Tank vs tankless water heaters: Which is best and perfect?

The Ultimate Comparison Guide on Choosing Between Tank and Tankless Water Heaters: Discover Which is Best and Perfect for You

In 2023, joseph went for a maintenance work of a tank water heater in Denver, he noticed the tank was old and inside there was rust and while he was cleaning at one point the tank it self got a hole in it. When he explained it to the home owner, owner asked I want to buy a new heater, please suggest me a good one.

Joseph asked would you prefer Tank or tankless? owner replied could you please give more details on tank and tankless heaters, their pros and cons, and which one is best for me. So, joseph explained every thing in detail and thought many people many not know about this, that thinking made this article “Comparing Tank vs Tankless water heaters”.

Choosing between a tank and a tankless water heater can be difficult, as both have their benefits and drawbacks. Tank water heaters are traditional and often more affordable, tankless water heaters offer energy efficiency and endless hot water. This comprehensive guide breaks down the pros and cons of each type, from energy efficiency to installation costs. We have covered every aspect. Let’s take a closer look at the differences and help you find the perfect fit for your home.

Don’t settle for just any water heater – make an informed decision with Tank vs Tankless water heaters.

What is a Storage Tank water heater?

A storage tank water heater is a traditional type of water heater that stores and heats a specific amount of water in a tank, typically ranging from 20 to 80 gallons depending on the capacity of the tank. The tank is insulated to help retain the temperature of heated water, and a thermostat controls the water temperature.

When hot water is used through faucets or showers, it is drawn from the top of the tank and replaced with cold water at the bottom. The tank is then refilled and heated until it reaches the desired temperature again. Storage tank water heaters are common in many households due to their affordable price and ease of installation, but they can be less energy efficient than newer tankless models.

What is a Tankless water heater?

A tankless water heater is a modern and energy-efficient alternative to traditional storage tank water heaters. Unlike storage tank water heaters, tankless units heat water on demand, which means they only use energy when hot water is needed. When a hot water tap is turned on, cold water travels through a heat exchanger and is quickly heated by a gas burner or electric heating element. Tankless heaters provide a constant supply of hot water without the need for a storage tank.

Ultimate Comparision of Tank vs Tankless water heaters

Energy efficiency:

The difference in energy efficiency between a storage-tank water heater and a tankless water heater is influenced by several factors, such as the size of the unit, the fuel source, the flow rate, and the temperature setting. However, on average, tankless water heaters are considered more energy-efficient. This is because tankless heaters heat water only when there is a demand for hot water, unlike storage tank water heaters which continuously use energy to keep a large tank of water hot. Using a tankless water heater can save substantial energy over time.

energy efficiency on tank vs tankless water heater

Winner: Tankless water heaters has higher efficiency than storage tank ones.

Continuous Hot water supply:

Both storage tank water heaters and tankless water heaters can provide continuous hot water, but there are key differences between the two.

Storage tank water heaters: In a storage-tank water heater, cold water is heated and stored in a tank and available for use whenever there is a demand in hot water. The amount of hot water stored at any given time depends on the tank capacity. If the demand for hot water exceeds the tank’s capacity, the user will have to wait for the water to refill and to be heated again to desired temperature. It is a time taking process which can result in some interruption in the flow of hot water.

Tankless water heaters: In a tankless water heater, hot water is heated as it flows through the unit, allowing for an endless supply of hot water. This means you can take long showers, run multiple appliances simultaneously, or do laundry without worrying about running out of hot water. There are several benefits of having continuous hot water supply, like an increase in convenience, Energy savings, Reduced water waste, and more.

Continuous hot water supply on tank vs tankless water heater

Winner: So, In terms of continuous hot water delivery, tankless water heaters have the advantage over storage tank water heaters.

Standby heat loss:

Standby heat loss refers to the amount of heat energy that is lost from a hot water heater over time when the unit is not in use. Both storage tank water heaters and tankless water heaters are subject to standby heat loss, but the extent of the heat loss can vary between the two types of systems.

Storage tank water heaters: In a tank water heater, hot water is stored in a tank and is constantly losing heat to the surrounding environment. The insulation around the tank helps to reduce the amount of heat loss, but there will still be some standby heat loss over time. The larger the tank, the more heat energy that will be lost through standby heat loss.

