Best Tankless Water Heater Reviews: An Extensive Guide

  • Average 30% energy savings compared to a typical hot water heater
  • Endless and instant hot water supply – doesn’t run out like conventional hot water heater products
  • Save a lot of space by being slim and compact
  • Lasts 5 – 10 years longer

These are just a few of the benefits of finding the best tankless water heater for your home. Tankless water heaters provide hot water on-demand when required, thus a storage tank isn’t necessary. They usually hang on the wall, have some cool features like digital displays with temperature controls, and come in a three different types such as electric, propane or gas, depending on what your energy set up is. In fact, conventional water heaters use significantly more energy as the heated water is stored, it is continuously heating water so it’s ready to go when you may need it.

How does a tankless water heating system work? Every tankless water heating system works by heating the incoming water flow on-demand. Water flow comes into the unit and is heated by a heat exchanger (elements) which is also activated on-demand. Electric water heaters have coils while a gas unit has a burner that heats the incoming water. Gas/propane units are stronger thus capable of a higher water flow output than electric units, this means whole-home systems are mostly of the gas or propane variety.

Our Picks of the Best Tankless Water Heater

NameSize (GPM)TypeCost
Rinnai Luxury9.4Gas Indoor / Outdoor
Propane Indoor / Outdoor
7.5Gas Indoor / Outdoor
Propane Indoor / Outdoor
Rinnai Value6.6Gas Indoor / Outdoor
Propane Indoor / Outdoor
Ecosmart6Electric View price
4.6Electric View price
Rheem Performance5.3Electric View price

Reviews by Category

Gas Tankless Water Heaters

Rinnai Luxury 9.4 GPM Series

high money heaters savings buy professional new costThis is one of the highest flow rate non-condensing units on the market. With superior energy efficiency to handle the heavy demand of more significantly sized homes. Because this is a tankless gas water heater it will provide even better savings in energy costs in comparison to even the best tankless water heater thats electric, along with a generous 12 year warranty on the heat exchanger and a 5 year on parts.

This line comes in an outdoor and indoor version to fit your needs or preference. The Luxury unit has a EF rating (energy factor) of 0.82 (82%) and comes with built-in recirculation tech for quicker water flow delivery. If you have a bigger family and require a heavy duty gas tankless water heater system, this unit is the right choice. You can read our detailed review here.

  • ideal for heavy demand
  • recirculation technology for quicker water
  • temperature display & control
  • low emissions
  • inside version does not come with venting supplies
  • if you have extremely heavy usage a second unit may be necessary
View Price – Outdoor View Price – Indoor

Rinnai Luxury 7.5 GPM Series

list parts options require install temperature supply bills This is the sister gas heater to the unit above, but made for mid to large homes. The Luxury gas tankless water heater has a impressive flow rate of 7.5 gallons per minute with an energy factor rating of 0.82 (82%), and also comes in a durable outdoor and indoor version as well to meet your requirements. It also has the same recirculation tech so as to deliver water quicker. Not to mention it includes a 12 year warranty on the heat exchanger, a 5 year on parts and a 1 year on labor.

  • ideal for average- higher usage
  • recirculation technology
  • temperature display & control
  • low emissions
  • inside version does not come with venting kit
View Price - Outdoor View Price - Indoor

Rinnai Value 6.6 GPM Series

takagi eco 27 bosch stiebel eltron tempra plus 9 5 price tagThe Value tier is the perfect combination of value and efficiency in a compact gas tankless water heater. This line offers the same brand reliability in a model that's practical and provides a generous supply for average size homes. It is just as efficient with a energy factor rating of 0.82 (82%), has a 10 year warranty on the heat exchanger, a 5 year on parts and a 1 year on labor and also comes in an indoor and durable outdoor model for your preference.. Read our full review.

  • ideal for average size homes
  • low emissions
  • temperature display & control
  • venting kit not included with inside version
  • does not have recirculation technology
View Price - Outdoor View Price - Indoor

Rinnai Ultra Series 8 GPM

The Ultra is one of the best tankless water heaters available that can seriously provide hot water with ease. It features condensing and recirculation tech that help make it one of the most energy saving with an energy factor of 0.96 (96%). This is a special feature that creates significantly more efficient hot water. Our review can be found here.

