5 Best Tankless Water Heaters for Showers Review

electric tankless water heater for shower

Bathing is the most enjoyable thing in our daily life, when you stop your busy work and go back home, a hot and satisfying bath relieve all your pressure and tiredness. To realize it, you need to get the best tankless water heater for shower, it provides constant hot water for you and you can use it instantly no matter in a busy morning or at midnight.

Unlike under sink tankless water heater, the heater for the shower has a large flow rate and needs to provide constant hot water. Size of it is of course much bigger than that but is still much smaller than a tank water heater, and can be perfectly used for small studios and outdoor.

If you intend to use it for outdoor, we have made the best tankless water heater for the camper, and RV tankless water heater reviews for you. And in this article, we mainly talk about the best tankless water heater for indoor shower, which in other words, the heater for residential use.

Top 5 Best Tankless Water Heaters for Shower in 2021

Best Tankless Water Heaters for Shower Reviews

In order to help you choose the best tankless water heater for shower conveniently and rapidly, we made a review for you and you can select based on your actual needs and requirement.

1. Rheem RTEX-13 240V Heating Chamber Residential Tankless Water Heater

It is the hot-selling tankless water heater on the market of 2020, because of its excellent performance, it is widely praised by customers.

best tankless water heater for a shower
tankless water heater for shower



  • Perfect for single room use

The temperature range of it is between 50 and 70 degrees F, and the maximum flow rate reaches up to 4 gallons per minute. If you intend to get one for single bathroom use, then this can be a perfect one. In warm areas, it supports one bathroom and faucet the same time effectively.

  • Fast heating time

It heats water fast, takes about 15 seconds only for hot water flowing to your destination on normal occasions. But if the heater is set quite far, then it may take a bit longer. Once it turns on, you can enjoy endless hot water in bathing.

  • Easy installation

The installation of it is quite simple and straight forward, you can hook it up all by yourself and takes about 1 hour only. By doing it yourself, a large number of installation costs are saved. However, if you really do not know how to do it, you can get a professional to help you, safety is the primary thing after all.

  • Stylish compact design

The compact design makes it a perfect one for small or tiny studio use, you can hook it up on your bathroom wall directly and it occupies an only small piece of space.


  1. Perfect for small studio use
  2. Endless hot water offer
  3. Money saver on electricity bill
  4. Multiple stranded wire makes the connection much easier
  5. Unbeatable price
  6. Stable water temperature


Can not be used for whole home or multiple bathrooms use

2. EcoSmart ECO 27 Electric Tankless Water Heater

This is an electric tankless water heater for shower, the required electricity is 27 kW at 240 volts.

best tankless water heater for a shower
electric tankless water heater for shower



  • High-temperature range

Temperature range is between 80 and 140 degrees F. In warm areas, it is able to process 6gpm water but the flow rate drops to 3gpm when the weather gets cold or being used in cold areas. It is said to be able to work for the whole home and can support two bathrooms to use simultaneously.

  • Easily operated temperature control

Water temperature is adjusted by the button, you can set it up and down with one increment, EcoSmart boasts that you can adjust the temperature easily with it, but still, you will find it takes some time to get the suitable water temperature. And it is unable to produce pipe hot water at a high flow rate.

  • Energy Saver

Like other tankless water heaters for a shower, this unit is equipped with self-modulating technology, drawing energy only when you use it. Therefore, it is able to save about 50% of water heating costs.

  • Well made materials

The unit is made excellent, copper and stainless steel components promise it to be highly corrosion resistance and heat resistance, service life is quite long. And the heating elements are easy to be replaced once something wrong happens.


  1. Energy efficient
  2. Unlimited hot water supply
  3. Easy operated digital control system
  4. Save 12 cubic feet after installation
  5. Well made materials
  6. Self-modulating technology


  1. Hard to adjust the right temperature
  2. Can not produce pipe hot water at a high flow rate

3. Stiebel Eltron Tempra Plus 24 kW Tankless Water Heater

This tankless water heater is an improvement series based on other Eltron models. It is more technologically advanced.

tankless water heater for shower
electric tankless water heater for shower



  • High technology

This unit is regarded as one of the technological electric tankless water heaters, it has an advanced flow control system to control water temperature in different level, thus for some public areas like school or hospital, it meets the demand of occasional hot water supply.

