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Point of Use Water Heater Buyers Guide: Finding the Best One for You

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It's not uncommon to see a point-of-use water heater near a sink. Due to their small size, they're often tucked under the counter where they can warm your water, yet be out-of-sight. Some are even a good fit for recreational use. There are two basic designs on how they operate. They can hold hot water (tank-style), or  provide instant hot water (tankless).

Selecting the right style and size can be tricky, especially if you don't want to waste money on an overpowered unit that'll deliver more hot water than you'll ever need. As a general rule, the more money you're willing to pay, the more hot water your water heater will be capable of delivering.

Best Point-of-Use Water Heaters

There's no shortage of Point-of-Use water heaters on the market today, but finding the right one for your needs can be a little tricky. We've complied 5 of our favorite POU water heaters, 3 are tank-style and 2 are tankless. Let's take a closer look at each: 

Bosch Tronic 3000 Mini-Tank

The Bosch Tronic 3000 Mini-Tank is one of the best selling point-of-use water heaters on the market. With three sizes to choose between (2.5-gallon4-gallon, and 7-gallon), you shouldn't have a problem finding the right one for your project.  

Bosch Electric Mini-Tank Water Heater Tronic 3000 T 2.5-Gallon (ES2.5)  - Eliminate Time for Hot Water - Shelf, Wall or Floor Mounted

The Bosch Tronic 3000 is a great mini tank water heater. Like all tank-style water heaters, maintenance is an important part of service life, but with a 6-year limited warranty, Bosch is definitely standing behind their product.

This unit can be installed in-line with your main water heater to reduce your wait time for hot water, or used as a stand alone unit. The 6-foot cord allows plenty of flexibility when installing, and being able to plug it into a 120-volt electrical outlet saves you from hiring a electrician.


  • The tank is glass-lined to protect it from corrosion, and it's well insulated to reduce standby heat loss. The unit has a thermal efficiency of 94%.
  • Compact, lightweight and easy to install. It can sit on shelf or be mounted to the wall.
  • The Tronic 3000 comes with a 6-ft cord that can plug directly into a standard 120-volt electrical outlet.


  • The temperature is controlled with a dial, which makes it not as accurate as a digital control. However, for the price of the unit, this is a minor annoyance.
Bosch Electric Mini-Tank Water Heater Tronic 3000 T 2.5-Gallon (ES2.5)  - Eliminate Time for Hot Water - Shelf, Wall or Floor Mounted

Bosch Tronic 3000 Mini-Tank

  • Capacity: 2.5-gallons (but also available in 4 and 7-gallons)
  • Dimensions: 13.75"W x 13.75"H x 10.75"D
  • Voltage: 120v plug-in
  • Max Amp: 12 amps
  • Warranty: 6-years tank

Stiebel Eltron 2.5 Mini Tank

It's hard to ignore Stiebel Eltron's products, they offer many different sized Point-of-Use tankless water heaters, but we especially like their Mini Tank series. These sleek European designed water heaters are available in three different sizes, a 2.5-gallon4-gallon and the larger 6-gallon model.

Stiebel Eltron 229729 4 gallon, 1300W, 120V SHC 4 Mini-Tank Electric Water Heater

Stiebel Eltron's Mini-Tank can be used as a stand-alone water heater or plumbed in-line with your main system and used as a booster to deliver hot water faster. The tank is well-insulated to reduce stand-by heat losses and increase the energy efficiency of the unit. 

A wall bracket is included and no special wiring is required since it can be plugged directly into a standard 120v outlet. If you're looking for a tank-style point-of-use water heater, this is an excellent pick.


  • Possibly the biggest advantage is the ease of installation. The 2.5-gallon can be plugged into a standard 120v electrical outlet. No need to call a electrician to hard wire it in.
  • Stiebel Eltron builds their products to last. The tank is glass-lined to protect it from corrosion. 
  • Making temperature adjustments are easy with the temperature adjustment dial located on the top of the unit. 


