The idea behind a tankless system is that it heats the water as you need it instead of continually heating water stored in a tank. Tankless heaters have been the norm in much of Europe and Japan for quite some time, but they haven’t gained popularity until recently in the United States — largely due to the green movement. If you’re a good candidate for a tankless system, you can save a substantial amount of money every year on your monthly bills while at the same time conserving natural gas.
Tankless heaters also last about five to 10 years longer than a tank heater, take up much less space and provide you with an unlimited amount of hot water. On the downside, a tankless system can cost up to three times as much as a tank heater and often requires costly upgrades to your natural gas line and an expensive venting system.