Best Under Sink Tankless Water Heater – Review + Buying Guide 2021

Groundbreaking scientific and technological inventions have made our daily life easier and better than the life of our ancestors.

One of the countless technological creations that have improved our lifestyle and made it luxurious is the best under sink tankless water heater. 

They provide you an endless stream of warm water instantly whenever you want, which is especially favorable during the freezing weather.

Trendy, portable, compact, energy-efficient, and affordable, these appliances are capable of resolving all the problems associated with chilly weather.

They are perfect for both domestic and commercial applications as they can deposit up to 7 GPM and operate silently.

Moreover, as the name suggests, these tiny machines are designed to be installed under the sink, kitchen counter, closet, RV, and any other non-traditional location in the residence.

You may have decided to purchase an under sink water heater for dishwasher, but you may be unaware of where to start from or which heater can cater to your needs proficiently.

There are tons of options available in the market, so picking the absolute perfect one according to your requirements can be difficult.

That’s why; we have designed this extensive buying guide in which we have reviewed the top ten best under sink water heater for shower.

Also, we will go through a couple of things worth considering such as recovery rate, weight, warranty, heater type, and much more before buying the unit.

10 Best Under Sink Tankless Water Heater

1. Bosch Electric Mini-Tank Water Heater Tronic 3000 T 4-Gallon – Bosch under sink water heater

The bosch under sink water heater is a point of use device that is available in three different sizes: 2.5 GPM, 4 GPM, and 7 GPM. It is an optimal choice for folks with lower warm water needs.

High-quality glass-lined material is used for its construction so that it will last as long as possible. A thick layer of CFC-free foam is used for its insulation that provides maximum energy efficiency and 98% thermal efficiency.

You can place it underneath the sink or mount it on the wall, thanks to its compact size. It is ideal for delivering warm water in one area.

This unit features a 2-year parts warranty and a 6-year warranty for the boiler itself. You can combine it with a larger heating source or use it alone under the sink.

Its simple yet stylish design can blend perfectly with your home décor. On the other hand, it has a built-in thermostat that allows you to select between “max”, “min, and “ideal”.

The Bosch electric mini-tank water heater has a smaller tank, but it does not mean you will obtain water for a single sink or application only, definitely not at once.

It is not an ideal option for getting water for multiple showers or large washing machine, as it is designed to be used in one area.

The nice thing about this product is that it supplies water instantly. It requires one or less minute to provide you water and when you turn off the fixture, it deposits the leftover water.

The downside of this cost-effective under sink water heater for shower is that its thermostat is too straightforward. It becomes intricate for users to determine the exact temperature since the temperature range is extensive.

Furthermore, if you want to put it on the floor, you will need a stabilizer to prevent it from moving because it has a curved bottom.  

Specifications:

2. EcoSmart ECO 11 Electric Tankless Water Heater – Under sink water heater for dishwasher

Purchasing the best under sink tankless water heater is an outstanding way to save power and decrease monthly energy bills while getting limitless hot water simultaneously.

As there are a wide variety of tankless heaters available, so it is difficult to decide which one to pick.

If you are on the outlook for a pocket-friendly, high-performance, and energy-smart appliance, you should give a shot to EcoSmart Eco 11 tankless water heater.

It is an electric device, which means it does not work with flames or burners. Also, it does not require a venting system, so the installation will be effortless and affordable.

Moreover, it boasts a sleek and compact size, so you have the liberty to hang it at your favorite location. This remarkable heater can heat water to 105 degrees F quickly.

Once the water reaches this temperature, it delivers water in various pipes. It comes with digital temperature control that permits you to alter the temperature in one-degree increments.

The controls provide you maximum control and assure regularity in generating warm water. However, when the temperature is less than 67 degrees F, its performance will be affected.

You may have to experience a decreased water temperature or water flow rate. This machine is an exceptional choice for those who want to cut down their energy expenses.

Depending on your location and fuel type, you can save hundreds of dollars annually. The manufacturer claims that this unit can help you save approximately 60% on your power bills.

Best of all, it works only when you activate the faucet or stops working when you turn it off. The residential machine is covered by a lifetime warranty. It encloses the heat exchanger, parts, and electronics of the unit.

Specifications:

3. Camplux ME25 Mini Tank Electric Water Heater – Under sink water heater for shower

Are you looking for an eye-catching appliance that can enhance your residence’s beauty? Camplux ME25 Mini Tank Electric Water Heater can be a fantastic addition to your property.