  • Comes with two heat exchangers for maximum performance
  • Energy star certified
  • Outside version only with freeze protection
  • Included 12 year warranty on heat exchanger and a 5 year on parts.
View Price

Propane Tankless Water Heater Reviews

Rinnai Luxury Series 9.4 GPM

list install temperature supply check pros bills place btuOne of the larger highest flow rate non-condensing units available. This high efficiency propane tankless water heater can power the heavy use of a bigger household. It comes in an outdoor and indoor version to fit your needs. This Luxury tankless heater has an EF of 0.82 (82%) and comes with built-in recirculation tech for faster water delivery along with a generous 12 year warranty on the heat exchanger and a 5 year on parts.

It's definitely one of the popular and top rated best tankless water heaters of choice, ideal for high capacity users who require a propane unit but also want to save energy.

  • Best for heavy demand
  • recirculation technology
  • temperature display & control
  • venting kit not included with inside version
  • if you have extremely high usage a second one might be necessary
View Price - Outdoor View Price - Indoor

Rinnai Luxury 7.5 GPM Series

warranty save heaters check rheem cost new you'll choice place pros marketSimilar to the unit above, but made for people with an average to large size family. The Luxury 7.5 gallons per minute output comes in at an EF of 0.82 (82%), and also comes in a weather resistant outdoor version and a indoor version too. It features the same recirculation tech to deliver water faster and includes a 12 year warranty on the heat exchanger, a 5 year on parts and a 1 year on labor.

Users appreciate the digital temperature display, simple compact design, the ability to heat water (and maintain water temperature) and keep up even in cold climates with ease make this a choice tankless hot water heater.

  • high flow rate & capacity best for mid-high use
  • recirculation technology
  • temperature display & control
  • easy to maintain
  • inside version does not come with venting supplies
View Price - Outdoor View Price - Indoor

Rinnai Value Series 6.6 GPM

you'll pros eco takagi bosch stiebel eltron tempra plus bit basedThe Value tier is a less pricey option that is a fantastic combination of value and efficiency in a compact unit. It offers the same reliability in a model for small to medium sized families. This is just as efficient as the Luxury tier hot water heaters with a EF of 0.82 (82%), comes in inside and a outside model for your preference, and a 10 year warranty on the heat exchanger, a 5 year on parts and a 1 year on labor.

These hot water heaters are excellent for people that want a simple and easy tankless water heater system that's reliable, save on costs, with a flow rate perfect for an average size household.

  • excellent output for small-average sized households
  • digital temperature control
  • inside version does not come with a air duct supplies
  • does not have recirculation technology
View Price - Outdoor View Price - Indoor

Another top pick...

Rinnai Ultra Series 9.8 & 8.0 GPM

takagi rheem rtgh-95dvln btu may need remote control price tagThe Ultra is one of Rinnai's highest tiers of tankless water heaters - this model has some serious power and output. Condensing & recirculation tech make it one of the most energy efficient system available - even more so than regular tankless heaters - with an EF of 0.96 (96%), not to mention it runs on propane so you're saving even more energy and comes along with a generous 12 year warranty on the heat exchanger and a 5 year on parts.

A popular choice for users who have heavy usage, especially those who want to make sure they have powerful performance in cold weather.

  • Comes with two heat exchangers for max performance
  • Condensing & recirculation features for max efficiency
  • Energy star certified
  • Outside version only
View Price - 9.8 GPM / View Price - 8.0 GPM

Best Electric Tankless Water Heaters

EcoSmart 6 GPM (36 kW 240-Volt)

rheem rtgh-95dvln gas tankless water heater website amazon orderA top pick tankless water heater that provides 6 gallons per minute – designed for a small to average household or summer cottages. This model is estimated to use approximately 30% less energy compared to conventional water heaters and includes a limited lifetime warranty on exchangers and electronics. This tankless water heater requires a dedicated 150 amp / 4 x 40 amp double pole breakers... (full review).

Great for users that just need or might want something on the more basic side that is still has a high rating as one of the best tankless water heaters.

  • Excellent for smaller-medium houses or rentals
  • self-modulating for advanced efficiency
  • temperature display & control
  • easy to replace heat exchanger
  • does not need a vent because it’s electric
  • slim design
  • not sufficient for heavier use, or houses in colder climates
View Price

Rheem Performance 5.3 GPM (27 kw)

rheem rtgh-95dvln gas tankless water heater email address eccotempOne the thinnest and most compact systems in the industry! Users enjoy easy maintenance plus the space savings this tankless water heater can provide: it fits perfectly in small spaces and you don't have to worry about venting. These tankless water heaters can provide a flow rate of 5.3 gallons per minute, excellent for smaller houses, apartments or condos and include a 5 year limited warranty on the heater exchanger and 1 year on parts.