  • Purchasing the right sized tank is critical. Once the tank is depleted of hot water, it'll take about 18-minutes for it recover. 
Stiebel Eltron 229729 4 gallon, 1300W, 120V SHC 4 Mini-Tank Electric Water Heater

Stiebel Eltron Mini Tank

  • Capacity: 2.5-gallons (but also available in 4 and 6-gallons)
  • Dimensions: 18-11/16"H x 11"W x 10-5/8"D
  • Voltage: 120v plug-in
  • Amp: 11.3 amps
  • Warranty: 6-year tank

EcoSmart ECO Mini Tank

EcoSmart is well known for their tankless water heaters, but did you know they also offer point-of-use mini tanks? Well, they do, and there are four sizes to help you find the right one for your needs. If you just need a hand washing heater, the Eco Mini 1 is the right pick for you, but if you're looking for a little more hot water, check out the Eco Mini 2.5, or the Eco Mini 4, or even the Eco Mini 6.

Ecosmart ECO MINI 4 4-Gallon 120V Electric Mini Tank Water Heater

The EcoSmart ECO Mini Tank is a very versatile water heater. It's an effective heater for one or two hand sinks, but you can also plumb it to work as a booster to your main water heating system or if you have a gas tankless system it can solve the dreaded "cold water sandwich" issue.

Adjust the temperature with the easy to reach dial on the front of the unit. The power light lets you know when power is reaching the appliance, and the heating light is lit when water is being heated.


  • The tank is glass lined to protect against corrosion.
  • Easy to install and can fit into small spaces.
  • Power cord plugs into a standard 120-volt electrical outlet.
  • The heating element is replaceable and can be changed in the field.


  • The recovery time is a little long at 24-minutes.
Ecosmart ECO MINI 4 4-Gallon 120V Electric Mini Tank Water Heater

EcoSmart ECO Mini Tank

  • Capacity: 4-gallons (but also available in 1, 2.5, and 6-gallons)
  • Dimensions: 16.25" W x 17.5" H x 13" D
  • Voltage: 120v plug-in
  • Amp: 12 amps
  • Warranty: 5-years leaks

Rheem RTEX-08 Tankless Water Heater

If you want a point-of use tankless with a little more power, you should take a look at Rheem's RTEX-08. The RTEX-08 is the smallest unit in Rheem's very popular RTEX line that can handle multiple applications. It's capable of delivering a maximum flow rate of 4.8 gallons of hot water per minute.

Rheem 240V Heating Chamber RTEX-08 Residential Tankless Water Heater

Rheem is a trusted water heater manufacturer that offers a wide range of tankless and tank-style heaters. The RTEX-08 is perfect for situations when you need more hot water to service multiple applications. But Rheem does offer smaller units in this line-up, the RTEX-04 and the RTEX-06, which are designed exclusively for a sink.

The RTEX-08 is easy to install and comes with a 3-ft electrical cable. It'll need to be hard-wired to a 40 amp breaker, and it draws 240 volts. The unit fits nicely under a counter or a kitchen/bathroom sink. 


  • Copper immersion heating elements with brass threaded top. Designed for easy replacement.
  • External digital display shows the outlet temperature and can be adjusted in 1° increments so you can dial-in the perfect temperature.
  • The RTEX-08 can be used for a single appliance, such as a shower or sink, or its powerful enough to provide hot water for multiple applications simultaneously.


  • Although the RTEX-08 is a nice size for RV's, campers, and mobile homes, check your existing wiring before purchasing. It requires a 8 AWG wire size and a 40 amp breaker, which may not be available in all rigs.
Rheem 240V Heating Chamber RTEX-08 Residential Tankless Water Heater

Rheem RTEX-08 Tankless

  • Capacity: Tankless
  • Dimensions: 4" x 9" x 13"
  • Voltage: 240v
  • Amp: 33 amps
  • Warranty: 5-years heating chamber

EcoSmart POU 3.5 Tankless Water Heater

EcoSmart has two sizes in their Point-of-Use line-up. The POU 3.5 which runs on 3.5 kW and requires 120 volts, and the POU 6.0. The 6.0 has a bit more punch, and requires 220 volts. Either would make a good choice, depending on your hot water needs.

