Pros and Cons of Point-of-Use Water Heaters: Top Models and Buying Tips

When it comes to hot water, waiting for it to arrive can be frustrating and wasteful. Point-of-use water heaters (POU) offer a solution by providing hot water instantly and precisely where you need it, without the need for long pipes.

But before you invest in a POU water heater, it’s important to weigh the pros and cons and consider factors such as hot water demand and installation requirements.

In this article, we’ll explore their advantages and disadvantages, highlight some of the top models available, and provide tips for making an informed buying decision.

What Are Point-of-Use Water Heaters?

Point-of-use water heaters are compact, energy-efficient devices that provide hot water directly at the location where it is needed, such as a sink, shower, or appliance. They are ideal for serving low-volume fixtures in small apartments, cottages, garages, and mobile homes (RVs).

These units come in different sizes and types, including electric, gas, and tankless models. Electric point-of-use water heaters are the most common and are often installed under sinks or in small spaces. Gas-powered models are more powerful and can serve larger households, but they require venting and professional installation.

The main advantages of point-of-use water heaters are that they provide hot water instantly, eliminate the need for long hot water pipes, and reduce standby energy losses.

They can be used in new or added to existing systems (retrofits), often installed under the kitchen or bathroom sink. This is why they are also called under-sink water heaters.

However, they may not be suitable for high-demand applications, such as multiple showers or large tubs, as they may not provide enough hot water. Additionally, they require a dedicated electrical circuit or gas line and professional installation, which can increase the upfront cost.

Related: See other popular types of water heaters

How Point-of-Use Water Heaters Work

Point-of-use (POU) water heaters, whether tank or tankless, heat water directly at the location where it’s needed, offering immediate access without the need for long wait times.

Tank-type

Tank-type POU heaters store a small amount of hot water in a compact tank. The water is heated by an electric heating element within the tank or by a gas burner located under the tank. When you turn on the hot water tap, the stored water is delivered directly to the fixture. Once the stored water is used up, the unit will begin reheating it for the next use.T

hese units are ideal for locations with low demand for hot water. However, they may have limitations when it comes to energy efficiency, as they continue to store and maintain water at the desired temperature, which can result in some energy loss.

Tankless

Tankless POU heaters, both electric and gas-powered, heat water only when it’s needed. Electric models use a heating element to instantly warm water as it flows through the unit, while gas models use a gas burner for the same on-demand heating process. Both types eliminate the need for a storage tank, offering endless hot water and significant energy savings by heating only when water is flowing. Tankless models are more energy-efficient than tank-type models, as they don’t require standby heat maintenance.

What to Consider Before Buying Point-of-Use Water Heaters

Advantages

Here are the benefits of installing a point-of-use (POU) electric water heater in your home:

1. Reduced Wait Time: Installing a POU electric water heater directly at the source can significantly cut down the wait time for hot water, which is often caused by central heating systems and long pipes.
2. Cost Savings: By installing the unit in your kitchen or bathroom, you save on both gas and electricity. These units also help reduce water consumption, which further lowers utility bills.
3. Ideal for Difficult Retrofitting: They are a great option in situations where retrofitting a traditional system is too costly or impractical.
4. Consistent Hot Water Flow: In large buildings, multiple units can be strategically placed to ensure a steady supply of hot water, eliminating the need for long central pipes.
5. Enhanced Efficiency with Tankless Models: Small models can work alongside storage tank-type heaters, reducing standby heat loss. Even tankless models benefit by minimizing temperature fluctuations, preventing issues like the “cold water sandwich” effect.
6. Precise Temperature Control: One of the key advantages is their ability to control the water temperature at the point of use, ensuring the ideal temperature every time.
7. On-Demand Hot Water: Tankless models provide endless hot water on demand, without the need for a storage tank.
8. Environmentally Friendly: Since POU tankless water heaters heat water only when and where it’s needed, they help reduce energy waste, lowering your carbon footprint.

