Best Tankless Water Heater 2019 – A Buyer’s Guide

tankless water heater

Winter brings about two of the most frustrating things: freezing temperatures and high electricity bills. If you are anything like me you avoid the cold and wasting money. Tankless water heaters are the answer to those cold winter days and a way for you to save a lot of electricity.

A heater of this type consistently provides hot water at much lower power consumption, and it is much slimmer than your traditional bulky tank. Not only are they skinnier, but they mostly do not require a special place in your home, i.e. no renovations necessary. Some can fit anywhere, others do need a small vent, but that is usually an easy thing to place.

Sounds great, right? Now, which one should you get? Sure, you can go to your local appliance store, but the choices there are endless and you might leave feeling overwhelmed and stressed out. But don’t you worry, We have a list of the best tankless water heaters to aid you in your search.

Here is an overview:

Top 7 Tankless Water Heaters

Vacuum CleanerTypePowerOur InputPrice
Stiebel Eltron 24 Plus Tempra
(Editor's Choice)
Electric24 KWPremium Quality

Our Review

Rheem RTEX-13


13 KW

Ideal for small homes

Our Review

Rinnai RUC98iN Ultra SeriesNatural GasNone, GasBest Gas Heater

Our Review

Atmor AT-910-18TP ThermoPro

Electric24 KWAffordable Option

Our Review

EcoSmart ECO 27

Electric27 KWGreat for cold climates

Our Review


Natural GasNone, GasHigh Quality Gas Heater

Our Review

Eccotemp FVI12-LP

Liquid PropaneNone, GasDecent Propane heater

Our Review

The overview above shows our top choices and contain different types of heaters, such as electrical and propane-based models. If your current water heater is a tank, any tankless model is going to be an upgrade, especially in terms of energy consumption. Tankless heaters are the next level. Below, you can find more in-depth information on each model and links to full reviews. At the bottom of the page, we also have a little buyers guide.

1. Stiebel Eltron – Tempra Plus 24 kW

At a glance: Our top pick! The best thing about this heater is how quiet it is. Beyond that, it is also compact and energy efficient.

There is a weird problem when looking at tankless heaters: not all of them are quiet. Some are actually quite annoying. But not the Stiebel Eltron Tempra, since its key selling point is the lack of noise. This heater contains high-end electronics and its cover is reliable, neither of which vibrate. In addition, mechanical switches are absent. This enables the heater to run silently. In our experience, you won’t even know it is there.

Apart from its silent run, the Stiebel Eltron has a technology called Advanced Flow Control which allows it to maintain consistent water temperature. Also, it is self-modulating, which means it modifies the heater in such a way as to keep its energy intake constant. Self-modulating units are also energy efficient only heating the amount of water you actually need.

This small heater does not need a lot of room, so if you live in a tiny apartment you will be able to find somewhere tucked away for it.

There is one small downside, Stiebel Eltron gives you a 36 months warranty, but requires installation from one of their licensed personnel so the warranty stays valid.

Final Thoughts

If you need something small and quiet the Stiebel Eltron Tempra Plus is the heater for you.


  • Constant temperature
  • Precise temperature sensor
  • Very quiet
  • Self-modulating


  • Poor warranty clause

2. Rheem RTEX 13 – Electric Water Heater

At a glance: Best for small apartments or homes, this heater is user-friendly, reliable, and compact.

This little unit is a wonder for small homes and apartments. And not only that, the Rheem RTEX is super affordable which means even if you rent, you can swing this.

The RTEX has a four Gallon Per Minute rate (GPM) which means there is no fighting for hot water while one-person showers and the other does dishes (a constant problem in my home!)

Like I said this unit is compact. At just 9 x 4 x 13 inches, even studio apartments can find a place for it. The RTEX will practically fit anywhere.

Beyond its compactness, affordable price and impressive flow rate, the RTEX uses electricity as a power source so there is no need to worry about having proper ventilation or a potential gas leak. Meaning, there is no renovations necessary. The RTEX really will fit anywhere.

