7 Best Tankless Water Heater Reviews of 2022

Hey, hot water lover! Welcome to our best tankless water heater guide.

If you’re keen on the convenience and money-saving potential of a tankless water heater, you’ve come to the right place. We’ve ranked the best tankless water heaters in this guide based on factors including performance, ease of installation, durability, customer satisfaction, and customer support from the manufacturers.

Feel free to buy a heavily discounted tankless water heater from your local hardware store, but we strongly recommend investing wisely in a heater that’s superior to all the other mid-range heaters available today.

#1 is our favorite, but #4 is our top budget pick, and #5 is the best portable tankless heater for RVs, camping, and outdoor use.

There are two sections of this guide:

  • A reviews section, which features [number] of the best tankless water heaters in 2022
  • A buyers’ guide, which discusses costs, sizing, installation, maintenance, and other things you’ll need to know when buying a tankless water heater

🥇 Best Tankless Water Heaters

📊 Comparison Chart of Best Tankless Water Heaters

ProductStiebel Eltron
Stiebel Eltron Tempra
Rinnai RU199iN
Rinnai RU199iN
EcoSmart ECO 27
EcoSmart ECO 27
Rheem RTEX-13
Rheem RTEX-13
<br data-lazy-src=Rheem RTGH-95DVLN
Rheem RTGH-95DVLN
Ecotouch ECO55
Ecotouch ECO55
Ranking1st2nd3rd4th5th6th7th
Ratings5/54.5/54.5/54/54/54/54/5
Price$$$$$$$$$$$$$
Power TypeElectricGasElectricElectricGasGasElectric
Flow Rate (GPM)3-8114.23.171.32111.3
kW12-3658.327135.5
Max Temperature140°F140°F140°F140°F114.8℉120℉114℉
Water Pressure Range5 ~ 150 PSI~150 PSI~150 PSI~150 PSI3~110 PSI14~150 PSIn/a
Warranty3 years (parts), 7 years (leakage)15 years (heat exchanger), 5 years (parts), 1 year (labor)Lifetime (limited)5 years (limited)1 year5 years Lifetime (limited)

⭐ Reviews – Best Tankless Water Heater Reviews 2022

Key Features:

  • Electric heating – The Tempra is an electric tankless water heater, meaning that it heats water with an electric element. The unit is available in 12 to 36 kilowatts, with 6 options to choose from depending on your household size and water needs.
  • 0.5-8 GPM flow rate – You get an average flow rate of 0.5-8 GPM from this on-demand hot water heater, depending on the heater’s size and power.
  • 68° F to 140° F temperature range – You can use the Stiebel Eltron to deliver water as hot as 140° F, for 2 bathrooms in warm climates or 1-2 bathrooms in cool climates.
  • 3-7-year warranty – This Stiebel heater is backed by a 7-year leakage warranty and a 3-year parts warranty.

Best For:

Households with up to 4 or 5 people looking for the most reliable, powerful, best-reviewed electric tankless water heater available today. We think the Tempra is suitable for everyone because of its 6 size options and flow rate of up to 8 GPM.

Pros:

  • The best reassurance that your water heater is energy efficient? A high Energy Factor. The Stiebel Eltron Tempra heater has an energy factor of 0.98-1.0, which is as high as it gets.
  • You won’t find a better value electric tankless water heater on the market. Prices start at just $530, and the largest 36 kW heater is just over $800. Considering the unit’s unmatched flow rate and efficiency, that’s unbeatable value.
  • Stiebel is a trusted name for water heaters, so you know you’re investing in a good product. Plus, the long warranty is the peace of mind you need to comfortably make a purchase.

Cons:

  • You’ll need 6 spare breakers or 350-amp breakers to install this unit.
  • It takes about 15 seconds for hot water to be delivered. We’ve reviewed quicker units.

Yes, the $2,500 price tag is high, but it’s still fantastic value given that this Runnai model is one of the most powerful gas tankless heaters currently available.

