Best Tankless Water Heater Reviews: An Extensive Guide

Best Tankless Water Heater Reviews: An Extensive Guide

An ENERGY STAR certified tankless water heater uses approximately 30% less energy on average, when compared to a traditional heater.

Overview

  • Average 30% energy savings compared to a regular heaters
  • Endless and instant hot water supply – doesn’t run out like conventional water heaters
  • Compact = saves a lot of space
  • Lasts 5 – 10 years longer than regular style water heaters

Tankless water heaters provide a continuous supply of hot water on demand as required, thus a storage tank isn’t necessary. They usually hang on the wall and come in a few different types such as electric, propane or gas, depending on what your energy set up is at your home. Conventional heaters use significantly more energy as the heated water is stored, it needs to continuously heat this stored water so it’s ready to go when you need it

How does a tankless water heating system work?

pros tempra rheem rtgh-95dvln check importantA tankless water system works by heating water directly as it is needed on demand. Water comes into the unit and is heated by a heat exchanger (element) which is also activated on demand. Electric units use coils while a gas unit has a burner that heats the flowing water. Gas/propane units usually have larger and better heating capacities than electric units, thus bigger whole-home units are mostly of the gas or propane variety.


Table of our Top Picks (Comparison)

NameSizePowerPrice
Rinnai Luxury Series9.4 GPMGas Indoor / Outdoor
  Propane Indoor / Outdoor
 7.5 GPMGas Indoor / Outdoor
  Propane Indoor / Outdoor
Rinnai Value Series6.6 GPMGas Indoor / Outdoor
  Propane Indoor / Outdoor
Ecosmart Series6 GPMElectric View price
 4.6 GPMElectric View price
Rheem Performance5.3 GPMElectric View price

Best Tankless Water Heater Reviews by Category

Gas Tankless Water Heaters

Rinnai Luxury 9.4 GPM Series

high money warranty heaters savings buy professional new cost prosThis is one of the highest output non-condensing units available. With superior energy efficiency to meet the heavy demand of more sizable homes. This line is available in an outside and inside version to meet you needs or preference. The Luxury model has an EF (energy factor) of 0.82 (82%) and comes with built-in recirculation tech for quicker water delivery. You can read our detailed review here.

Pros

  • ideal for significant sized homes / heavy demand
  • recirculation technology for quicker water
  • weather resistant
Cons

  • venting supplies not included with indoor version
  • if you have an unusually big home you may need a second unit
View Price – Outdoor View Price – Indoor

Rinnai Luxury 7.5 GPM Series

list parts options require install temperature supply pros bills This is the sister model to the unit above, but made for mid to large homes. The Luxury 7.5 GPM comes an energy factor of 0.82 (82%), and also comes in a weather resistant outside and inside version as well to meet your needs or preferences. It also has the same recirculation tech so as to deliver water quicker.

Pros

  • Ideal for mid-high demand
  • recirculation technology
  • weather resistant
Cons

  • venting kit not included with indoor version
View Price - Outdoor View Price - Indoor

Rinnai Value 6.6 GPM Series

best tankless water heater takagi eco you'll tempraThe Value tier is the perfect combination of value and efficiency in a compact unit. This line offers the same brand reliability in a model designed for a small to mid size household. It is just as efficient with a energy factor of 0.82 (82%), and also comes in an inside and weather resistant outside model for your preference. Read our full review.

Pros

  • Ideal for low-mid demand that’s perfect for mild regions
  • weather resistant
Cons

  • venting kit not included with indoor version
  • does not have recirculation technology
View Price - Outdoor View Price - Indoor

Rinnai Ultra 8 GPM

Condensing and recirculation tech make it one of the most energy efficient available with an energy factor of 0.96 (96%). Our full review can be found here.

  • Comes with two heat exchangers for maximum performance
  • Energy star certified
  • Outside version only (weather resistant) with freeze protection
View Price

Propane Tankless Water Heaters

Rinnai Luxury Series 9.4 GPM

list install temperature supply check pros bills placeOne of the larger highest output non-condensing units available. This is a high efficiency heater to meet the heavy demand of a bigger household. It is available in an outside and inside version to meet your needs. The Luxury model has an EF of 0.82 (82%) and comes with built-in recirculation tech for faster water delivery.