This tankless water heater is great for those who want reliable, continuous water that is easy to install and operate with digital temperature controls. Plus it is easily quite energy efficient a with self-modulating design that makes it even more highly cost saving in the long term. Information including full review...

  • digital temperature control
  • self-modulating technology = advanced efficiency
  • easy to replace heat exchanger
  • no vent needed
  • thin design
  • not sufficient for heavier use
View Price

EcoSmart 4.6 GPM (24 kW 240-Volt)

gas water heaters professional market rheem pros important eco takagiSlightly smaller than the one mentioned above, this white tankless water heater provides 4.6 gallons per minute – designed for a small household, rentals or summer cottages, especially those in warmer area where it can heat water with ease. Rated highly and a popular choice as one of the best tankless water heaters for being easy to operate, runs quiet plus the significant energy savings. Don't forget it includes a limited lifetime warranty on exchangers and electronics.

These tankless water heaters are perfect for low demand endless hot water for users that want a simple option, a easy digital system that's reliable and to save on energy. This model requires dedicated 3 x 40 amp double pole breakers.

  • Designed for small houses or apartments
  • temperature display & control
  • self-modulating technology for advanced efficiency
  • easy to replace heat exchanger
  • no ventilation necessary
  • slim design
  • not sufficient for heavier use
View Price

Buying Guide

What you need to consider before you buy

  • Deciding what kind of tankless water heater to get
  • The volume or amount of water the heater needs to heat as water flows through it – this is flow rate and is measured in gallons per minute
  • The desired temperature the unit can achieve
  • The temperature of the cold incoming water

Gas (natural gas or propane) vs. Electric

The setup you already have will dictate the best choice for you. The main types are natural gas, propane, and electric. However if you do not have a gas line where you live, it may make more sense and be best to go with an electric tankless water heater, not to mention they are less expensive to purchase upfront. If you happen to have either option available to you, consider the following pros and cons as a guide...

Gas Tankless Water Heater


  • More powerful for heavier hot water needs – best for mid to larger
  • Cheaper to operate than electricity usually
  • Best for cold regions


  • Units are more expensive to purchase
  • Gives off emissions/exhaust
  • Requires ducting to be vented

Electric Tankless Water Heater


  • Best for lighter to average hot water needs
  • Best for milder regions
  • Slightly smaller than gas units
  • Less expensive to purchase than gas units
  • Does not give off emissions
  • Does not require any air ducting


  • Mid to more sizable residences may need multiple units to provide the same amount as a tankless natural gas water heater
  • Heat exchangers require more maintenance due to mineral buildup
  • More expensive utility than gas
  • Multiple electric tankless water heaters have the same flow rate as one gas-powered unit
  • Need a electrician for installation to ensure proper wiring

How to find the proper tankless water heater for your home

Size / flow rate

First we need to help determine the rate of the single fixtures in your home, and then add them up to figure out what you'll need for high use times (such as getting ready in the morning), this ensures you will have plenty at your busiest time without going beyond what your unit is capable of. See our guide below...

FixtureAmount (GPM)
Sink1 - 2
Shower2 - 3
Bathtub3 - 4
Washing Machine2
Dishwasher1.5 - 2

 BathroomsAvg Use (GPM)
Small Home14 - 5
Avg Home26-8
Large Home3+8-10+

Determine your temperature rise

Depending on your climate, this will dictate what type of heater product you should consider getting. Keep in mind what setup you already have in your home – whether you have gas lines already setup or not as this can be an additional cost.

Electric units are able to heat the water approximately 30 degrees. This makes them suitable for people who live in a warmer area such as the southern US. They are also suitable for summer cottages or small condos.

A tankless natural gas water heater is more powerful and is able to easily heat the water 50+ degrees. These units are best for those living in colder climates or temperatures such as the northern US/Canada - so you are able to get hot water year round.

Frequently Asked Questions

I can’t decide between an electric or a natural gas powered tankless water heater. Any type is potentially a good fit - however most often the best and simple answer depends on your existing set up. Either are a suitable option for rentals, cottages, and small to mid size households. Larger residences should however consider keeping to gas only as they’re more powerful.

Electric units are not as powerful as gas & propane, usually they put out at the most a rate of about 5 gallons per minute which is enough to run a shower and a washer at the same time in milder climates.

Gas & propane units are much stronger and can handle heavier demands with ease which makes them practical for a more substantial household. Although gas models are more expensive to purchase upfront, they have condensing tech which means they’re twice the energy efficiency than electric models – so in the end it’s without a doubt the best value and the smart choice, if your set up allows for it of course.