Key Features:

  • Natural gas heating – The Rinnai RU199iN is a gas-powered heater, meaning that it uses a burner to heat water. The unit produces up to 199,000 BTUs (depending on the temperature rise required) to deliver instant hot water.
  • 8-11 GPM flow rate – The maximum flow rate offered by this Rinnai unit is 11 GPM. To give some perspective, the average whole-home flow rate is about 6-12 GPM, so the RU199iN should be able to keep up with peak demand even in large households.
  • Up to 140° F temperature range – Out of the box, the delivers hot water up to 120° F, which is ideal for most people. If you want to hit a slightly higher max. temperature of 140° F, follow the guidance in the user manual.

Best For:

Families of up to 6 or 7 who prefer to spend more money upfront for the reduced long-term running costs of the best gas tankless water heater available today.

Pros:

  • You won’t waste money or energy with the Rinnai RU199iN. This unit has an Energy Factor of 0.96 and a Uniform Energy Factor of 0.93, which tops the scale for a natural gas heater.
  • Rinnai pledges a 100-year commitment to quality, and the 15-year heat exchanger warranty, 5-year parts warranty, and 1-year labor warranty are certainly reassuring signs. Rinnai’s warranty offerings are better than those offered by most other manufacturers in this guide. Plus, the unit is manufactured in the USA.
  • Once you’ve got this system installed, it’s easy to set up and quiet to run.

Cons:

  • With a $2,500 price tag, the Rinnai RU199iN is probably a bit steep for some budgets.
  • It takes about 30-60 seconds for hot water to get warm.

Why does the ECO 27 take second place, and not first? Because the flow rate only gets up to 4.2 GPM (vs the Stiebel Eltron’s max. 8 GPM water flow rate), and the 0.998 Energy Factor is ever so slightly lower.

Key Features:

  • Electric heater – TheEcoSmart ECO 27 uses a 27-kilowatt electric heating element to rapidly heat water. The unit has a standard 240 voltage. You can also buy this heater in 8 kW, 11 kW, 18 kW, 24 Kw AND 36 Kw SIZES.
  • 8-11 GPM flow rate – This heating unit offers a maximum flow rate of 4.2 GPM. The exact flow rate depends on the temperature rise required – if you need to increase your water temperature to 65°F, the flow rate will drop to 2.8 GPM.
  • Heats water to 140° F – You can use the ECO 27 to heat water that’s as cold as 37° F to achieve a temperature of up to 140° F.

Best For:

Families of up to four people who want an affordable, reliable electric tankless heater, ideally for use in single-bathroom households.

Pros:

  • With a name like EcoSmart, you’d be worried if the ECO 27 wasn’t eco-friendly. Luckily, the unit has an 0.998 Energy Factor and uses self-modulating technology, which keeps electrical consumption low when you don’t require full-power heating.
  • Is EcoSmart confident in the quality of its products? Hell yes – that’s proven by the limited lifetime warranty.
  • $500 is a decent price tag for a tankless heater that’s as sturdy and energy-efficient as the ECO 27.

Cons:

  • The 4.2 GPM max. flow rate isn’t quite as impressive as our top-pick Stiebel heater’s flow rate.
  • You have to register to be eligible for the warranty, AND the warranty is only valid if a licensed professional installs the unit.

What’s the catch? This unit provides up to 3.17 GPM of water, so it’s more of a point-of-use heater (such as a showerhead heater) than a whole home solution. But if that’s all you need, you should be really pleased with the quality of this Rheem heater.

Key Features:

  • Electric tankless heating – The Rheem RTEX-13 uses electricity to heat up water for small apartments and showers.
  • 1.5-3.17 GPM flow rate – The flow of water from this point-of-use heater gets up to 3.17 GPM. There’s also an option to save water by setting the maximum flow rate to 1.5 GPM.
  • Heats water to 140° F – Like its competitors, the RTEX-13 provides a maximum water temperature of 140° F. You can use the controls to adjust water temperature in increments of 1° F.

Best For:

Folks with tight budgets who want an excellent tankless water heater without compromising on budget. Due to its limited size and flow rate, the Rheem RTEX-13 is best suited for single-appliance use, such as to heat the water for a showerhead.

Pros:

  • The RTEX-13 has similar features to Rheem’s larger electric heaters, but is easier to install and use thanks to its common ½-inch plumbing connections and fewer electrical demand requirements.
  • This heating unit manages to be budget-friendly and great quality. The RTEX-13’s competitors all have their fair share of negative reviews, but customers love this electric heater for the most part. It’s energy-efficient, too, with an Energy Factor of 0.998.
  • We’re pleased with the 5-year limited warranty – it’s good to know that you’re covered in the case of a defect or manufacturing issue.

