Holds a Master’s degree in Engineering and is keen on her own home’s climate. Sometimes we think that Carolina owns every single product she writes about – that’s how profound and insightful her reviews always are.
For 8 years, Richard had been working as an HVAC specialist and AC unit installer since his student years. Now, he’s our main consultant on every technical aspect that may arise during our tests and research.
Last updated: October 01, 2021
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While owning a home is one of the best things that could happen to anyone, maintaining it can be very frustrating, to say the least. Not only is everything always breaking and needing replacements, but you also have to pay exorbitant energy bills at the end of every month. Well, the good news is that you could cut down on your expenses by replacing your traditional water heater with the best tankless water heater. Apart from being cost-efficient, tankless models can also provide an endless supply of hot water on demand.
That said, it is important to note that buying the ideal model is never a straightforward task. Knowing how stressful it can be, we’ve compiled a list of the top ten tankless water heaters, just to help make things easier for you. But which fuel source would you prefer between electric and gas? Plus, how powerful do you want the water flow to be? And how large do you want the unit to be? To also help you answer those questions, we considered key factors like the fuel source, BTUs, flow rate, and dimensions.
As is the custom, a lot of hours have been spent on the research for this article, to make it as detailed as possible. First of all, there is a comparison table, which compares all the products and lists them according to how good they are. Then, you will find a section that contains comprehensive reviews of the products, which is followed by an eye-opening buying guide.
At ten gallons per minute, the Takagi T-H3-DV-N offers the highest water-heating capacity on this list and is the best tankless water heater on the market, in our opinion. Apart from serving as a water heater, this unit can also be used with radiant floor systems and hydronic heating systems. Thanks to this model’s high capacity, it is ideal for up to four bathrooms at the same time.
In fact, you can use it for different applications simultaneously. Although, it may be more suitable for a three-bathroom house if you reside in a colder climate. Apart from having a high capacity, this tankless water heater from Takagi is also extremely efficient. It provides ultra-low NOx condensing technology that complies with the regulations and maximum BTUs of up to 199,000.
To ensure its efficiency and quality, this unit also features an Energy Star rating. Plus that, the heat exchanger is backed by a 15-year limited warranty and a five-year limited warranty on components if the unit is used for residential purpose. Thanks to its construction that includes PVC venting, this water heater is engineered to be eco-friendly. Therefore, even though the device runs on natural gas, no heated air will be coming from the exhaust.
While the primary heat exchanger uses copper alloy, the second one uses stainless steel that provides superior corrosion resistance. Moreover, the unit can be linked to up to four units without using a Multi-Unit Controller. Meanwhile, it can be linked to up to 20 units if you use the Multi-Unit Controller. To ensure that the unit stays safe while running, it comes with a surge, freeze, overheating protection, and troubleshooting diagnostic codes as well.
For its downside, we must note that it has a quite noisy operation, which may be a deal-breaker for quiet-loving individuals.
A condensing model, the Rinnai RUC98iN is a special tankless water heater from a pretty reputable company. Apart from delivering hot water in a fast manner, it also offers PVC or concentric venting options. That means if you already have a PVC vent, you may be able to reuse it. Sporting a compact and portable construction, this tankless water heater is perfect for indoor installation. Although, it can be used outdoors as well, thanks to its rugged built.
Furthermore, the unit has a maximum flow rate of 9.8 GPM. This should be enough for the majority of average homes to run three to five water sources simultaneously. If you’re always doing laundry at your house or you have children that take showers and run the dishwasher all the time, this model may be ideal for you. And like other models from Rinnai, the unit is Energy Star rated and generates low NOx emissions. With this, your energy costs won’t be high at the end of the month.
Of course, the RUC series may be a bit too much for some homes, but there is almost no chance of requiring a second water heater to cover the whole house. With Circ-Logic activated, you won’t need to worry about running out of hot water or cold showers ever again. In terms of BTU, this unit has a maximum BTU of 199,000, which shows how powerful it is.
While its expensive price tag may deter some prospective buyers, we’re quite confident that it will deliver good value for its price. You just need to keep in mind that it may be a little difficult to install, especially if you’re doing it by yourself.
