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Small Water Heater Reviews: Tank-Style and Tankless

Small Water Heater Reviews

A small water heater can fill a variety of different needs; from a commercial hand sink, to an under served bathroom far from your home's main hot water heater. Tiny home, RV and boat owners can squeeze these units into tight places, and small businesses such as food carts and mobile pet washing vans all enjoy the features and convenience these powerful little units are designed to deliver.

Full-sized water heaters with a tank size of 30-gallons are often considered small in capacity, but they are rarely small in their physical size. They're also typically used as a whole house water heating system. In this article, we'll focus on the small water heaters that are installed near a point-of-use, such as a sink or bathroom. These systems are given a very specific task, which is to deliver hot water fast to the sink to which it is attached.

Benefits of a Small Water Heater

In most cases small water heaters are used to boost your home's main water heater by providing hot water at the point-of-use. Some household rooms are not well served by the main water heating system and this results in water taking a great deal of time to reach the faucet. A small water heater installed under a sink (or within a room) is a great alternative to solving this problem, and many are relatively inexpensive!

Here are a few of the benefits a point-of-use water heater can offer:

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    Improved Water Pressure: Since point-of-use water heaters are installed at the source where hot water is needed, there's an immediate increase in water pressure. This can be especially helpful in older homes where pipes and systems frequently can't deliver efficiently.
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    Improved Water Temperature: With a water heater installed closer, hot water can be delivered nearly instantaneously. Not only does this mean you'll spend less time waiting for hot water, but your overall water consumption will also be lower, saving you money on your water bill.  
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    Environmentally Friendly: Less water is wasted waiting for hot water. Installing a tankless point-of-use water heater can even reduce your carbon footprint.
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     Eliminates the need for installing a circulating pump to your main water heater. 
  • Read our Buyers Guide to help you properly select the right small water heater.

Tank-Style Small Water Heaters


  • Easy Installation
  • Easy Replacement


  • Standby Heat Loss
  • Shorter Life Span
  • Large and Bulky

Reliance Compact Water Heater

Model: 6 6 SOMS K

Capacity: 6-Gallon

Power: 120-volt 

Wall Mount: No

Dimensions: 15.2 x 14.1 x 14.1 inches

Warranty: 6 years

The Reliance Compact line is a very practical choice for a small water heater. This unit should be able to deliver more than enough hot water for a  frequently used hand sink, and it comes with a 6-year warranty on the tank and parts, and 1-year labor. 

There's a single 1650-watt, 120-volt copper sheathed heating element within the glass-lined 6-gallon tank. An anode rod is also installed to offer additional protection from tank and component corrosion, and to maximize safety, the T&P (Temperature & Pressure) Relief Valve is factory installed.

The Reliance Compact unit should be able to fit into nearly any tight space, whether it is tucked out of the way under the counter, on a shelf,  or within a crawl space. As a convenience, the water inlet and outlet connections are positioned on the side of the tank, but there are also optional connection points located on the top. 

Also available in the following size:

The Bottom Line

The Reliance Compact Water Heater is a solid choice. It's designed to fit into tight spaces and is reasonably priced. The 6-year warranty means the company stands behind their products and you can rest at ease. 

Rating: 4.5 out of 5

Bosch Tronic Mini-Tank Water Heater

Model: ES4

Capacity: 4-Gallon

Power: 12-amp / 120-volt

Wall Mount: Optional

Dimensions: 13.8 x 13.5 x 13.8 inches

Warranty: 6-year tank /  2-years parts

With the enclosed optional wall mount, the Bosch Tronic 3000T series can fit into nearly any space where you need a hot water boost. The 4-gallon (and 2.5-gallon) units can be plugged into a standard outlet, but the more powerful 7-gallon will need to be hardwired.

The tank is glass lined for added corrosion protection, and to as increase the unit's service life. There's also a factory installed T&P valve. 

Bosch's space saving mini-tanks are lightweight and compact, and they're designed with the option of working independently or in conjunction with your household water heating system. 

Available in the following sizes:

  • Model: ES2.5  / 2.5-gallon capacity 
  • Model:  ES8  / 7-gallon capacity
The Bottom Line

This competitively priced Mini-Tank Water Heater from Bosch is not only easy to install, but also offers a respectable 6-year warranty against tank leaks. With a temperature range between 65 to 145 degrees, and 3 tank sizes to choose between, you should be able to find the right model to meet your needs. 

