A man contemplating disadvantages of his new tankless water heater.

The Disadvantages of Tankless Water Heaters

Many homeowners have heard that tankless water heaters are beneficial over traditional tank-style water heaters. They are smaller in size and can save space. They heat water on demand, so they may save money on energy and water bills. They also may decrease the likelihood of running out of hot water. While these benefits are true in some cases, they are not always the case. In fact, there are some significant disadvantages that tankless water heaters may have in some homes, and you should be aware of these before you make a buying decision.

  1. You Can Run Out of Hot Water.

    One of the most common myths about tankless water heaters is that you will never run out of hot water. These water heaters heat water on demand as you request it from the tap. Therefore, water is heated as it passes through the hot water heater, and it is not stored in a tank in a limited supply. While you do not have a tank that would potentially run out of hot water in a high-demand situation, it is important to note that the heating coils in a tankless hot water heater have only a limited ability to heat water. In some cases, these heaters may not be able to keep up with demand when multiple sources in the home are requesting hot water at the same time. For example, two people may not be able to bathe at the same time, or someone may not be able to bathe at the same time the dishwasher is running.

  2. Hot Water Is Not Immediately Available for Use.

    Many people falsely believe that tankless water heaters are more convenient to use because they provide an immediate source of hot water for the residents to use. Consider the fact that a tank-style hot water heater keeps water stored and ready for use right away. When you access water from a tank-style hot water heater, the cold water that is stored in the pipes in your walls must pass through the pipes before the hot water reaches you. The water is not “heating up,” and instead, the hot water is pushing the cold water in the pipes through the system. Typically, a tankless hot water heater is installed in the same location as a tank-style water heater. It does not keep the water in the pipes hot for you, so this cold water in the pipes must still be pushed through the pipes before the hot water can reach you.

  3. They May Not Save Water Or Energy.

    Another common myth associated with using tankless water heaters is that they save the homeowner money on water and energy costs. One reason that is given for the savings relates to the belief that you do not have to wait for the hot water to heat up with a tankless water heater, but this is not the case. Any new model of water heater may have improved energy efficiency, so there may be savings to enjoy if you make any upgrade. In addition, a tank-style hot water heater does actually keep water heated in the tank, so a tank-style unit may use slightly more energy in some cases. However, this actually depends on the home and how frequently hot water is used. If you regularly run hot water throughout the day with a tankless hot water heater, the coils in the tankless heater will constantly be working. Therefore, savings may be negligible.

As you can see, there are many factors at play that impact how beneficial a tankless water heater actually is for your home versus a traditional hot water heater. You may consider researching the options thoroughly and requesting more guidance and advice from a plumber before you make your final decision.

Last Updated: February 05, 2016