While there are literally hundreds of models available, gas water heaters come in two basic styles:
Gas Tank style
This is the most common type of gas water heater currently in the U.S. Gas tank water heaters store hot water on a standby basis, heating and reheating the same water so it will be ready for you. The tank size typically ranges from 40 gallons to 100 gallons depending on the hot water demand.
Gas Tankless style
Already popular in Asia and Europe, gas tankless water heaters are becoming more widespread in the U.S. because they provide endless hot water, take up less space and save energy. Unlike tank-style water heaters that heat water in a storage tank, gas tankless water heaters heat water only when you need it.
When you turn on the hot water tap, a sensor tells the gas tankless water heater to fire up and start heating water as it flows through the unit. That is why they are sometimes referred to as “on-demand” water heaters. When you turn off the hot water tap, the tankless hot water heater turns off as well. The advantage over tank-style water heaters is that they are not continuously heating and reheating the same water. Water is only heated when it is needed, thus saving money and energy. Plus you never run out of hot water!
In general, gas tankless water heaters cost more than a gas tank model to purchase and install. However, the energy saved typically results in paybacks of a few years or less for a family of four. Gas tankless water heaters also last twice as long as a tank model, up to 20 years, and they take up less space in your home. Tankless water heating improves the quality of your family’s life by giving you all the hot water you need when you need it.