It delivers hot water whenever you need it without making you wait for too long. This 2.5 GPM device is easier to install and you can hang it anywhere such as under the sink, in the attic, or the bathroom.

The tank is made of glass-lined material, which means it has a long service life. The lining offers admirable insulation and prolonged sturdiness.

You will have to connect this under sink water heater for dishwasher to a cold water tap and it will produce warm water at your desired temperatures.

Furthermore, this mini-unit can cut down your electricity bills significantly because it is highly energy-efficient. It is extremely lightweight and vaunts a compact design that helps you save space.

The exciting thing about it is that you can take advantage of it as a heater for single sinks or connect it with a bigger device that may be at a distance from the unit sink.

Besides, it comes with thermostat control that lets you easily fine-tune the water temperature. Once you set it, it will automatically regulate the temperature.

It has a red light that stays on when it is heating the water. It equips overheating protection system that safeguards it from overheating.

If the water deposited in the container is not used for an extended duration, there is a greater chance of freezing. However, you don’t have to worry about the water freezing with this appliance.

It features a thermostat knob that can be rotated to the snowflake mode for frost protection. Otherwise, you can disconnect it from electricity and drain the water.

This high-performance heater integrates an external dial that empowers you to control the temperature ranges. Additionally, it incorporates temperature and pressure relief valves.

Specifications:

4. Ariston GL6+S Electric Mini-Tank Water Heater

Bosch is one of our forever favorite companies, and this model is one of their best under sink tankless water heaters. It is capable of providing adequate warm water for a big household.

If you are tired of running out of hot water before you finish your shower, then this unit is perfect. It comes with a 6 gallons water container that is quite big. Its length is 14.5 inches and its weight is 30 pounds. 

The point-of-use machine eliminates the wait time and gives you instant warm water. You can hang it independently or connect it with a bigger water heating source.

A good thing about it is that it does not require hard wiring; simply plug its switch into an electric outlet and it is ready to use. Moreover, a glass-lined boiler ensures long service life.

The excellent insulation provides rapid recovery with enhanced energy efficiency. Best of all, it is backed with a 6-year limited heat exchanger warranty and a 1-year limited parts warranty.

As it features a compact size, so installing tankless water heater under sink will be stress-free. Its downside is that it takes approximately ten minutes to heat the water.

This might be due to the bigger container. Some customers said its recovery time is a tad bit longer than other under sink heaters.

Specifications:

5. Stiebel Eltron 220816 Sink Tankless Electric Water Heater

German brand “Stiebel Eltron” has been serving its consumers for several years and its users are extremely content with its products.

They are ruling over the water heater industry with their high-quality, affordable, and highly energy-efficient products combined with the greatest features.

The manufacturer claims that their heaters are capable of eliminating standby heat losses. If we talk about this particular product, it heats the water instantly once you turn on the faucet.

The design is lightweight and compact, so you can save considerable storage space. This under sink water heater for shower is an incredible option for offices, houses, RVs, schools, and restaurants.

For its installation, you won’t have to worry about plumbing or wiring. A nice thing about it is that it is highly energy-efficient.

Typically, under the sink devices skyrocket the energy bills by 30 percent per month, but this machine promises not to put a burden on your pocket when it comes to water and power expenses.

Additionally, it does not need a pressure relief valve, circulating pump, and venting system. Best of all, it flaunts a 7-year leakage and a 3-year parts warranty.

It includes a pre-wired pigtail for electrical connection that makes hard-wired installation straightforward and faster. The only downside of this appliance is that it has a limited flow rate.

Specifications:

6. Bosch Electric Mini-Tank Water Heater Tronic 3000 T 2.5-Gallon (ES2.5) – Bosch electric mini-tank water heater

It is another fantastic electric tankless water heater by Bosch. This 2.5 gallons mini-tank unit is specifically designed for installation beneath the sink.

It is available in three sizes: 2.5, 4, and 7 gallons. You can use it in two diverse ways: hang it onto the wall or place it on the floor.

It features a compact size and weighs only 15.5 LBS, so you can easily fit it at your desired location. The Italian design may seem a little bit out-dated, but it is elegant and eye-catching nonetheless.  

The maintenance of bosch under sink water heater is easier. Its tank is glass-lined, so it safeguards the appliance and ensures extended service life.

If you want to install it independently under the sink, you will need a 120v electrical outlet to plug it in.

However, you also have the option to link it up with a large heating source for acquiring a large volume of hot water. Its hose is 10 inches long and the temperature ranges from 65 to 150 degrees F.