Ecosmart POU 3.5 Point of Use Electric Tankless Water Heater, 3.5KW@120-Volt

The EcoSmart POU 3.5 is designed specifically to be installed under the sink for a single application. EcoSmart does offer larger units that can handle multiple applications, such as a shower and a sink.

The POU 3.5 is ideal for a handwashing sink since it can deliver up to .50 gallons per minute of hot water. We recommend purchasing the POU 6.0 if you're looking for a heater to install in a wet bar or need just a little more power.

Installation is easy as no venting is required and the unit connects to a 1/2" NPT pipe fitting. The POU 3.5 is easy to operate and there are no filters to clean.


  • The EcoSmart line of tankless water heaters are extremely energy efficient. 99.8% of the electrical energy drawn goes to heating the water. This is an impressive number, even for electric tankless water heaters.
  • The heat exchanger is stainless steel, and the heating elements are made of copper and brass.
  • The set temperature is displayed on the digital temperature control.


  • Requires hard wiring, even though the POU 3.5 only draws 120 volts.
  • The 1-year warranty is a little tighter than many other manufacturer warranties, and the unit must be installed and registered within 30-days of purchase.
Ecosmart POU 3.5 Point of Use Electric Tankless Water Heater, 3.5KW@120-Volt

EcoSmart POU 3.5 Tankless

  • Capacity: Tankless
  • Dimensions: 3" x 11" x 6"
  • Voltage: 120v 
  • Amp: Requires a 30 amp breaker and 10 AWG wire
  • Warranty: 1-year tank

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Woman enjoying a hot bubble bath

Tank-Style Point-of-Use Buyers Guide

A tank-style point-of-use water heater uses a small tank to store the water until it's needed. Although, tank systems come in many different sizes, a true "small" water heater will have a tank size of 2.7-gallons to 7-gallons. But don't get caught-up in the "small" label. Focus on finding the right size to meet your needs.

Many top-of-the-line tank-style mini water heaters can be found for under $400, and some run far less. Stiebel Eltron makes a nice unit that's available in 3 different sizes, and Reliance has a popular 6-gallon unit

One of the most popular tank-style POU water heaters is the Bosch Tronic 3000. It comes in a variety of sizes, and is just a solid all-around good product.

This video explains how a tank-style point-of-use water heater works.

Watch the Video


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Selecting the Right Size

Tank-style water heaters measure capacity in terms of tank size.

Although, purchasing a tank-style mini water heater is pretty straight forward, there are a number of factors that you should consider to make sure you find the right size and set-up for your needs.

To determine the correct sized tank there are 2 factors that you need to consider: 

  • Tank Size - How much water the tank can hold.
  • Recovery Rate - The time needed to reheat the water within the tank.

Tank Size

Finding the capacity of the tank size is pretty straight forward. The larger the tank, the more hot water you'll have readily available. Most manufacturers offer POU heaters with a variety of different tank sizes, so you'll have several options to choose between.

Recovery Rate

The recovery rate is determined by the efficiency and wattage of the water heaters heating element. As a general rule of thumb, a heating element with a higher wattage should deliver a shorter recovery rate.

When the recovery rate takes less time to heat cold water, you'll spend less time waiting for the water to heat.  

That may sound simple, but it can be a big deal . . . especially if you're using your small water heater for a shower!

Plumber holding hoses and tools

POU Tank-Style Water Heater Applications

There are several different ways to set up your small tank-style water heater:

  • Standalone Water Heater
  • Water Heater Booster

Standalone Water Heater

One of the most common configurations is to install the small water heater directly to the water line so it'll function as a standalone water heater. 

