4 Best Under Sink Tankless Water Heater Reviews & Guides 2020

The under-sink tankless water heater is the machine that can be installed under kitchen counters, sinks, or even in the restroom closet. These are small units that are mounted under a sink to supply hot water directly to the faucet.


These are also called a point of use tankless water heaters or under counter tankless water heaters. Compact in size, these are trendy tankless water heaters that can be installed anywhere without any complicated wiring. Also, they are equipped with multiple features that make them better than tank water heaters.


These units are small in size but are efficient and effective. They can save up to 50% on electricity bills every month. Since they are designed to provide a continuous supply of hot water for smaller uses, they support single bathroom use or kitchen faucet. The best thing about under sink water heaters is that they Eco-friendly.


If you are looking for a new age water heater that provides sufficient hot water and saves energy, then under sink tankless water heater is the right choice. We have done a detailed review to help you with your shopping.

Best Under Sink Tankless Water Heaters Reviews:

1. Bosch Tronic 2.5-Gallon Electric Mini-Tank Water Heater

It is a good quality mini-tank water heater and is easy to maintain. It is a perfect unit for those who cannot bear the fluctuation of hot water. With a flow rate of 2.7 gallons per minute, it is not suitable for large hot water requirements. It requires about 120 volts to heat water.


To guarantee a long service life, it has a glass linked tank. Since it is a mini-tank water heater, it may give the impression that it is not easy to carry or place. But the fact is you can hang or place it anywhere without making any changes to that area. Bosch Tronic 2.5 gallon electric water heater is easy to install, so you don’t need to call any fancy plumbers.

You need to take care of the maintenance of the unit as it may leak, which actually arises a question on the durability of the unit.

Bosch Tronic 2.5-Gallon


  • External digital dial to control the temperature range
  • Compact design
  • Easy to install and operate
  • The flow rate of 2.5 gallons per minute
  • Heats water in less than ten minutes


  • Lacks consistency on water temperature
  • Not for large hot water requirements
  • Water may leak from pressure valves
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2. Atmor 27kW/240V Electric Tankless Water Heater

If you are looking for a tankless water heater that can save up to 50% on your electric bills, then Atmor 27kW/240 is the right choice. Install it either under the sink or hang it on the wall of your kitchen or bathroom; it will provide hot water on demand.


It features a digital temperature control that allows the user to set the temperature in increments of 1 degree. The unit detects the water flow automatically and reduces the wastewater flow. It features corrosion resistance that allows for heat efficiency. The stainless steel interior is durable. The unit has a splash-proof certification, which means you can install it anywhere near a sink and shower etc. It comes with a warranty of two years on its parts and seven years for no leaks.

Atmor 27kW240V


  • Digital temperature control
  • Self-adjusting system
  • Detects water flow automatically
  • Splash-proof certification
  • Energy-efficient
  • Corrosion resistance performance


  • You may need to install a pressure relief
  • The warranty is not the best.
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3. PrecisionTemp RV-550 Tankless Water Heater

It is an under sink tankless water heater specially designed for small households, cabins, trailers, and RVs. It is a four-season unit that gives you the endless supply of hot water on demand. PrecisionTemp RV-550 is an under sink tankless water heater that is light in weight and compact in size.


It features VariFlame technology that makes it stand out from competitors. The unit presents a stainless steel construction that which makes it a durable product. The best thing about this under sink tankless water heater is that it adjusts the amount of gas to the incoming water temperature. Under normal circumstances, it requires 1.5 amps of power.

PrecisionTemp RV-550


  • Automatic gas modulation
  • Compact in size
  • Supplies hot water instantly
  • Energy efficient
  • Patented VariFlow Technology


  • Need to winterize the unit
  • A bit expensive
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4. Ecosmart POU 3.5 Point of Use Electric Tankless Water Heater:

It is a point of use tankless water heater that provides a flow rate of 0.5 gallons per minute. It supplies hot water to only one faucet, which means it is not suitable for big homes. The water temperature adjusts according to the change of flow automatically. It is small in size and light in weight, which means you can use it in RVs, boats, and offices too. It saves up to 60% on energy bills.

Ecosmart POU 3.5 Point of Use


  • Energy-efficient
  • The advanced flow control system
  • Light in weight
  • Compact in shape
  • Perfect for recreational vehicles


  • Suitable for one sink only
  • Waiting time to heat water is long
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Features of under sink tankless water heater:

Features of under sink tankless water heater

1. Easy Installation:

The best thing about the under sink tankless water heaters is that the installation process is quite simple and easy. You do not need to call fancy plumbers and electricians to install these units. These water heaters are mostly electric type, and you can install it by yourself.

2. Fast heating time:

These are under counter water heaters, which means you can install them near the application fixture. As a result, you can get hot water without waiting for too long.

3. Compact in size:

Under-sink tankless water heaters are compact and small in size. They are designed to be installed under the sink so that you can save space. They are perfect for those living in small homes and have no extra space to install bulky tank water heaters.

4. The constant supply of hot water:

Since it is an on-demand water heater, it provides a continuous supply of hot water without any interruption. No matter you are washing the dishes or doing laundry, turn the tap on, and off frequently, you will get hot water without any difficulty.

5. Faucet use only:

With a maximum flow rate of 2.5 GPM under sink tankless water heater is only for faucet use. It does not support bathroom use. It is a small flow rate tankless water heater which cannot supply hot water for the whole house.

6. Fuel source:

Under sink tankless water heaters can run on different fuel sources such as propane, electricity, and gas. You should choose a unit according to the fuel source that is easily available to you. Make sure you choose a hot water heater model that is cost-effective for you.

FAQ: (People Also Ask)

Q: What is a hot water booster?

Ans: It is a small device that is attached or installed directly on the water line to provide more hot water. It can double your shower time.

Q: Can I use under sink tankless water heaters for bathing?

Ans: With a maximum flow rate of 2.5 GPM under sink tankless water heaters are for faucet use only. However, if you want to use them for bathing, you need to get a unit with a larger flow rate.

Q: Are Tankless Water Heaters Good For Restaurants?

Ans: No, not really. In restaurants, you require a continuous supply of hot water on all the faucets and taps. Under sink tankless water heaters have a low flow rate and do not meet large hot water requirements.


All the four water heaters mentioned above are perfect for your kitchen and bathroom etc. as you can install them under sink or counter. They are compact and small in size, which makes them the right choice for tiny studio use. No matter what type of heater you buy, make sure that it consumes less energy and is cost-efficient. Tankless water heaters are perfect for small homes because they occupy less space than tank water heaters.

We have given detailed reviews of these four products to make sure that you buy the best one. Take a look at the pros and cons of each unit to decide which one is the best. Here we have picked our top three units for you:

Best point of use type

Bosch Tronic 2.5-Gallon
Bosch Tronic 2.5-Gallon Mini-Tank Water Heater

Best under sink type

Atmor 27kW240V
Atmor 27kW/240V Tankless Water Heater

Best one for RV use

PrecisionTemp RV-550
PrecisionTemp RV-550 Tankless Water Heater

They heat the water fast and help you save money on energy bills every month. If you are getting attracted to the efficiency of these units, then check them on Amazon Now and enjoy a hot bath in chilling weather.