Pros

  • Perfect for big families / heavy demand
  • recirculation technology for faster hot water
  • weather resistant outside version
Cons

  • venting kit not included with indoor version
  • if you have an unusually big home you may need a second unit
View Price - Outdoor View Price - Indoor

Rinnai Luxury 7.5 GPM Series

warranty save heaters check rheem cost new you'll choice place pros marketA sister model to the unit above, but made for mid to large families. The Luxury 7.5 GPM comes in at an EF of 0.82 (82%), and also comes in a weather resistant outside version and a inside version too. It also has the same recirculation tech to deliver water faster.

Pros

  • Perfect for mid-high demand
  • recirculation technology
  • weather resistant outside model
Cons

  • indoor version does not come with a air duct supplies
View Price - Outdoor View Price - Indoor

Rinnai Value Series 6.6 GPM

best tankless water heaters you'll pros eco takagi tempraThe Value tier is a less expensive 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 mid sized families. This is just as efficient as the Luxury model, with a EF of 0.82 (82%), and also comes in inside and a weather resistant outside model for your preference.

Pros

  • Excellent for small-mid sized households / low-mid demand
  • weather resistant outside model
Cons

  • indoor version does not come with a air duct supplies
  • does not have recirculation technology
View Price - Outdoor View Price - Indoor

Another great pick

Rinnai Ultra 9.8 GPM & 8.0 GPM

best tankless water heaters takagi rheem rtgh-95dvlnCondensing & recirculation tech make it one of the most energy efficient available with an EF of 0.96 (96%).

  • Comes with two heat exchangers for maximum performance
  • Energy star certified
  • Outside version only (weather resistant)
View Price - 9.8 GPM / View Price - 8.0 GPM

Best Electric Tankless Water Heaters

EcoSmart 6 GPM (36 kW 240-Volt)

warranty gas water heaters rheem rtgh-95dvln gas tankless water heaterA good value model that provides 6 gallons/min – designed for small households or summer cottages. This model is estimated to use approximately 30% less energy when compared to your conventional water heater. This model requires a dedicated 150 amp / 4 x 40 amp double pole breakers... (full review).

Pros

  • Ideal for small houses or apartments
  • self-modulating technology that saves energy
  • easy to replace heater elements
  • does not need a vent because it’s electric
Cons

  • not suitable for heavier demand, or houses in colder regions
View Price

Rheem Performance 5.3 GPM (27 kw)

warranty gas water heaters rheem rtgh-95dvln gas tankless water heaterThis unit is from Rheem’s Performance range and has an output of 5.3 gallons/min, ideal for smaller houses and condos. This model is great for those who want continuous hot water while reducing and saving energy when compared to your regular heater. This model requires 3 x 40 amp double pole breakers... (full review).

Pros

  • Perfect for small houses or apartments
  • self-modulating technology that saves energy
  • easy to replace heater elements
  • no vent required because it’s electric
Cons

  • not suitable for heavier demand
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 model provides 4.6 gallons/min – designed for small households, apartments or summer cottages, especially those in warmer climates. This model is perfect for low demand endless hot water. This model requires dedicated 3 x 40 amp double pole breakers.

Pros

  • Designed for small houses or apartments
  • self-modulating technology that saves energy
  • easy to replace heater elements
  • no ventilation required
Cons

  • not suitable for heavier demand
View Price

Buying Guide

What you need to consider before you buy

  • Deciding if you need a gas, propane, or electric fired heater
  • 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 water flowing into the unit

Gas (natural gas or propane) vs. Electric

The setup you already have in your home will determine the best tankless water heater you will need. The main types are natural gas, propane, and electric units. If you do not have a gas line, it may be best to go with an electric model as it would be expensive due to additional setup and installation costs for that particular fuel type. If you happen to have both options available to you, the following are the advantages and disadvantages of each.

