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Best Tankless Water Heater Reviews

If you want hot water in your home, then you’re going to need a water heater. This one essential appliance will immediately heat your home’s water supply and then distribute it through your plumbing network. One easy way to get all the hot water that you need is to install one of the best tankless water heaters.

All the Best in One Chart

Tankless water heaters are one of the best investments a homeowner can make to avoid storing and constantly heating water to a specific temperature. It reduces a flooding risk because it eliminates the tank altogether. These are the top-rated models that are proven to get the job done.

PictureNameRatingWarrantyGallons Per MinuteMax BTUPrice
EcoSmart ECO 27 Electric 4.3
Takagi T-KJR2-IN-NG Indoor 4.5
10 Year
Rinnai Ultra Series Natural Gas 4.6
12 Year
Eccotemp L5 Portable 4.2
1 Year
Stiebel Eltron Tempra 24 Electric Whole House 4.7
3 Year
EcoSmart ECO 36 Electric 4.3
Takagi T-H3-DV-N Condensing High Effiency 4.4
10 Year
Rheem RTG-64XLN Low Nox Outdoor 4.5
10 Year

SioGreen Infrared Electric 4.0
10 Year
Rinnai RUR98iN Ultra Series Condensing Indoor 4.5
12 Year
PictureNameRatingWarrantyGallons Per MinuteMax BTUPrice

How Long Does a Tankless Water Heater Last?

Tankless units are generally rated to last for up to 20 years. Some models may be rated to last 25-35 years. This means a tankless heater will last 2 or 3 times longer than the standard tank-style model.

Tankless models usually come with a longer warranty as well. Manufacturers like Noritz offer a 10-year warranty on their models. Some warranties extend to 15 years. You also have an option to purchase an extended warranty at the time of purchase that will cover virtually anything that could go wrong with the equipment for up to 3 years after purchase.

The cost of maintenance must also be considered when looking at the longevity of the tankless design. Most tankless models rarely need to be serviced over the lifetime of the equipment. A standard tank-based unit will have mineral scale build-up on the inside of the tank, requiring it to be cleaned every year or two.

Over 75% of tank-based designs fail because a tank bursts or a leak develops. This means rusty water will cover everything that is in the room. If you have a finished basement, that’s bad news. Installing one of the best tankless water heaters will help to eliminate that potentially costly threat with one simple appliance upgrade.

What Size Unit Do I Need?

If you’re trying to determine the size of the tankless unit that you need, then it is important to calculate the average gallons per minute (GPM) that your household will use. You will also want to know what your peak flow output rate will be so that your new heater will be able to handle your demands.

To do this, you’ll need to consider all your water-consuming appliances. You have faucets in the kitchen and in your bathrooms. You might have a dishwasher. Maybe you have a washing machine in the laundry room. Here are the typical flow rates to expect from each fixture or appliance.

  • Bathroom Faucets: Up to 1.5 GPM.
  • Kitchen Faucets: Up to 7.0 GPM.
  • Shower: Up to 2.5 GPM.
  • Dishwasher: Up to 2.5 GPM.
  • Washing Machine: Up to 3.0 GPM.

If you have the dishwasher on, the washing machine on, and the shower on all at the same time, then you’d want a unit that could handle up to 8.0 gallons per minute.

Then you’ll want to determine how much you’ll need to heat the water. This is done by calculating the difference between your groundwater temperature and your desired hot water temperature, which is usually 120F.

You can access the current US groundwater temperature chart here:

Let’s use Seattle, WA as an example to determine the heating calculation. The EPA estimates that groundwater temperatures in Seattle are 52F. To create the correct hot water temperature, it would be necessary for the heater to create a 68F change.

It is simple subtraction: 120F – 52F = 68F.

Now you’re ready to go shopping. Just use the flow rate from you GPM estimates and the temperature rise data as calculated in the example below to find a unit that meets your needs. That way you can have hot water you need whenever you want to have it.

How Much to Install a Tankless Water Heater?

Much of the cost that comes with a tankless water heater is due to a higher installation cost. Labor rates vary throughout the United States, with an installation cost of about $1,450 coming from the Midwest to a high of nearly $3,000 along the East and West Coast. Averaging all estimates from all regions, most homeowners should expect a tankless unit installation to cost about $2,000.

If you have a storage tank model already and it needs to be removed, then you can add another $300-$700 to the final cost.

Much of the cost is due to the requirement of adding ventilation access to the unit. If you already have a site with ventilation access available, then you can potentially cut the installation costs quoted above in half.

When Should I Get an Electric Tankless Water Heater?

Electric models are a good option for homes that are in urban centers, have a large-scale generator that provides backup power, or if usage of the appliance is expected to be part-time. If you live by yourself or with a partner and only use a minimal amount of hot water every day, then this is the route to go for you.

