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9 Best Tankless Water Heaters that Reduce Time for Hot Water

Tankless Water Heater Installed on a Tile Wall

Tankless Water Heater Installed on a Tile Wall


Models Considered


Hours of Research


Experts Interviewed


Consumer Reviews Analyzed

W hen a household isn’t supplied with hot water, a prompt and lasting solution is in demand. This is when a heater becomes mandatory, and since it will imply a great long-term investment, the decision should be made after thorough research. A convenient option would be a tankless boiler. As its name suggests, it doesn’t include a storage tank. Instead, this is a demand-type water heater that takes up less space.

As explained by, these units heat the water on the spot. As soon as you turn the hot water faucet on, the cold water will pass through a heat exchanger that raises its temperature. Tankless or demand-type water heaters can use either an electric element or a natural gas burner for the heating process.

Models that use a natural gas burner are superior in terms of performance since they produce higher flow rates, so if you plan on running the dishwasher while you’re showering, chances are that you will be better served by a gas model. This is why tankless heaters like the Rinnai RL94iN or the Takagi T-K4-IN-NG are more hyped by experts in the field too, flaunting superior flow rates ranging from 8 to 10 GPM.

The aforementioned heaters aren’t the only viable choices to go for, however. In the following, we will present you with the tankless water heaters that are worth the money to help you make the right choice. Whether you end up with an electric or a gas-powered heater, what you can rest assured knowing is that the reviewed heaters are reliable, durable, and have the strength needed to deliver hot water to one faucet or the entire house.

Hard water can affect the functionality of the heater, so it is best to remove some of the magnesium and calcium content before letting it reach the heating chamber. This is why we recommend investing in a whole house water softener, which will give you more time between the maintenance tasks and help prolong your unit’s lifespan.

Top 9 Tankless Water Heaters Compared

Power Source
Temperature Range (°F)
Maximum Flow Rate (GPM)

Best Overall
Natural Gas
10,300 – 199,000 BTUs
98 – 140
12-year heat exchanger 5-year on parts5-year on parts 1-year warranty on labor

Best for Radiant Floor Heat
Natural Gas
11,000 – 190,000 BTUs
15-year on heat exchanger5-year on parts

Editor’s Choice
27 kW
Lifetime warranty on parts

Best for Commercial Use
24 kW
7-year against leakage 3-year on parts
24 kW
80.000 BTUs
2-year on parts

Best for the Money
13 kW
5-year on heating chamber1-year on parts
12 kW
5-year on heating element1-year on parts
6 kW

1. Rinnai RL94iN

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  • Type: Indoor
  • Power Source: Natural Gas
  • Power: 10,300 – 199,000 BTUs
  • Temperature Range: 98 – 140 F
  • Maximum Flow Rate: 9.8 GPM
  • Water Connections: 1/2″ NPT
  • Certifications: Energy Star
  • Warranty: 12 years on heat exchanger; 5 years on parts; 1 year on labor

Rinnai is one of the most renowned companies in the home appliance industry and has managed to maintain its good reputation over the years by providing only first-rate products with incredibly long lifespans. The RL94iN is no exception, and this aspect is easily noticeable just by looking at the specifications and the good reviews this unit received since it was released. Together with the Takagi T-K4-IN-NG and the Eccotemp FVI-12-LP, it is one of the best natural gas demand-type water heaters available. From the durable yet tightly built housing to the dependable technology that can keep the hot water coming without interruptions, everything is carefully engineered to deliver the best results.

Impressive Heat Output

The company offers this model in two variants, a bigger one, able to deliver up to 9.4 gallons of hot water per minute, and a smaller one that will go up to 7.5 gallons per minute. We’ve chosen the first option, as it has a greater capacity and can cater to the needs of a large household. In fact, according to the manufacturer’s description, this unit can easily cover 5 bathrooms. The maximum BTU supply is 199,000, a value that allows it to reach a temperature between 98F and 140F in a matter of seconds. It can also serve commercial purposes, with a high water heat level of 185F, but for this, you will need to purchase the commercial controller offered by Rinnai.

