Nicolette Forbes

By: Nicolette Forbes on July 28th, 2022

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How Do Tankless Water Heaters Work?

Tankless Water Heaters

Are you curious about getting a tankless water heater but are unsure how it works? Then you’ve come to the right place!

Tankless water heaters can be complex and understanding how they work can sound like bungee jumping to most homeowners, which is why we’ve created this content so that you are prepared for anything.

In this article, we will discuss: 

  • What is a tankless water heater
  • Identify gas and electric water heaters
  • How a tankless water heater works
  • Warranties on tankless water heaters

By the end of this article, you will not only be able to understand how a tankless heater works but also what happens when it isn’t working properly so that you too can become experts.


What is a Tankless Water Heater?

A tankless water heater is a device that heats your water without the bulkiness of a tank. Unlike a conventional water heater that is storing the water inside the tank, a tankless water heater has nowhere to store water. Instead, a tankless water heater heats the water as it moves through the heat exchanger, ultimately providing you with an endless supply of hot water. 

Read here to learn more about the key differences between tankless and conventional water heaters. 

But back to tankless water heaters! There are two types of tankless water heaters: gas and electric.


What is a Gas Tankless Water Heater? 

A gas tankless water heater is a tankless water heater that is powered by gas. There are two types of gas heaters: natural gas and propane. They are both similar, with their only real difference being the type of gas that is used.

A Noritz tankless water heater.

While anyone can get a gas tankless water heater, they are ideal for large families, people who like long showers or anyone who has a soaking tub. They can provide much more hot water, which is key for bigger households. You can easily knock out loads of dishes and laundry using only a small amount of water with a gas tankless water heater.


What is an Electric Tankless Water Heater?

An electric tankless water heater is a tankless water heater that is powered by electricity rather than gas.

Electric tankless water heaters are also normally used as “point-of-use” water heaters. So instead of covering the whole house, it would be used specifically for something like a kitchen sink. Read this article here to learn more about the two types of tankless water heater maintenance so that you are more than prepared for the different ways you can preserve your investment. 


How Does a Tankless Water Heater Work?

Tankless water heaters can be complex and how they work can be another story! Thankfully, how a tankless works can be broken down into a step-by-step process along with a fun graphic to help.

  1. Cold water enters your tankless water heater from the mainline and passes through the flow sensor.

  2. The flow sensor alerts the computer board that water is entering the water heater.

  3. The computer board then turns the fan on, and the gas valve opens. You may hear a clunking sound as this happens. Don’t worry, this is normal!

  4. Once gas flows into the unit, the burner roars to life.

  5. The cold water enters the heat exchanger and goes through a series of tight bends in the pipes to get up to the temperature set on the control panel.

  6. After the water reaches the correct temperature, it exits the heat exchanger, passes through the bypass valve, and comes out of your fixtures.

A diagram of how a tankless water heater works and heats up water.

Your tankless water heater will go through this process each time you use hot water in your home. 

Now that you know how a tankless water heater works, you must be wondering, do gas and electric work the same? The short answer: no. 

With an electric tankless water heater, the process of heating water goes like this: 

  1. The water flows into the tankless water heater through plumbing connections. It is then passed through the flow meter and into the internal pipes. As the water flows through the water heater, it passes an inlet thermostat that measures the temperature of the cold water.

  2. Then, the water moves from the inlet pipes into the heating chambers. Essentially, this is just another section of wider pipes with copper coils. The coils are heated by electric elements that convert the electricity into heat. The heated coils then transfer the heat to the water.

  3. Lastly, the water, which is now hot, exits the chambers and into your home through your fixtures.


Warranties Help To Keep Your Tankless Water Heater Working

A tankless water heater is a complicated device. Not only is there the water heater itself but there are also a lot of components inside that give you that endless hot water in your home. But how are you supposed to find these parts? Where do you even begin? 

Well, you are in luck as tankless water heater warranty normally covers the heat exchanger and then the parts separately. Typical tankless warranties on most brands cover the heat exchanger for 10 years and the rest of the parts for three to five years. Not a bad deal considering the typical lifespan of a tankless water heater is around 20 years.

It’s also important to know that with a tankless water heater, all the parts are replaceable. So even if the heat exchanger fails after its warranty period, you can still buy a new heat exchanger.


Closing Out How Tankless Water Heaters Work

Learning how a tankless water heater works sounds like a scary task but with a little help from some visual representation and a to-the-point bulleted list, it is as easy as turning on your car. Literally. Simply turning on the fixtures in your home, will give you endless hot water with a tankless heater almost instantly.

Continue your tankless water heater knowledge by clicking on the links below as we dive into how long a tankless heater lasts as different factors affect its lifespan and our tankless water heater page which covers all things tankless.

How Long Does a Tankless Water Heater Last?

Tankless Water Heaters with Monkey Wrench

We here at Monkey Wrench are dedicated to giving you all the information you need on tankless water heaters so that you can make the best decision for you and your home. If you live in the Los Angeles area and are interested in finding out if a tankless water heater is right for you, hit the “Book” button below. Or if you have any other questions regarding your tankless water heater needs, feel free to call us at 310-853-8690, and one of our call center representatives would be happy to help you.