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Best Indoor Tankless Water Heater Reviewed (2020) | Buyers Guide

The world of tankless water heaters is expansive and impressive. This goes for all categories, including indoor models. So then, what is the best indoor tankless water heater in 2020?

See our    Editors Pick    and    Comparison Table    at first if you’re in a hurry!



It’s a question that doesn’t come with one definitive answer. Lucky for you, it comes with many, great answers.

Many answers that can apply to you, your family, your friends, whoever.

Of course, you’re likely reading this article because you’re looking to arrive at one answer.

One answer that will tell you which is the best indoor tankless water heater in 2020 for you.

And that’s exactly what we’re going to do.

We’ll have to make sure to tailor that answer to your specific situation.

Your wants, your needs, and yes, even your location.

There’s much to review and much to go over. But I’ll help guide you through the exciting world of indoor tankless water heaters.

We’ll explore many details of 11 different models from 5 trusted brands and we’ll discuss all the specifications and regional tips that you’ll require.

And then that way, I can help you to make a decision that fits you and your region best!

So, let’s see our Editor’s Picks first, which is followed by a useful Comparison Table before going to the Reviews and Buyers Guide/FAQ!

Best Indoor Tankless Water Heater for Small Home or Point-Of-Use Applications

 

Electric Option:

Stiebel Eltron DHC-E 12

 

Natural Gas / Propane Option:

Eccotemp i12

 

Both are budget options that are great for small living situations or point-of-use scenarios. They have lot to offer!

See the review section for in-depth tech details, pros & cons, and regional use information!

Best Indoor Tankless Water Heater | Best Budget Option for Medium-Sized Homes

 

EcoSmart ECO 27

The EcoSmart’s self-modulating technology makes this an excellent choice for the energy-conscious and “eco-smart” consumers.

This Electric Eco option only uses energy when water needs to be heated, conserving loads of energy, and of course money in the long run.

Also, with an easy-to-read and simple-to-use digital display, you can adjust the temperature in 1-degree increments.

See the review section for in-depth tech details, pros & cons, and regional use information!

Best Indoor Tankless Water Heater | Best Budget Option for Large Homes

 

EcoSmart ECO 36

Having all the benefits of Eco 27, the ECO 36 Electric option is more powerful and supplies more hot water with maximum 8.7 GPM!

This works great for large homes.

Read the review section for in-depth tech details, pros & cons, and regional use information!

Best Indoor Tankless Water Heater | Best Electric Option for Medium-Sized Homes

 

For Warmer Climates:

EcoSmart ECO 27


The ECO 27 is not only the best budget but also the best electric option on the list for medium-sized homes if located in warmer regions.

Refer to the review section for in-depth tech details, pros & cons, and regional use information!

 

 

For Colder Climates:

Stiebel Eltron Tempra Plus 29 kW


You’ll love this Electric option with a maximum hot-water flow rate of 6 GPM, self-modulation and advanced flow-control technology.

Not only you can save energy and money in the long run, but also you will see no more cold-water surprises even if you live in cold regions!

Refer to the review section for in-depth tech details, pros & cons, and regional use information!

Best Indoor Tankless Water Heater | Best Electric Option for Large Homes

 

Rheem RTEX-36

Operating at 36kW, the most powerful electric option on the list, is able to achieve a maximum 8.8 GPM, which is great for large homes.

And you’ll have an external digital thermostat with an LED screen to let you change the temperature settings in 1-degree increments from 80 to 140 degrees.

See the review section for in-depth tech details, pros & cons, and regional use information!

Best Indoor Tankless Water Heater | Best Natural Gas/Propane Option for Medium-Sized Homes

 

Rinnai RL75

Among the options for medium-sized homes on this list, Rinnai RL75 comes as your choice of Natural Gas or Propane.

A much more powerful option to serve medium-sized homes with maximum 7.5 GPM!

It is Circ-Logic Capable and Control-R Wi-Fi Capable, so with some add-ons, you can have their incredible re-circulation technology so that you can control it from any of your Wi-Fi devices … phone, tablet, etc.

You’ll certainly love these great features!

Read the review section for in-depth tech details, pros & cons, and regional use information!

Best Indoor Tankless Water Heater | Best Natural Gas/Propane Option for Large Homes

 

Rinnai RUR199

And from Rinnai, the RUR series. Their best series.

And the most powerful option here, the RUR199 with options of either Natural Gas or Propane. It is able to hit a maximum 11 GPM!

It’s Energy Star Certified like the RU199, with a more consistent 0.93 UEF, which means more consistent savings on energy and money.

And the fantastic Circ-Logic Capability and Control-R Wi-Fi Capability that comes with select Rinnai lines… it comes already included here. No extra add-ons needed.

You already have the best recirculation and ability to control what you need, all from a tablet or phone!

Refer to the review section for in-depth tech details, pros & cons, and regional use information!

Before we dive head-first into all these indoor models, let’s dip into the things that you’re looking for in a tankless water heater.

Aside of the fact that you want the tankless water heater to be an indoor, what other qualifications does it need to have?

Do you want something that will be for a small home or perhaps a point-of-use situation?

Sometimes people just want a tankless water heater to service one appliance or one bathroom.

Or are you looking to service a medium-sized home?

Perhaps a large home?

Maybe your large home is quite large and has a lot of hot water traffic in the morning.

And what region do you live in?

This is important to know so we can determine what your average ground water temperature is.

Ground water temperature will have an effect on how well your unit operates.

Additionally, elevation above sea level of your region can make a difference.

Other things you’ll want to think about while we review these models.

What’s your budget?

How many people are in your home and how many use hot water appliances concurrently?

These will all play a part in your decision-making process.