It comes down to your homes heat and power system. Does it run on electricity? Do you have gas hookups or lines? Whatever you current set up is likely the easiest to go with.

gpm flow rate safety pipe uses support single range pressure closeCan mineral & scale buildup (hard water) damage my tankless water heater? Yes, it certainly can and is most often the reason why tankless water heaters need to be replaced. Mineral buildup and scale over time will coat and clog the heat exchanger system and internal running parts of your heater. This will cause your unit to eventually burn out and will damage it, if left unmaintained. Check the water hardness in your neighborhood, and definitely make sure you flush and treat your tankless water heater every 6 months to a year will help to maintain it and keep it in top working condition. We recommend simple natural vinegar because you don't want leftover chemical residues from a toxic cleaner product in your water.

How can I figure out the hardness of my water? You can always call your town office for this information - they may offer you a testing pack or you can order one yourself. You may also check out this map for water hardness in different areas of the United States, it should help a lot!

How long will a tankless water heater last? With proper system installation, regular cleaning & maintenance (in order to prevent hard water damage), your tankless water heater will last 15-25 years - significantly more than your average heater.

How hot can the water get? Normally it can get up to 140 degrees and usually the default setting is at 120 degrees. As you shop around you can find information in the system specs how hot it can get. Most if not all models have computer controlled systems that can be set to your desired temperature or if you might want to adjust it from time to time.

Why do I need electric power for my tankless natural gas water heater? Even though your system is gas-powered, your unit should have a standard plug in. This is because these particular models have a little electrical motor inside for the forced air blower for the exhaust to ventilate outside. A minimal amount of power is required for the digital remote, circuit board, and ignition systems to work so it can be turned on as needed, rather than having a pilot light burning constantly - even when not in use. However, the actual draw for these systems to work is minimal.

Will I have instant hot water with a tankless heater? A tankless water heater will heat the water instantly - but you need to understand regardless of the configuration of heater, it does take time for the water to move from the heater itself through the pipe to the faucet/fixture you're at. Many people expect hot water as soon as they turn on the tap, but forget the fact their tankless unit does need to fire up. Many tankless models do have recirculation tech for faster water delivery, so that might be something to search for when shopping around if you want.

two showers store kitchen appliance pump bathroom followWhat is the hot water temperature on average for washing hands, showering and baths? Usually good heated water for a shower or bath is around 95 - 110 degrees.

Do I have to turn the tap all the way to activate hot water? No, the flow rate for all models is very low so there is no need.

What kind of venting do I need? For an electric unit, none. For a natural gas tankless water heater: an indoor type will require venting, while an outdoor type ventilates naturally as it is already outside (most exterior types have built-in venting or blowers).

Users Reviews

“I am retired from the business and had hundreds of service calls for many name brands of tankless water problems but never for Rinnai models. I now own 2 tankless water heaters from this brand and am very pleased with them.”
“We’ve had our tankless water heater for 3 months. We love that we have never had to worry if we would have enough hot water. As with our previous regular heater however, you do have to wait for the water to warm up if you’re using the washer or the showers running, because we chose not to install a recirculating line system, but it’s not too bad. It’s only raised our gas statement about $10, but our power dropped $25. Definitely worth the money.”
“I was apprehensive about things switching to a tankless heater and the installation. We eliminated two 20 years old 50 gallon units with one Rinnai tankless device. Never runs out of hot water even when multiple showers and appliances are operating at a time.”
“The water is heated right away, when my son wants a really hot shower and turns the temperature up. It is easy to turn up, then back down to the temperature I like. As of right now I have had it about 2 months and my gas invoice is less than half.”
“Had my water heater roughly now 6 months. Very pleased. Consistent hot water all the time with 2 teenagers in house. No regrets from switching from tank.”
“I replaced my electrical tankless with a propane model from Rinnai and it’s already paid for itself within a short time.”
“Unlimited hot water is one of the best features. I can say my gas bill is much lower and so is my energy bill since upgrading to a modern system. Worth every penny!!”
“So far has been amazing. No more cold water during back to back showers and no more leaks in my attic from the old tank. I find just preventing insurance claims and product repairs is well enough to make me a happy customer.”
“Due to the removal of our tanks and placement outdoors of the units there is a lag to get water but where I get two storage closets back is great”
“Simple heater to operate and meets our need for hot water even when we have a bunch of people over from time to time. The only slight negative though is it takes a little longer than our old water heater. However we have never run out, even with two or three things going at the same time, wouldn’t want it any different.”
“old tankless brands had served us well but i didn’t know how much better the rinnai product would be. not only do we have hotter water a lot quicker but also at a greater gallon per minute rate. we are more than satisfied. thank you”
“I’ve had my unit for about half a year and I save about fifty bucks monthly on power.”

