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Best Tankless Water Heaters

Why Buy Tankless Water Heaters?

We've evaluated tankless water heaters since 2015, spending over 50 hours researching the best manufacturers in the industry. As we created this guide, we looked at representative models from each of the 10 best brands we found. Of these models, we chose to highlight ones that are best for various uses such as whole-home, single-sink and single-bathroom water heating.

Best for Most Homes

The EcoSmart ECO 27 is an energy-efficient tankless water heater that's a good option for average homes without huge demands for hot water. It can heat up to 6.5 gpm, which is enough water for up to four showers at the same time. While it doesn’t produce nearly as much hot water in cooler climates, it's still powerful enough to produce up to 3 gpm, which is enough water for two simultaneous showers and much better than smaller tankless water heaters. The EcoSmart ECO 27 has a digital display that lets you set the exact water temperature between 80 and 140 degrees Fahrenheit. This model has a lifetime warranty, which is exceptional among tankless water heaters. However, you must have a professional install it to qualify for warranty coverage.

Best Budget Model for Under Sinks

The Chronomite SR-20L/240 HTR has a flow rate of 0.5 gpm, which makes it ideal for heating the water in a single sink. This is particularly helpful if you have a sink that's far from your main water heater, as it can keep you from wasting water while you wait for it to heat up. This unit costs less than $200, which makes it an affordable way to increase your home’s hot water production without replacing your water heater. It does a good job raising water temperature at lower flow rates, but it can't provide hot water for an entire bathroom or home, especially in colder climates.

Best for Most Bathrooms

The Rheem RTE 13 tankless water heater is powerful enough to heat 4 gpm in warmer climates, which is enough to supply multiple bathrooms – up to three faucets, showers or bathtubs. In colder climates, however, it can only produce 2.54 gpm, just enough for a single bathroom sink and shower running together. The compact design means you can install it under your sink or inside the bathroom vanity to keep it out of view. The RTE 13 has an Energy Star certification, which means it’s more efficient than standard tankless water heaters. Rheem provides a 10-year heat exchanger warranty on the RTE 13, though the unit must be installed by a licensed technician to qualify for it. All other parts carry a one-year warranty.

What to Look For

A Professional Should Install Your Tankless Water Heater

Although it's tempting to install your new tankless water heater by yourself, most homeowners simply don't have the right skills and experience. Professionals can install water heaters correctly and safely while taking less time overall. They also often have water heater suggestions for your home. Furthermore, some brands only sell through installers.

To find the best plumber in your area, take some time to look at their online customer reviews on Yelp, HomeAdvisor, Angie's List and similar websites. If they don't clearly outline their pricing and estimated completion time and provide a written quote, don't use them, even if they are the lowest bid.

Electric Vs. Gas

Tankless water heaters use one of three power sources: electricity, natural gas or propane. In some cases, the type you buy is dictated by the power source available in your home, so you won't have a say in the matter. Still, it's good to know what your options are if you have more than one power source.

You can expect electric models to have lower operating costs but be more expensive to buy. In contrast, natural gas and propane models cost less to buy and have slightly higher operating costs. Gas models also work when your power goes out.

Size & Flow Rate

The tankless water heater’s size generally impacts its hot water delivery rate. For example, if you need hot water for your entire home, you need a larger unit to keep up with the demands of people using multiple faucets. Smaller models, with a flow rate of around 0.5 gallons per minute (gpm), may only work for a single bathroom or faucet, though they can also serve to supplement a traditional water heater or add hot water to a garage sink outside your home.

Tankless water heaters can only provide a fixed amount of heating based on the temperature of the water flowing through them. As such, if you live in a colder climate, you need a larger model with a higher flow rate to produce the same amount of hot water a smaller one can in a temperate climate.

Energy Efficiency

On the whole, tankless water heaters use less energy than conventional water heaters, though some models are more efficient than others. To maximize energy efficiency, look for one that is Energy Star qualified. However, keep in mind that the most efficient water heaters, like the Rinnai RUC98iN, usually have the highest prices. The Rinnai is not only efficient, it runs off both natural gas and propane, and has multiple venting options.

Traditional Water Heaters

Most homeowners choose traditional gas or electric storage-tank water heaters, which cost less than tankless water heaters. However, these units are also bulky, making them more difficult to transport and install. They're also not nearly as efficient as tankless water heaters.

Contributing Reviewer: John Carlsen