11 Best Tankless Water Heater – (Reviews & Buying Guide for 2020)

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Written by Eric

Last Updated: 12/03/2020

With an emerging global consciousness towards environmental friendliness and energy efficiency, tankless water heaters are a rising trend, especially in the US.

Choosing the best tankless water heater for your home isn’t easy, so we’ve put together a list of some of the best quality and top-rated tankless water heaters on the market today, along with an in-depth buying guide that’ll soon have you shopping like a pro.

Tankless Water Heater Reviews [Updated List]

1. Best All-Rounder: Stiebel Eltron Tempra (Electric)

Stiebel Eltron Tempra

Stiebel Eltron Tempra 15 Plus Electric Tankless Whole House Water Heater

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  • No Venting Required
  • Totally Silent
  • Max 3.1 GPM Flow Rate

The Stiebel heater is great for homes with a higher demand for hot water during certain periods of the day. The Tempra’s exclusive advance flow control feature allows it to self-allocate and distributes water so that you do not have to worry about water running out. When demand for water is high, it will automatically reduce the flow of water slightly so that a consistent temperature is maintained.

In addition to the conventional benefits such as energy efficiency and consistent hot water supply, the Tempra offers some extras. Since it’s an electrical tankless unit, another plus point is that you will not have to worry about venting or exhaust systems like in propane heaters. Simply mount it on the spot of your choice, and the majority of your work is done.

It also helps that it comes in a sleek and compact design, meaning it was made for the express purpose of seamlessly merging into your house without taking up too much space or requiring major adjustments.

This theme of seamlessly merging into the house is furthered by the fact that it is completely silent, owing to its electricity-based mechanism, which gives you even more flexibility when choosing the right place to install the Tempra in your home. To top it all off, these thoughtful design features, combined with high-quality German-made hardware in the form of solid copper heating chambers, make for a highly reliable piece of technology. It is no surprise then, that StiebelEltron offers a seven-year leakage warranty and a three-year warranty on parts, for their entire range of Tempra water heaters, including this one.

If you’re looking for a great-looking tankless unit with a bit of extra tech to keep up with your hot water needs, this could be the one for you.

2. Best Outdoor: Eccotemp L10 (Propane)

Eccotemp L10

Eccotemp L10 Portable Water Heater w/ EccoFlo Diaphragm

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  • 2.9 GPM Flow Rate

A great advantage of tankless water heaters is they can be powered by propane gas, making them super portable. When it comes to outdoor water heaters, Eccotemp is the name of the game. The L10 unit is designed specifically for the rugged outdoors. If you are a camping expert, or simply enjoy staying at your cabin every now and then, this product will serve you well.

There are various features that help the L10 in adapting to all kinds of outdoor environments. It comes in a small and lightweight body that is easy to store and transport, and is designed to work well with added components such as an electric pump or any kind of shower head up to a field-tested height of 5500 feet.

This water heater uses liquid propane as its energy source, which means it will work even in areas where you do not have access to electricity. In addition to that, the L10 is accompanied by a rain cap that ensures that it works smoothly, even when it is raining.

The L10 helps you save energy with its manual temperature and pressure control; so that you decide how much water you need, based on the kind of conditions you are using the heater in. Even though the ignition is manual and battery powered, it has an automatic shutoff timer, set at 20 minutes to make sure no energy is wasted. The best part is that the half-inch NPT lets you connect to a garden hose so that you can use it to bathe your dog or horse even when you are not out in the wilderness.

3. Best Space Saver: Takagi T-KJr2-IN-NG (Gas)

Takagi T-KJr2-IN-NG

Takagi T-KJr2-IN-NG Indoor Tankless Water Heater

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From the harsh outdoors, we now come to the comforts of indoors. If you are looking for the best tankless option to install in a small house or apartment with about two bathrooms, look no further than the Takagi T-k Jr2. As one of the smallest heaters in the Takagi’s line of tankless water heaters, it is designed to be simple efficient and effective. The small size allows you to mount it even inside a closet or simply hang it from a wall without having to worry about how it affects your living space.

This gas powered model is rated between 19000 BTUs to 140000 BTUs per hour, and requires a grade 3 stainless steel venting system, it also comes with its own stand-alone exhaust outlet. It can also be switched to LPG for situations where you do not have access to natural gas, and provides a stellar output flow rate of about 6.6 gallons per minute, with an energy rating of 0.82.