And finally, the Rheem has an easy to read and easy to change temperature display. You can control the temperature to a single degree.

Final Thoughts

If you live in a tight space and are looking for an inexpensive way to upgrade your water heater the RTEX might just be for you, but big homeowners will be hard pressed with this unit.


  • Great for small homes and apartments
  • Compact
  • Digital thermostat
  • Not expensive
  • Impressive flow rate


  • Only good for small homes/apartments

3. Rinnai RUC98iN Ultra Series

At a glance: By using natural gas, the Rinnai is energy efficient. Add that efficiency to a large GPM and you are on your way to the perfect unit for your large home.

Natural gas is definitely nicer on the energy bill but can be a bit of a problem to vent. To help with that, this model comes with 2 options for venting: concentric-PVC or twin-pipe. Just pick whichever one is easiest for you to install, then you are good to go.

This heater is easily equipped to handle several showers and faucets without losing hot water. Because it uses natural gas, the flow rate is much higher than another heater. A Rinnai heater has a flow rate of up to 9.8 GPM. Basically, if you have a big house this is the heater you want.

Natural gas might give you the impression that your carbon footprint will be high, but don’t worry that with this heater. The Rinnai has a 0.95 efficiency rating.

There is always a downside. Due to its large GPM, the Rinnai is a little on the bulky side and it might be a little hard to install.

Final Thoughts: If you own a big home and need an ample hot water supply this is the heater for you.


  • Energy efficient
  • Easy venting options
  • Great flow rate of hot water
  • Hot water provided to multiple outlets simultaneously
  • Great for large homes


  • Costly
  • Possibly hard to install
  • Bulky

4. Atmor AT-910-18TP ThermoPro

At a glance: The Atmor is inexpensive, compact, and easy to use.

Atmor water heaters have a really nifty feature: water sensors. Once you start using hot water, it creates a small storage of hot water for later use. But as soon as you turn off that tap, it stops heating, saving you money on the energy bill.

With just a single knob below its digital thermostat, anyone can use this heater with ease.

Apart from being easy to use, this tankless water heater is safe. Its internal parts have an IPS4 certification, meaning they remain dry. Plus, it comes with a seven-year leakage warranty, just to give you an extra bit of security and peace of mind.

However, with a 3.7 GPM it might not be enough for large homes.

Final Thoughts

This model is best suited for a single person or small apartment, especially with the safety warranty so there is no worry while you are away from home.


  • Easy to use
  • Safe
  • Wonderful warranty
  • Digital control for temperature
  • Its self-modulation is energy efficient


  • Not ideal for large homes because it is small

5. Ecosmart ECO 27 – Electric Water Heater

At a glance: If you live in the cold mountains, the Ecosmart is great for you. It is easy to install, has a precise temperature control, and good flow needed for cold climates.

We all don’t have the luxury of living in a tropical paradise. For those of us unlucky enough to live somewhere frigid, we have this heater.

The ECO 27 goes from 3-6 GPM (depending on the external temperature), giving a home enough warm water for two showers at the same time. Meaning this heater would work for small to medium homes and apartments.

This heater also uses that oh-so-wonderful self-modulation technology we mentioned before. Combined with its small price tag, you’ll see a lot of savings.

All the ECO 27’s parts are stainless steel and copper. Neither material rusts easily and both materials handle high temps with ease. Making this the ideal heater for cold climate dwellers. Copper and stainless steel retain heat much easier than other metals.

The only real downside is its warranty! ECO 27 claims to have a lifetime warranty, but with such a complex document full of loopholes, hardly anyone can actually use it.

Final Thoughts: If you live in a cold climate, this heater may just be made for you.


  • Great for cold climates and mountainous regions
  • Great GPM
  • Self-modulating
  • High-quality metal components
  • Easy installation
  • Precise digital temperature controller


  • Very poor and complicated warranty

6. Rheem RTGH-95DVLN

At a glance: This heater has the ability to connect both its vents, giving you a big water supply. It is also great for cold, mountainous homes.