Longer Lifespan

It integrates a scale detection mechanism that will let you know if the unit is gathering calcareous deposits. Thus, you will know when it’s time to descale (the manufacturer recommends using a vinegar solution for this action) and, by doing it on time, you will avert other problems that can lead to costly repairs and/or shorten the unit’s lifespan.

While periodical maintenance is a must for keeping this model in a good state, for any manufacturing flaws that may affect its functioning, you have good service contract coverage. Thus, the company offers 12 years on the heat exchanger, 1 year on labor, and will deliver free parts for 5 years. Nonetheless, to benefit from this advantage, you will need to have your boiler installed by a professional, which is not really a drawback, even if it would cost you extra, as you are dealing with a gas model, so the connections need to done carefully to avoid exposing your family to any risks.

Rinnai RL94iN Performance Ratings – Tester’s Feedback
We mention that we called in a professional for the installation process, and the whole procedure took 6 hours and a half. We warn against you trying to set the heater up by yourself since this automatically voids the warranty. Moreover, it is a complicated process and it wouldn’t be safe to try and do it on your own, even if you consider yourself to be a skilled DIYer. The building we installed it in has 2 showers, a kitchen sink, a washing machine, and a dishwasher. To test the flow rate and capability of the heater to face a fairly demanding household of the sort, we turned on the washing machine, dishwasher, and one of the showers. The flow was surprisingly good, so we then turned the other shower on to hot water too, and there was no noticeable difference. After turning the kitchen tap on there was a slight drop in flow rate, but nothing notable. Since it passed our test with flying colors, the Rinnai RL94iN was an obvious pick for the top spot.

Marcus Mackay

  • An impressive 9.4-gall water stream
  • High efficiency rate
  • Equipped with digital controls and a digital monitoring and troubleshooting system
  • Slim and easy to mount
  • Great warranty time

  • It takes about 30 seconds for it to heat the water, but then the temperature remains constant
  • The installation will cost you extra if you want to benefit from the warranty


Great for larger houses, it works on natural gas, but it can be easily converted to propane. It was built to meet the highest industry standards and features a 0.82 energy factor. Even though it is a little bit heavier, it manages to stay quite compact. Additionally, it integrates many helpful features and comes with a long warranty.

2. Takagi T-K4-IN-NG

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  • Type: Indoor
  • Power Source: Natural Gas
  • Power: 11,000 – 190,000 BTUs
  • Max Temperature: 165 F
  • Maximum Flow Rate: 8.0 GPM
  • Water Connections: 3/4″ NPT
  • Certifications: Energy Star
  • Warranty: 15 years on heat exchanger; 5 years on parts

This unit is built to last, and, since it is so small, it can effortlessly be mounted in tighter spaces inside the house. It can deliver water for 2-3 baths and ensures great power and stream for basically any activity, the full flow rate per minute being 8 gallons. Moreover, you can select a heat level between 98F-167F or use the preset temperatures, and the unit will quickly deliver with the amazing power of 190,000 BTUs. It was the obvious pick as our runner-up since the only demand-type water heater better than this Takagi is the top-ranking Rinnai PL94iN that is rated at 199,000 BTUs tops.

A top-notch technology stands behind this product, which is carefully controlled through a series of thermistors and a microprocessor. The system closely monitors the water heating process and steps in, in case it detects a malfunction to prevent accidents or costly damage being done to the unit. In this situation, it will shut it off and signal through a blinking LED that something went wrong. The error-detection system can also generate error codes that will be shown on the remote’s screen, so you can troubleshoot it with ease.

It is packed with a series of safety features such as freeze, overheat, or surge protection, so you won’t be bothered by any temperature oscillations while you shower. To help you enjoy it for a longer period, the manufacturer offers a very long warranty, namely 15 years on the heat exchanger, and 5 years on components for residential installation.

  • Can be converted to Direct-vent
  • Multiple safety features
  • Comes with a remote temperature controller
  • Features preset temperatures
  • Compact design

  • It takes a few seconds for the water to get hot, so there’s some water waste
  • The installation is a bit complicated, so you may need a plumber to do it for you


This model is expected to last about 20 years, so it is truly a great investment. It has a high heating capacity, but the first-rate technology allows it to remain cost-efficient, especially as the water is heated instantly, and it doesn’t need to work continuously to keep it hot in a reservoir. Besides, the company offers good backing in case you encounter a flaw, and you’ve got a clever error detection system to assist you when troubleshooting the unit.

