How It Works — High-Efficiency Gas Storage Water Heaters

High-efficiency gas storage water heaters employ the same technology as standard gas storage water heaters: a glass-lined steel tank is heated by a burner located at the bottom of the tank. But a few basic changes make them operate more efficiently.

Here's how:

High efficiency models simply have better insulation, heat traps, and more efficient burners, improvements that have a modest impact on price but increase efficiency by about 7.5%. To increase efficiency further, manufacturers may add a power vent to accelerate the venting of combustion gases. This may increase the installed cost, but savings are also greater.