 

But in this comprehensive Review/Guide article, I’ll help you to make sense of it all.

We’ll make sure it’s all crystal clear for you. We’re going to make you feel like an expert on tankless water heaters by the end of this detailed article.

So, let’s get to the fun part. Let’s review these models and hear what they have to offer you.

Let’s compare and contrast.

And let’s figure out what is the best indoor tankless water heater in 2020!

What is the Best Indoor Tankless Water Heater in 2020?

Quick Answer:

Comparison Table for the Best Indoor Tankless Water Heater in 2020

Indoor Tankless Water Heaters View on Amazon Type Maximum GPM (Depth, Height, Width) in inches Weight (Pounds)
Stiebel Eltron DHC-E 12 Electric 4.5 GPM 4.1 x 14.25 x 7.9 6 lbs.
Eccotemp i12 Indoor Natural Gas or Propane 4.8 GPM 11 x 29 x 17 29 lbs.
EcoSmart ECO 27 Electric 6.5 GPM 3.625 x 17 x 17 14.7 lbs.
Stiebel Eltron Tempra Plus 29 kW Electric 6 GPM 4.6 x 16.6 x 14.5 17.6 lbs.
Rinnai RL75 Natural Gas or Propane 7.5 GPM 9.6 x 24.3 x 14.04 43.6 lbs.
EcoSmart ECO 36 Electric 8.7 GPM 3.625 x 17 x 21 18.35 lbs.
Rheem RTEX-36 Electric 8.8 GPM 3.5 x 18.25 x 21.63 22.7 lbs.
Rheem RTGH-95DVLN Natural Gas or Propane 9.5 GPM 9.88 x 25.63 x 13.88 79 lbs.
Rheem RTGH-95DVLN Professional Prestige Natural Gas or Propane 9.5 GPM 9.75 x 27.5 x 18.5 82 lbs.
Rinnai RU199 Natural Gas or Propane 11 GPM 12 x 27.9 x 18.5 64 lbs.
Rinnai RUR199 Natural Gas or Propane 11 GPM 12 x 27.9 x 18.5 73 lbs.

Best Indoor Tankless Water Heater in 2020

Best Indoor Tankless Water Heater for Small Homes / Point-Of-Use Applications

We’ll start here with some options that are great for small living situations or point-of-use scenarios.

 

1. Stiebel Eltron DHC-E 12 | Best Electric Option for Small Homes/Point-Of-Use Applications

This is an incredible electric option, Stiebel Eltron’s DHC-E 12.

This is the cheapest option on this list, so you’re really saving money with this option.

And with incredible proprietary technology from Stiebel Eltron, you’ll be getting a fantastic deal.

And if you’re someone who’s very cautious about making decisions such as these, Stiebel Eltron boasts the best warranty in the industry.

So, you won’t be left out in the cold.

 

 

TECH SPECS

This electric option is going to give you a maximum 4.5 GPM, which will feel like you’re stealing hot water at this low price!

The DHC-E 12 has a 12kw output and is an extremely energy efficient option. Claiming over 99% energy efficiency!

Save the planet and save yourself more money in the long run!

With the tiny dimensions of 4.1 x 14.25 x 7.9 inches, you have one of the smallest in terms of depth with the DHC-E 12.

You also have the shortest, thinnest, and smallest in overall cubic inches of just 462!

And if small is an interest of yours, then light may be as well.

And this is the lightest option at just 6 lbs.

If you desire something small that you can tuck away in a corner and keep out of sight, then the DHC-E 12 may be the best indoor tankless water heater in 2020.

And it comes with an easy-to-use temperature dial that ranges between 86- and 140-degrees Fahrenheit.

The advanced electronics of the DHC-E 12 guarantee you 100% accuracy when setting temperature.

Want a 110-degree shower? Set it at 110, you get exactly 110!

 

 

REGIONAL INFO

Now, we want to take a look at what this unit can do for you, depending on where you are.

What you can get out of it, depends on where you’ll be using it, and what the average ground water temperature is.

In areas where the ground water temperature is around 40 degrees Fahrenheit, you’ll be getting somewhere between 1.2 – 1.7 GPM.

So, in places like Buffalo, St. Paul and Vancouver, you won’t get the full ability of this unit, but it will power a single bathroom sink.

Multiple low-flow sinks at once, or possibly a low-flow sink and a water-saver showerhead. A good choice for those up north wanting to just service a low-flow bathroom.

Northern parts of the U.S. that aren’t the farthest north with ground water temperatures around 50, expect around 2.1 GPM.

If you live in the likes of Hartford, Pittsburgh, Omaha… a kitchen sink could be serviced with the DHC-E 12, a low-flow shower along with a bathroom sink… or a utility/janitor’s sinks if this is going to be used in a commercial setting.

Moving south to large swaths of the middle of the country, ground water temperatures hovering around 60ish, you should expect to pull 3 GPM.

If you live in areas like Atlanta, Albuquerque, or Southern Kansas, you could power multiple sinks, low-flow or not. Service a bathroom, both shower and sink… and no need to choose low-flow if you don’t want.

And even farther south, areas where the ground water temperature is around 70 or even higher…

you’ll likely be able to achieve 4 GPM and in the farthest south areas you can hit that maximum 4.5 GPM!

Cities such as Orlando, Mobile, San Diego… you can definitely service a full bathroom with sink and shower and never worry about losing hot water.

You can likely even service two showers at once if you so desire.

 

 

There are also reviews for this Option here:

See also: Best Small Tankless Water Heaters

Pros

Cons

2. Eccotemp i12 | Best Natural Gas/Propane Option for Small Homes/Point-Of-Use Applications

Another great option for small homes or point-of-use situations, is the Eccotemp i12.