3. EcoSmart ECO 27

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  • Type: Indoor
  • Power Source: Electric
  • Power: 27 kW
  • Temperature Range: 80-140 F
  • Maximum Flow Rate: 6.0 GPM
  • Water Connections: 3/4″ NPT
  • Certifications: 1-UL Listed, CSA Listed, ETL Listed
  • Warranty: Lifetime on parts

Three elements make this model one of the best buys for the price. First, you pay a very reasonable amount of money for a strongly built unit, equipped with the newest technology that will provide excellent comfort for your showers in the following 15 to 10 years. Secondly, the self-modulating technology makes it incredibly cost-efficient, the company stating that it draws 50% less energy than similar models. The secret here is the division of the total 27kW heating power among 3 heating chambers, which allows the unit to use only the minimal amount required when heating the water. The last aspect that makes it a worthy investment is the Lifetime warranty, offered for parts, labor, and heating chamber.

Nonetheless, there’s a catch here, as in the case of most boilers, namely that you will need to call a professional to do this job, otherwise, you won’t benefit from the warranty. Moreover, note that the installation needs to be done within 30 days from the day of the acquisition.

In what concerns its performance, this entry can sustain a maximum water flow of 6 GPM and will heat the water at a temperature between 80F and 140F. The stainless and copper components guarantee that it will preserve its efficiency over the years. Just make sure to check that your home meets all the electrical requirements, so you don’t deal with any inconveniences. This unit is compatible with a 240V, 112.5 (max) amperes system.

  • Lightweight and compact
  • Features a self-temperature regulating setting
  • Impressive warranty
  • Widely-adjustable temperature
  • Hard-wearing housing and internal components

  • Requires professional installation for the warranty to remain active
  • The upkeep process is a bit bothersome, seeing how you need to remove the unit and flush it with vinegar every 6 months


With a slim and lightweight design, it will yield great in medium or small size houses. We like the digital screen and the simple temperature adjustment, which allows you to program and monitor the unit with ease. Even if you need to hire a professional to make the connections and take care to clean it with vinegar twice a year to prevent scale deposits, you will benefit from its excellent functionality and time resistance.

4. Stiebel Eltron Tempra 24 Plus

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  • Type: Indoor
  • Power Source: Electric
  • Power: 24 kW
  • Temperature Range: 86-140 F
  • Maximum Flow Rate: 4.0 GPM
  • Water Connections: 3/4″ NPT
  • Certifications: 4-UL Listed, CSA Listed, ETL Listed
  • Warranty: 7 years against leakage; 3 years on parts

This boiler was crafted using industry-leading technology to provide an uninterrupted stream of boiling water. It is an electric type that uses 24 kW and can bring the water temperature between 86 and 140 degrees Fahrenheit. To make it more intuitive, the manufacturer put a drawing on the housing to exemplify the ideal level of warmth for the kitchen faucet, a shower, or appliances like the dishwasher.

We should also mention that it requires two 60-amp circuits, which is quite a lot of power, so check if the electrical system can safely handle the electrical requests. With a full stream reaching 5 gallons each minute, it is enough to cover 2 bathrooms and one kitchen, so it’s perfect for average-size homes. Moreover, it has a variable flow so you can use several faucets at the same time without facing a poor water stream.

Another great particularity is the self-setting control of the temperature that guides it in achieving the chosen temperature. As for peace of mind, the manufacturer comes to your assistance with a 7-year warranty against any possible leakage and a 3-year warranty on components, but it must be mounted by licensed personnel to be covered by the warranty.

  • Self-modulating temperature
  • Lightweight
  • Intuitive digital controller
  • High water stream
  • German quality

  • While the company supplies parts, you will need to cover labor yourself
  • According to some of the purchasers, customer service takes a while to respond


Conditional to the outside temperatures, you can benefit from its efficiency in 2 bathrooms and a kitchen, meaning it is powerful enough to cover a regular-size home. It is energy-saving and uses all the power to the fullest so it won’t increase your bills. Since it’s so small, it can fit nearly anywhere without additional plumbing and it is very simple to set and use, aspects that contribute to its popularity.