You can use it in offices, schools, homes, RVs, boats, mobile homes, and anywhere you want. Regardless of where you install it, you can start using it right after its installation.

As it is an older model, so it won’t offer you modern functionalities like other Bosch heaters. The thermal efficiency of this machine is 98%.

Specifications:

7. Waste King AH-1300-C Quick and Hot Instant Hot Water Tank

Waste King is a lesser-known brand, but their products are very good enough. This best under sink tankless water heater provides you limitless warm water at 190 degrees F.

It works faster and has a compact design. We have included it in our list because of its superb functions. It heats 60 cups of water in just 60 minutes.

The best thing is that you can replace it if some glitch or malfunction occurs in it. Furthermore, it features a thermostat that lets you change the temperature as per your needs at any moment.

If you don’t want to wait for a long time to obtain warm water, you can install this device in your house as it generates the water in a few seconds.

You can link it with your hot water tap and use the water for taking shower, making coffee or tea, cooking, or washing dishes.

As it is smaller in size, so you can install it anywhere in your house, office, café, or restaurant. The tank is made of stainless steel, so it will last longer.

According to the reviews, Waste King AH-1300-C integrates many modern functions that can make your life easier.

This appliance can be an excellent replacement for tank storage heaters. The only disadvantage of it is that it tends to overheat. Self-resetting Therma fuse protects it from overheating.

Specifications:

8. Ecosmart ECO MINI 2.5 2.5-Gallon 120V Electric Mini-Tank Water Heater

Do you need a heater that can heat the water faster? If so, you can give a shot to Ecosmart ECO MINI 2.5-Gallon tankless heater.

We are all aware that older pipes take a long time to warm up the water, but this tiny appliance won’t make you wait for too long.

It does not store water in the tank, so when you turn on the faucet, you start getting the water. If we talk about its weight, it is lightweight and compact so that the deployment process will be much easier and convenient.

The unit weighs only 15.8 pounds, and its total dimensions are 16.2 x 11 x 11 inches so that you can fix it under the sink.

To obtain water, you will have to plug it in the power outlet and put it on the stand or shelf to heat the cold water. If you have a small house or apartment, the sleek and compact design will be beneficial for you.

It decreases the requirement of recirculating pumps and lines, but it must be mounted in a vertical orientation.

Along with that, the residential Ecosmart ECO MINI 2.5 device has a pressure and temperature relief valve that helps you release the pressure at 50 and 140 degrees F and shield the unit from excess pressure and temperature by releasing water.

Moreover, you can utilize this under sink water heater for shower, buffer, and point-of-use applications. Best of all, it is less expensive than other under the sink heaters. 

Specifications:

9. Stiebel Eltron 233219 Electric Water Heater

This water heater is made by the German brand “Stiebel Eltron” which is renowned for making superior quality products in the industry. It is anticipated to help users save energy, water, and ultimately, their hard-earned money.

It will give you instant warm water whenever you require it. The electric unit features a nice, innovative design, making it a tad bit good looking than other under-sink models available out there.

It is the best under sink tankless water heater that is obtainable at a very reasonable price. Furthermore, as it has a space-saving design, so installing tankless water heater under sink or at any other non-traditional place will be easier.

It is your personal choice whether you want to put it on the wall or the floor. To get water from it, you simply have to plug it into a 120v power outlet.

The good news is that it solely draws 11 amps, so you won’t have to invest money in upgrading your house’s power system.

Its temperature is easier to regulate as it comes with a thermostat dial that can be found on the machine’s top. You can adjust the temp between 86 and 140 degrees F.

Additionally, it does not get extremely hot as other heaters, so it is safer to use. The premium quality glass-lined tank will last longer and has a 6-year warranty.  

Specifications:

10. Eccotemp EM-2.5 Electric 2.5-Gallon Mini Tank Water Heater 

This product is again coming from a famous and reliable brand “Eccotemp” that has been operating in the industry for a long time.

The Eccotemp EM-2.5 water heating machine comes with a smaller 2.5-gallon boiler, but it has a mind-blowing heating performance.

It incorporates numerous features, but the noteworthy one is its temperature controller. The temperature regulator enables you to increase or decrease the temperature from 50 and 140 degrees F.

It is highly suitable for under the sink installation. However, you can also deploy it in the kitchen, bathroom, RV, or any other place you want.  

The under sink water heater for dishwasher boasts a compact construction, so you can hang it on the wall if you want to save precious space.