Whereas the last option was electric, here you get a model that can be either Propane or Natural Gas.

If that is more what you fancy, then the i12 from Eccotemp might appeal to you.

It’s a bit more expensive than the DHC-E 12, but it’s still fairly inexpensive.

If you choose to have it with Natural Gas, that’s about $325 and if you choose Propane, it’s about $350.

 

 

TECH SPECS

With the i12 you’ll get 30 – 80 PSI of water pressure and it generally only pulls 2 watts and 1.07 amps when operating.

Its power ranges between 25,000 – 80,000 BTUs and it’s also a fairly more energy efficient model from Eccotemp.

The maximum GPM it can hit is about 4.8! So, you’ll get a bit more out of this model than you would with the last.

With dimensions of 11 x 29 x 17 inches which come out to 5,423 cubic inches, it’s much larger.

Surprisingly, for serving such small purposes, it’s the largest in height on this list and the third largest in cubic inches.

Its weight of 29 lbs. keeps it on the lighter side, though notably heavier than the previous model.

You will get one of Eccotemp’s more advanced digital displays with fully automatic temperature controls that give you more accurate precision.

There’s also an easy-to-read LED touch screen that has a display that shows you the output temperature and GPM flow.

And if that wasn’t enough, it also has technology to keep it locked from your child.

You won’t have to worry about any surprises from the little ones accidentally changing some settings!

 

 

REGIONAL INFO

Now, with the Eccotemp i12, you also know that it’s been tested up to 2,000 feet elevation and is only recommended to not be used above 5,000 feet.

So, you can use this model in some fairly hilly and mountainous areas.

In areas where the ground water temperature is around 40 degrees Fahrenheit, expect between 1.4 – 1.9 GPM.

So, if you live in the likes of Syracuse, Milwaukee, or even the high-elevation-city of Calgary, you could usually service one kitchen sink.

Or one shower in most cases. A bathroom sink would be easy with this model. If you have low-flow appliances, you could potentially operate two at once.

Places in northern U.S. where the ground water temperature is in the 50’s, you’ll be looking at about 2.3 GPM.

So, if you’re in the likes of Manhattan, Cincinnati, or maybe have a cabin in some mountains near, Boise… this unit can operate one shower easily.

Depending on the water flow rate of your shower or bathroom sink… you might be able to service both at once and make this the option for your entire bathroom.

More central and southern portions of the U.S. where the ground water temperature is around 60, you should expect around 3.3 GPM from the i12.

If you live in cities such as Raleigh, Louisville and Sacramento, this easily services a shower and sink, nothing low-flow necessary.

If you’re not a low-flow user and want something for your entire bathroom, this might be what you’ll choose as the best indoor tankless water heater in 2020.

All the way down south, where ground water temperature tends to be about 70 or higher… expect 4.5 GPM and all the way up to 4.8 GPM!

So, if you live in the likes of Tallahassee, Southern Mississippi or even high-altitude Tucson… you’ll have no trouble getting endless hot water from two full showers!

On the grid, off the grid, don’t worry, this could be your two-person camping-adventure buddy!

 

 

There are also reviews for this Option here:

See also: Best Small Tankless Water Heaters

Pros

Cons

Best Indoor Tankless Water Heater for Medium-Sized Homes

3. EcoSmart ECO 27 | Best Budget Electric Option for Medium-Sized Homes

Turning to medium-sized homes, we start with a budget-friendly brand in EcoSmart. Meet the EcoSmart ECO 27, a great electric option!

At about $480, this is the third cheapest option on the list (only more expensive than the first two we reviewed) and it’s the cheapest of all the medium-sized home options we’ll review.

Looking to stay on a budget while heating your medium-sized home?

The EcoSmart ECO 27 may be the best indoor tankless water heater in 2020 for that!

 

 

TECH SPECS

Operating at 27kW, the ECO 27 can hit a maximum 6.5 GPM.

And, as the brand name suggests, the self-modulating technology makes this an excellent choice for the energy-conscious and “eco-smart” consumers.

The unit only uses energy when water needs to be heated, conserving loads of energy, and conserving you loads of money over time.

The dimensions of 3.625 x 17 x 17 make this one of the smallest on this list in depth and height.

And its overall 1,048 cubic inches makes it the second smallest on the list, only bigger than the DHC-E 12 from Stiebel Eltron.

It weighs in at just 14.7 lbs. which makes it the second lightest on the whole list and the lightest option among all the models suited for medium-sized homes.

Worried about lugging in a heavy unit to install yourself? Worry not with this option!

Another plus with this unit, you get the easy-to-read and simple-to-use digital display.

It shows the output temperature which can be adjusted in 1-degree increments.

Finding the sweet spot for the hot water in your daily shower can be done with ease!

 

 

REGIONAL INFO

If you’re looking to service your home with the ECO 27 and living in areas with ground water temperatures around 40 degrees Fahrenheit, you should be able to get about 2.5 GPM.

That means if you live in the likes of Michigan’s Upper Peninsula, Spokane or Toronto, you’ll definitely be able to power a shower no problem. Perhaps a shower and a low-flow bathroom sink.

For Canada and the far north of the U.S., this model is more so just a good point-of-use/bathroom option.

Northern U.S. a little farther from Canada’s border, areas where the ground water temperature is more like 50’s, expect about 3.4 GPM from this unit.

Cities like Providence, Indianapolis, Portland, and other similar areas, can most likely get two simultaneous showers running at once.

Perhaps one shower and a couple other appliances, if that’s all you’re looking for, this is a fantastic option!

Areas not so north in the U.S., where the ground water temperature is more in the likes of the 60’s, look to get 4.2 GPM from the ECO 27!