Cons:

  • Due to its low flow rate, you won’t be able to use this heater for anything more than a single bathroom (with a tub/shower and two sinks). Look elsewhere for whole-home solutions.
  • The affordable price of this heater is great, but the larger Rheem models are a better value for money.

Why do we love this heater for portable and outdoor use? Because it’s geared for easy operation and takes just 10 minutes to set up, delivering an impressive 1.32 GPM of water. Just make sure your water pressure is at least 3.0 PSI.

Key Features:

  • Propane-powered heater – The Camplux AY132 is powered by 2 “D” cell batteries, and uses a 20-pound propane tank to provide a maximum temperature raise of 114.8 ℉. The temperature you achieve depends on your input water temperature.
  • 1.32 GPM flow rate – For supplying an outdoor shower, this gas heating unit offers the best flow rate you’ll find.
  • Complete outdoor heating package – This Camplux heater offers everything you’re looking for in an outdoor shower setup, including the heating unit gas regulator, and a 5-foot shower head. The package also includes a US standard garden hose.

Best For:

People living off-the-grid or in low-electricity areas, or people who spend a lot of time camping or traveling in their RV, who want a durable, reliable outdoor portable heating solution for showering and washing.

Pros:

  • The folks at Camplux understand that when you’re on a trip, you don’t want to spend hours installing a water heater. We love how easy it is to set up this unit – within 10 minutes, you can have the heater ready to go and delivering hot water for your showers.
  • Portability? Check. This heater has a folding handle and weighs just 10 pounds, so it shouldn’t get in the way.
  • The 1-year warranty is pretty decent for a portable heater.

Cons:

  • The unit won’t work if your water pressure is less than 3.0 PSI, and it isn’t recommended for elevation above 2000 feet, so it’s not ideal for all camping situations.
  • We can’t find anything about this heater’s energy efficiency.

Although the RTGH-95DVLN is about $1,000 cheaper than our top-pick gas heater, the Rinnai RU199iN, we still think the Rinnai model is best. Why? Because it delivers a faster flow rate of 11 GPM, and Rinnai offers better customer service than Rheem.

Key Features:

  • Gas-powered heating – TheRheem RTGH-95DVLN is a powerful gas tankless water heater, using natural gas to deliver up to 199,900 BTUs per hour.
  • 9.5 GPM flow rate – You get a decent flow of 9.5 GPM from this unit. That’s 3 GPM lower than our top pick gas heater, but still great for the average family of four.
  • Heats up to 120 ℉ – According to multiple customers, the maximum water temperature provided by this heater is 120 ℉. That’s not quite the 140 ℉ temperature stated in the product description, but should still suit most people.

Best For:

Families of three or four people looking for an affordable gas-powered tankless water heater that won’t reduce their water flow.

Pros:

  • It’s good to see that this unit has a slightly higher-than-average Energy Factor of 0.96 and a Uniform Energy Factor of 0.93.
  • The 5-year warranty is reassuring. You’re covered in the case of receiving a defective product.
  • We think the safety features in this unit are great. There’s an overheat film wrap that prevents dangerous temperatures and freeze protection to -30°F.

Cons:

  • Rheem’s customer service is questionable. If your heater works, great – but we’ve read reports from customers who had a bad experience with the support team when they had an issue with their product.
  • The heating output only gets up to 120 ℉. If you like boiling hot showers, look elsewhere.

Why is the ECO55 second place in the point-of-use heaters lineup, and not our top pick? Because it only delivers a maximum flow rate of 1.3 GPM (versus the RTEX-13’s 3.17 GPM flow rate) and a maximum temperature of 114° F (versus the RTEX-13’s 140° F), and the overall ratings for this unit are slightly lower – some customers had quality issues.

