4 Best Under Sink Tankless Water Heater Reviews & Guides

Under sink tankless water heater refers to the heating machine installed mainly under the water sink no matter in the bathroom or in the kitchen. Of course, they can also be hooked on the wall, but the flow rate of it is quite small, some of which can support one single bathroom use, while others can use only for the faucet.

Under sink tankless water heater is also known as under counter tankless water heater, it is widely used for kitchen faucet and washing machine. The flow rate is hardly influenced by weather or climate.

Most of the tankless water heaters for the kitchen are electric types, they are more easy to be installed and needs no venting facilities. Battery operated design makes it convenient in using.

In order to better help you get the best under sink tankless water heater, we made a detailed review for you.

Top 4 Best Under Sink Tankless Water Heaters

ProductsNameRatings
small electric water heaterBosch Tronic 2.5-Gallon4.6
best tankless water heater for washing machineAtmor 27kW/240V4.5
best under sink tankless water heaterPrecisionTemp RV-5504.5
best tankless water heater for kitchenEcosmart POU 3.5 Point of Use4.3

Best Under Sink Tankless Water Heaters Reviews

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

best undercounter tankless water heater
best undercounter tankless water heaters

 

 

 

This is a tank water heater, a small amount of water is stored in its mini tank. The compact and small shape enables you to install it anywhere that is convenient. But for fast heating time, you had better install it under the water sink.

The flow rate of it is 2.5 gallons per minute, and it supports for sink only, not suitable for bathing. You can hang it on the wall or on the floor, the installation of it is quite simple and straight forward.

The operation of it is also quite simple, you need only plug it into the outlet and it starts to work, no complicated machinery is needed in the whole process. Hot water can be recovered soon to eliminate the long waiting time for hot water.

However, the only shortcoming is that it lacks consistency on water temperature, each time when you turn the tap off, you need to wait another few seconds to heat it up.

Pros:

  1. Compact design
  2. Easy to be installed
  3. Short waiting time for hot water
  4. 2.5 gallons water flow
  5. Cheap price

Cons:

  1. Lack of consistency on water temperature
  2. Not suitable for large home use


2. Atmor 27kW/240V Electric Tankless Water Heater

best tankless water heater for washing machine
under sink tankless water heater

 

 

 

This tankless water heater can be installed either under the sink or on the wall of the bathroom or kitchen. The temperature range is between 90 and 135 degrees F. Its small footprint saves much space for you.

It has digital temperature control to set temperature in an increment of 1 degree, so you can adjust the most suitable temperature in bathing or handwashing. The ThermoPro self-modulating system will automatically regulate the energy required to heat water, and it heats water only when hot water is needed.

It can also detect water flow automatically, it turns on and off all by itself, thus greatly eliminating wasted water flow and lowering water consumption. However, you need to install a pressure relief device and it has to be bought from the manufacturer only.

As for internal material, durable stainless steel with its perfect corrosion resistance performance prolongs the life expectancy of the unit.

Pros:

  1. Light weighted, only 17 pounds
  2. Digital temperature control
  3. Energy efficient
  4. Self adjusting system equipped
  5. Automatically detect water flow
  6. Small footprint

Cons:

Need to install a pressure relief


3. PrecisionTemp RV-550 Tankless Water Heater

under sink tankless water heater
best tankless water heater for sink

 

 

 

This tankless water is another type of under sink tankless water heater, apart from small tiny home use, it can also be used for trailers, mobile washing services, and RVs. Being a propane tankless water heater, it uses less propane, only 20 pounds of propane and you can get 940-gallon hot water.

It needs approximately 1.5 amp for the normal condition or warm regions, but in winter, you may need 3 amps to activate it up. It weighs about 32 pounds, it takes up the half size of space and weighs 1/3 as much as a 10-gallon tank.

The hot water output is 55000 BTU per hour. Free protection system allows the burner to fire and all the electric elements are activated once it senses the cold weather, so as to take action on protecting the machine.

Pros:

  1. Wide range of applications
  2. Free protection system
  3. Space saver
  4. Automatic gas modulation
  5. Energy efficient

Cons:

The waiting time for hot water is a bit long, takes about 1 minute


4. Ecosmart POU 3.5 Point of Use Electric Tankless Water Heater

best tankless water heater for kitchen
best undercounter tankless water heaters

 

 

 

This is a point of use tankless water heater, and is specifically installed under water sink for faucet use. The maximum flow rate is 0.5 gallons per minute, which is quite low but able to meet the demand of faucets use.

Though in small shape, it is also equipped with the advanced flow control system, according to the change of flow rate, the water temperature will adjust automatically. It proves to save up 60% on water heating costs for long term use.

It is the smallest EcoSmart tankless water heater and can support only one sink a time. And the lowest inlet water temperature is 57 degrees F, which means it activates only when the inlet water temperature is above 57 degrees F.

Because of its small shape and lightweight design, it can be perfectly used for recreational vehicles (RVs), boats and offices.

Pros:

  1. Save up 60% on water heating costs
  2. High energy efficient
  3. Suitable for under-sink use
  4. Flow control system
  5. Compact shape

Cons:

The waiting time for hot water is long


Features Of Under Sink Tankless Water Heater

1. Compact and small size

The under sink tankless water heater is normally designed small and compact, you can install it anywhere that is convenient, but of course the most commonplace is to install it underwater sink. Thus it saves much space in your home especially for tiny or small studios.

2. Easy installation

The under sink tankless water heaters are normally electric types, no complicated machinery is added, thus the installation process is quite simple and straight forward. You can totally install it by yourself and it takes only a few minutes.

3. Faucet use only

Being a small flow rate tankless water heater, the power of it is quite small and is not capable of supporting bathroom use. If you intend to use it for bathing, you need to get a tankless water heater for a shower or just order a whole house model. The maximum flow rate of under sink tankless water heater is only 2.5 GPM, which means you can use it for faucet use only.

4. Fast heating time

As it is installed right near the application fixture, the distance between heater and tap is short, thus hot water flows rapidly to destination spots.

5. Constant hot water supply

For under sink tankless water heater for kitchen use, you need to turn on and off the tap frequently in washing dishes or doing laundries, therefore, it is capable enough to provide constant hot water and heats water instantly to meet urgent needs.

best undercounter tankless water heater
best under counter tankless water heaters

FAQ:

1. Can the under sink tankless water heater used for bathing?

Some of the large power and large flow rate under sink tankless water heaters can be used as a bathing heater, but some of which are relatively low in power. If you intend to use it for a bath, it can not offer enough hot water for you.

Therefore, if you want a tankless water heater for shower, you can get a large flow rate one.

2. Are tankless water heaters good for restaurants?

Restaurants need a large sum of hot water and must heat water in a second to meet the busy and urgent needs, you can get several under sink tankless water heaters for restaurants use, but the costs are of course not a small deal.

Summary

All above-recommended products can be regarded as the best tankless water heater for the kitchen, for washing machine and also for the sink. They are designed pretty compact and small, suitable for tiny studio use.

To sum up, we picked out three best types according to different needs for you:

Best Type Tankless Water Heater
Best point of use type Bosch Tronic 2.5-Gallon Mini-Tank Water Heater
Best under sink type Atmor 27kW/240V Tankless Water Heater
Best one for RV use PrecisionTemp RV-550 Tankless Water Heater

There are also many types of under sink tankless water heaters on the market, to get one in the most reliable way, Amazon can be your best choice. Constant discount will save much money for you. If you have intention on the item, please feel free to check on Amazon.