5. Atmor ThermoPro

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  • Type: Indoor
  • Power Source: Electric
  • Power: 24 kW
  • Temperature Range: 90-135 F
  • Maximum Flow Rate: 4.6 GPM
  • Water Connections: 0.75″ NPT
  • Certifications: ETL Listed
  • Warranty: 2 years

This model is one of the smallest we have reviewed, so it’s ideal for tight mounting places. When it comes to power, it fares just as well as its better-ranked competitors, the Stiebel Eltron Tempra 24 Plus, both boasting a 24 kW rating. It is constructed of hard-wearing materials and it complies with the IP54 criteria so it can be safely fitted near water outlets. Additionally, it is lead-free. The design is simple, somehow futuristic, with a matte gray finish and a digital screen, with only one adjustment knob.

The 4.6 GPM capacity makes it great for 4 simultaneous applications. It is ideal for moderate to warm areas and is cheaper than most competitors. The simple design and setup make it among the most user-friendly models out here. Once you set it to the preferred temperature, there aren’t too many things to do. The digital switch increases the heat in 1-degree augmentations and it also features a self-modulating technology so it basically sets itself under the right parameters. It activates and shuts off automatically every time it notices water leaks or when it stops. There is little upkeep involved and the most important component, namely the heat exchanger, is accompanied by a 2-year warranty.

  • Self-modulating system
  • Packed with a safe overheat protection
  • Suitable for wall
  • User-friendly digital panel
  • Rated IP54

  • You must get a separate pressure relief valve
  • Some purchasers observed that the thermostat was a bit off on their units


This is an ideal option at a smaller purchase price and it brings some of the essential features seen in more expensive competitors. We consider it a real bargain as it is simple to mount, includes a digital screen for intuitive handling, and operates at low energy charges. Just make sure you have a pressure relief valve, otherwise, it will not work.

6. Eccotemp FVI-12-LP

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  • Type: Indoor
  • Power Source: Propane
  • Power: 80,000 BTUs
  • Temperature Range: 80-140 F
  • Maximum Flow Rate: 4.0 GPM
  • Water Connections: 1/2″ NPT
  • Certifications: UL Listed
  • Warranty: 2 years on parts

Chances are you will go for this unit once you learn that it will help you lower your energy usage by 50%, in comparison to a traditional boiler, so it will be of great support if you want to start a greener life. Take into consideration that it works on liquid propane so make sure you can supply it with a gas tank. Due to the sleek and slim design, it will easily fit anywhere, even underneath a sink. The maximum stream level per minute is 4.0 gallons while the heat can reach temperatures between 80 and 140F, making it strong enough to handle 1-2 bathrooms with multiple appliances, although it’s not the most powerful model out there. If you want a similar heater, a natural gas type, but that offers more when it comes to flow rate, then you will be better served by the Rinnai RL94iN that is rated at 9.8 GPM, or the Takagi T-K4-IN-NG that is rated at 8 GPM.

Although this model doesn’t come with innovative features, you will surely be impressed by its popularity among many customers and the reasonable price that makes it among the first choices for those who want to receive good results at reasonable costs. However, one of its disadvantages is the fact that the warranty covers the components only for 2 years, which is less than all the other models reviewed. However, this shouldn’t worry you too much, since, according to the general opinion, it is hard-wearing and unfailing, so it should provide great results.

  • The reduced dimensions make it fit for small apartments
  • Available in multiple colors
  • Separate controllers for gas and water
  • Accessible acquisition

  • Lower energy factor value
  • Short warranty


This model works on liquid propane and is fit for 1 or 2 bathrooms. The unit is medium-sized and comes in two color options, white, and silver. It boasts an intuitive digital screen and independent controls for water, gas, and stream. Unfortunately, the 0.79 energy factor makes it less efficient than competitors and the short warranty is definitely a drawback.