Being a mid-range recommendation, the Rinnai V75In is the perfect choice for an average household. With this tankless water heater, you’ll be able to simultaneously run up to three appliances. Of course, this is if the appliances are efficient and slow-flowing plumbing fixtures. With the impressive 7.5 GPM of this tankless water heater, it is perfect for any type of climate. Meanwhile, its performance is based on your inlet’s temperature and the efficiency of your appliances.
Furthermore, the Rinnai water heater is more eco-friendly in comparison to other mid-range gas tankless water heaters. Sporting a compact and neat appearance, it can be left exposed beside a white appliance like a washing machine. Also, you can choose your temperature range from 98 to 140 degrees Fahrenheit. The temperature lock it’s equipped with also helps to prevent unintentional changes in temperature settings and limit.
Another excellent feature you will find on the Rinnai V75iN is a built-in smart safety system, which is made to keep everything in excellent conditions for years. There is also a scale detection, which helps prevent damages by turning the unit off automatically if descaling is required. Another impressive feature is that the device offers a mobile app that features schedules and timers through the day and enables you to put the unit into vacation mode remotely.
However, this unit is on the expensive side, which means not everyone will be able to enjoy its range of advanced features. We think it delivers value for money though, which may serve as a reprieve.
For many good reasons, the Takagi T-KJr2-IN-NG Tankless Water Heater is one of the most popular models on the market. With a maximum flow rate of 6.6 gallons per minute, this unit is perfect for the average-sized home. If you’re living in a hot region, this flow rate is sufficient for as many as four low-flow showers simultaneously. If you’re living in a colder climate, however, you should keep in mind that the flow rate may fall to between three and five gallons per minute.
Sporting a lightweight and compact design, the Takagi T-KJr2-IN-NG Tankless Water Heater is very easy to install, albeit costly. The compact nature of the unit also means it can easily be a wall-mounted or fit in a small closet without issues. As soon as you have set the heater up, you don’t need to be accessing it frequently. That’s because it comes with a digital remote control which can be used to turn it on and off remotely. You can also use the remote control to change the temperature.
Being a self-modulating unit, this unit from Takagi is certain to deliver great performance consistently. The unit monitors entering water temperature to prevent changes in water flow and temperature. While this model may be quite noisy during its operation, you may opt for the outdoor model if the noise is likely to bother you.
Lest we forget, this unit comes with internal freeze protection, which makes it an ideal choice for places where temperatures are likely to drop very low during the winter. Added to that, it’s backed with excellent warranty terms, which suggests that the manufacturer is pretty confident in this product.
Eccotemp is a big player in the world of water heaters, and their Eccotemp i12-NG Tankless Water Heater shows exactly why the company is so revered. This unit is an excellent, well-performing tankless water heater that is certain to do the job admirably. This water heater is engineered for small and confined spaces where more than two or three individuals won’t be using hot water simultaneously. Apart from small apartments, it’s also ideal for cottages and townhomes.
While tankless water heaters usually require some getting used to, this one is very easy to use. This unit is nearly totally powered by propane gas. Plus it features an already included venting kit, produced using stainless steel, which allows you to install it without any help. There is also a digital display and an exhaust fan, which are being powered by the 110-volt power cord. However, it utilizes little energy as most of the device is powered by propane gas.
The display and fan’s energy consumption is ten watts while it’s running and two watts when it’s idle. It’s also equipped with genuine 1/2 water fittings, plus it’s a modern, artistically pleasing design that has excellent safety features incorporated in it. In terms of construction, this unit is also very small and easy to manage. Additionally, it’s equipped with completely automatic temperature controls with child lock technology and an energy-saving mode.
In terms of drawbacks, it doesn’t come with many, but that also doesn’t mean it’s perfect and without flaws. First of all, it’s not ideal for big apartments, which may be a deal-breaker for people with big homes. Besides, it also doesn’t work well with more than one appliance.
