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Best tankless water heaters 2021: Electric and gas tankless water heaters for home

Best tankless water heaters 2021: Electric and gas tankless water heaters for home
(Image credit: Getty)

The best tankless water heaters are a great space saving option if you want hot water fast. With an advantage over even the best water heaters, tankless water heaters won’t take up as much room in your home. 

In this guide, you’ll be able to choose from the best electric tankless water heaters and gas models too but whichever you decide to go with, you’ll need to make sure the heater can provide your home with ample hot water. The power each tankless water heater can provide depends on the flow rate, which is measured in gallons per minute (GPM). A higher GPM means your tankless water heater will be able to create hot water for more faucets. 

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The best gas tankless water heaters will typically cost you more than an electric version, however, they are often more powerful too. If you have quite a few bathrooms in your home, we’d recommend opting for a gas model, however, you can save with an electric tankless water heater if you live in a small apartment. 

The best tankless water heaters will help to keep your energy costs down by self-modulating so that they only create hot water when you actually need it. Aside from that though, it’s important to note that the ground water temperature where you live will affect the flow rate of your heater. This means that while a tankless water heater might promise a high flow rate, where you live might compromise its power. 


1. Stiebel Eltron Tempra 29 Plus: Best electric tankless water heater 

Stiebel Eltron Tempra 29 Plus review

(Image credit: Amazon)

Stiebel Eltron Tempra 29 Plus

The Stiebel Eltron Tempra 29 Plus is the best electric tankless water heater.

Suitable for: Max three bathrooms | Type : Electric | Digital display: Yes

 Easy controls 
 Energy-efficient  
 Short warranty  
 Not smart enabled 

The Stiebel Eltron Tempra 29 Plus is an electric tankless water heater that is suitable for homes that have up to three bathrooms. Depending on the ground water temperature where you live, this electric tankless water heater can provide a flow rate of up to 6 GPM but you will need a 240 volt electric service for this water heater to work.

Easy to control, the Stiebel Eltron Tempra 29 Plus tankless water heater has a digital display and also benefits from a sleek and modern design that won’t impose on the space in your home. 

Another reason why we highly rate the Stiebel Eltron Tempra 29 Plus tankless water heater is its Advanced Flow Control functionality. What this means is that you shouldn’t ever really run out of hot water. When hot water levels are getting low, this tankless water heater automatically adjusts its output so that the water’s temperature is maintained. 

The Stiebel Eltron Tempra 29 Plus is also energy-efficient and only uses the minimum amount of energy needed to provide you with hot water.


2. Rinnai RUC98iN Ultra Series: Best gas tankless water heater  

(Image credit: Amazon)

Rinnai RUC98iN Ultra Series

The Rinnai RUC98iN Ultra Series is the best gas tankless water heater.

Suitable for : Three + bathrooms | Type : Gas | Digital display: Yes

 Powerful  
 Energy Star certified 
 Heavy
 Pricey    

The Rinnai RUC98iN Ultra Series is a gas tankless water heater that is both powerful and energy-efficient. This tankless water heater won’t take up much room, however, it is quite heavy. 

Featuring a digital display to control your water temperature, the Rinnai RUC98iN Ultra Series also has a temperature lock so that children won’t be able to adjust it. This gas tankless water heater has a wide flow rate range, meaning it can be used for homes with multiple bathrooms. Its flow rate varies from 0.26 right up to 9.8 GPM. 

What’s more, the Rinnai RUC98iN Ultra Series tankless water heater has an energy factor of 0.95 and can be used with natural gas or propane. It is also Energy Star certified, however, you will pay more for the initial purchase, as this tankless water heater doesn’t come cheap. 


3. EcoSmart ECO 27: Best small tankless water heater 

EcoSmart ECO 27 review

(Image credit: Amazon)

EcoSmart ECO 27

The EcoSmart ECO 27 is the best small tankless water heaters.

Suitable for : Max two bathrooms | Type: Electric | Digital display: Yes

Lifetime warranty  
Compact design  
Not suitable for large homes 

The EcoSmart ECO 27 tankless water heater is an electric heater that has been designed for small homes or apartments that have no more than two bathrooms. 

The EcoSmart ECO 27 provides an output of 27kw and it’s compact. It will need a 240-volt electrical system in order to work but it has a sleek finish and wouldn’t look offensive if you’re unable to hide it away. 

Providing a maximum flow rate of 6.5 GPM, this tankless water heater isn’t as powerful as some of the others in our round up but it also isn’t designed to be used in a home with multiple bathrooms. 

What is great about this tankless water heater is that it’s self-modulating. This means it’s energy-efficient and the water heater automatically adjusts the amount of energy it uses depending on how much hot water you’re using and what temperature you need the water to be. 


4. Rheem RTEX-13: Best point-of-use tankless water heater

Rheem RTEX-13 Tankless Water Heater review

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Rheem RTEX-13

The Rheem RTEX-13 is the best point-of-use tankless water heater.

Suitable for: Boats, small apartments, RVs | Type: Electric | Digital display: Yes

The Rheem RTEX-13 is an electric tankless water heater that is suitable for small homes or apartments, as well as boats, RVs, or point-of-use water heating. This tankless water heater is small and light, making it ideal for installing in small spaces. 

You can expect a flow rate of 4.8 GPM from the Rheem RTEX-13 tankless water heater, which is about enough for a shower and two faucets. On the front of the water heater, you’ll find a digital display and nine different temperature settings. 

This water heater, however, isn’t Energy Star certified and it does require 240 volts and 54 amps of electricity in order to work. Nevertheless, you can expect the same self-modulating features that other tankless water heaters use, and overall the Rheem RTEX-13 scores well for energy efficiency.


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What to look for in a tankless water heater

Electric water heater vs gas water heater

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 and 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 usually have the highest prices. 

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.