If you do not have a backup generator, then it is important to remember that your hot water heater will not operate during a power outage. If you have an extended outage, then it would be difficult to access any water from your home’s plumbing systems.

It also depends on what utilities are serviced at your property. If there isn’t a gas line available to you, then the cost of having one installed could potentially double your final costs. Go with the electric model instead, even if you don’t have a backup generator, to avoid this unnecessary expense.

Should I Purchase a Gas Tankless Water Heater?

If you have calculated your GPM to be above 5, then you should be considering a gas powered model. Natural gas heaters provide more heat and will cost less to operate compared to electric models. Unless you have multiple showers, appliances, or faucets running simultaneously, you should never run out of hot water.

There is also the added benefit of not requiring electricity to operate. This allows you to have access to hot water, even if the power goes out. Some tankless designs do require an electrical connection to operate, but are powered by gas – this design would not offer this specific benefit.

One model that should be considered is an outdoor tankless propane-fueled design. Propane often costs less than natural gas and is much cheaper than electrical models. A homeowner can save up to $25 per month and up to $4,000 over the lifespan of the unit by going with propane.

Tank vs. Tankless: 5 Important Differences

Tankless units are much smaller than the traditional models that often hold between 50-100 gallons of water. They are also very eco-friendly compared to the traditional design, which can save you money each month while expanding your hot water access. Here are the key differences that you’ll want to consider if you’re deciding between a tank or a tankless design today.

#1. Tankless models require a larger up-front investment. You can pay up to 3 times more for a tankless model at current pricing levels. There may also be higher installation costs if you are converting from a tank to a tankless design. You can make up the pricing difference through cost savings over 12-24 months in many cases, but the initial investment is still going to be greater.

#2.  Tankless units hang on the wall. You’ll have a lot more floor space in your garage, shop, or utility room with a tankless unit. Most models hang on the wall and do not require insulation or spacing to operate.

#3. Tankless water heaters do not run out of hot water… usually. With a traditional hot water heater, you know about how long of a shower you can take before the water turns cold. A tankless unit is designed to not run out of hot water, so you can stay in the shower even longer. Only when there are periods of heavy usage will a tankless design offer cooler water.

#4. Tankless designs require ventilation. You’ll need to ventilate a new tankless water heater for it to operate correctly, which a traditional model does not always need, especially if it is an electrically-powered model. This will limit the number of installation points you have in your home, unless you’re willing to run install a ventilation pipe or duct.

#5. Tankless water heaters reduce energy consumption. How much can you save by using a tankless model over a traditional model? For homes using a water heater that is 10+ years old, the savings could be over 50%. The average homeowner will save about 30% on the amount of energy they consume to heat water.

There is one down side to using a tankless model vs. a tank model. Many homeowners rely on their hot water heater as an emergency source of water should they be cut off from services. A tankless design offers no on-site storage, so this resource would disappear.

Pros and Cons of Going Tankless

Pro: Less Energy

Tankless models use up to 50% less energy than a tank-based model. The average family of 4 can save about $116 each year by upgrading to a tankless model.

Con: Special Venting

Tankless designs typically use a high-powered burner to heat water on-demand. This means they require a special dedicated and sealed vent system to operate. Most communities require this to be performed by a licensed and bonded contractor due to coding requirements. Natural gas burners need a larger-diameter pipe as well, and this all adds to the initial installation cost.

Pro: Unlimited Hot Water

Most hot water heaters provide about 50 gallons of heated water to use at any given time. Some models may offer 80-100 gallons. Extenders could add 5-10 gallons on top of this. Tankless units remove this limitation.

Con: Limited Flow Rates

Many of the smaller tankless units that are available today will only provide enough hot water for a single faucet, shower, or appliance. If you run the kitchen faucet while someone is taking a shower, neither one of you will get hot water. It will be lukewarm at best.

Pro: Longer Lifespan

Many tank-based units are rated for about 10 years of life. Most warranties will only cover 4-6 years. Tankless water heaters can last for 20+ years, have a warranty that is more than 10 years, and requires very little maintenance over the life of the unit.

How Much is a Tankless Water Heater?

Units are priced on the flow rate they can provide and the temperature change they can produce. Entry-level models are typically priced in the $400 range, producing a 4.0 GPM and a 40- to 50-degree water temperature change. From there, expect to add an extra $100 for every 0.5 GPM and 3 degrees of temperature you need to produce the correct levels of hot water in your home.

Premium tankless hot water heaters are priced above $1,000. Commercial-grade models can be priced above $2,000. These are typically for homes with large families or businesses that are looking for LEED certification.