The Stiebel Eltron Tempra 24 Tankless Water Heater is one of the most popular tankless heaters on the market, and it’s not really difficult to see why. This unit is pretty small and features a smooth exterior, which means you don’t have to worry about it consuming much space, and it can be used as an under sink water heater. Besides, it’s equipped with a dial selector which allows you to select the right water temperature that you require. This can be between 86 degrees Fahrenheit to 140 degrees Fahrenheit.
By consistently delivering very hot water without any problem, this unit surpasses expectations. It comes with a unique technology that allows it to work in determining the temperature settings and water flow by adjusting it according to the length of time the showerhead or tap is used. Whether you have multiple showers running simultaneously or not, this unit is capable of keeping the hot water coming.
Furthermore, your residence’s climate should not be a problem. Unlike some tankless water heaters, this unit is capable of performing in both cool and warm climates. All things considered, it’ll perform better in warmer/hotter climates. In colder regions, it’ll take a bit longer for the water to warm up, but we assure you that it won’t take an excessively long time. This makes it an exceptionally adaptable unit to own, whether you reside in warm or snowy conditions.
However, we must not forget to mention that you might need to hire a third party for its installation. Plus, the pressure is usually low when used with multiple washing appliances.
Why are we impressed?
Features a smooth exterior
Adjusts according to the length of time the tap is used
What negatives must you be aware of?
A professional is needed for its installation
Doesn’t work well with multiple washing appliances
The Ecosmart ECO 11 Tankless Water heater is an excellent product in all ramifications. Apart from being reasonably priced, the unit also comes with a compact body that doesn’t consume much space, which makes it perfect for people who don’t have a large space available. That’s not all – the machine also comes with adjustable temperature control, which allows users to choose the ideal temperature for them. Excellently, there is a digital control panel that allows you to do this effortlessly on the unit.
In terms of maintenance, this unit can be maintained and cleaned easily, which is an advantage considering that some models are just difficult to clean. While it makes some noise while heating water, it does it in a fast and efficient manner. Besides, the unit is also equipped with a self-modulating technology, which effectively controls the energy output of the heater to provide efficient result and use.
Plus, the water heater is capable of heating up to two gallons of water per minute, which is another appealing feature that makes it very popular. Being a tankless water heater, it is quite easy to install, thereby helping you to save up extra expenses that you might spend on installation.
Although, it’s worth noting that not all tankless water heaters are easy to install, as you will later find out in this article. With that being said, this unit also comes with a limited lifetime warranty, which shows how confident the manufacturers are in this product. Apart from that, it also comes with WaterSense certification, which means it is Eco-friendly and safe to use.
It’s high time we introduced to you the best space-saving heater on our list, and unsurprisingly, it’s a SteibelEltron creation. Apart from being a space-saving unit, the Stiebel Eltron DHC-E12 Tankless Water Heater also helps save energy in the long term. To achieve that, it utilizes dynamic technology to produce optimum output. Besides, this tankless heater delivers two models in one, as you can easily use a simple jumper to switch from 9k watts to 12k watts and the other way about.
Furthermore, this unit is a perfect choice for lower temperatures. That’s because it features a small knob on the front which serves as a dial that you can use to change or adjust temperature settings. In the same vein, the temperature range starts from 86 degrees Fahrenheit and goes up to 125 degrees Fahrenheit. In terms of installation, the entire process is quite straightforward. Therefore, it is not likely to take time to install this compact unit wherever you want in your home.
To be honest, this tankless water heater from Stiebel Eltron is a genuine game-changer. It supplies hot water always, and with minimal energy costs, which makes it an excellent choice for people looking to cut down on their energy costs. Apart from that, it’s made with high-quality materials, which means it will remain in good shape for several years without you needing to replace any component.
However, something you may dislike about this unit is that the hole in which you hoist cover plays may be too small. While this is not likely to be a deal-breaker, it may be quite troublesome. Besides, the instructions manual is very hard to understand, which means users may have to figure out a lot of things on their own.
Tankless water heaters are generally expensive, which is why you need to ensure you’re getting your money’s worth when you finally decide to buy one. While some people may disagree, most people will say that the Gasland BS158 is one of the best tankless water heaters on the market. With a decent BTU of 41,000, this unit is capable of heating a decent flow of cold water to a very high temperature.
