Best Tankless Water Heater: Top 10 Models

one of the best tankless water heater models

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If you’re tired of cold showers, choose the best tankless water heater of 2018. This list will give you 10 excellent and cost-effective options.

While most homes use a storage tank water heater, some individuals are choosing to heat their water with a tankless water heater. If you’ve never owned a tankless water heater, there are many reasons to consider switching to this type of water heater.

Stiebel Eltron Tankless Water Heater – Tempra 24 Plus – Electric,...

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This complete guide will give you all the information you need to choose the best tankless water heater in 2018.

Use the helpful FAQ list if you need more information about tankless water heaters. These units are easy to install, so a professional will have no problem replacing your old water heater with an energy-efficient tankless water heater.

How We Reviewed Tankless Water Heater Models

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When it comes to choosing the best tankless water heaters, there are a few important factors to consider.

We arranged this list based on a few important factors. Professional ratings, best-selling lists, and highest-rated lists were all used to find the top ten best tankless water heaters.

There are electric and natural gas tankless water heaters, so you can choose which best suits your needs.

Price Range

When determining which water heater to buy, you should consider both the initial cost and the energy cost. Electric tankless water heaters are far less expensive than natural gas heaters, but they also have a higher energy cost.

If you don’t have access to natural gas at your home, electric is more cost-effective than propane for heating your water. Determine the amount of hot water you need, and how often you will be using it, to see which energy choice is the best for your water heater.

At the high end are natural gas tankless water heaters that are capable of more gallons per minute. On the low end of the price range, you’ll receive a small electric model that isn’t capable of heating many gallons per minute.

Whichever model you choose, each tankless water heater on this list is a best seller.

10 Best Tankless Water Heaters

One of the most expensive water heaters, the Rheem Performance Platinum, can heat an impressive 9.5 gpm.


It has a long PVC venting capability, so you have more flexibility with its placement.


Customers love the water conserving feature, as well as the energy efficiency. However, this is one of the more expensive tankless water heaters, so it may take longer to begin saving money. Like most tankless water heaters on this list, there are different lengths of warranties for different parts.

The heat exchanger comes with a 12-year warranty, while the rest of the parts have a 5-year warranty. Consider this water heater if you want a reliable and heavy-duty tankless unit for a larger household.


  • Energy efficient


  • Expensive

EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240 Volts with...
  • Endless On-Demand Hot Water; Consistent hot water when you need it that never runs out; Continuously monitored water...
  • Save Space; EcoSmart tankless electric water heaters are 90% smaller than traditional tank heaters; may be installed on...
  • Save Energy; EcoSmart tankless electric water heaters are 99% thermal energy efficient; Only heats water when called...

Like most electric tankless water heaters, the EcoSmart heater is far less expensive but offers less gallons per minute of continuous hot water.

You can use this water heater in any climate, but it’s ideal in colder climates. Enjoy this water heater without any stress, thanks to the lifetime warranty.

While it only heats 5.3 gpm, this is enough for many households.

However, because it is electric, it may be more expensive than other units throughout its lifetime due to higher energy costs.


  • Price, reliability and technical support are right up there


  • In colder climates you may need to keep your flow low so as to get warm water especially if you have more than one pipe running

Rheem RETEX-36 Performance 36 kw Self-Modulating 6 GPM Electric...
  • This refurbished product is tested and certified to look and work like new. The refurbishing process includes...

One of the best mid-range options, this expensive electric water heater combines the affordable cost of electric units with the high gallons per minute of a natural gas water heater.

It can heat up to 6 gpm, which is perfect for a small family or a couple. The electronic controls and lack of exhaust venting makes it easy to install and operate.

However, you’ll still want a professional to make sure the heater is installed correctly and safely. Choose this model if you want the largest electric water heater on this list


  • Simple and practical


  • 1-year warranty on parts

Stiebel Eltron 224196 240V, 1 Phase, 50/60 Hz, 12 kW Tempra 12 Plus...
  • Digital temperature control
  • Proven reliability
  • No venting required

For a smarter water heater, check out the Stiebel Eltron Tempra Plus tankless water heater. Not only does this electric unit have digital controls, it also uses self-modulating technology to keep consistent hot water. 

If you ever need more hot water than the heater is capable of producing, it will decrease the flow slightly in order to keep your water hot. You’ll never worry about a cold shower again.

It’s a great choice if you want a high-quality electric unit that produces a reasonable amount of hot water for two bathrooms in most climates.


  • It was easy to install and easy to use


  • Tempra 24 doesn't work so well if the incoming water is cold. It is better for warmer climates.

Rinnai RUC98iN Ultra Series Indoor Natural Gas Tankless Water Heater,...
  • INDOOR installation only. Fuel Type: NATURAL GAS.
  • Concentric or PVC venting option
  • Up to 0.96 Energy Factor/Up to 0.92 Uniform Energy Factor

The most expensive tankless water heater on this list combines excellent flow volume with low emissions. 

The Rinnai Ultra Series heater works for both propane or natural gas and provides low NOx emissions for a cleaner alternative. 

The sleek, durable look matches the warranty and build quality. This unit has an easy-to-use digital control panel, which makes it easy to adjust the temperature or turn the heater on and off. 

It’s an excellent choice if you want an efficient and high-volume tankless water heater.


  • Bigger and heavier than the most home tankless water heater brands


  • It is difficult to install and requires maintenance

Atmor 13kw/240v, 2.25 GPM Tankless Water Heater Electric, Multiple...
  • IDEAL for a FULL Bathroom - Sink and Shower Combination
  • Recommended flow rate 2. 25 GPM (Gallons per Minute). Water saver shower head (1. 5 GPM) highly recommended for optimal...
  • Requires a direct connection to a 60 Amp single-phase, double pole breaker. Required wire size: 4 AWG. 240 volts.