In order to ensure complete safety, the T-K Jr2 has electric ignition so that you can have absolutely zero physical interaction with the fuel source.

Current users of the T-K Jr2 generally credit their satisfaction to its simplicity. It does not boast the features of some tankless water heaters but does the one job it is meant to do, which is providing you with a consistent, uninterrupted supply of hot water. The exhaust requirements might require some extra work at first, but it will be negligible in the long run, considering the 13-year warranty that this heater comes with.

4. Best Outdoor Portable: Camplux (Propane)

Camplux Heater

Camplux 5L 1.32 GPM Outdoor Portable Propane Tankless Water Heater

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  • 1.32 GPM Flow Rate

The Camplux heater is the best outdoor portable tankless water heater unit that is good for taking on camping vacations. Its size is more compact along with a foldable handle that makes it functional for outdoors. You can also fit it into indoor ventilation systems because it comes with Oxygen Depletion Sensor Protection. Obviously this is one heater that can literally go where no tank water heater can take you.

One of its features is that it provides you with an ignition option with 2 “D” batteries. This means that you can operate this hot water heater with or without it. The water heater’s performance is great even at low water pressure. For example, if the pressure ranges between 2.5 PSI and 110.0 PSI, the outdoor portable heater will easily perform its function.

For the 1.32GPM Camplux, temperatures between 114.8℉ (46℃) and 46.4℉ (8℃) are best. This heater can also work well when the water system is attached to a 12-volt pump. The Camplux tankless water heater is equipped with energy saving technology in which you can instantly get hot water. Its hot water flow rate is 1.32 GPM and the pressure is 0.4PSI generated using 34000 BTU per hour.

You can also configure the wall hanging heater by using a foldable handle. You can also easily connect the cylinder with the regulator and the hose. Start using hot water by connecting a shower hose and head to the outlet, and the water hose to the inlet. Insert your 2”D” batteries in the heater and you will instantly have hot water.

5. Runner-Up Space Saver: SioGreen IR30 (Electric)

SioGreen IR30

Sio Green IR30 POU Infrared Electric Tankless Water Heater

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The SioGreen is the member of the latest generation of electric heaters. As compared to previous technologies, there is no metallic heating tube used. An inject-heating BTU into water is passed over the heating exchanger.

There are Quartz heating tubes used in this unit. Quartz has been used for many years because it provides thermal properties and keeps the system stable. A special layer is applied to the Quartz tubes from the outside which reflects the infrared energy that heats the cold water as it passes through the heating chambers. This energy is safe as well as helpful with the condition of hard water deposits.

This system energizes your water with the help of the quartz elements by allowing no corrosion and calcium deposits that heat up the water without instant contact to metal. Through this method, there is a lesser chance of producing bacteria in the water. The IR30 POU operates on four power levels that you can alter manually according to your requirements. You are able to adjust the current from 8 to 30 amps and results in generating power between 0.85kw and 3.4kw.

You can change the temperature by using the water flow regulator. If you want to increase the temperature, you can turn the regulator clockwise. There’s A Thermocouple Constantly Monitor Temperature outlet which displays the temperature on your screen.

The POU water heater by SioGreen is well designed and is only slightly larger than a shoebox. The space-saving design allows this tankless unit to fit under any small cabinet and is easy to install, so you can place or mount it to any suitable place such as a kitchen, bathroom, apartment, or utility room.

6. Rheem RTGH-95DVLN (Gas)

Rheem RTGH-95DVLN 9.5 GPM Indoor Direct Vent Tankless Natural Gas Water Heater 

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  • 9.5 GPM Flow Rate

The RTGH-95 DVLN meets industry standards by keeping the quality and reliability of the product accurate and stable.  Because there is an efficient manufacturing process that has overseen every phase from the raw materials to finished products, it ensures excellent quality for the consumer.

Rheem products are frequently tested in labs to assess their performance. In addition to that, the company also involves third-parties to check the quality standards of its hot water heaters.  For this reason, the product is also certified according to government benchmarks.

In this water heater, a self-diagnostic system is available and it eases up the installation process. An LCD screen displays the temperature of the water heater and other details associated with maintenance requirements or the current status.  For commercial use, the operable temperature range is from 85°F to 185°F.