Key Features:

  • Electric point-of-use heating – The ECO55 is a small electric unit for point-of-use heating, available in just one size: 5.5 kilowatts, with a standard 240 voltage.
  • 1.3 GPM maximum flow rate – This tankless heating unit delivers a flow rate of up to 1.3 gallons per minute – a bit lower than the maximum showerhead flow rate of 2.5 GPM.
  • Maximum water temperature of 99 ° F to 114 ° F – You can use the ECO55 to deliver water as hot as 114 ° F, depending on your flow rate and inlet temperature. The unit automatically adjusts power to give you the “ideal temperature” based on your water flow.

Best For:

Folks who aren’t looking for a whole-home heating solution, but want a hybrid choice for a primary bathroom or kitchen unit.

Pros:

  • Trying to cut back on energy use? The ECO55’s 0.998 Energy Factor ensures that virtually no heat is lost before water reaches your shower or faucet.
  • Modern homeowners don’t need to hide this heater in their cupboards. We love this Ecotouch unit’s sleek touch-screen design. It should blend in nicely with your decor, rather than looking out of place.
  • The limited lifetime warranty speaks for itself: the manufacturer knows you’ll love this product.

Cons:

  • This unit is nowhere near powerful enough to use as a whole home tankless water heater, so don’t even try it!
  • We read reports from customers who said that the ECO55 doesn’t heat as well as they expected.

🧾 Buyer’s Guide: How We Selected The Best Tankless Water Heaters

Choosing the right tankless water heater for your needs is a big decision. To make sure you choose wisely, consider the following factors. We kept these factors in mind when shortlisting the water heaters for this list.

Budget

Your budget is the first thing to consider when choosing a tankless water heater, since it will affect the size and type of system you can choose.

The average cost of a tankless water heater is $100-$2,500. Why is the price range so significant? Because the upfront cost depends on the system fuel and size (we’ve shared more on this below).

As for installation costs, tankless gas water heaters cost the most, at an average of $1,000 to $1,500 for whole house models. Electric water heaters cost around $700 to $1,000 on average.

You’ll also need to pay for maintenance and small repairs throughout the heater’s lifespan.

Flow rate

Choose a tankless water heater that provides a suitable flow rate for your household size and the amount of water used. If you want your heater to supply your entire home, it shouldn’t disrupt your flow rate even at peak times of water usage.

The size, power, and intended use point of a tankless water heater determine its potential flow rate.

  • Electric tankless heaters tend to have a slightly slower flow rate (by 2-3 GPM) than gas tankless heaters.
  • Whole home tankless water heaters have a flow rate of 8-12 GPM on average
  • Point-of-use tankless heaters provide an average flow rate of 1.5-3.5 GPM

📌 Make sure to correctly size your water heater (more on that later in this guide) so you have enough water to use all your appliances at once.

Energy Factor (EF)

All tankless water heaters have an Energy Factor (EF) that denotes their efficiency in converting energy during use.

According to Energy Star, electric tankless water heaters have Energy Factors that range from 0.96 to 0.99, while natural gas heaters need to meet an Energy Factor requirement of .062 for efficiency (though the best gas tankless water heaters have an Energy Factor of up to the early 90s).

📌 Electric tankless heaters are more efficient than gas tankless heaters in general, but natural gas water heaters can heat up water at a faster rate, so you will usually save money in the long term.

Temperature rise

The efficiency of a tankless water heater largely depends on the time it takes to raise water temperature.

The best tankless water heater can raise water temperature from around 40 to 50 degrees to around 100 to 110 degrees (the average temperature of a shower) in less than 10 seconds.

The exact temperature that your tankless water heater can achieve depends on the input temperature of your water supply.

tankless hot water heater

Fuel Type

Gas and electricity are the two most common fuel types for a tankless water heater.

📌 Gas tankless water heaters are cheaper than electric heaters in the long run, but their upfront investment is about $600-$1,500 higher, on average.

Because of the risk of gas leaks or explosion, gas tankless heaters aren’t quite as safe as electric heaters (although gas heaters have safety features to minimize their risks to almost 0%).

Your chosen fuel type could come down to convenience. You may want to avoid the fuss and hassle of installing gas lines for a gas heater, for instance.

Size of System

The size of a tankless water heater depends on its power, heating capacity, and flow rate.

Gas water heaters take up more room than electric heaters, and need to be installed in an area where proper ventilation can be achieved.

