When compared to traditional storage tank heaters, Bosch-Aquastar's line of tankless propane-fired water heaters are almost unbelievably efficient, and incredibly long lasting. With traditional water heaters, heating efficiency can be as high as 78% when brand new, but that rating declines annually as minerals and debris settle on the bottom of the tank. Most tank heaters will also require replacement in 9 years or less.

A quality gas tankless water heater can be expected to last 20 years, with absolutely no loss in efficiency during that time. Also, because tankless water heaters only heat water when it's actually being used, instead of heating a full storage tank 24 hours a day, a Bosch heater can save you over $400 per year when compared to an electric tank water heater. In addition to financial considerations, with a tankless water heater you never need to worry about running out of hot water. As long as your hot water tap is open, your Bosch-Aquastar will keep heating water.

The Bosch GWH-425-EF (formerly the Aquastar 128X) model can supply enough hot water for one major appliance (or a shower) at a time. It has spark ignition powered by standard 120V electricity. The 425-ES is approximately 30x18x9 inches. You will need sufficient wall space to mount the unit, a source of 120VAC power, and be able to install an exhaust vent to the outdoors. The optional FXHOOD vent hood is recommended in very cold climates, as the back-draft flapper prevents cold air from freezing the unit.

Bosch-Aquastar ProTankless water heaters are state of the art tankless heaters, with a 15 year limited manufacturers warranty to protect your investment. A modulating gas valve controls the water temperature, according to your setting, and an included pressure relief valve helps ensure safe, reliable operation. Bosch ProTankless heaters are available in propane (LPG) or natural gas (NG) configurations. Please select your preference when ordering. NOTE: The natural gas 425-EF does NOT qualify for the 2007 $300 Energy Efficiency Tax Credit. The 425-EF LPG model does.