By heating water only when it's needed, ENERGY STAR qualified gas tankless water heaters cut water heating expenses by 30%, while also providing continuous hot water delivery. Gas tankless models are a great choice for new construction and major remodeling, but are also becoming popular as a replacement for gas storage water heaters. See if you should make your next water heater an ENERGY STAR qualified tankless model.
ENERGY STAR qualified gas tankless water heaters provide hot water on demand, plus a whole lot more. Consider a qualified tankless water heater for your home and enjoy these benefits: Save energy and money. You don't use hot water 24-hours a day. Yet a standard tank-type water heater consumes energy round the clock to keep the water in its tank hot. By heating water only when you need it, ENERGY STAR qualified tankless water heaters save the typical family more than $100 per year on gas bills compared to a standard storage model. Larger families can save even more.
Continuous hot water. Tankless water heaters provide a continuous flow of hot water, so there's no need to suffer through a cold shower if you're the last one out of bed. Unlike with a conventional tank-type water heater, the hot water is always there when you need it.
Space-saving design. A qualified tankless model saves you an extra closet's worth of space compared to a tank-type water heater. Gas tankless water heaters are small and wall-mounted, unlike bulky tank-type water heaters. Models designed for outdoor installation free up even more space and add versatility to your basement, garage, or utility room.
Fewer worries. Tankless water heaters have a life expectancy of 20 years, much longer than any conventional tank-type water heater. And with a tankless model, the risk of tank leaks and water damage is a thing of the past.

How It Works — Whole-Home
Gas Tankless Water Heaters
Whole-home gas tankless water heaters apply the same principle to heat water as standard gas water heaters, but without a storage tank. They save energy by heating water only when needed, eliminating energy lost during standby operation.
Here's how:
When a hot water tap is turned on in the home, cold water is drawn into the water heater. A flow sensor activates the gas burner, which warms the heat exchanger. Incoming cold water encircles the heat exchanger and leaves the heater at its set-point temperature. Combustion gases safely exit through a dedicated, sealed vent system.
By heating water only when needed, instead of maintaining a tank full of hot water at all times, tankless water heaters can achieve greater efficiency than standard tank-type water heaters.