The Best Tankless Water Heater Reviews

Switching from a traditional hot water tank to a tankless water heater is one of the best ways to save money every month on your utility bill. According to Energy.gov, tankless heaters can offer up to 37% energy savings. That’s why we put together the best tankless water heater reviews to make your purchase decision easy.

Millions of people are the world are making the switch to tankless hot water heaters for more than just saving money, they are saving the environment too.

Why Go Tankless?

Tankless water heaters provide instant, on-demand hot water. Hot water tanks keep a fixed amount of water hot at all times.

This is an important distinction. The hot water tank uses energy all day long (gas or electric) whereas the tankless heater only draws power when hot water is demanded.

How do Tankless Water Heaters work?

All tankless water heaters work more or less the same way: incoming water enters a heating chamber and energy from the power source for the heat exchanger. Energy is transfered from the heat exchanger to the chamber and water is then drawn to the outgoing pipe where the demand is coming from. [source]

Different tankless heaters use different materials and are used for different purposes. That’s why it’s important to do your research to ensure you get the right tankless hot water heater for your exact needs.

In our guide, we will try to simplify all the important factors that would impact your buying decision.

Gas vs Electric Tankless Water Heaters

The first choice you’ll need to make is what power source you need to heat your water. The main power sources are natural gas (propane can be used as well) or electricity. If your home doesn’t have a gas line, the choice is easy. If both options are available, here are the pros and cons of each:

Gas Powered Tankless Water Heaters

Whether it is natural gas or propane, these pros and cons will apply to the unit.

Advantages:

  • Much more powerful, able to heat multiple faucets at once
  • Lower cost than electricity in most cases
  • Able to heat water from cold incoming water temperatures

Disadvantages:

  • More expensive than electric heaters
  • Emit emissions directly from the unit
  • May require ventilation, depending on the unit and placement

Electric Tankless Water Heaters

Electric tankless water heaters are smaller and more affordable than gas powered heaters.

Advantages:

  • Doesn’t directly emit CO2 (your electricity may come from a coal plant, however)
  • More affordable than a gas powered heater
  • Doesn’t require any ventilation

Disadvantages:

  • Most homes would require multiple units to produce the same amount of hot water as a gas powered unit
  • Require more maintenance due to limescale and calcium build-up
  • Electricity is generally more expensive than gas

Buying a single, large, gas powered tankless water heater or buying multiple electric tankless water heaters can produce the same hot water output for roughly the same initial cost.

Incoming Water: Hardness and Temperature

Temperature

If your incoming water temperature is below 50F, you will have to get a gas powered tankless water heater. Electric heaters are simply not powerful enough to raise the temperature more than 30F at best. Unless you are willing to give up hot water during the winter, you’re likely better off going with a gas powered unit. If you have a cottage or cabin that is only used in the summer, then electric might be a great choice.

In general, using an electric tankless water heater all-year round in a home is only available in the southern United States.

Hardness

If your water is particularly hard (ie, you need to use a water softener), then you will require to do more maintenance on your tankless water heater, or use additional equipment to soften the water before it enters the hot water heater. Limescale and calcium build up can destroy your unit if it’s not cleaned regularly.

Tankless Water Heater Reviews by Category

1. Best Whole House Tankless Water Heater: Rinnai RUC98iN

Best Whole House Tankless Water Heater

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We can say with confidence that if you’re looking for a tankless water heater to provide on-demand hot water for your whole house, then the Rinnai RUC98iN Ultra Series is the unit for you. With the ability to produce a staggering 9.8 GPM of hot water with a temperature rise of 50F, this natural gas powered water heater is perfect for nearly every home in the United States. Many tankless water heaters, especially electric, aren’t capable of providing hot water for an entire house, and many natural gas powered ones don’t have the same GPM flow rates as the Rinnai RUC98iN.

It’s important to note, as with any tankless water heater, that it may take up to 20 seconds for the water to heat up from the heating unit to the faucet; but once it’s warmed up, you have an unlimited amount of hot water while enjoying cost savings from the energy efficiency.