📌 Generally, standard-sized electric tankless water heaters are around 7 inches wide and 10 inches high, while gas heaters are at least 20 inches wide and 30 inches in height.

🚰 What is a tankless water heater?

A tankless water heater, or an instant or on-demand hot water heater, is a type of heater that heats water instantly. As the name suggests, a tankless heater doesn’t have a tank. Instead, water flows straight through the system, where it is heated on demand.

📝 Types of tankless hot water heaters

There are two types of tankless hot water heaters: gas water heaters and electric water heaters.

Electric

Electric tankless water heaters use an electric element to heat water. They are about half the size of a gas tankless water heater, and they don’t need ventilation, so they’re suitable for storing in smaller spaces.

Electric heaters require less maintenance than gas alternatives, but they use more power and are less efficient in the long run.

These water heaters also produce a lower flow, and if your home has a power outage, you’ll be left without hot water.

Gas

Gas tankless water heaters use a burner to heat water and are powered by natural gas. They have a higher capacity and a faster flow rate than electric alternatives.

While gas heaters are more expensive to buy upfront, their running costs tend to be lower since they’re more efficient, and they can be used in homes with no power.

Installing a natural gas heater is more complex than an electric heater; more space is needed, and ventilation is a must. These heaters also require more maintenance than electric heaters.

tankless water heater reviews

🤔 How does a tankless water heater work?

When you switch on your hot faucet, a flow sensor prompts a tankless water heater to kick into action.

In an electric heater, electric elements are used to rapidly heat the water. These elements are a bit like the ones in an electric stove – they can quickly reach a high heat, and they remain switched on until the flow sensor detects that you have shut the hot water faucet.

In a gas tankless water heater, the process is exactly the same, but a powerful burner is used to heat the water.

📏 How to size a tankless water heater?

The size of a tankless hot water heater determines several things: how much space it’ll take up and its heating power, flow rate, and capacity. If you undersize a tankless heater, the heater won’t be able to meet your demands.

Here’s how to correctly size a tankless water heater in your home.

Determining flow rate

First, consider the flow rate you need in your home. To do this, you need to look at how many water-based appliances you run and add up their required flow rates.

For example, let’s say your shower has a flow rate of 2.1 gallons per minute, your washing machine has a flow rate of 2.0 gallons per minute, and your dishwasher and your kitchen faucet have a flow rate of 1.5 gallons per minute each.

This means that your tankless water heater’s flow rate needs to be at least 7.1 GPM to accommodate all your appliances at the same time.

2.1 + 2.0 + 1.5 + 1.5 = 7.1

The larger a tankless water heater, the higher its GPM water delivery. The average required flow rate for most homes is 6-12 GPM.

Determining temperature rise

Your next step is to determine your temperature rise.

Your input water temperature will affect the temperature rise that a water heater can achieve.

📌 Most tankless heaters have a maximum heating temperature of 140 ℉. But if your input temperature is lower than average, your output temperature will likely be lower, too.

The average water heater can raise temperatures by 50-70 ℉.

🆚 Pros/Cons of Tankless Water Heaters

Let’s take a look at the biggest benefits and setbacks of owning a tankless water heater.

Pros:

  • They deliver on-demand hot water. You don’t need to wait for a tank to fill, so you’ll never run out of hot water.
  • They last, on average, twice the amount of time of a traditional water heater with a tank (usually around 20 years).
  • They’re up to 30% more energy-efficient than tank-based heaters, helping you to save energy and money.
  • They save a significant amount of space as they’re completely tankless.
  • They don’t repeatedly heat up water, so they don’t produce “standby loss” – another energy-saving and money-saving benefit.

Cons:

  • Tankless heaters have a reputation for delivering low or inconsistent temperatures, especially if you have multiple appliances on the go.
  • You’ll need to pay more upfront for a tankless water heater than you will for a heater with a tank.
  • They usually need additional equipment for installation. This especially applies to gas tankless water heaters, which require appropriate ventilation.
  • After you buy a tankless heater, it’ll take several years for investment to pay off.
  • They’re ideal for smaller homes with only a couple of water-based appliances. You may need two heaters if you have a large household.