So, if you live in areas like Charlotte, Little Rock, Las Vegas… that’s easily two showers at once, even the most powerful showers.

Run the dishwasher while you run a shower. Or a couple sinks and the dishwasher. Plenty of options are available to you.

And going south… places where the ground water temperature is 70 and up, look for at least 5.5 GPM and some areas definitely hitting that maximum 6.5 GPM!

Places like Tampa Bay, Houston, Palm Springs, your house can run three showers at once and most likely have no issues with that.

If it’s a two-shower household, but a four-person household, likely all four people can still get ready at once with this unit!

 

 

There are also reviews for this Option here:

See also: Best Small Tankless Water Heaters

See also: Best Whole House Electric Tankless Water Heaters

Pros

Cons

4. Stiebel Eltron Tempra Plus 29 kW | Best Electric Option for Medium-Sized Homes

Another great model from the Stiebel Eltron brand. In the Tempra Plus line, the Tempra Plus 29 kW.

This is another electric model for medium-sized homes.

It’s a bit pricier at around $760, but that comes with the brand.

 

 

TECH SPECS

The Tempra Plus 29kW has a maximum hot water flow rate of 6 GPM, so a tad lower than the last model we reviewed.

And it has dimensions of 4.6 x 16.6 x 14.5 inches, so it is larger than the ECO 27 in depth, but shorter and thinner.

Measuring at 1,107 cubic inches, it’s just a bit bigger overall. Another small option to tuck away for your medium-sized home.

And weighing in at 17.6 lbs. it’s a little heavier than the ECO 27, but it is by far one of the lighter options on this entire list.

The Tempra Plus 29 also has self-modulation to save energy and save you money.

And it has advanced flow control. So, if the demand of hot water is more than what the model can handle at that moment, don’t fret.

No cold-water surprises… the flow of water is automatically decreased in order to keep the hot water flowing to all your appliances.

 

 

REGIONAL INFO

This model may not achieve as high a maximum GPM as the last unit, but it seems a bit more consistent across regions.

In Canada and Canada-adjacent U.S. areas where the ground water temperature is floating around 40 degrees Fahrenheit, you can actually achieve about 2.8 GPM.

So, if you live in the likes of Main, Green Bay or Montreal, this can serve a shower as well as most bathroom sinks simultaneously.

A great little point-of-use option.

Areas in northern U.S. where the ground water temperature tends to be close to 50, look to get about 3.8 GPM.

If you are looking to use the Tempra Plus 29kW in the likes of Newark, Cleveland or Tacoma, that’s almost guaranteed to let you tun two showers at once!

Warmer areas in the U.S. with ground water temperatures around 60, you should expect about 4.3 GPM.

That means the likes of Charleston, Birmingham and Oakland could get any two showers running. If you have even one low-flow shower, you could even add on a bathroom sink to that mix!

Moving far down south, where the ground water temperature is about 70 and up, look to get at least 5 GPM and ranging all the way up to that maximum of 6 GPM. 

So, Baton Rouge, Houston, Hawaiian Islands, and other places at similar latitudes, two showers and a sink or two, no problem.

Three showers at once? Most likely.

 

 

There are also reviews for this Option here:

See also: Best Whole House Electric Tankless Water Heaters

Pros

Cons

5. Rinnai RL75 | Best Natural Gas/Propane Option for Medium-Sized Homes

Checking out the incredible brand Rinnai, the RL75 is an excellent unit to use for your medium-sized home.

Among the options for medium-sized homes on this list, the last two were electric, this option comes as your choice of Natural Gas or Propane.

This is the most expensive of the units for the mid-sized home.

If you go with Natural Gas, it’s about $935 and if you choose Propane, it’s about $1,127. Either way, it’s a pricier option.

And either way, you’re getting some high quality from the brand Rinnai.

 

See also: Best Rinnai Tankless Water Heaters

 

 

TECH SPECS

This is the unit that will get you the highest maximum GPM in this category. A max 7.5 GPM is a sizeable difference from the past two units.

And with the power of this model ranging from 10,300 BTU minimum, and 180,000 BTU maximum, you’re looking at a mighty powerful option.

With dimensions of 9.6 x 24.3 x 14.04 inches, it is the thinnest of the mid-size options.

However, it’s the largest in depth, height and its cubic inches of 3,275 make it, by far, the largest overall of the three.

Tipping the scales at 43.6 lbs., it’s about three times the weight of the previous two models.

Though this is a more powerful option, it’s also much larger. Make sure to consider the space you have available if considering the Rinnai RL75.

Though the size and weight may be a downside for you, here’s an upside…

The RL75 is Circ-Logic Capable and Control-R Wi-Fi Capable!

With Rinnai’s brand, that means with some add-ons, you can have their incredible re-circulation technology and you can control this unit from any of your Wi-Fi devices.

Pick up your phone or your tablet… and have the ability to get the hot showers running for you and your family, like magic!

 

 

REGIONAL INFO

Among the medium-sized home options, the Rinnai RL75 will likely be getting you more hot water no matter what your region is.

If you live in Canada or near, where the ground water temperature is around 40, you should be able to achieve about 3.7 GPM.

Places like New Hampshire, Montana and Quebec City, for most households that’s going to allow you to run two showers at once!

Finally, an option suited for two showers in Canada!

Other northern U.S. states where the ground water temperature is around 50 or so, expect about 4.7 – 4.9 GPM.

Places like Boston, Des Moines and Reno, you’re looking at the ability to run two showers and a bathroom sink with limitless hot water. If your house is set up for low-flow… consider four simultaneous appliances!

If the climate is warming up then the ground water is too. If you live in places with ground water temperatures floating around 60, the RL75 is good for about 6.3 GPM.

