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2020’s Top Picks for the Best Tankless Water Heaters: Expert Reviews & Price Comparison

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Reviews of the Best Tankless Water Heaters

If you’re looking for a way to save energy and cost each month, a tankless water heater can be a great investment. While the initial investment can be pricey (with installation costs considered), you will save money in the long-run compared to the cost of owning or renting a hot water tank.

This buying guide will cover gas powered tankless water heaters, which are suitable for providing hot water to multiple faucets in your home. We recently reviewed the best tankless electric water heaters, which might be a better choice if you’re trying to provide hot water to a single faucet.

This buying guide includes our expert tankless water heater reviews.

Best Tankless Water Heaters: Compared

Let’s take a look at the table below and see the products we’ll be reviewing.

Best Overall
Takagi T-KJr2-IN-NG Indoor Tankless Water Heater, Natural Gas
Tagaki T-KJr2-IN-NG Indoor Tankless Water Heater
Editor Rating:
5 Star Rating
Flow Rate:
6.6 GPM
Price not availableLearn More
Budget Pick
Marey Power Gas 10L 2.7 GPM Natural Gas Digital Panel Tankless Water Heater
MAREY Gas 10L Digital Panel Tankless Water Heater
Editor Rating:
4.9 Star Rating
Flow Rate:
3.1 GPM
$399.99Learn More
Best Value
Rheem RTG-84XLN 8.4 GPM Low NOx Outdoor Tankless Natural Gas Water Heater
Rheem RTG-84XLN 8.4 GPM Outdoor Tankless Natural Gas Water Heater
Editor Rating:
4.9 Star Rating
Flow Rate:
8.4 GPM
Price not availableLearn More
Best Portable
Camplux 5L 1.32 GPM Portable Outdoor Tankless Propane Water Heater
Camplux 5L 1.32 GPM Outdoor Portable Tankless Water Heater
Editor Rating:
4.9 Star Rating
Flow Rate:
1.32 GPM
$129.99Learn More
Best Outdoor
Takagi T-KJr2-OS-NG Outdoor Tankless Water Heater, Natural Gas
Takagi T-KJr2-OS-NG Outdoor Tankless Water Heater
Editor Rating:
4.8 Star Rating
Flow Rate:
6.6 GPM
Price not availableLearn More
Highest Flow
Rinnai RUC98iN Ultra Series Indoor Natural Gas Tankless Water Heater, Twin Pipe
Rinnai RUC98iN Ultra Series Natural Gas Tankless Water Heater
Editor Rating:
4.9 Star Rating
Flow Rate:
9.8 GPM
$1,510.00Learn More

Reviews of the Best Tankless Water Heaters

Best Overall – Takagi T-KJr2-IN-NG Indoor Tankless Water Heater

Takagi TJR2-IN-NG

Features We Love

  • Whopping 10 years warranty.
  • 140,000 BTU.
  • An impressive flow rate of 6.6 gallons.
  • Optional conversion kit from NG to LP.
  • Effortless installation
  • The high water flow rate of 6.6GPM is impressive considering the compact size of the unit.
  • Compact and simplistic design that gets the job done effortlessly.
  • 10 years warranty on the heating element and half of it on other parts.
  • There’s a conversion kit for owners who would like to switch from natural gas to propane.
  • Creating ventilation for it can be slightly tough.
  • Quite pricey.
Editor's Review - Click to Expand/Collapse

Tagaki T-KJr-IN-NG Indoor Tankless Water Heater is one of the two best tankless water heater units from Tagaki. Although small like it’s twin which we reviewed immediately below, it can meet the hot water demand of your home if you have two or three bathrooms.

It is very compact sized and measures just about 6.7 x 13.8 x 20.3 in. Tagaki equipped the unit with the ability to handle 140,000 BTU. This is in addition to the energy factor which hovers between 0.81 and 0.83 as the case may be.

The Tagaki T-KJr2 indoor tankless water heater is cost and energy efficient not forgetting that it’s eco-friendly. That notwithstanding, the unit must be installed by a Tagaki professional. DIY installations void the warranty on the unit.