Tankless Water Heater Reviews

Rheem RTG-64XLN

This is an outdoor-use only model, but it does feature next-gen burner technologies so you still receive a highly efficient appliance. If all you need is a 35-degree shift in water temperature, then you can expect a GPM of 6.8. A 45-degree temperature increase results in a GPM rating reduction to 5.3. In colder climates that need 60+ degrees Fahrenheit of adjustment, the flow-rate can be sub-4.0. It has certain challenges that need to be met, but if your household can do so, then this is a solid buy.

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Takagi T-H3-DV-N

The installation of this unit is a bit frustrating. Many homes will likely need to upgrade their natural gas piping to ¾-inch to accommodate this model. Once installed, achieving a 72F rise in temperature is a simple process without compromising the total GPM which can be achieved. Even with cold source water, it is possible to maintain a 5-6 GPM while heating water up to 120F – though this may be considered a commercial usage of the product for warranty purposes. We found this unit to be sturdy, well-made, and extremely dependable. It will work with PVC for exhaust venting.

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EcoSmart ECO36

EcoSmart offers self-modulating technologies within their heaters, allowing the unit to adjust temperature ratings based on the source input that is being received. This model is so strong that it can provide a 3.5 GPM flow rate at 105F even when the incoming water is just 37F. You have the ability to set your temperature controls with this model as well, in 1-degree increments, so you will receive the right water temperature whenever it is needed. This could be the answer you need. It has earned our strongest recommendation.

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StiebelEltron Tempura 24

Many hot water heaters that are tankless and electric tend to operate on lower PSI levels. It’s not that unusual to see a rating between 80-120 PSI for models that are promoted as a whole-home option. The StiebelEltronTempra 24 offers users a working pressure of 150 PSI that remains very consistent. It does require a 2×50 minimum circuit breaker to be properly installed, pulling 208/240 volts. When properly installed, it can achieve a maximum temperature increase of 92F degrees when measured from a single faucet or fixture.

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Eccotemp L5

This model provides just enough support for continuous, but low-flow, hot water for various needs. You get an 11-inch water column that can be manually-controlled from a temperature standpoint for a 30F-35F temperature rise thanks to the maximum 37,500 BTU of support it receives. There is an automatic timer that will shut the unit off after 20 minutes to avoid using too much fuel and it can be wall-mounted in a home if desired quite easily. It weighs just 14 pounds. If you need a portable solution, this is an option that is worth considering.

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Rinnai RUC98IN

We did notice that there was a small reduction in water pressure compared to tank-based models when using older high-flow faucets and fixtures. Homes that are still using older equipment may wish to upgrade their fixtures at the same time to take full advantage of what this unit can provide. Unlike some other makes and models, however, we found that this specific unit was surprisingly quiet. Even if you are pulling water at its full capacity, you can barely notice this heater is working when you’re in the same room. It definitely earns our recommendation.

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Takagi T-KJR2-IN-NG

For the average home, we see the GPM rating being more accurate in the 4-5 range. That’s still good enough for the needs of most families, especially if low-flow showerheads have been installed in the home. You won’t be able to run the dishwasher, the washing machine, and take a shower at the same time, but with some schedule management, it does get the job done. This means the square footage of the home matters less than personal usage of hot water. We found that this Takagi model works well for families of 4-5 people, perhaps 6 if a schedule has been highly organized.

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EcoSmart ECO27

Outside of its ability to self-modulate, we really appreciated how this electric model puts control into the hands of the user. It offers a panel which gives users access to digital temperature controls. Instead of spinning a dial and hoping for the best, you have 1-degree precision over the temperature of your water at the faucet or fixture. It has also been designed with stainless steel and copper components, which promotes a greater efficiency for the unit during periods of long-term use. We found it to be a compact, efficient, and durable system thanks to these design benefits.

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This infrared tankless electric water heater offers whole-home hot water supports. It features coil-less technology that features quartz, which minimizes corrosion and scale deposits that can occur. It is virtually maintenance free, providing up to a 60% improvement in energy efficiencies. It does require 220 volts at 60 amps in order to operate, so some homes may need to have an electrical installation before this model is installed. There are smaller models that feature 20-amp, 30-amp, or 40-amp setups as well, so every home has the potential to receive endless hot water.

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Rinnai RUR98IN

If you have a large household that demands a lot of hot water, then a tankless model might seem like the wrong decision. It’s not when you have this premium water heater working for you. Although it is a large investment, it also provides up to 9.8 gallons of hot water per minute with a 0.96 energy factor. The amount of space that it requires is minimal and it works with PVC or Concentric venting, giving you more options than most. It also has condensing technologies that allow for drainage instead of gas control, which is useful for homes with limited venting space. It’s easily one of the best tankless water heaters available right now.

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The best tankless water heater reviews will help you create an endless supply of hot water for your home. Once you get the source water temperature down and know what temperature of hot water you prefer, you’ll be able to find a water heater that can give you blissful showers and much more thanks to its consistent flow rates.

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