In most cases, a small tank will be fine if you plan to use it for a hand sink or other low demand outputs. EcoSmart makes 4 small units specifically for low demand usage, such as hand sinks.

Or, you could purchase a larger tank for a wet bar or RV. Bosch offers a 7-gallon tank with their Bosch Tronic 3000 line-up. If you're planning on using it for a shower, dishwasher, etc. it's usually best to go for the larger tank size. 

A tank-style water heater can only deliver the amount of hot water within it's tank. Once the tank is depleted you'll have cold water until the unit can recover.

Water Heater Booster

If you're looking to give your main hot water system a boost, many units are designed with the option of installing it in-line with your home's main water heating system.  

When you open the hot water valve, you'll immediately have hot water delivered by the small water heater, thus eliminating the need to wait until the hot water runs through the plumbing from your main water heating system.

This configuration is nice since it's only meant to give your hot water a "boost" until the main system can deliver. Because of this, there's less pressure to purchase the right sized tank. A smaller tank can often carry the load until hot water from your household water heater runs through the plumbing.

This video shows the different installation options.

Watch the Video


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Holding a small and large tape measure

Tankless Point-of-Use Buyers Guide

Tankless water heaters are sometimes called flow-thru heaters because the water enters the unit cold and leaves hot. Since a tankless heater doesn't use a tank to store the water, the amount of water the unit can deliver is determined by its flow rate.

The flow rate is measured in gallons per minute (GPM) and it's the critical piece of information you need in order to properly size your water heater. Any small tankless water heater that delivers less than 2.25 GPM would fall in this category. Although a larger unit could be used as well.

There are many different brands available on the market today and most are at or below $300:

This video explains how a tankless point-of-use water heater works.

Watch the Video

Selecting the Right Size

When purchasing a tank-style water heater we look at the size of the tank, but a tankless system doesn't have a tank. Instead, they are sized by their flow rate.

Flow rate is simply the amount of hot water the tankless heater can deliver in a minute, and its often abbreviated as gpm (gallons per minute).

The flow rate is influenced by the temperature rise, which how warm the water heater needs to heat the incoming water. As an example, if the water coming into your home is 50°F and your water heater heats the water to 110°F, the temperature rise will be 60°F.

The higher the temperature rise, the lower the flow rate.

But it is important to note that sizing a point-of-use tankless water heater doesn't need to be exact. If you're simply looking for hot water for a hand sink or a wet bar, you most likely don't need to worry too much about how many gallons of hot water the unit can deliver per minute.

However, if you're looking for a POU tankless that can service more than one hot water source at a time, then we recommend using our tankless water heater sizing calculator. It'll do the math for you and provide you with the information you need to purchase the right size unit. 

Woman enjoying a hot shower

Tank vs. Tankless Point-of-Use Water Heater

Both tank-style and tankless point-of-use water heaters have their advantages and disadvantages, and before making a decision, there are a few things to consider.

Advantages of Tankless POU Water Heaters

  • One of advantage of choosing a tankless point-of-use water heater is the amount of space they require. Since they don't hold water within a tank, they simply require less space. They can be tucked under a counter, mounted on a wall or nearly anywhere else.
  • Tankless POU water heaters are also a great option if you need a water heater that'll be frequently used. Since hot water is always available, there isn't a worry about depleting the tank and needing to wait for it to reheat. This makes a tankless POU water heater a popular choice for hand washing stations at restaurants or other applications where there's a frequent demand of low volume hot water.

Disadvantages of Tankless POU Water Heaters

  • Many tankless POU water heaters draw more electricity than many homes can handle. The amperage requirements can be as high as 150 amps. A tank-style POU water heater is typically a better choice if you don't require a high volume of hot water.

Further Reading

We have many helpful guides and resources to help you find the right water heater. Here are two articles that address small water heaters specifically:


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