This is probably a huge turn off considering the fact that one can save some money since they have prior knowledge. The installation is not difficult, although you may have to deal with venting and some other connections.

It has a TV10 conversion kit, although buying it is optional. This can be used to attach the unit to a direct vent unit in the garage.

As for the flow rate, it’s very impressive, to say the least. It has a maximum flow rate of 6.6 gallons per minute and has a BTU of 140,000 maximum.

Dealing with the ventilation can be a tough one for owners of this unit. You’d have to shell out some extra bucks to buy any fittings and other accessories that will be needed during installation.

Tagaki doesn’t ship the unit along with all the accessories you’ll need for installation. It does, however, include the basic ones that are vital. The installation manual is detailed properly to aid anyone installing the unit.

There is a 10-years warranty on it. The Tagaki indoor water heater doesn’t come cheap – it costs exactly the same as its other sibling.

Budget Pick – MAREY Gas 10L Digital Panel Tankless Water Heater

Marey Gas 10L Tankless

Features We Love

  • Budget-friendly.
  • Energy efficient.
  • A good flow rate of 3.1 GPM.
  • Digital display panel.
  • 79,000 BTU.
  • Electric pulse ignition.
  • Works with either propane or liquid gas.
  • The unit comes with a digital display which shows you the temperature of the unit at the moment.
  • We love the 3.1 GPM flow rate. It’s not as high as the 6.6 GPM on the Tagaki, however, it’s effective, considering the price of this unit.
  • The unit is energy efficient.
  • You can use the unit with propane or liquid gas. You’ll need a conversion kit for this purpose.
  • There’s an electric pulse ignition feature that powers the unit. This means that no electricity is required to get hot water from the unit.
  • Venting can be tough and if not done properly, can lead to damages.
  • Not suitable for a whole house
Editor's Review - Click to Expand/Collapse

Our budget pick for this best tankless water heaters review is the Marey Gas 10L tankless water heater. It sports a digital panel which was lacking in our overall best model.

The most distinct features about this product are its low price, an impressive flow rate of 3.1 GPM, size, and energy efficiency. It can supply hot water to up to four showers and faucets all at the same time before the flow rate decreases.

Although the Marey 10L tankless water heater is a budget unit, it is energy efficient. Marey listed the energy efficiency of the unit as being between 54% and 87% – we didn’t verify the claims, however, the energy star rating is a good alibi for it.

The Marey 10L tankless water heater is designed to work with an electric ignition feature. Thus, no electricity is required since it draws its power from the gas line. Let us also mention that there are 2 batteries powering the unit.

Control knobs for the unit are situated in front of it. You can control the gas as well as temperature using the knobs.

There’s a 50ft distance to the point of use. This implies that this unit is suited for point of use purposes and as such, should be installed close to the point of use. In addition, installing it close to the point of use will significantly decrease lag time experienced.

One setback of this product lies with the ventilation. It does not have any venting mode, so you’d have to make the necessary arrangements for that.

Best Outdoor – Takagi T-KJr2-OS-NG Outdoor Tankless Water Heater

Takagi T-KJR2-OS-NG

Features We Love

  • Adequate minimum and maximum temperature.
  • Dip switches for controlling temperature.
  • Compact sized.
  • 6.6 GPM flow rate.
  • 140,000 BTU.
  • The unit can run on either natural gas or propane. You’ll need a conversion kit for switching to your preferred choice.
  • It has a BTU of 140,000 in addition to its 0.82 energy factor.
  • It’s designed to be installed outside the house and can withstand unfavorable weather conditions.
  • Controlling the temperatures is very much easy, thanks to the dip switches and the rest.
  • It can only be installed outdoors for homes in a temperate climate.
Editor's Review - Click to Expand/Collapse

The Takagi outdoor tankless water heater is the twin of the indoor model which we chose as our best pick. They both share the same features which include a flow rate of 6.6 GPM, an energy factor of 0.82 as well as a BTU rating of 140,000.

Unlike the indoor model we reviewed above, this outdoor model is designed for external installation. This is to say that it is meant to be installed outside the home. Hence, you won’t need to vent the unit since it is already outside.