Places like Nashville, Tulsa and Santa Fe can operate three simultaneous showers easily.

And down south, ground water temperatures around 70 and up, look to get at least 7 GPM and to hit that maximum 7.5 GPM.

Places like Daytona Beach, New Orleans, Phoenix and the likes, run three showers and a couple sinks while you’re at it!

Run the dishwasher while multiple people shower! The RL75 makes the morning routine so easy in the south!

 

 

There are also reviews for this Option here:

See also: Best Rinnai Tankless Water Heaters

See also: Best Small Tankless Water Heaters

See also: Best Outdoor Tankless Water Heaters

Pros

Cons

Best Indoor Tankless Water Heater for Large Homes

Now, we take a look at some models you could consider if you have a larger home, or a home with more simultaneous hot water traffic.

 

6. EcoSmart ECO 36  | Best Budget Electric Option for Large Homes

EcoSmart showed what it could do with a smaller model, now let’s look at the bigger ECO 36, another electric model!

The ECO 36 costs just about $560, which you’ll see is the cheapest option among those suited for larger homes.

You’ll also probably notice, it’s even cheaper than the last two medium-sized home units we reviewed.

Good quality for a low price… that’s an advantage you’ll get from EcoSmart’s line.

 

 

TECH SPECS

Now, when I say it’s the bigger option from EcoSmart, it isn’t all that much bigger.

The dimensions are 3.625 x 17 x 21 inches, so it’s just as deep and high as the ECO 27, only a little wider.

It actually is one of the smaller units in terms of depth and height, but one of the largest in width.

These will be important dimensions for you to consider when you take a look at the space you plan to put your tankless water heater.

The ECO 36 is just 1,294 cubic inches, so it’s relatively small. And weighing just 18.35 lbs., it’s also fairly light.

To touch again, on when I say bigger… the maximum 8.7 GPM that you can achieve with the ECO 36, that’s what I mean by bigger.

This supplies you with more hot water than the last brand from EcoSmart… though this is the lowest on the list for large home options.

And just like the last unit from EcoSmart… you get fantastic self-modulating technology that saves energy and saves money in the long run, as your model will only use energy when water needs to be heated.

 

 

REGIONAL INFO

In and near Canada, where ground water temperatures are around 40 degrees Fahrenheit, expect the ECO 36 to get you about 3.5 – 3.8 GPM.

Places like Vermont, Alaska and Ottawa, at the very least that’s most likely two concurrent showers or a shower and a dishwasher at the same time.

Northern U.S. with ground water temperatures around 50, look to achieve about 4.4 – 4.8 GPM.

Places like Philadelphia, Baltimore and Kansas City, that’s two showers you can run with ease. If you have a low-flow bathroom sink, that could be run at the same time too!

Looking to warmer areas in the U.S. with ground water temperatures around 60ish, you’ll likely be getting around 6.2 – 6.7 GPM.

Cities such as Richmond, Oklahoma City, Santa Barbara and more, the ECO 36 will give you the luxury of running three showers at once.

If a fourth person wants to run a low-flow bathroom sink at the same time, you’ll most likely have no problems!

And in the southern U.S. where the ground water temperature is at least 70, look to achieve at least 8 GPM and many areas will reach that maximum 8.7 GPM.

Places like Puerto Rico, Austin, Montgomery… say hello to four showers at once!

 

 

There are also reviews for this Option here:

See also: Best Whole House Electric Tankless Water Heaters

Pros

Cons

7. Rheem RTEX-36 | Best Electric Option for Large Homes

Let’s take a look at some models from the brand Rheem. This is the RTEX-36, their electric solution to heating water for a large home.

This is an excellent brand with option of electric, natural gas and propane.

We will start with this electric option, which is the less expensive of the options at about $790.

 

 

TECH SPECS

With the RTEX-36, you get a model operating at 36kW and that is able to achieve a maximum 8.8 GPM. A tad bit higher than the last model we reviewed.

That could be important to note if every little bit of extra hot water counts for you.

The dimensions of this model are 3.5 x 18.25 x 21.63 inches, which make it the smallest in terms of depth, the widest model of them all, and somewhere in the middle for its height.

Not so great if the space you intend to put it needs a thin model, but if you’re more concerned with how much your unit juts out from the wall, well this unit won’t bother you there!

And its 1,382 cubic inches keep it on the smaller side overall.

Weighing in at 22.7 lbs. means it’s on the lighter side overall.

It is the heaviest electric model on the list, but it’s also the most powerful.

If you want the most powerful electric option, then the RTEX-36 may be your best indoor tankless water heater in 2020!

And you’ll have an external digital thermostat with an LED screen that will let you change the temperature settings in 1-degree increments from 80 to 140 degrees Fahrenheit. How’s that for accuracy?

 

 

REGIONAL INFO

Now for the ever-consistent across many regions, Rheem RTEX-36 to show you what it can do!

If you live in North America, and aren’t too far north, like say, ‘able to see the North Pole from your backyard’ type North, the RTEX-36 is going to achieve at the very least somewhere between 4.8 – 5 GPM.

For those of you in the likes of Minneapolis, Lansing, Nov Scotia, and other areas with ground water temperatures of around 40, this means you can run two showers and another appliance like a low-flow kitchen sink or bathroom sink concurrently!

Of course, other areas will get even more out of the RTEX-36.

Other northern areas with ground water temperatures of around 50 will likely achieve somewhere between 6 – 6.2 GPM.

So, if you live in Delaware, Washington D.C., Seattle, etc. keep those two showers running, toss some dishes in the dishwasher and let that run also!

Warmer regions where the ground water temperature is about 60, you should be getting more like 7 – 7.2 GPM.