Rating: 4.5 out of 5

Rheem 20-Gallon Point-of-Use Water Heater

Model: PROE20 1 RH POU

Capacity: 20-Gallon

Power: 120-volt

Wall Mount: Optional

Dimensions: 15 x 15 x 30 inches

Warranty: 6-year tank and parts

Rheem has a solid reputation for quality in the hot water heater industry, and the company's impressive 6-year warranty on both the tank and parts should leave you feeling confident. 

Let's face it, sometimes you just need a little more hot water, and the Rheem Professional Classic Point-of-Use line-up has you covered. This series offers small water heaters from 2-gallons to a robust 30-gallon tank capacity.  

The 20-gallon model uses a high efficiency single restored stainless steel heating element and for safety, has an Over-Temperature Protector to shut off the power if the heater ever exceeds the high temp limit.

Rheem has an exclusive tank lining called Rheemglas which prolongs the life of the tank and resists corrosion. The temperature and relief pressure valve as well as an anode rod are also included.  

Also available in the following sizes:

  • Model: PROE2 1 RH POU / 2 Gallons
  • Model: PROE6 1 RH POU / 6 Gallons
  • Model: PROE10 1 RH POU / 10 Gallons
  • Model: PROE15 1 RH POU / 15 Gallons
  • Model: PROE30 1 RH POU / 30 Gallons
The Bottom Line

It's hard to go wrong with a Rheem as they are a long-term player in the water heater business. With a 6-year warranty on the tank and parts and a 2,000-watt heating element the 20-gallon tank should be able to handle your more demanding hot water needs. 

Rating: 4.3 out of 5

Eccotemp Mini Tank Water Heater

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

Model: EM-2.5

Capacity: 2.5-Gallon

Power: 12-amp / 120-volt

Wall Mount: Optional

Dimensions: 14.5 x 11.8 x 10.4 inches

Warranty: 5-years leaks/ 2-year parts

The Eccotemp Mini Tank 2.5 can be used as a stand alone unit or added to your home's water heating system for a boost. It's compact and lightweight design means it can fit into the tightest of spots, and with the enclosed mounting bracket it can even be installed on the wall.

The tank is welded steel and glass lined to help prevent corrosion. An anode rod, high limit temperature switch and T&P Pressure Relief Valve is also included. 

Also available in the following sizes:  

  • Model: EM-4 / 4-gallon capacity
  • Model: EM-7.0 / 7-gallon capacity
The Bottom Line

Eccotemp has put together a sharp looking, competitively priced water heater. It's capable of delivering 1440 watts of heating capacity and offers a 5-year warranty against leaks. We'd recommend this unit for an area where the hot water demands aren't high. 

Rating: 3.5 out of 5

EcoSmart Mini Tank Water Heater

Model: Eco Mini 6

Capacity: 6-Gallon

Power:  12-amp / 120-volt 

Wall Mount: Yes

Dimensions: 20 x 13.8 x 14.5 inches

Warranty: 5-year leaks / 1-years parts 

EcoSmart offers 4 different sizes in their Eco Mini series. Each can be used as a stand alone unit or added to give your household water heater a boost.

With the exception of the larger Eco Mini 6, these unit's can be plugged into a standard outlet. However, the more powerful Mini 6 must be hardwired. The Mini 4 and 6 units can be used at home or on boats and RV's.

Also available in the following sizes: 

The Bottom Line

The EcoSmart Mini Series is a nice mid-priced option. With a 5-year warranty against leaks and 1440 watts they offer a nice versatility between home and on-the-go (RV) hot water. Unfortunately, the Mini 6 needs to be hardwired which may make it a bit more challenging to install. 

Rating: 3.8 out of 5

Stiebel Eltron Mini-Tank Water Heater

Model: SHC 4

Capacity: 4-Gallon

Power: 11.3-amp / 120-volt

Wall Mount: Yes

Dimensions: 26.5 x 16 x 16"

Warranty: 6-yr tank / 2-yr parts

Stiebel Eltron has 3 high quality small water heaters in their Mini-Tank series. The tanks are glass-lined to reduce corrosion and extend the service life. A wall mount bracket is included as well as a T&P Relief Valve. Each draws 120-volts of electiity which allows them to be plugged into a standard outlet.

Stiebel Eltron is a high-end company and takes pride in their products, and this series is no exception. You can expect to see some of the lowest stand-by heat losses in the industry with their units, which translates into savings on your electric bill.

The 4-gallon unit is capable of recovering in a speedy 27-minutes! and easy installation makes this mini-tank worth serious consideration whether you're looking for a small water heater at home or in a boat or RV.

Also available in the following sizes: 

  • Model: SHC 2.5 / 2.5-gallon capacity 
  • Model: SHC 6 / 6-gallon capacity
The Bottom Line

We love the Stiebel Eltron Mini-Tank Water Heater. Although, the price runs on the higher end for a point-of-use tank small water heater. We think the added price is well worth it for the sleek design and quality workmanship, plus, the company offers a solid 6-year warranty on the tank.