Disadvantages

• POU units are not suitable for applications with high hot water demand.
• Should not be used as the backup for the solar heating systems and geothermal heat pumps, as they cannot meet the demand when these do not operate.
• The upfront cost of installing multiple POU electric water heaters in your building is higher than that of a centralized heating system.

Types

As mentioned previously, there are two types of point-of-use water heaters: mini-storage tank-type, with a capacity ranging from 2 gallons up to 30 gallons, and tankless units with a low water flow but a continuous supply of hot water.

Tankless point-of-use heaters are rated by the number of gallons per minute they can provide, while tank-type units are based on their tank capacity.

POU tank-type units are similar to large and tall models but typically have only one heating element with a thermostat.

Popular Manufacturers

• Eemax
• Stiebel Eltron
• EcoSmart
• Bosch
• Rheem

Top-Selling Models

Top 3 selling POU tank-type models

• Bosch Tronic 3000 T
• Ecosmart ECO MINI 2.5
• Stiebel Eltron SHC 2.5

Top 3 selling POU tankless models

• Ecosmart POU 6
• Stiebel Eltron DHC-E 8/10
• Rheem RTE 13

Features

The best point-of-use water heaters are designed with features that enhance durability, performance, efficiency, and energy savings, while providing reliable automatic control.

• Convenient Installation: Smaller electric units generally operate on 120V, with a plug that fits into any standard outlet. For 240V models, a junction box is included for easy and straightforward installation.
• Durable Construction: Most point-of-use heaters come with a metal tank, though some models, like Marathon units, feature corrosion-resistant plastic tanks.
• Efficient Heating Elements: Typically, electric models have a single screw-in style heating element with a power range of 1.5 to 2 kW, which efficiently transfers heat directly to the surrounding water. Their gas counterparts use smaller gas burners but still require a venting system.
• Corrosion Protection: Storage tank-type units are safeguarded against corrosion through a ceramic or glass coating, combined with an anode rod, to extend their lifespan.
• Automatic Control: These units include a surface-mount thermostat with an ECO feature, ensuring automatic temperature regulation for safety if temperatures exceed safe levels.

Installing Tips

With its space-saving design, the point-of-use water heater is perfect for installation in areas with limited space where standard types cannot be installed.

These mini electric heaters can be mounted in a variety of locations, including under sinks in kitchens and bathrooms, inside cabinets in apartments and condos, on walls, on the floor, in camps and recreational properties, as well as in stores, offices, and wash stations.

The size of the POU heater you need depends on the installation location and the available power supply. Smaller units are best suited for tasks like hand-washing, while larger models with higher flow rates are designed for tasks such as dishwashing, shaving, showering, or even supplying multiple fixtures simultaneously.

Note: Always follow the manufacturer’s instructions and manual when installing a point-of-use water heater. You can install the heater as a standalone unit or integrate it into an in-line system with other heaters, such as tankless models.

These heaters can be installed directly at the sink, on the cold water supply line, and as close as possible to the hot tap, eliminating the need for recirculating lines and pumps. Depending on the model, some units can be installed horizontally, while others must be installed vertically.

Summary

Point-of-use (POU) water heaters are an excellent solution for homes and businesses that require a small amount of hot water and have limited space. They are especially useful when traditional cylinder-type heaters take up too much floor space or when a buffer is needed to support tankless water heaters. By being installed close to the point of use, POU units reduce the length of pipes, providing faster delivery of hot water and leading to energy, space, time, and water savings.

These heaters are ideal for distant sinks, remote bathrooms, or areas with increased hot water demand, such as older homes or new constructions where higher efficiency cannot be achieved with other systems. POU units are also well-suited for small tasks like handwashing, dishwashing, and brewing coffee or tea, and can supplement existing electric, gas, or solar tankless or tank-type heaters.

In summary, if you need a compact, energy-efficient hot water solution, a POU water heater is a smart investment. It offers convenience, energy savings, and improved comfort, making it an excellent choice for both residential and commercial applications.

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