Living in Lexington, Roswell, San Francisco, similar cities, three people need to shower in the morning at the same time? No problem. Someone else needs to use a bathroom sink? Also, not a problem.

And how about farther south, where the ground water temperature is 70 and even higher?

This is where you’ll be getting at least 8 GPM and also hitting that maximum 8.8 GPM!

Places like Jacksonville, Temecula, and hey don’t forget about Mexico… a big four-shower household can run all the four showers at once and still have leftover hot water for another smaller appliance.

 

 

There are also reviews for this Option here:

See also: Best Whole House Electric Tankless Water Heaters

Pros

Cons

8. Rheem RTGH-95DVLN | Best Natural Gas/Propane Option for Large Homes

Another model from Rheem, now in the arena of Natural Gas or Propane.

The RTGH-95DVLN is a larger more powerful option.

Your choice of Natural Gas or Propane, either way, this unit costs about $1,190.

This is another great choice for large homes, especially large homes at higher altitudes as the Rheem RTGH-95XLN can be used up to 8,400 feet above sea level!

 

 

TECH SPECS

As stated before, this unit is more powerful than the past two electric options. It’s able to pump out a maximum of 9.5 GPM.

The RTGH-95DVLN is Energy Star Certified. The energy factor of 0.82 is fairly good and will save a decent amount of energy.

It has a minimum 11,000 and maximum 199,900 BTU and this model still manages to be classified as having low emissions.

You’ll love the ‘hot start technology’ which is a great feature that recognizes when hot water is in high demand and minimizes fluctuations in water temperature to any, and all of your appliances.

Say bye-bye to cold surprises in the shower!

The RTGH-95DVLN has dimensions of 9.88 x 25.63 x 13.88 inches, so it’s definitely larger in depth but isn’t too wide or too high.

The cubic inches of 3,514 does put it on the high end for overall size among all the options on this list.

And yes, it weighs 79 lbs. making it the second heaviest on the list. Perhaps you’ll excuse its size and weight due to its power.

Another plus, this unit is ‘EcoNet Enabled’ so it can connect to the EcoNet mobile app via the Tankless EcoNet Accessory Kit.

So, you can control your hot water from your smart phone… or if you want to use the digital remote control, they got that too!

Rheem also claims an industry best for this line… freeze protection to -30 degrees Fahrenheit!

 

 

REGIONAL INFO

Living in Canada or northern U.S. areas can make it tough with the hot water situation.

Living at high altitudes can possibly complicate that as well. The RTGH-95DVLN wants to make it easier for you.

If the ground water temperature is around 40 in your region, this unit can get you around 4.7 GPM.

So, North Dakota, high altitude Missoula, even higher altitude Banff and its great camping destinations… this unit can get you two showers without any problem, and probably a bathroom sink to boot!

If the ground water temperature in your area is about 50, look to get about 5.5 GPM.

The likes of Atlantic City, Detroit and ski destination and high-altitude Park City… that could be three showers depending on their flow rate. It’s at least two showers and a couple more sinks along with it!

How about if you live farther south where the ground water temperature is around 60?

You should expect around 7 GPM from this unit. Places like Myrtle Beach, Virginia Beach, Dallas… that’s definitely three showers at once along with a bathroom sink!

And in places far south where the ground water temperature is at least 70, you’ll be looking at least 8.5 GPM and many areas getting that maximum 9.5 GPM.

So, U.S. Virgin Islands, Los Angeles, Corpus Christi, and many more southern cities, let four showers run at once without issue.

Depending on your specific area, you could possibly let the dishwasher run at the same time too!

Pros

Cons

9. Rheem RTGH-95DVLN Professional Prestige | BEST EVER Natural Gas/Propane Option for Large Homes

And if you liked the last model, then you might really like this one.

Rheem took the last model, and made a deluxe version of it. The RTGH-95DVLN Professional Prestige.

It does cost quite a bit more, priced at about $1,490. It also lets you choose Natural Gas or Propane.

Let’s see what else the Professional Prestige has in store for you.

 

 

TECH SPECS

You’re going to get a lot of the same with this unit. Rheem is still granting you 9.5 maximum GPM and a minimum 11,000 and maximum 199,900 BTU.

So, the power is just as incredible. And this is another low emissions model.

You still get the industry best freeze protection all the way to -30 degrees Fahrenheit.

The Professional Prestige also incorporates ‘hot start technology’ so you don’t have to worry about using too many appliances here and there.

Is it ‘EcoNet Enabled’ allowing me to use Wi-Fi devices to start and stop hot showers?

You bet.

 

So, what’s different?

The dimensions of 9.75 x 27.5 x 18.5 inches are a little different, for starters.

It manages to be a little smaller in depth, but is sizably larger in height and width.

If you’re getting the Professional Prestige, make sure you got the room for it.

At 4,960 cubic inches, overall, it’s noticeably bigger. And if you plan to install it yourself, just be aware at 82 lbs., you’re getting the heaviest model on this entire list.

This is another Energy Star Certified unit from Rheem; however, this one has a 0.93 UEF. That is vastly better than the last.

This means you save energy. Better for the environment.

And saving energy, over time, will save you a good deal of money. Better for your bank account.

If you can afford the upfront cost and are looking to make a good investment, then you may consider this to be the best indoor tankless water heater in 2020.

 

 

REGIONAL INFO

Like the RTGH before it, the Professional Prestige is fantastic for cold climates and high elevations.

If you live in Canada or northern U.S. where the ground water temperature is about 40 degrees Fahrenheit, expect about 4.7 GPM.

And don’t worry about your area being high-altitude.

Places like Albany, South Dakota, and Winnipeg, you can run two showers at once, and probably a bathroom sink along with them!