It comes with tons of features that allow it to work well even in the harsh conditions of the external walls of the house. There is a minimum temperature setting of about 122 degrees while the maximum sits at 140 degrees.

Although this unit is designed to be installed outside the home, only homes in a  temperate climate are covered. So if you’re not living in a temperate climate, opt for the indoor version. This, however, is a major turn off for many people considering the fact that it is advertised as an outdoor unit.

Best Value – Rheem RTG-84XLN 8.4 GPM Outdoor Tankless Natural Gas Water Heater

Rheem RTG-84XLN

Features We Love

  • A fantastic flow rate of 8.4 GPM.
  • Remote controlled.
  • Comes with 10-feet thermostat wire
  • 180,000 BTU
  • The unit is remote controlled, thus saving you the stress of having to go outside to set the temperature.
  • It comes with 10 feet of thermostat wires for installation.
  • The installation is pretty easy and straightforward, unlike some other tankless heaters.
  • It has a BTU rating of 180,000
  • The remote control can easily be misplaced.
  • Temperature settings aren’t as flexible as we expected.
Editor's Review - Click to Expand/Collapse

We picked the Rheem RTG tankless water heater as the most valuable tankless water heater. It is an embodiment of all you can ever want in a gas powered tankless water heater. However, it will cost you something to get and install this unit in your house.

Why do we like it?

First, the Rheem RTC tankless water heater is from a known brand in the industry. This was a major deciding factor as we had to look at the notable names and what people are saying about them. As for this unit, it has been 95% praises and a few complaints.

Secondly, the unit is well equipped to power a large household more than the overall best unit we reviewed earlier. It has a flow rate of 8.4 GPM – that is the flow rate of our budget and overall best picks combined together. Now, that’s massive power.

It is designed for outdoor installation and as such, will save costs associated with venting. Of course, it comes with all the necessary installation accessories to make installation easy. Rheem recommends getting a professional to handle the installation – we also recommend that considering the price of the unit. However, it is much easier to install than some of the other units on this review list.

One feature we love about the unit is the remote control. It’s not every day you get to see tankless water heaters that come with a remote control. The unit is pretty much responsive to the controls from its UMC-117 remote control.

Don’t bother looking for knobs or a digital display, as both are lacking. As for the BTU rating, the unit has a BTU rating pegged at 180,000.

Best Portable – Camplux 10L 2.64 GPM Outdoor Portable Propane 

$60.00 off
Camplux 10L 2.64 GPM

Features We Love

  • Lightweight and portable.
  • Low startup pressure.
  • 2.64 GPM flow rate.
  • Compact size.
  • The unit is portable and lightweight. Thus, it is suitable for use as a camping tankless water heater.
  • It has a moderate flow rate of 2.64 GPM.
  • The unit has an impressive low startup pressure of 2.5 psi which is good when compared to other units.
  • It has important features such as an anti-freeze protector, an oxygen depletion shut off switch as well as a flame failure device.
  • There’s a thin rubber hose inside the metal hose that comes with the unit. This internal rubber hose is prone to easy damage with high temperatures.
Editor's Review - Click to Expand/Collapse

Camplux 10L 2.64 GPM Ventfree Outdoor Portable Propane Tankless Water Heater is one of the newer models on the market. It is a very portable water heater with a 6L water pump. Arguably, it is one of the best deal you can get right now.

It is designed to deliver hot water with a maximum temperature of 114 degrees and a minimum of 46 degrees. It’s compact-sized and easy to install and control.

The Camplux water heater has one of the lowest pressure-startups in the market among many of the units we saw during this review. The startup pressure is about 2.5 psi. Another unique selling point of the unit is its portability. Given its small design, Camplux included a handle for easy carrying.

In terms of weight, the unit’s weight is barely noticeable – it’s really lightweight, to say the least. This makes it a good choice for people who go on camping often. You’ll, however, devise a means to deal with the weight of the gas tank which you’ll bring along.