Remember how I said stainless steel can handle high temps? This heater has a heat exchanger out of stainless steel, which retains those toasty water temperatures. In addition, it has two vents that you can connect together when you need an ample amount of water. Plus, the temperature does not fluctuate no matter how much water you need.

Maybe you are thinking that you have to sacrifice your energy savings for tons of water. Not true! At a 94% efficiency rating, this water heater will keep your energy bills low even if you use a lot of water.

Mountain homeowners this is the heater for you. It can handle temperatures all the way down to -30 Fahrenheit and high elevations up to 9,800 .

But with a high price tag, this heater is a bit expensive.

Final Thoughts

If you live somewhere high and cold, spending a bit more upfront may be needed in order to give you a heater that lasts a lifetime.


  • Digital temperature control
  • No temperature fluctuations
  • Energy efficient
  • Great installation instructions
  • Propane or natural gas options
  • Great for mountain homes and cold climates


  • Premium price

7. Ecotemp FVI-12-LP – A Propane Water Heater

At a glance: The Ecotemp is compact, lightweight, and easy to install.

Good things come in small packages. At 20 pounds, this a small and lightweight model. The Ecotemp has a GPM of 3.4 meaning you can shower and wash your hands simultaneously. But that also means that this heater is best suited for a small home or apartment.

This little heater is powerful. At full throttle, it uses 110 Watts. When sitting idle, it only uses 2W, so it will not waste your money when it’s not doing anything.

Besides its LCD temperature display, there are only two other knobs, one being for gas and one for temperature regulation. Like pretty much all tankless water heaters today, this makes it very easy to use.

The Ecotemp is easy to install with only three pipes: water and gas inlet, and a hot water outlet. Fortunately, they are labeled so there is no guesswork if you want to install this heater by yourself.

This heater uses propane to power itself, but because of that, it will need an outside vent.

Final Thoughts

If you have a small outdoor space for this little heater, then we find the Eccotemp FVI-12 to be perfect especially for small homes and apartments.


  • Good flow rate
  • Easy installation
  • Easy to use
  • Energy efficient
  • Small and lightweight
  • Propane powerhouse


  • Needs a vent to the outside

Final Thoughts and Buying Guide

Apart from the list above, is there anything else you should know before purchasing?

Yes! Because there are so many great options available it is important to keep in mind what exactly you are looking for. To truly get the most of your money, you need to take into account your household size.

I know a water heater with large amounts of GPM sounds like a dream, but if you live in an apartment you may not need all that power and can probably go with something smaller and more compact. Consequently, if you live in a large home I know you are looking to be cost and energy efficient, but buying a small unit may do more harm than good in the long run and cause a lot of headaches and tensions when the hot water runs out.

In order to make sure you are buying the most cost-efficient unit, you will need to figure out the GPM usage of your home. Check anything that uses hot water including shower heads, sinks, dishwashers and washing machines for a GPM rating.

After you have checked those, you will need to figure out how much GPM you actually use. For instance, families that shower at the same time or that run the dishwasher or washing machine while the shower will need to add each of those items together. Singles just showering will only need to check their shower head. But it is a good idea to round up by about half just to leave yourself with a margin for error and to give yourself some flexibility.

Remember that climate dictates the temperature of the starting water. Since colder climates will start with colder water, the heater needs to work harder to heat that water up. That’s why cold climate dwellers should round up their GPM usage even higher by about 75% to 100% to account for the cold starting water. Warm climate dwellers can get away with a smaller GPM since their heaters will not be working as hard.

Lastly, consider your installation costs. Tankless water heaters that use gas require venting and/or weatherproofing so they are more expensive than electric units to install. Even if you already have a gas line to your house the size of the line might be too small (or big) for most heaters. It is important to talk to a plumber before installing (or even buying) a heater to see if your options are limited.

I know this may sound like a bunch of turnoffs, but most buyers have said that their unit has paid for themselves in about two years. You will save money in the end and I hope this list helps you find the best product for your needs. is a participant in the Amazon Services LLC Associates Program, and we get a commission on purchases made through our links.