at time of publish: $810

_{Fuel Type: Electric | Wattage: 36,000 watts | Flow Rate: Up to 7.5 GPM | Heating Power: Not listed}