“I’m very happy with my tankless water heater. I was spoiled because i used to have one in my old house a number of years ago and was still going strong when we moved.”
“Thanks to the outside model I chose, I’ve got some space back in my garage. After having two or three regular water heaters leak and cause damage, I’m very happy that can never happen with this one cause the installation is outside.”
“Only used for three or four months so far and have found my energy bill go down over a third of what it was.”
“I have a jacuzzi and it’s the first time I’ve been able to fill it completely. It also got rid of that big water heater in my laundry room giving me a lot more space to put my things”
“We have nasty well water & now that we don’t have a tank cooking the minerals, the water is much better! This is a 2nd home, so using propane on demand is a real cost saver.”
“We installed one at our old place, for endless hot water and to gain space in the pantry and we loved it. We were using a basic electrical heater and the first shower was awful. I immediately went to our local gas service company and bought a Rinnai. I wouldn’t have a house without one.”
“This is the third and best water heater we have had. Wouldn’t go any other way! One was installed as a replacement/upgrade, the other two installed in new construction. Fabulous company, product & features! Thanks!!”
“We were one of the first to install a tankless water heater system 30 years ago. The newer Rinnai sure proved to be the better one and its superior to the older tech we used. It handles a shower, can run the dishwasher and a washing machine without leaving you in a cold shower. No problem using it or running out. Takes up much less space compared to the old tankless water heaters and the install was straightforward.”
“4 water heaters in 20 yrs. No more! Tank water heaters always seem to leak just out of the warranty time. Had a talk with some people and a life long friend who owns and operates a HVAC company. He suggested I please consider a Rinnai. After searching, and asking a few things, I took the leap. This might be some of the best advice I’ve received in a long time. This unit is well built and I save a bunch of space. I’m loving the product features and the fact I no longer need to think about things like running out from back-to-back showers, using the clothes washer or a dishwasher competing during a shower.”
“We purchased our first home last year and we knew we were going to have to renovate and purchase a new water heater. We didn’t hesitate for long to look into more energy efficient and quality rate products. We are so pleased with our decision to go tankless. We knew this investment was not only practical but also necessary to making our older place more efficient from all the tankless water heater reviews we read. I would recommend one to anyone who is considering upgrading or replacing a heater and is conscious about costs.”
“The water heaters (yes, 2 of them) that failed were traditional tank water heaters and costly to run. The install took the place of both of them and well it sure works great. Also gotta add my bills dropped by over $100 while my gas barely notched up.”
“very pleased with my new tankless water heater. my old unit leaked and made a mess, i swore never again and got a tech to come out the next day to install this one. it can heat water just as good, if not better, don’t have to worry about crazy energy bills or safety with a big tank bursting. should’ve done this a long time ago.”
“switched from a regular old gas water heater to a new gas tankless water heaters, i feel like it can heat water way hotter than the old one i threw out. looking at my bill it uses less gas for heating water too so it’s a win-win for me, never going back.”
“excited to see how low i can get my bills now. recently moved into a new home, with the option of getting either a electric tankless water heater unit or a gas tankless water heater. decided to go with one of the gas heaters to save even more each month.”
“Happy to say even though i’m typically not impressed by much, my gas tankless water heater impressed me. it was easy enough to install with some help from a technician. figured a pipe or two would need to be moved because of my set up, or the plumbing messed with but it worked out and my wallet is happy now that my bills are lower.”


If you're in need of the best tankless water heater that's propane or a gas tankless water heater which provides the most value with a limited budget, I recommend checking out Rinnai's Value Series which is made just for people like you. This unit will easily be able to keep up with your hot water demand regardless of climate while keeping energy consumption minimal.

If you're looking for something with more oomph and budget isn't an issue, both the Luxury & Ultra Series are some of the best tankless water heaters on the market. These tankless units have plenty of water heating power with some impressive high flow rates - definitely more than enough to keep up with serious demand while still being the most efficient on the market. Not to mention they come in a beautiful stainless steel finish.

If you require an electric heater, I recommend either the Ecosmart Series or Rheem Performance model, both are generously sized at 5 to 6 gallons per minute so they still pack some heating water power making them a top pick in our books. These tankless units actually use self-modulating technology to help achieve advanced efficiency, some of the highest in the industry, making them some of the best tankless water heaters you can purchase. Thank you for reading my water heater buyers guide, I look forward to hearing your feedback.