Highest Flow – Rinnai RUC98iN Ultra Series Natural Gas Tankless Water Heater

Rheem RTG-84XLN

Features We Love

  • Straightforward installation procedure.
  • 9.8 GPM flow rate.
  • 0.93 energy factor.
  • 199,000 BTU.
  • Touch control buttons.
  • Compact design.
  • The unit sports touch control buttons in place of knobs which we’ve been used to.
  • Its compact design makes finding an installation space easy.
  • The unit has a massive flow rate of about 9.8 GPM – this will no doubt power multiple points of use at the same time.
  • Although we recommend professional installation, several users have voted this unit as having a straightforward installation process.
  • One of the more expensive units
Editor's Review - Click to Expand/Collapse

Before we wrap up on this review of the best tankless water heater, let’s talk about the Rinnai RUC98iN tankless unit.

The first thing you’ll probably notice about it is the compact size and the fact that it is devoid of control knobs. Instead, it makes use of touch responsive buttons paired to a small digital display which was otherwise absent on the Rheem.

We love the touch control button. It was pretty responsive to touch inputs and changed the temperatures quickly.

Installing the unit is pretty expensive. Considering the fact that the unit itself is expensive, you may be spending almost the same as its cost price just to get it installed. The warranty won’t be voided if you self-install it, however, if you self-install it the wrong way, the warranty will be voided.

The unit has an energy factor of up to 0.96 as against the 0.83 we’ve seen on some models on this review list. In addition to that, it’s BTU is the highest – 199,000 to be exact.

Rinnai designed the unit to work with both PVC and concentric venting options, However, we recommend using metallic venting options as such will not get damaged easily in the long run.

The Rinnai  tankless water heater has a flow rate of 9.8 GPM. This is by far the highest flow rate you’ll see in the market. Of course, it’s designed to power large households and can supply hot water to several points of use simultaneously. Thus, your daughter can take longer showers without ever running out of hot water. You’d only have to pay for more water.

Honorable Mentions

There are other great tankless water heaters in the market that are worth considering, even if they didn’t make the #1 spot in their category. Check out some of our other recommended tankless water heaters below:

Tankless Water Heater Comparison Table

NameOur RatingBTUFlow RatePower SourceTypePrice
Takagi T-KJr2-IN-NG5140,0006.6 GPMNatural GasIndoorPrice not available
Marey Gas Digital Panel4.979,0003.1 GPMNatural GasIndoor$399.99
Rheem RTG-84XLN4.8180,0008.4 GPMNatural GasOutdoorPrice not available
Camplux 5L Outdoor Portable4.934,0001.32 GPMPropaneOutdoor$129.99
Takagi T-KJr2-OS-NG4.8140,0006.6 GPMNatural GasOutdoorPrice not available
Rinnai RUC98iN4.7199,0009.8 GPMNatural GasIndoor$1,510.00

About Gas Tankless Water Heaters

The gas tankless water heaters have been much around like their electric powered counterparts. There’s not much difference between both save for the fact that one is gas powered and the other, electrically powered.

Gas/propane tankless water heaters are believed to be much more powerful than the electric tankless water heaters. We, however, didn’t do any tests to compare the two. Two major things must be considered before going for gas/propane tankless water heaters.

  1. The first is to check if your gas supply is large enough to power the water heater.
  2. The second is to find a way to pass out the exhaust from the heat.
  3. Is the gas pipe long enough to reach the heater?
  4. What is the gas consumption rate of your home?

All of these will determine how much of the upgrades you will be needing to power your new gas tankless water heater. We explained these aforementioned factors and others in the buying guide below.

Is the best tankless water heater for everyone?

The answer is yes and no.

Yes: If you can afford the unit and the installation costs, please go ahead and install one for your self.

No: If you’re tight on a budget or you already have a means of getting hot water. However, you should have in mind that the benefits of installing the best tankless water heaters are endless in the long run.

Unlike the traditional water heater that can only contain a limited amount of water, a tankless water heater does not have any limited amount of water it can contain. So, every member of your family has uninterrupted access to hot water.

Buying Guide: Best Tankless Water Heater

Tankless water heaters are designed to provide unlimited hot water and also maximum energy savings. However, not all products termed tankless water heater can offer these features.