7. Rheem RTEX-13

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  • Type: Indoor
  • Power Source: Electric
  • Power: 13 kW
  • Temperature Range: 86-140 F
  • Maximum Flow Rate: 4.8 GPM
  • Water Connections: 1/2″ NPT
  • Certifications: CSA Listed, ETL Listed
  • Warranty: 5 years on heating chamber; 1 year on parts

This model is the upgraded version of the Rheem RTE 13 and uses electrical power. It best suits household use and it perfectly fits small homes with 2 bathrooms or one bathroom and a kitchen. It is wall-mountable and you can only use it inside the house. Thanks to the slim shape, it will perfectly fit beneath cabinets or sinks. It is approximately 12 inches tall, 8.25 inches wide, and 3.62 inches deep and it weighs around 7 pounds.

It operates within a temperature choice of 80 and 140 F and a pressure between 25 and 150 PSI, delivering a maximum stream of 4.8 gallons each minute. It is NSF/ANSI certified for lead-free and is ETL and CSA listed. This unit lets you set the preferred temperature with 1-degree additions, so it will be incredibly accurate. You can read the settings on the large LCD screen.

Additionally, it features copper heating components. The mounting part is quite straightforward because it includes all the electric cables and adapters. It is 99.8% efficient, so it will help you limit energy expenses. The heat exchanger is covered by the warranty for 5 years while the parts for only 1 year.

  • External temperature adjustment
  • The upkeep on the heating components is simple
  • Lead-free certified
  • The multiple safety features provide a safe operation
  • Provides instant boiling water

  • Not a good choice for large places
  • Not suitable for cold areas


We chose it as one of the top options for small houses or apartments. It is less expensive than most units although not as powerful. The power usage is minimal while the flow rate is very impressive for a model of this size. Maintenance is also very simple, with easily accessible components and a satisfying warranty. However, it’s not the most appropriate for cold areas.

8. Bosch Tronic 3000

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  • Type: Indoor
  • Power Source: Electric
  • Power: 12 kW
  • Temperature Range: 0-131 F
  • Maximum Flow Rate: 2.3 GPM
  • Water Connections: 1/2″ NPT
  • Certifications: 1-UL Listed, CSA Listed
  • Warranty: 5 years on heating element; 1 year on parts

With a thermal efficiency of 98% and a built-in thermostatic control, this heater is worth considering. It is available in four sizes to meet your needs. The one we selected measures 12.75 x 6.5 x 3 inches and weighs 5 pounds. This makes it ideal for tight spaces, but you can also install it in a visible place as it features a very simple design. Another option that works perfectly for confined spaces is the Atmor ThermoPro that we recommend if you have a higher demand in terms of flow rate since it’s a 24 kW model that flaunts a 4.6 GPM rating.

The heating components are made of high-grade copper that is guaranteed to provide superior heat conduction. If it rises the temperature with 45F, it will provide an output of 1.8 GPM while at 75F it has a 1.1 GPM output.

Furthermore, it’s very simple to adjust the heat to your liking due to the intuitive thermostatic controller. To support your purchase, the producer warrants the heating component for 5 years and the other components for 1 year.

  • Allows you to set the chosen temperature
  • The heat exchanger is made of cooper
  • Electric pulse ignition start
  • Doesn’t require a temperature or pressure release valve
  • Energy-efficient

  • Installation is quite cumbersome
  • Low water stream


All in all, this model features a small footprint and it is very versatile– you can use it for a series of common applications. As for the price, it’s among the most reasonably priced options to go with. You might find it a bit difficult to install but reading the instructions carefully will get you out of trouble.

9. Sio Green IR260 POU

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  • Type: Indoor
  • Power Source: Electric
  • Power: 6 kW
  • Temperature Range: 30-60 F
  • Maximum Flow Rate: 1.5 GPM
  • Water Connections: 1/2″ NPT
  • Certifications: N/A
  • Warranty: 2 years

This model differentiates from the others as it doesn’t use a metallic heating tube. Instead, it is paired with a quartz infrared heating component that is highly resilient to erosion, calcium deposits, and scaling. In general, quartz heating tubes are known for their durability and fast thermal properties. As a result, it requires less maintenance and lasts for a longer timer. Also, since the heating part doesn’t come into contact with the water, there are fewer chances to develop bacteria or a metallic taste. It measures 13.5 x 8.5 x 3 inches, so it’s small enough to fit underneath most cabinets. At approximately 7 pounds, it is extremely lightweight.