Although the water pump is not included with the purchase, it requires only 2.18 PSI to operate. Therefore, a small 12-volt pump will do just fine to deliver right water flow with the preffered temperature. Don’t forget about two D batteries for this unit. This heater has two knobs to make adjustments to deliver hot water that is precisely where you set it. To save on gas, you can decide to make the water temperature cooler or you can raise it up if you want to have on-demand hot water.
In addition, the unit has a freeze protection that will discharge the residual water when the ambient temperature gets too low. There is no need for you to be concerned about burst pipes in ice-cold weather. Still, additional insulation might be required against cold weather.
Despite being a compact unit, this tankless model from Gasland it delivers an unlimited supply of hot water. Moreover, this device has high water temperature protection that will shut off the gas supply automatically in case anything goes wrong. The unit doesn’t cost much while showing excellent performance each time.
If portability is your primary concern in a water heater then the Camplux 5L Tankless Water Heater might be a perfect option for you. This heater can be easily carried anywhere you wish to go, added to the fact that it is extremely energy-efficient. Thanks to its portable and lightweight construction, it is ideal for families who often travel around. It can easily be fit in your RV, car, or backpack if you’re feeling adventurous. Besides, your 12-year-old kid can easily carry it around on your family trips.
Apart from the fact that this water heater will fit perfectly on your TV, it will also function at the lowest PSI. As a matter of fact, it’s the most efficient heater in terms of operating with very low PSI. It’ll activate when it detects pressure that’s as low as PSI, which is good news for people who worry about the low GPM you can get in some regions. For example, this unit will function even if the water flow is only 0.4 GPM, which usually happens when you go to a cabin in a jungle.
With small PSI, the BTU of 28,000 per hour that is produced by this unit will be sufficient for you. Thanks to the 2D batteries it comes with and the fact that it runs on propane, it’s also an excellent option for off-grid trips. We also love how easy it is to install this tankless water heater, which is down to the fact that it comes with literally everything you will need to properly install it. If you’re willing to do it on your own, it should not take more than 20 minutes.
However, this unit features non-standard connections, which is rather unfortunate. This means that if a component gets spoilt, you will need to either be ready to spend a lot of time searching for it or buy it online. Meanwhile, the hose and cord burst are made with cheap plastic, which causes them to burst easily. On the bright side, it doesn’t need wall venting and is extremely affordable. In fact, it is our budget pick, making it perfect for people on a budget.
Why is it special?
It doesn’t need wall venting
Can work at any PSI
Comes with literally everything required for installation
Compact and lightweight construction
What are the flaws?
The hose and cord are made with cheap plastic
Things to Consider
The information that has been given by this article wouldn’t be complete without a buying guide. If you want to find the best tankless water heater available, then you need to go through this section.
Apart from some enlightening tips that you will get to see therein, you will also find answers to some of the most common questions about tankless water heaters.
How do they work?
If you are looking to make the most out of your new water heater, then you need to understand how it works first. Before we get to that though, let’s begin by explaining how a tanked water heater operates. The traditional heating system usually features a big tank in which the water is held and heated.
In order to deliver hot water to you, the tank continually heats the water to make sure that it remains at a fixed temperature. The energy required to ensure that the water stays hot even when you are not using it is called standby heat loss.
On the other hand, tankless water heaters heat only the water when it’s needed. This means that there is nothing like standby heat loss. As a matter of fact, tankless heaters are more efficient due to the fact that there is no standby heat loss.
To increase the temperature of the water, a tankless water heater utilizes something known as a heat exchanger. This is a device that is used to transfer heat from one heat source to the other and it is common in air conditioners, refrigerators, and car radiators. In this case, the heat exchanger is activated by the incoming water flow.
Otherwise stated, when you switch your hot water tap on, it activates the incoming water to flow through the heat exchanger which subsequently heats the incoming water at the temperature you desire.
Will a tankless water heater make your life easier?