One of the best built-in features of this water heater is that it is energy efficient. Approximately 94% of the energy is conserved through its stainless-steel condensing heat exchanger. It enables you to electronically control its intelligent digital remote controls that are specially designed to increase the energy in a safe and efficient manner.

A special cable which is known as an EZ-Link cable is used to connect the two different tankless units that work as one. Some products of Rheem have high altitude capability if supplied with a 120-volt power cord and this is only for indoor models. The water heater comes with freezing protection of up to -30°F.

In this product, the Cold Water Sandwich technology is used and is excellent in helping minimize the fluctuations in water temperature where this heater automatically performs on/off operations. It also comes with a limited ten-year warranty of a heat exchanger as well as one-year limited warranty for its parts.

7. Rinnai RL75iN (Gas)

Rinnai RL75iN Tankless Water Heater

The Rinnai RL75iN is a well-designed indoor model and is equipped with direct electronic ignition system. The water heater uses a direct vent to continuously control the temperature of the flowing hot water through the system.

This water heater consumes gas and its maximum gas consumption ranges from 10,300 to 80,000BTU/h. The temperature range of this product is categorized according to its place of installation or purpose, such as residential or for commercial. For residential use, temperature settings range between 98°F and 140°F and for commercial use temperature settings ranges between 98°F and 160°F.

The flow rate of the RL75iN water heater ranges between 0.26 and 7.5 GPM. This means that the water heater can save energy and money too. For this reason, its thermal efficiency is up to 82%. This product can easily support two to three bathrooms in a home. The pressure of the water supply plays a vital role in the operation of this heater. Its minimum pressure is 20 PSI while its optimal performance recommended pressure is 30 to 80 PSI. The water pressure cannot exceed 150 PSI.

This heater is covered by a twelve-year warranty for the heat exchanger, five-year warranty for parts, and one year labor that is only for residential installation. The size of the RL75iN heater is large and it is specifically designed for indoors. You can mount it on the wall if you want to conserve space.

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8. Takagi T-H3-DV-N (Gas)

Takagi T-H3-DV-N Water HeaterIf you’ve had bad experiences with frequent breakdowns and malfunctions of water heaters, then the Takagi Condensing Water Heater is definitely the right product for you. The Takagi weighs an incredible 59 pounds, and has been a customer favorite since it first came out. This tankless water heater requires little to no maintenance, and works automatically as well as manually. The Takagi is great at space saving, with its dimensions of a length of just 11 inches, making it extremely compact and portable, though it is a bit big to handle.

This is one of the best tankless models for keeping the right temperature. Most customers report that the temperature was maintained exactly how they wanted it. The Takagi Heater truly is remarkable. One drawback of the Takagi is its loudness, and some consumer reports mention loud noises every time the water is heated.

One of the best parts about having a Takagi Unit in your home is that there are absolutely zero exhaust fumes, which means that the unit can run and waste little amounts of gas. The entire product is cost-efficient and eco-friendly like a good tankless water heater should be.

And the best part? There is a one to three-year warranty policy which means that you can be sure that your Takagi Water Heating unit will work for a very long time. It’s definitely worth the price.

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9. Rinnai RUc98iN (Gas)

Rinnai RUc98iNAlthough tankless water heaters were an innovation when they first started out, they have now become a bit commonplace in the modern world. However, the Rinnai changes all of that in the blink of an eye.

The Rinnai Water Heater relies on a PVC venting system that allows it to give off a monitored temperature. The installation is extremely easy and simple, and setting the Rinnai tankless water heater up in your room will only take a few minutes. The product weighs around 82 pounds, which is a bit heavy, but will hold up against the wall perfectly. The Rinnai has almost zero NOx emissions, which means that the entire mechanism is environmentally friendly. This water heating unit can reach incredible temperatures, all of which are exceedingly comfortable to use.

The maximum power of this tankless unit is approximately 199 thousand BTU, which means that the entire machine can operate at tremendous speeds and still function perfectly. The Rinnai Ultra Series Heater is definitely one that is worth your money. The best part about the Rinnai is that it has a very inexpensive price, which means that almost everybody from all financial classes can afford a nice water heater.

