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Best tankless water heater

Which tankless water heater is best?

Everyone can appreciate a long, hot shower, but the electric bill can be a bitter pill to swallow. Water heating with a traditional tank heater makes up an estimated 18% of your total energy use, but there is a way to cut that bill and still enjoy a luxurious shower or bath: adding a tankless water heater. The best tankless water heater is an estimated 34% more efficient than the old tank style. 

The Stiebel Eltron Tempra 29 Plus Tankless Water Heater is a premium option that provides seemingly endless hot water, even in cooler climates.

What to know before you buy a tankless water heater

Flow rate

Before you buy a tankless water heater, consider how many people or appliances use hot water in your home. Measured in gallons per minute, this number is located on showerheads and other water-using appliances. Select a tankless water heater that can accommodate the most common situations in your house (e.g., two people showering at once, running the dishwasher and doing laundry, etc).

Temperature of incoming water

To select the appropriate tankless water heater, you'll need to figure out the temperature of the groundwater entering your home and the target temperature created by the tank. Most groundwater hovers somewhere around 50 degrees, but extremes at either the hot or cold end can change that considerably. 

The flow you get from your fixtures will vary depending on how much you’ll need to raise the temperature of the water coming through the tank. If your water is cold and you want your temperature hot, not only will the flow be reduced, but you’ll also use more power to get there.

Whole-house heaters vs. point-of-use heaters

Tankless water heaters are available in whole-house or point-of-use models. Whole-house heaters do exactly what it says —  they provide hot water to the entire structure from one heater. These are best for sending hot water to more than one appliance at a time, but they can be very expensive (and much larger).

Point-of-use heaters are more compact and designed for use on one specific appliance (often a shower). They are installed close to their intended fixture and can supply nearly instant hot water. Many people use these for tiny houses, outdoor showers and RVs.

What to look for in a quality tankless water heater


With recirculation, cold water loops from the hot water line back into the heater using a pump to push it through a return line. This means hot water is available nearly instantly, which reduces water waste. 

Digital temperature display

No one wants to step into a freezing shower, and a digital temperature display helps prevent that. This easy-to-read number tells you when your water is ready to go. 

Memory settings

This set-it-and-forget-it feature allows you to program settings for things like washing clothes and dishes or taking a shower. It takes the guesswork out of deciding when the water is hot enough by remembering (and returning to) specific temperature settings.

Easy temperature adjustment

From a simple temperature knob to digital controls with up and down arrows, look for something that has easy temperature adjustment. You should not need an advanced degree to dial it in every time.

Simple installation

Some tankless water heaters are as simple as connecting a few hoses, plugging them in and turning on the water. If the one you select is a little more complicated, make sure the installation instructions are clear and easy to follow (or you can find a professional to do it for you).

How much you can expect to spend on a tankless water heater

Depending on the size and type, expect to spend $400-$2,000.

Tankless water heater FAQ

When do you choose an outdoor water heater vs. an indoor water heater?

A. Indoor water heaters are protected from the elements, but they have a few distinct disadvantages. They require venting drains to remove condensation that can damage your home if left standing. They also need ventilation for airflow. 

Outdoor water heaters do not need these vents, and they are purpose-built to hold up to the weather. You do need to drain them when not in use, as a freeze-thaw cycle can cause pipes to burst (which results in leaks). If you are adding to an existing home, an outdoor water heater is much easier and does not require new pipes. 

Do you need electricity for a tankless water heater?

A. No. Tankless water heaters can also be powered by natural gas and propane.

What’s the best tankless water heater to buy?

Top tankless water heater

Stiebel Eltron Tempra 29 Plus Tankless Water Heater 

What you need to know: It is easy to install and provides hot water for multiple fixtures at once.

What you’ll love: It has advanced control of water flow rate and temperature. The design is compact and does not require separate venting. The digital screen is easy to read, and it comes with both memory settings and an easy knob for temperature control.

What you should consider: It’s a high-end product with a high-end price.

Where to buy: Sold by Amazon

Top tankless water heater for the money

Ecosmart Eco Electric Tankless Water Heater

What you need to know: It’s energy efficient and a good choice in warmer climates.

What you’ll love: It heats 6 gallons of water per minute and is energy efficient. The design is compact and features a digital display with a dial that can set temperatures ranging from 80 to 140 degrees. 

What you should consider: It struggles to heat water in cold weather and cooler climates. 

Where to buy: Sold by Amazon and Home Depot

Worth checking out

Eemax Electric Tankless Water Heater

What you need to know: It is battery-powered for operation even when the power goes out. 

What you’ll love: It charges as you use it for on-demand hot water. Heat water from 80 to 140 degrees just one degree at a time. It can handle water pressure from the fixture ranging from 25 to 150 pounds per square inch. The slim stainless steel has a trendy blue finish.

What you should consider: It doesn’t work as well heating icy cold water.

Where to buy: Sold by Amazon and Home Depot


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Suzannah Kolbeck writes for BestReviews. BestReviews has helped millions of consumers simplify their purchasing decisions, saving them time and money.

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