The primary reason for wanting to buy a tankless water heater for your home is to reduce the amount of money you pay for energy monthly. The best tankless water heater is certain to help you save as much as 40 percent on your utility bill monthly, which is over 30 percent more efficient compared to a tanked water heater.
Apart from making you spend less on energy, tankless water heaters make your life easier in many other ways, which include.
You won’t ever run out of hot water
By design, tankless water heaters are on-demand water heaters. Essentially, this means that they will ensure you have access to hot water each and every time you need it. As a matter of fact, they enable you to access hot water by just pressing a button. Apart from that, there is nothing like standby heat loss with them, as we explained earlier. Also, it’s worth mentioning that these tankless water heaters require only a little power to carry out their operation at any given time.
Compared to a tanked water heater, a regular tankless water heater is supposed to last you for up to ten years. While the majority of the high-quality models come with steep prices, by extension, the durability providers value for the money you spend in the long term.
One of the primary differences between a tanked water heater and a tankless model is that mounting the later doesn’t require much space. As a matter of fact, the best tankless water heaters are designed to save space and provide several mounting options. The majority of models that we have included in this guide offer outdoor and indoor installation alongside an anti-freeze kit. Besides, you can choose a smaller unit that you will be able to fit beneath your closet or cabinet for nearer point of use.
Gas tankless water heaters usually emit nothing, which therefore makes them eco-friendly. Most gas models like the Takagi T-H3-DV-N utilize low NOx technology to ensure that emissions are very low. The gas-powered models apart, even the electric tankless water heaters don’t produce toxic greenhouse gas. Besides, these water heaters are equipped with ground-breaking features to prevent scalding water from reaching your faucet or showerhead.
Easy to operate
Operating a tankless water heater doesn’t need a lot of skills or knowledge. They are very easy to operate. The installation is probably the most difficult part of using them, of which most models usually come with installation manuals. As soon as you have mounted your tankless water heater, you just need to set the temperature on the dial of the unit and you are good to go. In fact, you may even select a model that comes with remote control for remote operation.
No chance of flooding
Unlike tank-style water heaters, you will never need to worry about any likely occurrence of flooding that is often caused by a burst tank. This means that tankless water heaters are safe for your household. To even aid safety, some models are equipped with a built-in system that automatically detects internal faults and warns you in advance.
So, as we have shown, there are many reasons why you need to install a tankless water heater at your home. Just make sure you check the water flow rate of any unit you’re interested in before buying it.
Ultimately, you want a unit that is capable of handling your hot water needs, regardless of whether it’s for commercial or residential purposes. Keep in mind that we will explain what water flow rate means and why it is important later in this article.
Features to consider while choosing a tankless water heater
In your quest to find the ideal tankless water heater for your needs, you must remember that there are many factors you must consider. That’s because there are many factors that make a good tankless water heater. Therefore, we have listed some of the most important factors you need to consider below:
Type: electric vs. propane vs. natural gas
Normally, tankless water heaters utilize either of three sources of power – electricity, propane or natural gas. In some circumstances, the kind of water heater you buy will be determined the source you have available at home, so it won’t really depend on your personal preference. Nevertheless, it’s nice to be informed of the other options you have apart from the power source at your home.
While electric water heaters usually have lower running costs, they are usually costlier to purchase. Propane and natural gas models, in contrast, are less expensive to purchase and have somewhat higher running costs. Gas models are also reasonably alternative when your electricity goes out.
The BTU, also known as the British thermal unit, is utilized to quantify the cooling and heating power of water heaters. It helps to measure the heat quantity required to raise one pound of water by one degree Fahrenheit. Therefore, the more the BTUs, the more heating power your water heater will have, which means you should always look for models with very high BTUs. At 199,000 BTUs, both the Takagi T-H3-DV-N Tankless Water Heater and the Rinnai RUC98iN Tankless Water Heater have the highest BTUs on our list.
Gallons per minute
Commonly called the GPM, the gallons per minute is the amount of water that a tankless water heater can heat each minute. It is vital to know this so as to ensure that you don’t lose hot water when excessive demand is put on your water heater. You can find information about the exact GPM needed by various activities on the internet and you can also find the GP of various tankless water heaters.