If you live in northern areas where the ground water temperature is around 50, expect about 5.5 GPM.

Places like West Virginia, and notoriously high-altitude cities like Denver and Salt Lake City will love the Professional Prestige and its ability to run three showers in many scenarios, and at the very least, two showers and a couple sinks!

What if you live farther south, where the ground water temperature is floating around 60?

Expect around 7 GPM. Cities like San Jose, Norfolk and Knoxville, families of three can run a shower all at the same time. Fourth person in the house? They can use a bathroom sink simultaneously, if need be!

And in far south areas where the ground water temperature is 70 and up, you’ll be getting anywhere between 8.5 GPM to the maximum 9.5 GPM.

Areas like Pasadena, Flagstaff and Fort Lauderdale, residents will love the ability to have four concurrent showers… and maybe even a little extra hot water left over!

 

 

There are also reviews for this Option here:

See also: Best Outdoor Tankless Water Heaters

Pros

Cons

Best Indoor Tankless Water Heater for the Largest Homes

Now, to give the category of ‘Large Homes’ a sub-category of ‘Largest Homes’, we look at a couple models from Rinnai.

The following two options are great for large homes, but if yours is larger than just plain large, or you tend to have a lot of concurrent hot water traffic, then you may be looking for something with a lot of oomph!

 

10. Rinnai RU199 | Best Natural Gas/Propane Option for Largest Homes

From Rinnai, say hello to the RU199. Available in Natural Gas or Propane.

Both options will run you about $1,660. It’s the second most expensive option on this list, but for good reason.

 

 

TECH SPECS

One of the best reasons, this unit can get you a maximum 11 GPM! Let the hot water flow!

With a minimum 15,000 and maximum 199,000 BTU, this is a powerful unit to serve you and the family well.

Condensing technology and the fact that it’s Energy Star Certified make this an efficiency master!

Ranging between 0.91 and 0.93 UEF, you’ll love the energy and money that you save, year after year.

The dimensions of the RU199 are 12 x 27.9 x 18.5 inches, so it’s tied with the next Rinnai model on the list for largest in depth.

It’s also one of the largest in height and width. The overall cubic inches of 6,194 also have it tied for largest overall.

Though smaller than big, classic tanks… this is no small model as far as tankless options go. Weighing 64 lbs. it’s on the pricier end, but it isn’t the most expensive.

And another great feature from Rinnai, the RU line is Circ-Logic Capable and Control-R Wi-Fi Capable.

So, with some add-ons you can have the best recirculation technology that Rinnai has to offer and you can have control over your tankless water heater from any Wi-Fi device!

Get a shower warmed up on a cold, winter morning… all from the comfort of your warm bed!

 

 

REGIONAL INFO

Time to see what the big boys from Rinnai can do.

Attention Canada and those living far north in the U.S., if your ground water temperature is around 40 degrees Fahrenheit, the RU199 should be getting you about 6 GPM!

So, Rochester, Grand Rapids, New Brunswick, plenty more, that should be getting you three showers concurrently.

Canadian families of three that all need to get ready at the same time, this may be the best indoor tankless water heater in 2020.

Cities in the north of the U.S. with ground water temperatures around 50, expect about 7 GPM.

So, Brooklyn, Cape Cod, most of Wyoming, and many other northern places, your family can get three showers running and a sink!

If your area is warmer, with ground water temperatures floating around the 60’s, you’ll likely be achieving 8.1 – 8.9 GPM.

Places like Memphis, El Paso, Palo Alto will love the ability to run four showers concurrently. Or three showers and a dishwasher. Your choice!

And if the ground water temperature in your area is 70 or higher, you’ll be getting over 10 GPM and will have a good chance of hitting that maximum 11 GPM!

If the RU199 I intended for the likes of Miami, Scottsdale, Malibu… that’s five showers at once, and probably hot water left over for another appliance. Plenty of appliances can be run at once!

 

 

There are also reviews for this Option here:

See also: Best Rinnai Tankless Water Heaters

See also: Best Outdoor Tankless Water Heaters

Pros

Cons

11. Rinnai RUR199 | BEST EVER Natural Gas/Propane Option for Largest Homes

And from Rinnai, the RUR series. Their best series.

From the RUR series, the RUR199, is the most powerful option.

Is it safe to say, this is the best of the best from the brand Rinnai?

I think so.

Is it also the most expensive option on this entire list?

At about $2,075, it sure is. But you won’t mind spending this kind of money if you are looking for this kind of quality.

You have the option of either Natural Gas or Propane with this unit, as with all Rinnai units.

Let’s see what else you get with this unit.

 

 

TECH SPECS

Here’s another extremely powerful unit, able to hit a maximum 11 GPM.

That’s a lot of hot water for your household. And a minimum 15,000 and maximum 199,000 BTU means power is no issue here.

The dimensions of the RUR199 are identical to the RU199… 12 x 27.9 x 18.5 inches. So, it’s large all around… depth, height, width, and the cubic inches of 6,194 make it tied for the largest all around.

Add onto that the weight of 73 lbs. making it the third heaviest unit on this list… and this is no small unit.

Large, heavy (for a tankless unit, that is) but you can expect that with the quality you get.

Some of the best features of this unit is that, yes, it’s Energy Star Certified like the RU199, but it has a more consistent 0.93 UEF.

That means more consistent high savings on energy and money. Who doesn’t love that?

This is another great investment-unit.

And the fantastic Circ-Logic Capability and Control-R Wi-Fi Capability that comes with select Rinnai lines… it comes already included here.


No extra add-ons needed
.

You already have the best recirculation and ability to control what you need, all from a tablet or phone!



REGIONAL INFO

The RUR199 will be very similar to the RU199 in its ability.