We recommend professional installation since this unit requires a natural gas hook up.

The Pros

  • Can meet nearly any capacity need
  • Produced by an industry leader in water heaters
  • Hassle Free Warranty Process
  • No Expansion Kit Required
  • Very Silent
  • Dual Pipe makes unit more efficient by using condensation water

The Cons

  • Most expensive unit you will find for residential use
  • Requires venting and does not come with a venting kit
  • Might be excessively powerful for smaller homes

2. Best Electric Tankless Water Heater: EcoSmart ECO

Best Electric Tankless Water Heater

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If you have a simple need to place a water heater under your sink, perhaps for a cabin or a new powder room added to your home, then the EcoSMART ECO electric tankless water heater is the right unit for you. With the ability to provide 1.5 GPM flow rate with a 50F temperature rise, this unit would be perfect even if your incoming water temperatures are quite cold. Generally, electric tankless isn’t capable of handling high GPM flow rates, but for a simple sink, this unit will be more than enough for nearly any home of any incoming water temperature.

EcoSmart is a highly trusted brand in electric tankless water heaters, and for good reason. They have one of the most efficient units on the market and is a best seller 3 years in a row on major online retailers, while consistently maintaining a very high positive review score.

Pros

  • Great value – flow rate and quality for the price
  • Trusted by many verified online purchases and reviews
  • Great warranty for peace of mind

Cons

  • Somewhat unknown brand
  • larger unit than expected
  • louder than the competition

3. Best Value Tankless Water Heater: Takagi T-KJr2-IN-NG

Best Value Tankless Water Heater

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If you are looking for that “middle of the road” tankless water heater, that is both of high quality and reasonable demand, then look no further than the Takagi T-KJr2-IN-NG Natural Gas Tankless water heater. Takagi is a well known name in the industry (although not as reputable as Rheem and Rinnai), and they come very highly rated on various online shopping websites. With the ability to generate a maximum of 6.6 GPM for under $500.00, this is the absolute best value in GPM on the market today.

Pros:

  • One of the most powerful tankless heaters below $500 price mark
  • Built by a reputable brand name
  • Comes with a standard 10 year warranty
  • Very easy to maintain, comes apart easily

Cons

  • One of the louder units you can find
  • 6.6 GPM won’t meet the needs of a medium sized house
  • Only 81% energy efficient, so in some respects it’s more expensive than the high efficiency counterparts.

4. Best Outdoor Tankless Water Heater: Rheem RTGH-95XLN

Best Outdoor Tankless Water Heater

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A very high quality and highly rated outdoor tankless water heater, the Rheem RTGH-95XLN Prestige is one of the best water heaters you can find in the market, for the outdoor category. With one of the highest energy factors in the market (94%) and one of the highest flow rates (9.5 GPM), this can meet the needs of the majority of American homes, and requires no ventilation!

Pros:

  • One of the best brands in water heaters, Rheem
  • Standard 10 year warranty
  • Leading energy efficiency rate at 94% (Compared to other outdoor units)
  • Very high flow rate at 9.5 GPM
  • Does not require any ventilation, since it is outdoor.

Cons

  • While it seems expensive up-front, the high energy efficiency will make it cheaper over time.

5. Best Recreational Vehicle (RV) Water Heater: SioGreen IR260

Best RV Tankless Water Heater

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Since an RV is likely to be subjected to a variety of different water sources, we recommend using the SioGreen IR260 Infrared Electric Tankless water heater for your recreational vehicle. This innovative water heater uses materials that resist the build up of calcium and limescale, which requires minimal maintenance. With the ability to produce up to 2.0 GPM, you could even provide hot water for a shower with this small unit.

One of the biggest draw backs to electric tankless water heaters it the build up of limescale and calcium, especially when the water source is hard. When you are traveling in your RV, you will encounter hard water, even if you usually have a soft water source. That is why it’s imperative to use an infrared water heater instead of a traditional electric tankless unit.