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10. Rheem RTG-84XLN (Gas)

Rheem RTG-84XLNThe Rheem Heater is one like I’ve never seen before. Apart from the fact that the design is entirely compact and deluxe, the overall working power, and heat generated are definitely things that we’ve fallen in love with. For one thing, the Rheem relies on natural gas to heat up the water, with almost zero NOx emissions. As a result, this tankless water heater is extremely safe, and will not poison the air with toxic emissions. This is certainly one of the best tankless offers in town.

This may be the best tankless water heater option for those who prefer a lighter model. This unit weighs only 54 lbs. and is extremely easy to install. The Rheem tankless hot water heater is a great choice for all types of users, with a flow rate of up to 8.4 gallons of hot water in one minute at an average temperature rise of about 35 degrees.

The best part about the Rheem is that no additional venting is required. Forget about all those PVCs, as this unit will not only be cost-efficient but also extremely convenient. The water gushes out almost instantly. The Rheem takes up hardly any space, and has a 10-foot thermostat wire included in the shipping. What’s more, the heater unit has a remote control which can operate the Rheem from a far distance.

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11. Eccotemp I12-LP Indoor (Gas)

Eccotemp I12-LP Indoor Tankless HeaterThere’s more to the Eccotemp than meets the eye. But of course, even what meets the eye is enough to convince us that this tankless hot water heater is top of the class. Let’s start with the design; the Eccotemp uses a sleek black look that looks stunning, even if it is in the middle of your entire house.

You don’t need to worry about the performance. The Eccotemp works wonderfully indoors. The Eccotemp has child locking technology, which ensures that your children will not touch the settings, mess it up, or injure themselves in any way. This, and the fact that there are zero NOx emissions, makes it the safest and securest heater out there.

As for the heating power and flow rate, the Eccotemp can heat up to three gallons in a minute, which might be just a bit lower than most tankless water heaters, but it is definitely worth the try. The Eccotemp uses a pipe venting system, and the parts and kits may be a bit rare or costly to find, but it is well worth it.

And as for the weight, the Eccotemp has a weight of just 28 pounds. This is the lightest we have seen, and we’re sure that you can agree. It also costs nothing more than a regular water heater.

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Tankless Water Heater Buying Guide

Best Tankless Water Heater Reviews

We hope that now you’ve looked through our list of the best tankless options, you’re feeling more confident about understanding what’s on the market.

Still, before you decide which is the best tankless water heater for your home, you need to understand everything that they have to offer and how tankless water heaters work. We’ve brought together all the tankless heater information you need in order to make an informed buying decision, so you can be sure that the heater you choose meets your demands.

If you’re still on the fence about whether a tankless solution is for you, see our article on why you should go for a tankless water heater.

  • How Tankless Water Heaters Work

Tankless water heaters rely on the same principle as a tank-style units, in that there is an incoming water supply of cold or room-temperature water, which is heated with the help of a built-in connection to fuel.

Coil Technology

Tankless water heaters employ a superior use of technology, and some of the best tankless heaters pack a lot in.

The entire idea of the tankless system is based on the real-time flow of required hot water. As such, they need to be quick and efficient in heating the incoming water as it flows through the heater. The primary component that helps in achieving this magic in tankless water heaters is called a heat exchanger; which is essentially a device that transfers heat generated from gas burners or electrical heating coils, to the water that it comes in contact with, primarily through conduction. This technology surpasses the need for having a built-in tank to store hot water because the process of heating water is so fast that it can be done in real time.

Ignition And Exhaust

As you turn the faucet on, cold water flows through the pipes that are in contact with the heat exchanger, which then heat it to the temperature you have set. This is why, with tankless water heaters that use gas, LPG or any fuel that may combust to release fumes of any sort, an ignition and exhaust system are necessary to work properly.

Flow Rate

Flow rate is measured in gallons per minute (GPM), and tells you how much hot water your tankless water heater can produce. Typical flow rate ranges from 4 to 5 GPM, but some of the best tankless water heaters can do even better. Gas powered tankless water heaters tend to provide better flow rates than their electric counterparts.

However, there are some limitations that apply to all models. For example, washing the dishes and taking a shower at the same time might cause the temperature of the water to be lower than what is preferred because it is not easy to supply hot water for such high-demand activities at the same time. For such situations, it may be better to opt for two or more smaller dedicated tankless water heaters that are connected in parallel so that nobody is deprived of hot water.