In Canada and northern cities in the U.S. where the ground water temperature is about 40, expect about 6.3 GPM from this unit.

Places like Oshkosh, Duluth and Edmonton can easily run three concurrent showers.

Other northern areas where the ground water temperature is about 50, you’ll be getting about 7 GPM.

This includes, but is not limited to, places like Chicago, Toledo and Long Island.

And if you’re living in areas like this, your household will be able to run three concurrent showers and a bathroom sink!

More southern areas where the ground water temperature is around 60, you can expect a range of about 8.3 – 9.1 GPM.

That means places like Fort Worth, Fresno and Savannah could run four showers for families of four with ease! You’ll even likely be able to run a bathroom sink or low-flow sink as well!

And if we keep going south, where the ground water temperature is 70 and up, here’s where you can get over 10 GPM and up to the maximum 11 GPM!

Places like Long Beach, Mesa and Dominican Republic, your residents can run five showers at once if they choose, likely with hot water leftover for another smaller appliance.

If this is intended for commercial use, places could service several break rooms or perhaps several hotel rooms!

If you live down south and want to run the greatest number of concurrent showers, then the RUR199 may be the best indoor tankless water heater in 2020!

 

 

There are also reviews for this Option here:

See also: Best Rinnai Tankless Water Heaters

See also: Best Outdoor Tankless Water Heaters

Pros

Cons

Best Indoor Tankless Water Heater — Buyers Guide

Now, that’s a lot to think about!

Luckily, we’re going to go over all the details and simplify them the best that we can.

Reading the above reviews may have already helped you narrow down your search.

It may have helped you already pick out the best indoor tankless water heater for your specific scenario.

For those of you still deciding, for those of you still trying to decide between multiple choices, I’m still here to help!

We’ll go over some frequently asked questions from others when making these kinds of decisions.

Likely, these questions will be the same as the questions you have, or at least similar enough to help you along.

I’ll cover several different areas so that any kind of question you may have should be touched on.

Sometimes, there’s so much information, some of it can get lost in your mind. So, we’ll simplify some of it as well.

Let’s go over some of these questions and finally boil it down for you.

Let’s look at your situation and find you the best indoor tankless water heater in 2020!

What’s the cheapest indoor tankless water heater in 2020 for small homes/point-of-use situations?

The Stiebel Eltron DHC-E 12 at about $290.

What’s the cheapest indoor tankless water heater in 2020 for medium-sized homes?

That would be the EcoSmart ECO 27 at only about $480.

What’s the cheapest indoor tankless water heater in 2020 for large homes?

The EcoSmart ECO 36 at just about $560.

What’s the best ELECTRIC indoor tankless water heater in 2020 for small homes and point-of-use situations?

You’ll want the Stiebel Eltron DHC-E 12.

What’s the best ELECTRIC indoor tankless water heater in 2020 for medium-sized homes?

I would say, the warmer your climate, the more likely you’d want to choose the EcoSmart ECO 27, with a higher maximum GPM and lower cost.

However, in colder climates, northern U.S. and Canada, the Stiebel Eltron Tempra Plus 29 kW may be a better choice for you.

It’s more expensive but may grant you a tad higher hot water flow rate.

What’s the best ELECTRIC indoor tankless water heater in 2020 for large homes?

For large homes, I’d choose the Rheem RTEX-36.

What’s the best natural gas/propane indoor tankless water heater in 2020 for small homes and point-of-use situations?

That would be the Eccotemp i12 Indoor model.

What’s the best natural gas/propane indoor tankless water heater in 2020 for medium-sized homes?

The Rinnai RL75.

What’s the best natural gas/propane indoor tankless water heater in 2020 for large homes?

That would be the Rinnai RUR199.

What are the best indoor tankless water heaters in 2020 if I live at a high altitude?

If it’s a somewhat high altitude and not too overwhelming, and you’re just wanting to service a small home, perhaps a cabin, maybe a point-of-use option, then choose the Eccotemp i12 Indoor.

If you need to service a larger home, or you are at a higher altitude, especially 4,000 feet and up, the Rheem RTGH-95DVLN saves you money initially but the Rheem RTGH-95DVLN Professional Prestige may be the best choice as it will save you more money in the long run.

What’s the best indoor tankless water heater in 2020 if I want Wi-Fi capability?

The Rinnai RL75 is the perfect choice for Wi-Fi capability in a medium-sized home.

Larger homes at high altitudes… the Rheem 95XLN or the Rheem RTG-95XLP Professional Prestige have got you covered.

The absolute largest of homes that desire Wi-Fi capability… the Rinnai RU199 and the Rinnai RUR199 both can do that.

Best Indoor Tankless Water Heater — Conclusion

As you can see, the world of indoor tankless water heaters is as great as it’s ever been.

It’s as if the indoor tankless water heater universe came together and decided to give you all the best possible options.

Whatever it is that you want or need, it’s there for you. It’s just a matter of selecting the perfect model.

And there is a perfect model for everyone.

Whether cost is most important to you, or maybe power is at the top of your list.

And no matter your region or your intended use. There are units for everyone on this list of best eleven.

Even those who are energy-conscious… those who are at high-altitudes… worry not.

So, we’ve gone over everything in great detail. Asked a lot of questions. Answered a lot of questions.

All the information you could possibly need is here.

So, now it’s time for you to answer the most important question of all. What’s your best indoor tankless water heater in 2020?

And then once you got that answer… go ahead and go get it!

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Mike has a PhD in Engineering and is currently a Scientist in an international research institute. He is 39 and loves researching about interaction of light with solid materials. Application of his research includes but not limited to solid state lighting, white-light emitting diodes (LED)photodetectors and optoelectronic devices

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