Besides, this unit has the fastest recovery rate, so you can acquire instant and on-demand water. Along with that, it also arms a pressure and temperature relief valve which elevates your safety and defends the machine at the same time.

It comes with a 5-year warranty, so it is an outstanding deal for individuals who want a device that is actually effective and not falsely advertised. According to reviews, it is a little bit slow in its working compared to other heaters.

Specifications:

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Imperative Things To Consider While Buying The Best Under Sink Tankless Water Heater

There are plenty of factors you have to consider while buying the right unit for your needs. Below is the list of essential elements you have to remember during your shopping.

Capacity

It does not matter if you are looking for an under the sink or over the sink device, you must consider its capacity and demand.

With the tank-style units, you can easily figure out the meaning. The tank refers to how many gallons the tank can store in it.

On the other hand, tankless machines don’t have a container, so you will have to determine how many liters of water they produce in one minute.

First, determine how many liters you need regularly, what your area’s cold water temperature is, and how high you want the unit to raise its temperature.

Flow Rate

The heater’s flow rate is estimated in gallons per minute. The higher flow rate means the machine can generate water easily. If its flow rate is one GPM, it can heat only one gallon in 60 seconds.

Therefore, if you need more water, you need to pick the one with a higher GPM so that you can enjoy an uninterrupted supply of water.

Voltage

You must also consider the electrical equipment’s voltage. Make sure to check that the power outlet you utilize can competently handle the new unit’s energy needs. Many models use 110v and 120v, but there are some that use 220v or even more.

Energy Rating

Regardless of which type of appliance you are going to buy, you should determine its energy rating. Energy rating determines the heater’s capacity to work efficiently without using excessive energy.

If an under-sink unit has a higher energy rating, it means it can offer you a higher volume of water without consuming too much energy.

Heating Power

The bosch electric mini-tank water heater’s heating power refers to the power it utilizes for heating the cold water. Devices with less heating power can’t create a large amount of hot water.

The number of KW it needs is reliant on how many gallons of water you need per minute. Units with high heating power can heat huge water quantities faster and offer a higher temperature rise. 

Maintenance And Installation

All heaters involve diverse types of deployment and maintenance. The plug-in units are easier to install. Some appliances require additional hard wiring and electrical work.

If you can’t handle the plumbing and electrical work, it is better to hire professional services. Also, read all the maintenance requirements and instructions before buying the product.

Tank Or Tankless

The selection of a tank or tankless machine for your needs depends on various factors. The upfront price of tankless units is higher compared to tank-style ones.

Besides, they are environment-friendly, compact, more energy-efficient, and provide unlimited water on-demand.

On the other hand, tank-style heaters require more energy, space, and frequently run out of water if you have higher hot water needs.

Warranty

You should always buy an appliance with a warranty. The heater’s warranty terms might vary from brand to brand. Pick a model that offers a longer guarantee because it is an indication of reliability and robustness.

Many units are covered by a 5 to 7 years warranty, but some of them are backed up by a lifetime guarantee as well.

Perks Of Installing Tankless Water Heater Under Sink

• They can reduce heating expenditures by 50% including energy and water consumption.
• It serves one or two sinks for dishwashing and hand washing.
• You save money in the long run as it eliminates the requirement for recirculation pumps and lines.
• They save water because they are used whenever you need water.
• You can hang them anywhere such as laundry, garage, cabin, RV, office, and under the sink.
• A tiny and compact heater does not consume much storage space.
• You can choose between a tank and a tankless unit to get hot water.
• You can set the temperature by using the temperature knob.
• They are available at a reasonable price.
• It has an attention-grabbing design and equips several important features.
• Under-sink units are dependable, safe, and energy-smart.
• They are easier to install as almost all manufacturers provide installation guide.
• You can fix them on the wall or floor.

Drawbacks Of The Under Sink Water Heater For Shower

• Some products are high performing, so you will have to invest a heavy amount for buying them.
• The modern units consume more energy, so you can expect increased energy bills.
• They require periodic maintenance. So, you will have to hire professional services for a regular inspection for leaks, limescale buildup, and other problems.

How To Install The Under Sink Tankless Heater?

1. Hang the device on the wall and attach the water source to the machine’s inlet side.
2. Then, link a pipe to the unit’s outlet fitting.
3. Make sure, you have connected all the plumbing correctly.
4. Now, check you have the appropriate electrical wiring to support your heater.
5. Attach the wires to the appliance and circuit breaker.

Frequently Asked Questions