Energy and Efficiency Ratings

From a customer’s standpoint, it is also important to at least have a sense of what energy and efficiency ratings mean. Tankless water heaters that use combustible fuels are rated in BTUs or British Thermal Units, while electric heaters come with kW or kilowatt rating. The higher the rating, the more energy your heater is capable of investing as heat.

Efficiency ratings come in decimals between 0 and 1, indicating the percentage of input energy that heats the water and the percentage that is lost. If a tankless water heater’s efficiency is rated at 0.80, it means that 80% of the energy you invest in it comes out as hot water while the remaining 20% goes to waste.

Don’t forget to also check out our list of best-selling EcoSmart tankless water heaters, the Best Rinnai tankless water heaters, Bosch water heaters buying guide, and Rheem tankless water heater reviews.

  • Tankless Versus Tanked Water Heaters

The main differences between tanked and tankless water heaters boil down to placement versatility, water storage capacity, energy consumption, and price.


The name says it all; tankless models are not accompanied by a cumbersome water tank. As a result, they are small, lightweight making them easy to transport. The smaller size also allows them to be more versatile in terms of placement, which will help you maximize space in your home.

Storage Capacity

The most significant difference is that a storage tank water heater is able to store 30 to 50 gallons of water in the tank. That preheated water can be used whenever you need to use it for taking a shower or for washing dishes or doing laundry etc. Once it becomes empty, it will refill and reheat. Tankless water heaters, in comparison, heat water by using electric or gas technology and work on the principle of demand. It means that whenever you need hot water, a tankless water heater will provide it to you instantly without using storage.

Energy Consumption

A tanked water heater consumes more energy as it continues to turn on hot water if needed or not. Additionally, there’s always the risk of water being stale considering that it has been sitting in a storage tank for a long time. This is not an issue with tankless water heaters since water that is heated flows into the heater as it is needed and is not allowed to stagnate at any point.


Product price is a noteworthy difference between tanked heaters and tankless water heaters as well as their installation costs. Traditional storage tank water heaters are more affordable but they are not used in the long run and they also have a short lifespan because they are constantly performing their function. These units also need more maintenance. It also increases your utility bill because it heats the water constantly without switching off.

Tankless options are costly because of their complexity as compared to tank water heaters or traditional units. However, a tankless unit saves your money and is a lot more durable as you can use it in the long run, between fifteen to twenty years easily. Obviously the best tankless water heaters are pretty pricey, but it can pay to work out these long-term costs and see how much they save you in the long run.

  • Why Should I Descale My Tankless Water Heater?

Even the best tankless water heaters will need descaling, because the water containing minerals will cause deposits. A proportion of minerals in the water will be effected according to your country regions. Those people who are living with a higher percentage are said to consume harder water while those with a low percentage will consume soft water. For building up of rust or lime, you can coat heating components including your water pipes and it will enable you to save up to 30 % of energy consumption.

  • Gas Versus Electric Tankless Heaters

The choice between a gas heater and an electric heater is one the most important considerations you need to make when choosing a tankless water heater. Prices vary greatly based on whether a model is electrically powered or gas powered; gas-powered models being more expensive. For gas powered models, outdoor units tend to be more expensive than indoor ones. Electric tankless water heaters are generally the cheapest. This is due to their small size and lower output flow rate.

Power Consumption

With electrical units, the main consideration is the amount of electrical power that they require. It is important to assess whether you have the necessary electrical wiring to house such a heavy load. In case you don’t, you may have to spend extra on modifying and upgrading the wiring on your panel.

You also need to remember that the significant electrical requirements of a tankless heater unit mean that you may have a problem allocating power to your heater if you already have other heavy appliances running. It may also cause an increase in your electrical bills if you go for a heavy duty electric heater.


The major consideration for gas-powered heaters is having the a suitable location, both for the supply of gas as well as the ventilation of exhausts. If you have a built-in gas connection you may be restricted to placing it next to an outlet. If not, you may have to spend money on hiring a service to accommodate the heater.

Companies also have very specific exhaust requirements for gas heaters, which too, will require extra pipework and will dictate where you can or cannot place your heater, especially keeping the safety considerations of indoor heaters in mind. Outdoor units meanwhile may not pose such a challenge since the open ventilation is taken care of, and the supply of oxygen is virtually endless.

