Tankless vs. Tank Water Heaters: Which One Should You Get?

Christine Herrington


Last Updated on June 3, 2021

When choosing a new water heater, it’s essential to know the differences between a tankless water heater and a conventional water heater. Tankless water heaters are more modern and tend to be expensive, while conventional ones are more affordable and easy to install. 

Both of them present pros and cons and suit different people and families depending on their lifestyle. Some significant differences are the energy efficiency, cost, and maintenance or durability. Perhaps the biggest difference is that a tankless water heater provides hot water on demand. It simply heats it quickly whenever you open a hot water faucet in the house. 

How to Choose Tankless Water Heater vs. Tank Water Heater
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Table of Contents

How Do They Work?

Everyone has experienced the unpleasant feeling of taking a hot shower and suddenly running out of hot water. Tankless water heaters were designed in the 1990s to solve this issue.

Hot water deficits occur because conventional water heaters have a limited amount of hot water. Once it’s used, the thermostat notices the temperature difference, and the tank slowly fills up again with cold water. The new cold water is then heated by the element underneath the tank, which can take some time. For the average 50 gallon heater, it takes about 45 minutes to heat up completely. 

As the name implies, tankless heaters have no tank or water reservoir. They simply have an inflow and outflow valve, and water is heated using a heat exchanger. You’ll notice that tankless water heaters are smaller than conventional ones for this reason.

When hot water taps are turned on, fresh water is pushed into the unit through the inflow valve, where it gets warmed by the heat exchanger. Once warmed, it flows out seconds later through the outflow valve. This system ensures the hot water supply in a house is never exhausted

The Key Difference: Hot Water On Demand vs. Stored Hot Water

The main difference between the two types of tanks has to do with the flow of water. With tankless water heaters, you not only solve the problem of running out of hot water, but you also get better hot water flow. A high-quality tankless water heater can simultaneously provide up to three hot showers for the household. 

It’s important to mention a common myth when comparing a tankless water heater vs. tank water heater. The myth is that tankless water heaters provide instant hot water. This is not possible because the water has to travel through the heat exchanger. 

You can expect an added delay of about 10 to 15 seconds for fixtures that are further away from the water heater. Nevertheless, a high-quality recirculating pump can be installed to improve the water flow speed in your home. 

Difference in Energy Efficiency

Tankless water heaters offer better energy efficiency than a tank water heater. Since they heat the water on demand, they use less power, saving you money on your utility bills. 

However, energy savings can vary significantly across different households. For example, while some families might be very conscious of their consumption, another might be so excited about their new tankless water heater that they go overboard and start taking very long showers.  

Differences In Maintenance And Durability

When comparing a tankless water heater vs. tank water heater, it’s important to consider how long the unit will last. Tankless water heaters can last a lot longer if they are well maintained. 

Tank Water Heaters 

Without proper maintenance, water can slowly damage the inner lining of a water tank. Water carries minerals such as calcium and magnesium, which settle in the bottom and sides of the tank and slowly lead to scale build-up and rust. 

With so much water sitting inside the tank, conventional water heaters need to be cleaned and flushed once a year to get rid of all the sediments. It’s relatively easy to clean and flush a water heater, and it can be done in about 30 minutes

The problem with conventional water heaters is that when they reach the end of their lifespan, they can cause a big mess. A common problem for very old tank water heaters is that the bottom breaks and floods your basement

Conventional tanks can provide an advantage in terms of resistance. Without regular maintenance, they can last up to 8 years. However, their total lifespan is short compared to that of tankless water heaters. 

Tankless Water Heaters

In contrast, tankless water heaters don’t have any corrosion or rusting problems. There simply isn’t enough water sitting inside to cause them. On the downside, because the system is modern, cleaning a tankless water heater is a bit more complicated. Most people sign up for yearly maintenance, but it’s possible to clean it and flush it yourself

The modern systems of tankless water heaters are also less durable unless they receive proper care. Without yearly maintenance, they’ll break down in just a couple of years. However, if they receive proper maintenance, they can outlast tank water heaters, working for up to 20 years

Differences in Cost

There’s a big difference in terms of the initial cost. A traditional tank water heater costs about $600. With the installation and additional parts, the price can go up to about $2,000. Installation is quick, and the unit is easy to replace.

Tankless water heaters can be a lot more expensive. What drives up the price is the installation and the changes in the pipes and gas lines that are often needed. 

Contrary to what many people believe, the difference in running costs isn’t huge. The assumption is that the superior energy efficiency of tankless water heaters results in higher energy savings. However, if you do the math for a typical household with two bathrooms, the financial difference amounts to just $10 a month. 

Choosing Between Tankless Water Heaters vs. Tank Water Heaters

Each type of water heater has unique advantages and disadvantages. Before making your selection, it’s essential to be clear about two common myths of tankless water heaters that are false. One is that they provide instant hot water. The second one is that they can help you save a lot of money on energy costs. 

The installation of a tankless water heater can be much more expensive, which is important to keep in mind when comparing the total costs of installing and running either option. If you’re willing to pay the high price, a tankless water heater is very convenient, especially for a big family. 

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