Comparing Tank Storage Water Heaters and Tankless Water Heaters

Water,system,fitting,full,bore,brass,ball,valve,with,butterflyWhen it comes to choosing a water heater for your home, two popular options are tank storage water heaters and tankless water heaters. Each has its own advantages and considerations that you should be aware of before making a decision. In this article, we will compare these two types of water heaters to help you determine which one is the best fit for your needs.

1. Operation and Efficiency

Tank storage water heaters work by storing and continuously heating a large quantity of water in a tank. When hot water is needed, it is drawn from the tank and replenished with cold water, which is then heated. This constant heating and reheating process can result in standby heat loss, where energy is wasted heating water that is not being used.

On the other hand, tankless water heaters, also known as on-demand water heaters, heat water only when it is needed. These units use high-powered burners or electric coils to heat the water as it passes through the unit. Tankless water heaters are more energy-efficient than storage tank water heaters because they eliminate standby heat loss. However, they may have a limited flow rate and may struggle to meet high demand simultaneously in large households.

2. Hot Water Supply

One significant difference between tank storage and tankless water heaters is the hot water supply. With a tank storage water heater, you have a reservoir of hot water readily available. This makes it suitable for households that require a large volume of hot water for showers, baths, laundry, and dishwashing. However, if the demand exceeds the capacity of the tank, you may experience a temporary shortage of hot water until the tank refills and reheats.

In contrast, tankless water heaters provide hot water on-demand. They heat the water as it flows through the unit, eliminating the need for a storage tank. This allows for an endless supply of hot water, as long as the demand does not exceed the unit’s flow rate. Tankless water heaters are ideal for smaller households or those with limited space, as they can be mounted on walls, saving valuable floor space.

3. Energy Efficiency

Tankless water heaters are generally more energy-efficient compared to tank storage water heaters. As mentioned earlier, tankless heaters eliminate standby heat loss, which can account for a significant portion of energy consumption in storage tank heaters. The on-demand heating feature of tankless units means they only use energy when hot water is needed. This can result in lower utility bills over time, especially if you have a high demand for hot water.

Tank storage water heaters, however, may have lower upfront costs compared to tankless units. They are widely available and have a relatively simple installation process. While they may lose energy due to standby heat loss, newer models often feature improved insulation to minimize this loss. It is important to consider the energy efficiency ratings and long-term savings when comparing the two types of water heaters.

4. Size and Installation

Tank storage water heaters require a significant amount of space due to the presence of the storage tank. The size of the tank will depend on the household’s hot water needs. The tanks can vary in capacity, typically ranging from 20 to 80 gallons. The size and weight of the tank also pose installation challenges, especially if there are space constraints or if you live in an apartment or a small home.

In contrast, tankless water heaters are much smaller and more compact. They can be mounted on walls, saving valuable floor space. This makes them ideal for homes with limited space or for those who prefer a minimalistic look. However, it is important to ensure proper ventilation and gas supply for gas-powered tankless units. Depending on the location and existing plumbing, retrofitting your home for a tankless unit may require additional work and expenses.

5. Maintenance and Longevity

Maintenance requirements and the lifespan of water heaters are also important factors to consider. Tank storage water heaters typically require periodic maintenance, such as flushing the tank to remove sediment buildup. Over time, the accumulation of sediment can reduce the efficiency of the unit and result in a shorter lifespan. On average, tank storage water heaters last around 10 to 15 years.

Tankless water heaters, on the other hand, may require less maintenance. However, hard water can cause mineral buildup in the heat exchanger, requiring periodic descaling. With proper maintenance, tankless water heaters can have a longer lifespan of around 20 years or more.


When choosing between tank storage water heaters and tankless water heaters, it is essential to consider factors such as operation and efficiency, hot water supply, energy efficiency, size and installation requirements, and maintenance and longevity. While tankless water heaters are more energy-efficient and provide an endless supply of hot water on-demand, tank storage water heaters may be more suitable for larger households with higher hot water demands. Consider your household’s hot water needs, available space, budget, and long-term energy savings to make an informed decision about the best type of water heater for your home.

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