  • Natural Gas Versus Propane Tankless Heaters

Within gas powered tankless water heaters, in most cases, you will further be faced with the choice of whether to go for a natural gas-powered heater or a propane-run heater to get your hot water. More often than not, this decision is driven by availability more so, than by choice.

Available Fuel Supply

The first consideration that should be made is whether you have quick and easy access to the fuel that your heater of choice uses. Opting for a natural gas-powered tankless heater means that you have natural gas available in your area, in which case I the heater can easily be connected to the mains supply. In cases where users do not have access to natural gas, a propane-powered water heater will have to be used.

Natural gas is generally cheaper than propane per unit. Not only that, but it burns more cleanly as well, making it a better choice than propane overall. With some expert assistance at the time of installation, you can have a reliable natural gas powered system in your household.

Environmental Considerations

If you go for a propane-powered heater, it means you have a propane tank connected to your heater or heaters at all times. The best part about a propane-based system is that it is very easy to set up; perhaps the easiest. However, do bear in mind that propane does not burn as cleanly as natural gas, so ventilation of exhaust fumes becomes all the more important with propane-powered water heaters; not that it should be neglected with natural gas powered systems. If it is all the same to you, then going for the natural gas-powered tankless water heater is a better option out of the two as it is both, more environmentally friendly as well as cheaper in the long run.

  • Best Tankless Water Heater Size

With these water heaters, bigger is always better. If you go for a large whole house tankless water heater, you will have more room to simultaneously distribute the hot water supply. It will also heat the water much more quickly, and the temperature difference between input water and output supply will be greater. If, however, you’re looking for a top-rated portable or RV tankless water heater then we have a guide for those here.

Energy Considerations

Larger tankless water heaters cause greater energy costs per unit volume of water heated since they use higher power exchange to heat water. At the same time, the hot water will run less than it would if it was smaller.

So which is the best tankless water heater for you from an energy perspective? Ultimately, you will have to assess three main factors before deciding what kind of water heater to get. First, you will have to see how many occupants regularly use hot water. A number of occupants are usually indicative of how frequently the heater will experience simultaneous demand. Second, you will have to see which activities or appliances in your household require the hot water. Third, you will have to see what kind of climate you live in.

Family Size

With a small family with moderate usage, a normally sized heater will be adequate, however, if the family size is larger, you may need to go for a larger heater. Similarly, if your household will be drawing from several points simultaneously, you may opt for a larger option simply because the volume of water needed can be supplied by a larger heater.


If you live in a cold region where snow days are common you may have to go for a larger heater regardless of house size because the incoming water will be near freezing temperature. Whereas, a smaller heater for the same family in a warmer climate will be fine.

Tankless Water Heater Questions and Answers

Q: Do I Have to Change The Way I Use the Shower?

How to Install a Tankless Water Heater

Every decision to do something new implies some kind of change. However, the recommended way of using a tankless heater’s water supply is to allow the hot water to flow at the maximum rate. Once the water is as hot as it can be, cold water should be used to fine-tune its temperature. This method allows the water heater to function at maximum efficiency, while also providing you with maximum control.

Q: If the Power is Out, Will It Still Work?

It will still allow the water to flow through but it will not be heated because the heating element, which relies on electricity to work, will not have the necessary electrical supply.

Q: How Long Does the Water Take to Actually Become Hot?

The lag between turning the tap on and hot water flowing through is mere seconds. That too is not because the heater takes time to start working, but because there is water sitting in the pipelines prior to usage, which needs to flow out in order for the hot water to start flowing out.

Q: Do High Altitudes Affect Tankless Water Heaters?

For electric heaters, not at all. With gas-powered heaters, however, efficiency is generally lost at a rate of 4% beyond altitudes of 400ft, unless your unit is made for use at higher altitudes.

Q: How Much Hot Water Do I Need?

The right way to go by it would be to consult the user manuals of all the fixtures in your house through which hot water is supposed to run. There should be a rating in these manuals for the respective fixtures, in gallons per minutes, which will basically specify the flow rate of each fixture respectively.

In order to calculate how much hot water you need, you will need to calculate average time of use for the fixtures in question and multiply it with their respective flow rates to get a reasonable estimate of how much hot water you tend to use daily. However, if you’re looking for a very rough estimate, the rule of thumb is to assume a flow rate of three gallons per minute (GPM) per bathroom.

Q: What is Maximum Temperature Rise?