Tankless water heaters: In a tankless water heater, hot water is heated as it flows through the unit and is not stored in a tank. This means that there is no stored hot water to lose heat over time, and standby heat loss is minimal. However, the heat exchanger in a tankless water heater will still lose some heat energy to the surrounding environment when the unit is not in use.

standby heat loss on tank vs tankless water heater

Winner: Overall, tankless water heaters tend to have lower standby heat loss than storage tank water heaters.


The cost of installing a water heater depends on various factors like the type of heater, fuel source, location of installation, size and capacity. It is recommended that a good and professional plumber must be hired to install a water heater.

Storage Tank water heaters:  These are less expensive than tankless ones and easy to install. It has a large tank that needs to be fixed with a gap for air circulation. Connect it with water, gas/ electric connections, and components like an expansion tank and basic ventilation. On average, it costs between $200 to $1,100 for a plumber to install a tank water heater.

Tankless water heaters: These are much more expensive and complex to install. The initial buying costs are higher, and installation costs are between $300 to $2500, depending on the parts and extra modifications. It needs separate ventilation pipes recommended by the manufacturer. For some units, recirculation pumps need to be added, which costs extra.

product and installation on tank vs tankless water heater

Winner: The cost of tankless water heaters are higher than storage tank heaters.


When we talk about maintenance, both storage tank water heaters and tankless water heaters require maintenance to work properly for longer life. But the frequency and complexity of maintaining both these heaters are different. Let’s look at how it differs.

Storage tank heaters: Storage tank water heaters require relatively simple maintenance, including flushing the tank annually to remove any sediment buildup at the bottom, checking the temperature and pressure relief valve, and checking the anode rod for signs of corrosion. Additionally, the storage tank may need to be replaced every 8-12 years, depending on the tank type and the water quality in your area.

Tankless water heaters: Tankless water heaters require less frequent maintenance than storage tank water heaters, but maintenance is typically more complex. Maintaining a tankless water heater includes flushing and descaling the unit to remove any scales and mineral buildup, checking the inlet and outlet water temperature and water flow sensors, and cleaning the heat exchanger to ensure efficient operation. Additionally, the combustion assembly should be inspected periodically for proper operation, and the unit should be serviced by a professional every 2-3 years.

maintenance and its cost on tank vs tankless water heater

Winner: The complexity and cost of maintainance in tankless heaters is higher than tank ones.


The lifespan of a water heater refers to the number of years it works perfectly without any major repairs. Water heaters’ life span depends on a few factors, one of which is water quality. The higher the water contact with the components, the lower the life span.

Storage tank water heaters: The life span of Storage tank water heaters range between 10-15 years. These have tanks in which water is stored. Eventually, water will corrode the tank and damage it, reducing its life span.

Tankless water heaters: The life span of tankless water heaters ranges between 20-25 years if you perform regular maintenance by flushing and descaling the areas where water flows. Tankless water heaters are typically more energy efficient than storage tank water heaters, which can help extend the unit’s lifespan.

lifespan on tank vs tankless water heater

Winner: The lifespan of tankless water heaters is more than the tank ones.

Pros and Cons of Tank and Tankless water heaters

Tank Water Heaters Tankless Water Heaters
Pros 1. Lower Initial Cost 1. Endless hot water on demand
2. Widely available 2. Energy Efficiency
3. Large storage capacity 3. Space Savings
4. More reliable 4. Longer lifespan
5. Recovery time is faster 5. Digital Display
Cons 1. Limited hot water supply 1. Higher Initial Cost
2. High Energy Bills 2. Professional Installation Required
3. Requires periodic maintenance 3. Potential for Limescale Build-up
4. Space consuming 4. Requires consistent water flow rate

Conclusion: Which heater to buy

When deciding between a tank or a tankless water heater, it ultimately comes down to your personal preference and your household’s hot water needs. Traditional storage tank water heaters are reliable, affordable, and can provide a large hot water supply. However, they are less energy-efficient and have a shorter lifespan. On the other hand, tankless water heaters are more energy-efficient, have a longer lifespan, and provide endless hot water on demand. However, they can be more expensive to purchase and install. Consider upfront costs, long-term energy savings, and the size of your household’s hot water demands.

TanklessHelp Staff

TanklessHelp Staff has an experienced writers and researchers in the field of water heating technology. With a background in HVAC and plumbing, Tanklesshelp staff has in-depth knowledge in many types of waterheaters in America and Canada. They have a passion for educating homeowners and businesses on solving easy to hard repairs and guide them on how to maintain them to save money.

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