This lightweight unit is inexpensive and offers enough hot water for three faucets, like a bathroom and kitchen.

It’s a very affordable option for a smaller household and perfect for a home that isn’t connected to natural gas. 

The thermostat dial is easy to control and offers you a range of temperatures from 90 to 135 degrees.

While it doesn’t have the best warranty or adjustable settings, it’s perfect for a small cottage or as a second tankless water heater.


  • Value for money


  • Small display

Takagi T-K4-OS-NG Tankless Water Heater, Natural Gas, Outdoor
  • 190,000 BTU
  • 8.0 GPM max flow rate
  • No venting required

If you’re looking for a durable model that balances cost and efficiency, the Takagi T-K4-OS-NG is an excellent choice. This unique model is designed to be installed outdoors only. 

It’s more durable and has built-in venting that isn’t acceptable for indoor installations. This unit features 8 gpm, 190,000 BTUs, and comes at a reasonable price for a natural gas tankless water heater. 

Choose this option if you aren’t able to properly vent an indoor water heater.


  • A remote control is included to make it easy to change the hot water’s temp as needed.


  • The warranties offered by Takagi are not as good as other competitors.

Because the Sio Green water heater is the most affordable on the list, it shouldn’t be surprising that it offers the least amount of hot water. It’s best used as a point-of-use water heater, which is meant to supply consistent hot water to only one faucet or shower head. 

It’s perfect for a guesthouse or upstairs bathroom that has trouble getting consistent hot water with good pressure. If you live in particularly cooler climates, this unit will only be suitable for a low-flow sink and not a shower head. 

This heater won’t supply hot water to your entire house, but might be a perfect addition to a house that needs a little boost in hot water.


  • Doesn’t require maintenance


  • Mostly suitable for low flow applications

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Similar to the Takagi T-K4, this Rheem tankless water heater is designed for outdoor use. It’s slightly more expensive and offers similar gallons per minute. 

Just like the Takagi outdoor unit, it’s designed to resist freezing temperatures. You can install this water heater outdoors even in areas that experience -30 degree temperatures. 

The additional cost of this outdoor tankless water heater also covers the impressive warranty. Not only are the parts covered under a 5-year warranty, you’ll enjoy a 12-year warranty on the heat exchanger. 

Choose this outdoor model if you want more peace of mind with a longer warranty. Otherwise, the Takagi T-K4 is a more cost-effective option.


  • Reputed manufacturer.


  • None so far

Westinghouse 11 GPM Ultra Low NOx Natural Gas Condensing High...
  • Dual stainless steel heat exchangers resist corrosion and provide a longer life expectancy; backed with a 12 year...
  • ENERGY STAR certified with Uniform Energy Factor of .96 (.98 Energy Factor)
  • 199,000 BTU provides endless hot water

In terms of cost-effectiveness, the Westinghouse tankless water heater is the best option on the market. You’ll receive an impressive 11 gpm. It’s covered with an excellent 12-year warranty and has low NOx emissions. 

Many customers experience water pressure and temperature issues. When it works well, it’s the best model on the list, but there are build quality issues with this unit. 

Choose this model if you want the most cost-effective and heavy-duty water heater on the list.


  • High energy efficiency.


  • Costly product.


1.   Why Choose a Tankless Water Heater?

A tankless water heater isn’t the right choice for every household, but there are a few reasons to consider using one. First, the overall energy costs are lower. A tankless water heater heats the water as you use it, so it doesn’t waste energy storing hot water constantly like a storage tank water heater.

Tankless water heaters are also much smaller, so you can mount them to the wall rather than forfeiting space in your home. Because they only run when you need them, these heaters are a great choice for a part-time home, like a summer home or cottage.

It’s also a great choice if you won’t use a lot of hot water, like in a tiny house or guest house. However, consider using a storage tank water heater if you need large amounts of hot water.

2.   Should I Choose Electric, Propane, or Natural Gas?

There are pros and cons to each, so consider each one carefully. The initial investment for an electric tankless water heater is less than natural gas or propane. Electricity is more expensive than natural gas and doesn’t provide the same amount of gallons per minute.

If you have access to natural gas, your overall savings will be the highest with this option. Determine the amount of hot water you need, as well as the best system for your location and access to utilities.

3.   What Is GPM?

GPM, also known as gallons per minute, is used to describe the amount of hot water a water heater can provide. It’s the best way to measure the power and effectiveness of a tankless water heater.

Storage tank water heaters use the first hour rating to describe how much hot water is available in one hour. Each faucet and appliance has a GPM rating, so you can use these to discover what tankless water heater you’ll need.

Consider hiring a professional to review your home, because it isn’t as straightforward as it appears. The distance from the faucet to the water heater also affects how many gallons per minute are needed.

Comparison Table

The Verdict

There are plenty of excellent options to choose when you’re looking for a high-quality tankless water heater. Finding the best tankless water heater depends on your personal situation. 

First, determine whether you want to use electricity, natural gas, or propane. Then, you’ll need to determine the amount of hot water you’ll need. 

For a large household in a cool environment, consider the Westinghouse natural gas tankless water heater. Or, if you want a smart water heater for less, choose the EcoSmart heater. 

Whichever option you choose, you’ll enjoy plenty of hot water and a lower energy bill. With proper installation, you’ll never run out of hot water again.

Last update on 2021-09-23 at 12:54 / Affiliate links / Images from Amazon Product Advertising API


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