It is the maximum rise in the temperature that the heating element in your tankless water heater can ensue when running at maximum power, in the incoming groundwater. Ratings of maximum temperature rise can be an important factor in the choice for a tankless water heater, as it will give you a sense how hot your hot water will be. This is an especially important concern during cold climates.

Q: What are the Downsides of Tankless Water Heaters?

Every piece of equipment is bound to have some downsides. For tankless water heaters, one of the major downsides is cost. While running costs are much lower, they are more expensive than a tank water heater in terms of purchase as well as installation. You will need to worry about setting exhaust and ventilation systems even after you have purchased the unit as well. You will hear frequently, of the cold-water sandwich problem by those who do not find the idea of tankless heaters convincing.

Lastly, just as a tank water heater poses limitations in the quantity that can be used at once, tankless heaters limit the number of users that can use hot water at once. The nature of the technology is such that can accommodate a certain extent of simultaneous users. However, this is not even a problem, if you carefully assess your requirements before purchase and opt for a suitably sized and powered tankless system accordingly.

Q: What is The Cold-Water Sandwich Problem?

To start with, the so-called cold-water sandwich problem is overrated.It is a name given to the few seconds of cold water you have to experience before hot water flows through. This is basically a result of the kind of technology tankless heaters employ. Because they heat the water as it is needed, naturally, the water sitting in the pipes when the faucet is off, tends to lose heat and get cold. Once the tap is on, in order for the hot water to reach it, the cold water needs to be flushed out first. This necessary flow of cold water is termed as the cold-water sandwich.

However, it is important to remember that it is not even a problem in most cases, and becomes a cause for concern only in larger houses or in cases where the distance between the faucet and the water heater is significantly large. Meanwhile, there is no reason the same problem cannot occur in tank-style heaters as well. If you live in a house where the tank heater is far away from the faucet where hot water is required, you are likely to encounter the same problem.

Q: How Much Do Tankless Water Heaters Cost?

It is no secret that the initial cost of tankless water heaters can be two to three times as that of equivalent performance tank-style heaters. Furthermore, it is likely you will have to spend a considerable amount on hiring professional help during the heater installation process. We can expect that to be several hundred dollars, although the exact amount will vary greatly based on where you live and how familiar you are with the market.

Lastly, you will have to spend on building the capacity within your existing infrastructure to accommodate a tankless water heater. This might include installing exhaust ventilation systems or creating new electrical outlets etc.

Q: How Does “Hard Water” Affect My Tankless Water Heater’s Performance?

We’ve already talked about the importance of regularly having your water heater scaled, and this is true whether you have a tank water heater or tankless. If you used it with hard water, it simply increases the likelihood of calcium deposits appearing on your heating element. While scaling is inevitable, particularly hard water may simply increase the need and frequency of scaling.

Whatever the case, it is very important to keep a regular check on your water heater if you are using hard water, and not allow too much mineral deposit to calcify on the heating element, as it can cause hard water damage, or in extreme cases, complete breakdown. As rule of thumb, when using hard water, descale your water heater with store-bought descaler and rinse with white vinegar, between every 6 months to a year. Check out our water softener reviews if you are dealing with hard water problems.

Tankless Water Heater Comparison Chart

ModelBrandPower SourceWeight
Tempra 24 kWStiebel EltronElectric-Powered 16.1 pounds
L10EccotempLiquid propane 27 pounds
T-KJr2-IN-NGTakagiGas-Powered38 pounds
5LCampluxGas-Powered10.8 pounds
IR30Sio GreenElectric-Powered6.4 pounds
RTGH-95DVLNRheemGas-Powered82 pounds
RL75iNRinnai Gas-Powered65.9 pounds
T-H3-DV-NTakagiGas-Powered 59 pounds


Stating all the reason that make tankless water heating systems superior to the other options is not possible in the span of one guide. However, the most important takeaway from this should be understanding that if you want to save energy cost, move to a more efficient and cost-effective use of energy that will help the planet. You should definitely consider switching to a tankless heating system.

In order to find the right product for yourself, the first thing you must assess is your usage patterns, the volume of water you consume, how frequently you need hot water, and most importantly, how much money you are willing to invest. Even though a tankless model will be cheaper in the long run than a tank system, finding the right balance between all these factors will allow you to go for the optimal arrangement for your household.


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