Rating: 4.8 out of 5
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Tankless Point-of-Use Water Heaters


  • Uses Less Space
  • Very Energy Efficient 
  • Endless Amount of Hot Water


  • Can be output challenged if not sized properly
  • Professional Installation Recommended

Atmor Instant Water Heater

Model: AT-900-04

Flow Rate:  .56 GPM* 

Power: 20 amp/240 volts

Dimensions: 11.9 x 8.7 x 4.2 inches

Warranty: 2-year parts / 7-year leaks 

*45 degree Temperature Rise

Atmor Industries Ltd has been manufacturing electric tankless water heaters for decades. Their website states that over the last 30-years they have "sold over 2 Million heaters all over the world on an O.E.M. basis under its brand and 'Private Label.'"

Their units offer all the benefits of a tankless water heater at a reasonable price point. The AT-900-04 is capable of delivering .56 GPM of hot water with a 45-degree Temperature Rise, making it a perfect choice when you only have a single sink to service. 

Like most tankless systems, these units  will need to be hardwired. You'll also need a dedicated circuit breaker and 240 volts of electricity. The Atmor 900 Series Inline offers 6 different sized heaters that range in GPM from .50 to 2.25.

Also available with the following flow rate:

The Bottom Line

Atmor branded tankless water heaters offer a solid 7-year warranty against leaks with a respectable 2-year parts coverage. But over all, we are on the fence with this unit. Many owners are extremely happy with it's performance, while others couldn't be more disappointed. However, if you're looking for an inexpensive tankless, this is probably a pretty good choice, especially if it's properly sized for your needs.

Rating: 3.5 out of 5

EcoSmart Point-of-Use Tankless

Model: POU 6

Flow Rate:  1.4 GPM* 

Power: 220 volts 

Dimensions: 5 x 12.8 x 8 inches

Warranty: 1-year 

*45 degree Temperature Rise

EcoSmart's company mission is to deliver efficient and economical green energy products to consumers. Since their water heaters have come on the market, they've been well received and steadily gaining in popularity.

The POU 6 model has a 99.8% energy efficiency rating and is capable of delivering 1.4 gallons per minute (GPM) of hot water with a 45-degree temperature rise. 

It's compact size and versatility makes it a great option for RV'ers or boat owners, drawing 220 volts of electricity it'll require hardwiring. The heating chamber is hand welded and made from stainless steel, and the heating elements are manufactured to last, yet designed to be removed if replacement is necessary. 

Also available with the following flow rate:

Model: POU 3.5 / 3.5 GPM

The Bottom Line

EcoSmart offers a 1-year warranty, which is one of the shortest warranties in the industry. In addition, the unit must be professionally installed by a licensed plumber/electrician within 30-days of purchase to be eligible for the warranty. Although we like the company and their products, we wish they would stand behind their water heaters with a better warranty. Still, if you're looking for a small, low cost point-of-use unit and you're not concerned about the warranty, this unit is worth a second look.

Rating: 3.0 out of 5

Bosch Point-of-Use Tankless

Model: US 9

Flow Rate:  1.40 GPM* 

Power: 208 or 220 volts 

Dimensions: 12.2 x 3 x 6.5 inches

Warranty: 1-year parts / 5-years element

*45 degree Temperature Rise  

The Bosch Tronic 3000 series offers 5 different sized units to choose between, ranging from their small .50 GPM unit to a tankless that can deliver 1.8 GPM (assuming a 45 degree temperature rise) running on 220-volts. 

These lightweight and ultra compact units can squeeze into tight spaces, and with the exception of the US 12, they can be mounted either vertically or horizontally. The copper heat exchanger, coupled with copper-sheathed heating elements help deliver a solid 98% efficiency rating. 

Also available in the following flow ratings:

The Bottom Line

We like the Bosch Tronic 3000 series. They are no-nonsense and reasonably priced, and the versatility to mount them horizontally or vertically (except for the US 12) means they can fit into the tightest of spaces.

Rating: 4 out of 5

SioGreen Point-of-Use Tankless

Model: IR-260

Flow Rate:  1.50 GPM*  

Power: 220 volts

Dimensions: 14.3 x 12.8 x 4.4 inches

Warranty: 2 years

*30 degrees Temperature Rise  

SioGreen is a Florida based company which was founded in 2008. They're the only company in the world which manufactures infrared tankless water heaters. The concept of an infrared tankless is unique, and with only a decade of experience for this type of technology under their belt, there are some positive selling points.