So, how do you know the one that is right for you then? Consider the following. You can read more on the factors to consider when buying a tankless water heater here.

Size of the Household

The first thing to look for when buying a tankless water heater is the size of your household. The bigger the size of your household, the higher the quality of the unit you’ll need.

If you have a large household, your hot water needs will definitely be much. Therefore, you need to get a unit that will supply hot water to everyone in the house.

Price Tag

Consider the price tag. A small household does not necessarily need a higher heater that is expensive. A small tankless heater will provide enough hot water for the whole house if all faucets are not turned on at the same time. Price varies according to models and functionality. The more powerful the heater is, the more costly it will be.

Installation Cost

In addition, you need to consider the installation cost. The cost can be prohibitive or cheap – this depends on the manufacturer and the type of home you live in. For indoor heaters, ensure that proper venting is provided for it. This is one of the things that can significantly increase the cost of installation.

Again, some manufacturers insist on having their technician install the unit. If you do a DIY installation, you’ll void the warranty on your unit. Opt for a unit which doesn’t require professional installation.

Digital Display

Digital displays have become a standard feature in newer models of tankless water heaters. This helps in better monitoring and maintenance of the heater. It also helps you to keep an eye on the temperature of the water.

Warranty Period

If you see a water heater with a warranty of more than 3 years, this is a good deal, grab it with both hands. Anything below that is not advisable, in our opinion.

Drainage Valves

There are two types of drainage valves namely; brass and plastic. The brass is more durable than the plastic. When buying a water heater, consider the ones that have a brass drainage valve.

Antifreeze Protection

This feature helps to prevent the water from freezing when the temperature is low. This feature is most common in the outdoor water heater models while some indoor models also have the feature. This is good for places with low temperature.

Safety Features

Safety features are a must when it comes to buying tankless water heaters. One of the most important safety features is the flame protection which helps in detecting issues whenever the heater is malfunctioning.

There is also oxygen depletion. Most newer models of tankless water heaters have these safety features except the cheap ones.

Showerhead Capability

Some models of water heaters have showerhead capability whereby you can mount a showerhead to the water heater and take a bath directly. Anyways, this is not a common feature in most tankless water heaters.

Gas Tankless Water Heater vs Electric Water Heater, which is best?

The truth is there is no best choice between the two. They are both very good. If you’re looking to replace your existing unit, we suggest buying the same type. That is, if you have been using the gas type and you need a replacement, simply replace it with a gas tankless heater.

Switching from electric tankless water heater to gas tankless water heater or vice versa will require additional cost for fittings and installation. But, if you do not mind the cost, either of the two is best.

How to care for your Tankless Water Heater

Tankless water heaters tend to store up minerals after a long while. The minerals in water which cause its hardness are the sole culprits. We strongly advise installing a water softener as well as a whole house water filter in your home. This will greatly reduce the number of impurities in your water thus prolonging the lives of your appliances that use water.

To keep your tankless water heater in good shape, always flush it at least once every 6 months. It is not tasking to flush the heater although you’ll need to screw and unscrew. You can hire experts to do the flushing if you don’t want to get your hands dirty.

Here’s a video tutorial showing how to flush a tankless water heater.

Video 1

Video 2


Going tankless is a great decision. The units on we reviewed above are here because they met our criteria. Which would you go for – the gas or the electric tankless water heater?

Share your thoughts in the comment section below.

*last price update: 2020-09-20 - See Details


  • Hey Walt, I’m curious why Takagi was selected as the best tankless water heater, why not a more popular brand like Rinnai or Rheem?

    • Hey Victor, thanks for your question. In my experience, the Takagi units perform just as well, heat water to the same temperature, require the same maintenance and use the same power as the more expensive brands, like Rinnai and Rheem. After installing these units for many customers over the years, I haven’t heard of the Takagi units breaking down or otherwise missing the mark on performance. Given that they are cheaper than the name brands, and have the same performance, it justified selected it as the best. Basically you can the same performance for less money, and this guide is all about helping you find the best bang for your buck. Hope that helps! — Walt