  • High flow rate

The ideal working condition of it is 45 degrees F, and it is able to raise the water by 54 degrees F at 3 GPM. Compared with another electric tankless water heater, the flow rate of it is quite high, reaching up to 5 GPM. In warm areas, it supports two bathrooms at the same time easily.

  • Self-modulating technology

The self-modulating technology enables the machine to work only when you need hot water, thus less cold water is wasted in using period. Besides, unlike natural gas tankless water heater, it is super quiet, you can hardly hear the working noise in working.

  • The advanced flow control system

Built-in advanced flow control is used to regulating water pressure automatically. When the water temperature drops, it senses quickly and corrects it to the normal level.


  1. Full power modulation, available for commercial use
  2. Easy for installation
  3. 99% high energy efficiency
  4. Powerful machine
  5. Quiet working condition
  6. Compact size for all applications


Unable to install more heating elements inside

4. Rinnai RUC98iN Ultra Series Tankless Water Heater

This is a natural gas tankless water heater and is the hot-selling type of Rinnai tankless water heater for shower.

tankless water heater for shower
electric tankless water heater for shower



  • Commercial use available

Temperature ranges from 98 degrees F to 140 degrees F, it can also be used as a commercial heater, and the temperature rises up to 185 degrees F if used commercially. But you need to get a commercial remote to control it elsewhere.

  • Double venting facilities

There are both concentric PVC and twin-pipe you can choose on venting. The heating time is quite short, takes about 20 seconds for water flowing to destination. Once it turns on, the unit provides flawlessly hot water for you.

  • High flow rate range

The flow rate reaches up to 9.8 gallons per minute, it is really a high flow rate type. Power requirement is between 15200 and 199000 BTU per hour. As for energy efficiency, Rinnai boasts it reaches up to 0.95.


  1. Needs only 2 watts to keep the machine up and running
  2. Quiet working condition
  3. Endless hot water supply
  4. Easy operated water temperature control panel
  5. Powerful enough
  6. Two venting options offer


Difficult to install

5. Takagi T-KJr2-IN-LP Indoor Tankless Water Heater

This is a propane tankless water heater, and you can also power it with natural gas. For indoor installation, venting facilities are needed.

electric tankless water heater for shower
tankless water heater for shower



  • 6.6 GPM flow rate

The flow rate of the machine reaches 6.6 gallons per minute, able to support two bathrooms and two faucets use the same time in warm areas. But in winter or cold regions, the flow rate drops to 3-5 gpm. Though having a relatively large flow rate, we do not suggest it be used as a whole house model, for it is not powerful enough.

  • smallest shape

It is the smallest and lightest one among all the Takagi tankless water heaters for a shower, so you can install it anywhere you want. But for propane type, you need to install it somewhere airy for better performance.

  • perfect for residential use

It provides hot water with a temperature of over 150 degrees F, perfect meets all the demands of residential use. The required power input is 140000 BTU per hour. The energy efficiency is quite low, reaching only 81%.


  1. Multiple bathrooms support
  2. Digital remote
  3. Easy to be installed
  4. Lightweight design
  5. Demands minimal maintenance


The working noise is too loud

Things To Consider On Choosing Best Tankless Water Heater For Shower

In taking a bath, we normally have the trouble of getting long waiting time for water to heat up, hard to adjust suitable water temperature, water temperature changes from hot to cold and from cold to hot frequently, and you may also run out of hot water for long time washing.

Therefore, in order to avoid the above problems and enjoy relaxing bathing, there are some factors you need to consider in picking:

1. Fast heating time

This problem is actually solved by tankless water heater design. The conventional tank water heater stores cold water in the tank and heats it in use, it takes at least thirty minutes for the water to heat up. Getting a tankless water heater and you can take a bath whenever you want.

But you need to consider the transfer time, it takes much time for hot water to flow to your destination, some takes only a few seconds, while some even take as long as 1 or 2 minutes. In such a process, much cold water is wasted and your water bills will be added for long term use.