It is intended with plenty of safety features like overheating thermal cut-off or high limit temperature safety cut-off. Also, it includes residual leakage current detection. The manual mode features 4 levels of power, from 1 to 4. The temperature is displayed on the LCD screen. This model also features a self-cleaning design for no-hassle maintenance. Additionally, you will benefit from a period of 2 years of warranty.

  • Quartz infrared heating element prevents rust, calcium deposits, and scaling
  • Light and slim design
  • Includes a thermostatic controller
  • Features a self-cleaning design for low maintenance
  • Multiple built-in protection features

  • No automatic restart in case there’s a power outage
  • Poor instruction guidebook


Features an innovative quartz infrared heating element that requires little maintenance and lasts for up to 20 years. Also, the heating elements promote cleaner water. This unit comes with many features that increase its value and it’s pretty easy to mount although the included instructions are rather poor. A major flaw is the fact that in case the power gets off, it won’t restart automatically.

What’s Behind Our Ratings

When we created the chart, we looked at a series of aspects that we believed to be essential in finding the heater that best yields. Here is how we rated each model:

  • Capacity: since every heater has a different capacity, it’s very important to know this aspect about every one of them. Normally, an average-size home should be fine with a model that can handle two water outlets, but bigger residences could need a more powerful unit that can provide boiling water for 3 bathrooms, let’s say. The products we selected are whole-house, destined for all household sizes. However, you should know that you can always link more tanks together if the model you want is not capable of handling more bathrooms.
  • Power source: in terms of alimentation, you have two options available, electric or gas that can be natural or liquid propane. Both are equally rendering, but there are some differences to mention: the electric ones come at a lower price and are cheaper to maintain over the years while being more environmentally conscious. Gas ones are more expensive to buy and maintain, but the monthly costs are smaller.
  • Temperature range: this represents the limits between which you can set the boiler. Normally, for warm water, a 90-110F range will be more than enough, while for receiving boiling water you will need a 140-150F range in most cases.
  • Maximum stream rate: it represents the maximum amount of water heated within a minute, measured in gallons or GPM. To determine this, run simultaneously more fixtures you normally use and see how long it takes each fixture to fill a gallon container. In general, a showerhead, a dishwasher, and a clothes washer will need a stream rate between 3.5 and 7.5 GPM.
  • Energy factor: this depicts the energy efficiency of home appliances or equipment, such as heaters, clothes washers, and dryers, or refrigerators. The higher the energy factor, the lower the consumption.
  • Additional specifications: they show you important particularities of every model presented in our evaluation chart. They are mostly features or other technical specifications that differentiate one product from another.
  • Warranty: this detail is highly significant because it lets you know for how long the manufacturer is willing to protect their product and which are the parts and defects they cover.

Tankless vs. Tank Water Heater

Although they do the same thing, which is heating water, the entire process is slightly different in what regards the operating mode and the construction. Both types are commonly seen in households worldwide and each was selected for a good reason, based on the owner’s requirements and possibilities.

  • Traditional heaters: they can hold in a reservoir a certain amount of previously heated water. Therefore, they will be using power continuously to prevent the water from getting cold and requiring it to be heated again. This adds to the long-term costs and even though this type is more inexpensive to purchase, the money loss will be noticed with time. The reservoir has a certain capacity and when it gets empty, it will take some time to refill, and you will run out of water in the meantime. Such a model can only be electric and it is high-consuming because of the large capacity. The setup part might be simpler but the lifespan is shorter. Also, you must have enough room to fit it because the housing is very large.
  • Tankless heaters: from the operating point of view, they tend to be more practical because there is no reservoir involved, just water heated instantly. The compact size makes it easy to fit even underneath the sink. Also, you are not at risk of dealing with an empty tank while you shower. Unlike the previous model, this one doesn’t rely on electricity solely, as you can opt for one powered by gas if it seems more convenient to you. The model is more durable, with a lifespan of over 20 years, and a simpler operating mode that prevents energy waste. Their main drawback is they cost more to purchase and install.