Gas

Advantages:

  • More powerful – best for mid to larger
  • Cheaper to run than electricity usually
  • Best for cold regions

Disadvantages:

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

Electric

Advantages:

  • Best for small dwellings or an apartment
  • Best for milder regions
  • Slightly small than gas fired units
  • More affordable than gas fired units
  • Does not give off emissions
  • Does not require any air ducting

Disadvantages:

  • Mid to more sizable residences would need multiple units to provide the same amount as a gas powered one
  • Heat exchangers need more maintenance due to mineral buildup
  • Electricity is usually more expensive than gas
  • Multiple electric tankless heaters have the same output as one gas powered unit

How to find the proper tankless water heater for your home

Size / flow rate

First we need to determine how much the singular fixtures use in your home, and then add them up to figure out how much you will need for high demand times (such as getting ready in the morning), this ensures you’ll have plenty at your busiest times without going beyond what your unit is capable of.

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

Home SizeBathroomsAvg Demand (GPM)
Apartment13-4
Small Home14 - 5
Avg Home26-8
Large Home3+8-10+

Determine your temperature rise

Depending on your climate, this will dictate what type of the best tankless water heater you should get. Keep in mind what setup you already have in your home – whether you have gas lines installed or not as this can be an additional cost.

Electric units are able to warm the water approximately 30 degrees. Electric units are suitable for those who live in warmer climates such as in the southern US. They are also suitable for summer cottages or small vacation homes.

Gas fired units are more powerful and are able to easily warm the water 50+ degrees. These units are best for those living in colder climates such as the northern US/Canada - so you are able to have hot water year round.


Frequently Asked Questions

I can’t decide between an electric or a gas tankless water heater

Gas and electric tankless are suitable for apartments, condos, cottages, and small to mid size households. Larger homes should keep to gas only as they’re more powerful.

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

brands higher save control rating heaters money high design control save higher brands heatersGas & propane units are much stronger and can handle heavier demands with ease which makes them great for a more substantial household. Although gas models are more expensive to purchase upfront, they have condensing tech which means they’re twice as energy efficient than electric models – so in the end it’s without a doubt the best value and the smart choice.

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

Can mineral & scale buildup 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 and internal running parts in your heater. This will cause your unit to eventually burn out and will damage it, if left unmaintained.

Check the water hardness at your home, and definitely make sure you clean and treat your tankless water heater every 6 months to a yr to steer clear of this.

Where can I find out the hardness of my water?

You can always call your town office for this information - they may offer you a home testing pack or you can purchase one yourself. You may also check out this map for water hardness in different areas of the United States.

How long will a tankless water heater last?

With proper installation and cleaning maintenance every so often to prevent hard water damage, a tankless water heater will last 15-25 years which is 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 in the model specs how hot it can get. Most if not all models have computer controlled systems that can be set at to your desired temperature.

Why do I need electric power for my tankless gas water heater?

Even though your model is gas fired, your unit should have a standard power plug in. This is because these particular models have a small electrical motor inside to power the forced air blower for the exhaust to ventilate outside. A minimal amount of power is required for the digital remote, circuit board, and electric ignition so it can be turned on demand, rather than having a pilot light burning constantly - even when not in use. The actual draw for these is minimal.

Will I have instant hot water with a tankless heater?

A tankless water heater will heat water on demand, 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 piping in your home to the faucet/fixture you're at. Many people expect hot water as soon as they turn on the tap, but forget this fact that their tankless unit does need to fire up and start as needed. Many tankless models do have recirculation tech for faster hot water delivery, so that's definitely something to look for when shopping around.

What is the hot water temperature on average for washing hands, showering and baths?

Usually good warm 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 is required?

For an electric type of unit, none. For a gas fired model, it depends on if it's an outside and inside version.

Outdoor: Direct vent as it's already outside, so it will ventilate naturally.

Indoor: Will need a special set up to be ventilated outside as to avoid filling your home with exhaust.