2. Large water flow

The water flow rate of tankless water heater for shower can be relatively low, it takes about 2/3 GPM, so even a small flow rate model can also meet your demand for single bathing. However, if you intend to use hot water in multiple spots, such as two bathrooms or multiple faucets the same time, then you need to get a large flow rate type, known as whole house tankless water heater.

The flow rate selection is determined by your use; if, for a large home, the large flow rate is needed. And low flow rate supports hot water only for a single bath.

3. Stable temperature

Some of the tankless water heaters are equipped with self to adjust skills, it keeps the water temperature stable all the time. Once it senses the temperature drops, it quickly takes action and corrects it into normal level by adjusting the water pressure.

There is also a common phenomenon called cold water sandwich, cold water, and hot water flows alternately, causing bad experience in bathing.

4. Constantly hot water

Actually, nearly all the tankless water heaters are able to provide constant hot water for you, because it needs no tank and heats water directly through internal heating elements. Thus buying a tankless water heater, you do not need to worry about running out of hot water in taking a bath.

5. Smart technology

For other smart technologies, such as overheat protection and overpressure protection, you can decide on your budget and your needs. These are helpful in keeping safe using and prolonging service life. If you have enough budget, then you can get one with smart technology.

tankless water heater for shower
electric tankless water heater for shower

Size Of Tankless Water Heater For Shower

Tankless water heater size is normally small and suits different needs of various families, it can be installed either in a tiny studio or large apartment. However, when comparing with under sink or point of use tankless water heaters, it is relatively large. You need to hook it up on the wall of the bathroom or kitchen, you can also install it outdoor if possible.

There are also slight differences between each type of tankless water heaters. Thus you’d better estimate the size you intend to install it and make sure there is enough space for it and are convenient to use.

The Best Tankless Water Heater For Shower

Types Of Tankless Water Heaters For Shower

According to the power source, there are altogether three types of tankless water heaters for the shower, which include natural gas type, electric type, and propane type. Natural gas tankless water heater and propane tankless water heater are basically the same in user experience.

Electric tankless water heater for the shower is less powerful than gas models but is still able to meet the demand of a single bathroom or one bathroom and one faucet use the same time. It uses electric as main power and no ventilation facilities are needed in installation.

The natural gas tankless water heater is normally a large flow rate and high power type, it is capable of supporting multiple bathroom use the same time and is also able to be used as whole home type.

On using costs, the electric tankless water heater is a bit more expensive than gas types for long time use, but natural gas tankless water heater needs more upfront costs on installation and venting facilities purchasing.

electric tankless water heater for shower
best tankless water heater for shower

Tips On Installation

Working performance is to a large extent determined by the installation of tankless water heater; if you install it in the wrong way, the water leaks out and there are also potential dangers in using process. Therefore, in order to use it safely and prolongs its life expectancy, there are some tips you need to pay great attention to installation:

  1. For natural gas or propane tankless water heater, you should install it somewhere airy and never install it in the bathroom. Besides, the venting facilities must be added for indoor installation.
  2. Do not get the unit wet
  3. Install it somewhere convenient to operate
  4. For outdoor installation, there must be protection cover to protect the unit from complicated outdoor weathers
  5. Always install and use it under instructions
  6. If you lack relative knowledge on plumbing, get a professional to help you


Best TypeTankless Water Heater
Best selling typeRheem RTEX-13 Tankless Water Heater
Best electric type for small tiny homeEcoSmart ECO 27 Electric Tankless Water Heater
Best one for a large familyRinnai RUC98iN Ultra Series Tankless Water Heater

There are still many other types of tankless water heaters for the shower you can find and buy on Amazon; if you have interest in such item, please feel free to check the price and more details on products on Amazon, the constant discount will also help save much money for you.

Will Montgomery

Will Montgomery: Electro-Mechanical Engineer, Serial Entrepreneur, and Real Estate Enthusiast. Met David at Penn State, where he earned a BS in Electro-Mechanical Engineering and a minor in Business. Expertly manages capital equipment manufacturing, refurbishing, and repair businesses, while exploring opportunities in real estate and advocating for practical heating solutions.

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