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-635-ESO tankless propane water heater outdoes even their 425-ESO in terms of overall efficiency and convenience. The 635-ESO has an energy efficiency rating of .85 (NG model) to .86 (LPG model), far and away the most efficient water heater available today. The 635-ESO also provides up to 5 gallons of hot water per minute at a 55 degree temperature rise, allowing the use of two major hot water outlets at one time. You could fill the bath and run the dishwasher at the same time, with plenty of hot water flow for both. For even higher volume hot water needs, you can even link ("cascade") two 635-ESO units to provide twice as much hot water at one time, with the optional TLINK kit!

The 635-ESO uses 120VAC power for ignition, and measures approximately 26x16x9. This unit is designed to be installed outdoors, so no venting is required. It is freeze-protected to 5degF. The optional wireless remote allows you to adjust your water temperature without having to walk to your installation site.

Bosch-Aquastar ProTankless water heaters are state of the art tankless heaters, with a 15 year limited manufacturers warranty to protect your investment. A computerized 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 625-ESO DOES qualify for the 2007 $300 Energy Efficiency Tax Credit.