User Reviews

“I am retired from the business and had hundreds of service calls for for tankless water problems but never for a Rinnai heater. I now own 2 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 or previous regular electrical heater, you do have to wait for the water to warm up, because we chose not to have a recirculating line installed, but it’s not too long. It’s only raised our gas statement about $10, but our power dropped $25. Definitely worth the money.”
“I was apprehensive about switching to tankless equipment. We eliminated two 20 yr old 50 gallon units with one Rinnai tankless device. Never runs out of hot water even when multiple showers and appliances are operating.”
“The water is hot right away, even when my son wants a really hot shower and turns the temp up. It is easy to turn up, then back down to the temp I like. I have been in my home about 2 months and my gas invoice is less than half.”
“Had my water heater now 6 months. Very pleased. Consistent hot water 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 yr in my home.”
“Unlimited hot water is the best feature. My gas bill is low and so is my energy bill since upgrading to a modern system. Worth every penny!!”
“So far the has been great. No more cold water during back to back showers and no more leaks in my attic from the old tank. Just preventing insurance claims and repairs is enough to make me happy.”
“Due to the removal of our tanks and placement out doors of the units there is a lag in getting hot water but getting two storage closets back is great”
“Meets our need for hot water even when we have a bunch of guests. The only slight negative is it takes a little longer to get hot water than our old water heater. However, we have never run out of hot water, even with two clothes washers, dishwasher and two showers going”
“old tankless had served us well but i didn’t know how much better the rinnai would be. not only do we have hotter water quicker but also at a greater gallon per minute. we are more than satisfied. thank you”
“I’ve had my unit for about half a yr and have saved about fifty bucks monthly on power.”
“I’m very happy with my tankless water heater. I was spoiled because i had one installed in my old house a number of years ago. Probably about 5 years ago and was still going strong when we moved.”
“I chose an outside model so I’ve got some space back in my garage. After having two regular heaters leak and damage my home, I’m very happy that can never happen with this one.”
“Only had for a few months and have already seen 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 with hot water. It also got rid of that big water heater in my laundry room giving me a lot more space”
“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 only using propane on demand is a real cost saver.”
“We installed one at our old home, for endless hot water and to gain space in the pantry and we loved. We moved into our home with a basic electrical heater and the first shower was awful. I immediately went to our gas company and bought a Rinnai. I wouldn’t have a house without one.”
“This is the third and best tankless 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 product!”
“We were one of the first to install a tankless water heater 30 years ago. The newer Rinnai proved to be the best tankless water heater and its superior to the older tech. It handles a shower and dishwashers and a washing machine without leaving you in a cold shower. No problem running out. Takes up far less space compared to the old tankless water heaters.”
“4 water heaters in 20 years. No more! Tank leaks always occur just out of warranty. Had a talk with a life long friend who owns and operates a HVAC business. He suggested I consider a Rinnai. After researching, and a few follow-up questions, I took the leap. Best advice I’ve received in many years. This unit saved a bunch of space. I’m loving the fact that I no longer need to think about running out of hot water because of back-to-back showers, 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 replace the existing water heater. We didn’t hesitate to look into more efficient and quality products. We are so pleased with our decision to go tankless. We knew that this investment was not only practical but also a necessary need for making our older home 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.”
“The water heaters (yes, 2 of them) that failed were traditional tank ones and costly to run. I bought this to replace both of them and it works great. My bill dropped by over $100 while my gas barely notched up.”
“We replaced the electric water heater in our former home with a Rinnai heater in 2005. Our monthly invoice was immediately reduced by 1/3 and no increase in our propane usage.”

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Conclusion

To wrap it up, if you're in need of the best tankless water heater that's propane or natural gas fired, that provides the most value with a limited budget, I recommend checking out the Value Series by Rinnai which is made just for people like you. If you want something with more oomph and budget isn't an issue, the Luxury & Ultra Series' are rated best for you! If you are in need of an electric-only heater, I recommend the Ecosmart Series or the Rheem Performance model as it offers the best value at a good size of 5.3 gallons/min that's suitable for most households. Let me know how you make out with your tankless heater and which one you ended up getting! I look forward to hearing from you 🙂 I have some more posts I've published since writing this article in regards to maintenance and other important things to know, check them out on our blog.