🛠️ Tankless water heater installation and maintenance

In nearly all cases, it’s recommended that you call a professional to install your tankless water heater. This is especially the case for installing natural gas water heaters, which can pose a serious safety risk if they’re installed wrong.

But if you have the skill and plumbing experience behind you, you’ll save a buck or two by installing your tankless water heater yourself.

Here’s what you need to know about installation.

How to install

Professional

The majority of professional plumbers offer installation of tankless water heaters as part of their service. Installation can cost anything between $350 and $5,000 and takes 2-8 hours, depending on the type of heater and the job required.

DIY

If you’re appropriately skilled to install your tankless water heater yourself, here’s what to do:

You will need:

  • A diverse toolkit
  • A wall bracket
  • A means of ventilation (for natural gas heaters)
  • A tape measure
  • Plumber’s tape

What to do:

  1. Choose a location. Consider a location with space for installation, with appropriate ventilation and nearby gas lines for gas tankless heaters.
  2. Prepare for installation. Mount your water heater vertically on the wall. Connect the power and water supply connections at the bottom.
  3. Install shut-off valves. Shut-off valves allow you to switch off the water for maintenance. You may also need to install a pressure-relief valve.
  4. Open water valves. Don’t switch on your gas or electricity just yet. Open the faucets in your home and allow water to run through.
  5. Clean filter. Remove the inline filter out of the water heater and clean out the debris. Then slot it back into place inside the heater.
  6. Turn on the gas or electricity and run your hot faucet. If you notice a fault, consult your user manual.

🧰 How to maintain your tankless water heater

tankless water heater dial

Here’s a step-by-step on how to maintain your tankless water heater:

Part 1: Flushing the System

You will need:

  • 2.5 gallons of white vinegar
  • A bucket
  • Hosing lines

What to do:

  1. Turn off your power source.
  2. Turn off your water valves.
  3. Open your pressure valve.
  4. Attach your hosing lines (these should be included in the purchase)
  5. Flush your system with about 2.5 gallons of white vinegar. The process takes 30-45 minutes.
  6. Remove and rinse the hosing lines and close the valves.
  7. Restart your heater.

Part 2: Cleaning the Inline Filter

The majority of tankless water heaters have an inline filter that protects the heating elements from large sediment particles You’ll find this filter somewhere along the unit’s water intake line.

Here’s how to clean this filter:

You will need:

  • A bucket
  • Approx. 1 gallon of white vinegar

Here’s what to do:

  1. Switch off your water supply.
  2. Remove the filter.
  3. Clean the filter in the vinegar solution.
  4. Return the filter.

The manufacturer may recommend replacing the filter occasionally. Check your user manual for more information.

👉 You might also like: Top 4 Must-Buy Tankless Reverse Osmosis Systems

🧠 Frequently Asked Questions

Is Rheem batter than Rinnai?

Rheem and Rinnai products have both made our best tankless water heaters list, but we think that Rinnai is best for gas heaters and Rheem is best for electric tankless water heaters. Both manufacturers are reputable and reliable, so no need to worry about quality.

Is it worth switching to a tankless water heater?

Yes, For most people, tankless water heaters are worth it. Tankless heaters only supply hot water when you need it. In comparison, heaters with hot water tanks store water that might not even be used in a day. This wastes energy heating up the water for longer periods of time until it’s used. Tankless heaters are cheaper and more energy-efficient to run than tank-based heaters.

What brand of gas tankless water heater is the most reliable?

In our opinion, Stiebel is the most reliable tankless water heater brand for natural gas heaters. Other reliable brands for tankless water heaters are Rheem, Rinnai, EcoSmart, Camplux, and Ecotouch.

What is the life expectancy of a tankless water heater?

The average life expectancy of a tankless water heater is 12 to 20 years, as long as the heater is properly operated and maintained. Tankless water heaters last about 10 years longer than tank-based heaters.

How can I control the temperature of my water in a tankless water heater?

You can control the temperature of your water at your faucet/ showerhead or at the tankless water heater itself. Ideally, adjust your hot/cold faucet or shower head until you achieve the ideal temperature. If you have a separate hot faucet that gets too hot to use, or you want to adjust water for your washing machine or other appliances, you can manually adjust it at the tankless water heater’s control system in 1-2-degree increments.