First, they use infrared Quartz heating elements, which the company claims to be the most energy efficient heaters in the world. The heating elements never come into contact with water, which should, in theory, prolong the life of the heating elements since they won't corrode.

However, when comparing GPM (gallons per minute) it should be pointed out the company factors a 30-degree temperature rise, the lowest among the tankless units we reviewed. This doesn't make SioGreen a poor choice, it just means that they won't need to work as hard as a tankless that uses a 45-degree temperature rise to achieve the same GPM output. In other words, they likely won't have as much power. 

Either way, it's an interesting concept and giving it a try with a point-of-use water heater is a great testing ground.

Also available in the following flow ratings:

  • Model:  IR-30 / .50 GPM @ 30 degree Temp Rise (hand sink model)
  • Model: IR-245 / 1.2 GPM @ 30 degree Temp Rise
  • Model:  IR-288 / 2.2 GPM @ 30 degree Temp Rise
The Bottom Line

SioGreen has a really interesting concept with these water heating units. As a relatively new product, they don't have a lot of history. However, the company estimates that their water heaters will last 10 to 20 years. We wish SioGreen would have provided a longer warranty to back up their claims. Still, those who have purchased these units have been, for the most part, very happy. We think it's definitely worth giving this technology a try, however, we would recommend erring on the side of a higher GPM output. 

Rating: 4 out of 5

Stiebel Eltron Point-of-Use Water Heater

Model: DHC-E 8/10

Flow Rate: 1.5 GPM*  

Power: 240 volts 

Dimensions: 14.2 x 8 x 4.1 inches

Warranty: 7-years leaks / 3-years parts

*40 degree Temperature Rise

These German made tankless water heaters are not only elegant looking but they're designed to last. Stiebel Eltron backs their products with an impressive 7-year leak and 3-year parts warranty . . .  one of the best in the industry. 

Stiebel Eltron offers 2 units in their Multi-Point-of Use series (DHC-E), the larger DHC-E12 with a Flow Rate of 2.0 GPM. Both of these powerful units are manufactured to handle the larger more demanding work of kitchen sinks and other areas where more hot water is needed.

Designed with the convenience of a front panel temperature knob, and a temperature range of 86- to 140-degrees, making temperature adjustments is simple. The advanced microprocessor technology keeps the temperature from deviating from the set point, even when there are variations in the water flow. 

A smaller series (DHC models) is also available for Single Point-of-Use units with Flow Rates that range from .50 GPM to 1.6 GPM at a Temperature Rise of 40-degrees. Here's a list and an easy to read chart to help determine the GPM.

With their sleek good looks it's easy to fall in love with these tankless units, but quality engineering and rigid product standards mean they not only look good, but they're designed to perform.

Also available in the following flow rating:

The Bottom Line

Hands down Stiebel Eltron manufactures one of the best tankless point-of-use water heaters on the market, and they back it up with an impressive warranty. We don't think you'll be disappointed with the quality and performance of these units, and should you ever need to contact them, we've found their customer support to be top notch. However, quality does come with a higher price tag. 

Rating: 5 out of 5

Rheem RTEX Tankless Water Heater

Model: RTEX-08

Flow Rate: 1.5 GPM*  

Power: 240 volts 

Dimensions: 4 x 9 x 13 inches

Warranty: 5-years / 1-year parts

*36 degree Temperature Rise

Rheem is a big player in the water heater world and their RTEX series delivers an impressive 99.8% energy efficiency rating. Making nearly every dollar you spend on electricity put to use in delivering hot water.

The RTEX series is compact and stylish with a digital temperature dial and display on the front panel. It'll allow you ultimate control as you can adjust the warmth of the water in 1-degree increments between 80- and 140-degrees.

The durable and powerful copper immersion heating elements are designed with a brass top which allows for easy replacement when the time comes. 

Also available in the following flow rates:

  • Model: RTEX-11 / 2.0 GPM (38 degree temp rise)
  • Model: RTEX-13 / 2.5 GPM (36 degree temp rise)

*Rheem manufactures 2 smaller point-of-use tankless water heaters in their RTEX line-up:  RTEX-045 / .50 GPM and RTEX-06 /1.0 GPM Flow Rates.

The Bottom Line

The Rheem RTEX series is an excellent choice for a point-of-use tankless water heater. The larger units (RTEX-08/-11/-13) pack enough power to deliver hot water to a small home. However, be careful when sizing, as the GPM is based off of a lower temperature rise (36 degrees). If sized improperly you may find these units won't meet your expectations, especially in cold climates. 

Rating: 4.5 out of 5