Tankless Water Heater Pros & Cons

The Pluses of a Tankless Model

When you need an appliance that will deliver hot water on demand, a tankless boiler scores some extra points from many perspectives. Buying this type brings a series of welfares like follows:

  • Eco-friendly: while reducing your once-a-month bills, you will also minimize the impact on nature. Since it only starts when needed, there is no power usage in the meantime, so no carbon footprint.
  • Convenient: a tankless boiler offers great convenience to its users because it can deliver a continuous stream for the entire family. Therefore, you won’t be forced to schedule your chores or bathing times since the appropriate model will successfully deliver great performance.
  • Durable: without question, the tank-free heater is more durable and less prone to damage. With an average 20-years lifespan compared to the tank model that has short 10-year durability, they represent a long-term investment.
  • Fewer bacteria growth: since water is not stored in a container, the bacteria growth will be notably decreased. Therefore, the odds to get an infection will be significantly decreased, so your entire family won’t be exposed to all sorts of health risks.
  • Safe: this type is a safe choice for many reasons, one of which being the fact that it only uses power when the water is turned on, so it doesn’t represent a fire hazard. Plus, there is no tank to leak or cause a flood.
  • Space Saving: these models are slim and can be easily fitted wherever you want in the house. Therefore, having one of these and not a bulky tank will save space and it will also look much better from the aesthetic point of view.

…and the Minuses

Although they seem like heaven’s sent, it’s not all about advantages. They have their downsides as well. Before making a decision, it’s best to know both sides and decide only after a thorough analysis.

  • Expensive: besides being money-saving and more convenient to use, they also require a large investment that is not always fit in the budget.
  • The electrical system might require an upgrade: not every home can handle tankless boilers because the electrical system might require an upgrade that can only be performed by a professional electrician. Rewiring your house can imply high costs which are added to the initial buying cost.

Buying Guide

As it happens with every item you buy, you want to make sure you will only receive positive results from it. Therefore, you will have to spare no time and effort while doing some research regarding the specs that differentiate the obtainable models. In case you’ve decided to buy one and you want to discover which important aspects to consider, read the lines below and see what differentiates the best-value models.

  • See what size you need: this involves two aspects: the housing’s size and how many fixtures it can cover. The first one is simple to clarify since each model has the measurements labeled, so you can quickly determine which one you have space for. The second aspect is based on how many water outlets you have. Most models can cover around 3 faucets or two faucets and a shower.
  • Decide the flow rate you need: you need to count the number of kitchens and bathrooms you have, the family members, and your schedule. Turn on every faucet and calculate how much time each one takes to fill a 1-gallon container, then divide 60 seconds by the actual number of seconds it took to fill it and that will be the flow rate of each fixture.
  • Decide on the fuel: this is usually among the first things to analyze before making the payment. The choices are either electric or gas, depending on your house’s supply. The gas and propane ones will offer you a higher stream and they are less expensive, while the electric models are more durable and more costly to purchase.
  • Measure the temperature rise: The arriving temperature usually relies on the outside conditions that may vary from one area to another. So, turn on a cold water spout, wait several minutes, and then measure the temperature. If it is, let’s say, 80F and you usually shower with water 105F hot, the difference is the rise you need to achieve from your boiler.
  • Choose a reliable brand: this is also very important because since there are many models available, you have to invest in a reliable brand. To do so, do some research on the company, the materials, and technology they use, the warranty they offer, how committed they are to helping their clients, and so on. A good brand usually receives good reviews from customers, so see what other buyers have to say about a specific model before deciding to buy it.

Frequently Asked Questions

Is it worth getting a tankless water heater?
The chief advantage offered by these systems is that they only heat the water when necessary. Thus, there’s no reservoir where they should store the water and maintain it hot, so the energy or gas costs are reduced considerably. Even if the upfront price is higher, a tankless heater is truly a worthy investment that will pay for itself in the long run.

Where should I place the heater?
In the manual, you will learn that they need to be placed near the water pipe. Basically, you can mount the presented models wherever you want. Most users prefer to hide the unit, so they prefer the space under the kitchen basin, in a cabinet in the bathroom, in the basement, or any other hidden place. As long as you strictly follow all the instructions, you can put it anywhere.