The performance of the water heater greatly depends on the range of its temperature. Apparently, you need a unit with a higher temperature range as you do not know where it may just come in handy. So, you need a tankless water heater that you can use whether you’re in a hot or cold region.
Size is a very important factor that a lot of people tend to overlook when shopping for their ideal tankless water heater. To know the right size you need, then you must carry out some research. The size usually determines the flow rate, so you need to, first of all, determine the flow rate you need. When you’re making that decision, take things like washing machines, dishwashers, and showers into consideration as they are machines and that you will likely be using simultaneously.
After you’ve figured out the right flow rate suitable for all your likely simultaneous activities, you’ll surely find out the size of the water heater you need. Also, the temperature will play a part in the determining size of the unit that you’ll be needing. Find a water heater that is capable of producing the temperature you want for your water.
When we talk about home appliances like tankless water heaters, we usually expect them to serve us for a very long time. Having said that, things usually break, and it is usually comfortable to have a product that’s backed with a long-term warranty. Taking into account the long-wear expectancy of products such as water heaters, a short-term warranty rather useless.
While some of the water heaters on our list have a quite disappointing warranty, some of them stand up to the mark. In the event that you’re worried about spending unnecessarily on repairs, you should opt for a product with a longer warranty. The products with the longest warranty periods on our list include the Takagi T-KJr2-IN-NG Tankless Water Heater and the Rinnai V75iN Tankless Water Heater.
You also need to consider some other important factors like design, ease of installation, and controls. For remote access to the machine, some water heaters come with a remote control that will allow you to adjust to turn them on/off or adjust the temperature remotely. However, you must bear in mind that you will need to pay more for a feature like this as models with such features usually cost more.
Logically, tankless water heaters heat the water faster than tank-style models, since they do not need to transfer the water to a storage tank first before transferring it to the faucet where it’s needed. This is why you often see people also referring to them as on-demand, instantaneous, or flash water heaters. The truth is that they are fast in their operation and more energy-efficient, which explains why they are considerably more expensive.
Since tankless water heaters don’t keep water in storage tanks, they heat water only when it is required. As a result of that, a tankless water heater that delivers 40 gallons of water daily utilizes about 34 percent less energy than a traditional water heater.
And if you’re looking for even greater efficiency, you may consider a condensing tankless water heater like the Rinnai RUC98iN, which runs with an energy efficiency rating between 90 percent and 98 percent. Non-condensing tankless models operate at about 80 percent efficiency rating, which is still impressive.
The answer to this question greatly depends on the brand and kind of tankless water heater you’re buying. When it comes to installation, there are a lot of factors that may affect it. Such factors include clarity of the installation instructions of the manufacturer and the type of venting your home has.
The question, however, isn’t how difficult installing a tankless water heater is, but if you even should try to install it on your own. To be honest, the answer is a resounding no.
While there’s an increasing number of people who’ve installed a tank-less water heater on their own, manufacturers encourage customers from doing so. First of all, the issue of safety comes into mind. For instance, if a gas-powered tankless water heater isn’t connected properly to its supply line, there could be a gas leak.
Also, if your home’s existing wiring can’t supply electricity adequately to your water heater, there is a chance of the wiring getting short, which potentially could ignite a fire. The second reason is that most manufacturers won’t honor the warranties unless the device is installed by a professional.
We bet Takagi isn’t a name you hear every day, but with a product like the Takagi T-H3-DV-N Tankless Water Heater, the brand is set to become one of the most talked-about brands in the world of home appliances. Not only is the Takagi T-H3-DV-N extremely versatile and beautifully designed, but it is also the most powerful unit on our list. By a long margin, it is the best tankless water heater on our list.
Both the Rinnai RUC98iN and the Rinnai V75iN take the second and third positions respectively, and it is not surprising that both models are from the same company. Apart from being powerful in their operation, both models also pack some excellent safety features, which make them all-round superb. On top of that, they are backed with excellent warranty terms, which indicates one thing – Rinnai is not here to play.