facebook pixel How a Storage Water Heater Works | HomeTips
Select Page

How a Storage Water Heater Works

The traditional tank water heater heats and stores water for home appliances and fixtures.

Electric and Gas Storage Water Heater Diagrams  ©HomeTips

Fundamentally, a water heater is an appliance that converts energy to heat and transfers that heat to water. It’s connected to a cold water supply pipe and has an outgoing hot water pipe—or system of pipes—that supplies heated water to faucets and appliances.

The majority of water heaters are fueled by natural gas, though propane-fueled and electric water heaters are not unusual. Where natural gas is available, it is a much less expensive energy source than electricity.

A gas-fueled storage water heater heats water by means of a burner beneath the tank. Natural gas (or propane or kerosene, in some cases) is piped to a gas valve.

A thermostat that detects the temperature of water in the tank regulates fuel delivery to the burner, which is ignited by a pilot light or spark ignition. A vent collects toxic emissions from the burner and pipes them up through the tank, out the top, and normally up through the roof. Some newer, high-efficiency water heaters have fan-assisted vents that can be piped out through a wall.

Because the tank is under pressure, hot water exits through the hot water outlet at the top. When the hot water leaves, cold water enters through a diffuser dip tube that extends down inside the tank. The cold water pipe normally has a shutoff valve. A magnesium or aluminum anode rod utilizes the principle of ionization to minimize the water’s corrosive elements, which can significantly shorten tank life. The larger the anode, the longer a tank is likely to last.

The drain valve at the water heater’s base is used for draining the tank or flushing sediment out of it. This important maintenance step should be done once or twice a year, according to the manufacturer’s recommendation.

A temperature-pressure (TP) relief valve near or on the top of the tank opens automatically if temperature or pressure exceeds safe levels. This valve should be tested at the same time the tank is drained, according to the manufacturer’s instructions.

With an electric water heater, a heavy electrical cable delivers energy to heating elements. An electric water heater doesn’t create combustion gases, so no vent is required. It typically has one 5,500-watt or, for faster heating, two 4,500-watt elements. Separate thermostats control each element, cycling on and off as needed.

Featured Resource: Find a Local Pre-Screened Water Heater Pro

Call for free estimates from local pros now:
[telnumlink] 1-866-342-3263[/telnumlink]

About Don Vandervort
Author Image
Don Vandervort developed his expertise more than 30 years ago as Building Editor for both Sunset Books and Home Magazine. He has written more than 30 home improvement books and countless magazine articles. He appeared regularly on HGTV’s “The Fix,” and served as MSN’s home expert. Don founded HomeTips in 1996.

Related Posts:

Join the Conversation


  1. My hot water heater was leaking and the bottom of the water heater was filled with water. I drained the water heater I can’t get the igniter to light the pilot after drying out,do I have to replace the whole water heater?

  2. Here goes my current situation. I’ve had my water heater for about 3 to 4 years already and at first we had the issue of it shutting off and having to turn it back on but it was minimum only, so i exchanged some parts installed them and it seem to work for a while. Now as time has past we noticed it happening more and more often and with my busy schedule i had little to no time to inspect it. So as time been passing by with hot days and cold we starting to notice a pattern, first with the summer heat we needed to reset the thermal coupling im assuming, to start pilot back up and repeated multiple time a day. During cold days (winter )not once did we need to reset and start up. What is going on here?


Submit a Comment

Your email address will not be published. Required fields are marked *