How do I determine what size water heater I need?
This may seem difficult but in fact, it isn’t. In order to properly size it for your house, you simply have to pay attention to its specifications. Check the capacity and see how many water outlets it can handle. Some units are appropriate for 1 or 2 bathrooms while others can easily handle 5 bathrooms

Is this boiler type expensive?
The price depends on many aspects, including the fuel, capacity, brand, and so on. Some units can cost up to $1500 while others are much less expensive. However, the most expensive models usually include the most features or are designed for larger houses, so the price is justified.

Can you run out of hot water with a tankless water heater?
No. These models don’t need a reservoir to store the hot water, so there’s no need to wait for the necessary volume to gather before taking a bath. Just let the water run, and, in about 30 seconds, it will become hot.

How long does a tankless water heater last?
They are more durable than their tank equivalents, which last about 10 to 15 years. A tankless unit that is fitted correctly and maintained according to the company’s guidelines can have a lifecycle of up to 20 years.

How often should a tankless water heater be flushed?
Most companies recommend flushing the unit twice a year or once every 9 months. This depends on how hard the water in your area is, as the purpose of flushing is to dislodge calcareous deposits. The flushing is usually made with pure white vinegar, which should be circulated through the heater for at least an hour.

Why does it take so long to get hot?
In general, it takes 15 to 30 seconds for the water to get hot, but if you are experiencing long delays, the problem may have to do with the unit being positioned too far from the bathroom. You need to consider that cold water stays on the pipes, and, when you open the faucet, you need all this volume of water to flow before getting hot water. In this case, the longer and wider the pipes, the more it will take for the hot water to reach its destination.

Does a tankless water heater run all the time?
No, and this is the huge advantage this design brings. The unit will draw power or gas only when you open the faucet to deliver as much hot water as you need. Once you’ve taken your shower, the power/gas consumption will be interrupted.


Finding the most reliable and trustworthy model wasn’t an easy task, because the offer is generous and variate. However, we’ve managed to pull out 12 exceptional models that meet the highest standards of efficiency and safety. The choice is up to you now, based on the information we have provided.

Best Tankless Water Heater for Sale: Rinnai RL94iN

The toughest model on the market, the Rinnai RL94iN impresses through its hardwearing construction and exceptional circuitry crafting, two elements that recommend it for long-term use in large households. The digital control panel offers easy access to its functions, while the integrated thermostat guarantees that the water is always delivered at the preferred temperature. Besides all these, the high BTU power guarantees that the water hotness will be maintained constant at an excellent water flow.

Editor’s Choice: EcoSmart ECO 27 Electric

Houses located in low-temperature areas are best suited with this powerful model that can turn 37-degree cold water into 140-degree without overexerting the electricity bill. Designed to deliver 3 gallons every minute, it is suitable for households with multiple bathrooms and is packed with every feature you could need. Moreover, the parts are covered by a life-long warranty, so you won’t have to deal with repair costs.

Best Tankless Water Heater for Radiant Floor Heat: Takagi T-K4-IN-NG

Homes with a floor heating system can be paired with this boiler powered with propane that is incredibly powerful, at 190,000 BTUs, being able to create a maximum heat level of 165F. Moreover, it provides a high flow level of 8 gallons so it can handle several water outlets.

Best Commercial Tankless Water Heater: Stiebel Eltron Tempra 24 Plus

This high-grade unit is designed to handle large homes or business places such as small motels or accommodation suppliers. It can deliver boiling water of 140F to high-demand bathrooms. The innovative flow adjustment ensures there will be enough water stream for multiple fixtures at a time. In addition, it’s energy-saving with a 0.99 energy factor.

Best Tankless Water Heater for the Money: Rheem RTEX-13

From every point of view, it turned out to be highly efficient and advantageous. Since it’s slim, it easily fits tight hard-reachable areas and it boasts a generous display that lets you see your selections. The stream and heat are reasonable and can be easily adjusted, and you won’t have to break your budget to get it.

Markus Mackay
Markus Mackay
Our resident expert in all things AC-related, Markus is a never-ending source of knowledge regarding how these systems work. What makes him so savvy in this field is his direct experience that he acquired while working in sales. The connections he made during that period also came in handy here as Markus knows a lot of experts in this field. With each article uploaded, he makes sure to gather the expertise of his more experienced ex-peers as well, making sure to provide readers with reliable reviews and articles.
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