Plumbing

How A Water Heater Works

Written by Whitney Bennett

THE MATERIAL CONTAINED IN THIS ARTICLE IS PROVIDED FOR GENERAL INFORMATION PURPOSES ONLY AND DOES NOT CONSTITUTE PROFESSIONAL ADVICE.LANDMARK HOME WARRANTY DOES NOT PURPORT TO BE A SUBJECT MATTER EXPERT WITH REGARD TO THIS MATERIAL, AND YOU SHOULD CONDUCT YOUR OWN RESEARCH AND/OR SEEK THE ADVICE OF APPROPRIATELY QUALIFIED PROFESSIONALS WITH REGARD TO YOUR SPECIFIC CIRCUMSTANCES BEFORE YOU TAKE ACTION. LANDMARK HOME WARRANTY ASSUMES NO RESPONSIBILITY, AND SPECIFICALLY DISCLAIMS ALL LIABILITY, FOR YOUR USE OF ANY AND ALL INFORMATION CONTAINED HEREIN.


Learn how a water heater works with these animation and diagrams.

In the United States, when you want hot water for a shower, to run a load of laundry, or to wash your dishes, you usually rely on a water heater. The most popular type of water heaters in the US is the conventional storage water heater, where water is heated to a set temperature and then stored at that temperature in a tank until a homeowner turns on the "hot" water tap. This article teaches you how the two most popular types of water heaters, gas and electric, work and heat the water in your home. 

If you're interested in learning about alternative water heaters, check out our list of the pros and cons of the tankless water heater

Most gas and electric water heaters function similarly. The only difference is what heats the water. 

Gas Water Heater

How a gas water heater works diagram.

A gas powered water heater has cold water brought into the tank through a dip tube (1). This water is heated with a gas burner (2).  This burner burns gas, releasing extremely hot but toxic air up through a chimney in the middle of the water heater tank (3). The chimney moves this toxic air outside, all while heating the metal of the chimney (4). As this chimney heats up, the surrounding water is heated as well.  

Heat rises, and water heaters use this to bring warm water through the plumbing of your home.  Warm water rises to the top of the water heater tank and is moved throughout the home through the heat-out pipe (5). As you open the faucet for hot water, cool water is brought in through the dip tube (1), displacing the hot water and pushing it through the heat-out pipe (5). Homeowners can set the temperature they would like their water to be heated with the thermostat (6), which is connected to the gas line and brings the right amount of gas to the burner to reach the correct temperature.

Water heaters also have some protective measures. The temperature and pressure-relief valve, or the T and P valve, (7) will open and release water if the temperature of the water is too hot, or the pressure inside of the tank is too high. This helps to ensure the water heater doesn't explode.  All water heaters have a drain valve (8) on the side of the tank to drain the water heater to reduce sediment build up, which should be done once a year. (Learn how to remove sediment from your water heater.)

How en electric water heater works diagram.

The tank itself is insulated to keep water warm for a longer period of time and to ensure the water doesn't transfer the heat to the metal of the water heater tank (9). Finally, the water heater has a sacrificial anode rod (10), which is a rod made of a metal that rusts faster than the metal making up the water heater tank. This anode rod prevents the water heater tank from rusting... as long as it is replaced every 1-2 years after rusting away. Learn more about what a sacrificial anode rod is and why it's in your water heater here.

A Landmark home warranty plan will cover a gas water heater, as long as it is properly maintained.

Electric Water Heater

How en electric water heater works diagram.

An electric water heater works essentially the same way as a gas water heater. It brings cold water in through the dip tube (1) and heats it using the electric heating elements (2) inside of the tank. The hot water rises in the tank and is moved throughout the home through the heat-out pipe (3).

As with the gas water heater, an electric water heater has a thermostat (4), temperature and pressure relief valve (5), a drain valve (6), the tank is insulated (7), and it has an anode rod (8).  The only big difference is the water is heated by electric elements and is thus plugged into a power supply (9).

A home warranty plan will cover an electric water heater if it fails from normal wear and tear.

Water Heater Maintenance

A homeowner should be doing regular maintenance on their hot water heater, such as:

  1. Set the thermostat on the water heater on a safe temperature. Most manufacturers recommend around 120 degrees to save money on heating bills.
  2. Flush out sediment from your tank annually. Otherwise, a water heater can stop working prematurely.
  3. Check and change the anode rod. This rod keeps your tank from rusting, by “sacrificing” itself and rusting.
  4. Test your pressure relief valve by cooling the water, putting a bucket under the pipe, and opening the valve.

A Landmark home warranty protection plan does cover repairs and replacements of water heaters up to 70 gallons. Protect your budget by purchasing a home warranty plan and pay only a service call fee to repair or replace your water heater and other systems and appliances in your home. Learn more at www.landmarkhw.com/home-warranty-plans

Plumbing Articles

Have a clogged sink or water heater that isn’t working? Check out our plumbing maintenance articles and infographics.

Subscribe to our Resources Newsletter

Don't miss out on our monthly newsletter! Sign up to get tips on everything about home ownership, from maintenance tips to home selling advice delivered to your email once a month.

Get a Free Home Warranty Quote!

Input your information and get a free, personalized home warranty quote. You can customize the coverage and pricing to fit your needs. Experience what over 70,000 homeowners already know: A Landmark Home Warranty helps provide protection for your home and budget!