Pros

  • Maintenance free water heater
  • Well reviewed by thousands of users
  • Industry leading warranty
  • Quiet unit for electric tankless

Cons

  • Low flow rate, doesn’t work well for high flow showers
  • Larger than expected

6. Best Outdoor Shower Water Weater: Eccotemp L10

Best Outdoor Shower Water Heater

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If you plan to spend an extended period of time in the outdoors, be it at your cabin, camping or otherwise, there is nothing better than a hot shower at the end of the day. The Eccotemp L10 Portable Outdoor Tankless Water heater is one of the best you can find to suit that need. Powered by propane, this water heater is able to heat nearly any incoming water temperature and provide refreshing hot water to your ourdoor shower.

This unit works with the standard 20lb propane tank and comes with the standard garden hose adapter. Simply buy it, hook up your gas line and garden hose, and you are off to the races! This unit is even capable of handling temperatures below freezing!

Pros

  • Powerful unit capable of handling any incoming water temperature
  • Backed by one of the biggest names in water heaters
  • Industry leading warranty
  • Works with standard garden hose and BBQ propane tanks

Cons

  • Water can take a while to heat up
  • Uses more propane than you would expect
  • We recommend an external cover to keep it protected, not included

What size tankless water heater do I need?

For the purposes of this chart, we will assume that incoming water temperatures are 67F or above. If not, you will generally want to play it safe and buy our top pick for the best whole house tankless water heater.

Demand TypeSize
Bathroom Sink0.5 GPM
Standard Shower2.5 GPM
Low-Flow Shower1.5 GPM
Dishwasher1.0 GPM
Washing Machine1.5 GPM
Kitchen Sink0.5 GPM
Laundry Sink1.0 GPM
DwellingBathroomsGPM
Apartment / Condo13.0 GPM
Small House (<1000 sq. ft.)14.0 GPM
Average House (<1600 sq. ft)27.5 GPM
Large House (1600+ sq. ft)3+10+ GPM
1 bedroom 1 bathroom apartment with appliances
2 bedroom 2 bathroom
4 bedroom 3 bathroom, in-law suite

Indoor vs Outdoor Tankless Water Heater

While in general, we recommend buying indoor tankless water heaters, you have to consider two important factors before ruling out an outdoor heater.

Space

In some instances, space may be a serious constraint and you can save space by placing the water heater outdoors. For example, in a small cabin or cottage, or a multi-unit building that requires multiple units can save a lot of indoor square footage, proportionally speaking.

Sound

Some water heaters make more noise than others, although all of them make some noise. In a small enclosed space, this can be irritating, and can be avoided by placing the unit outside.

Ventilation

If ventilation will be overly complicated or constrained for some other reason, you may want to place the unit outside to avoid all ventilation concerns. Ventilation tends to also take up more space than is available.

Tankless Water Heater Cleaning and Maintenance

If you are already a handy person and familiar with water heater maintenance, check out these quick refresher videos on how to flush your water heater.

It’s also important to clean out the filter, which can accumulate some sediment as well. This video quickly explains how to do it.

If you are a beginner and have never performed maintenance before, are you are nervous about performing your up-coming routine maintenance on your tankless water heater, this 8 minute video takes you through the process — step by step.

It’s important that you don’t use store-bought descaling products, as they contain harmful chemicals that can run off in your tap water. As mentioned in the video below, use all natural, pure white vinegar. It’s completely safe for humans to consume, no need to worry if you don’t flush 100% of the vinegar out of the system.

Conclusion

Tankless water heaters are not a new technology and tens of thousands of households are benefiting from their wise decision to save money every month. Preserving the environment by using less energy (thus, less coal to be burned in power plants) while saving money is a win-win situation. Most homes that use traditional hot water tanks are also renting them from utility companies, costing them even more in rental costs. If you switch from a hot water tank rental to a tankless hot water heater you can reduce your monthly utility bill by up to 50%!

The draw back of course is that you have to do routine maintenance on your water heater, but hopefully this guide shows that it pretty easy and straight forward, and doesn’t involve any danger.

We hope that our tankless water heater reviews helped you choose the perfect water heater for your home, cabin, cottage, RV or a simply to put under your sink.

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