When compared to traditional storage tank heaters, Bosch'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 up to 20 years, with almost 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 hundreds of dollars 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 will keep heating water.

The Bosch Therm 520 HN (formerly GWH-425-HN) can supply enough hot water for one major residential appliance (or a shower) at a time. It has an innovative micro hydro turbine ignition system, which generates a concentrated ignition spark when you turn on your hot water faucet. This unit does not require any electricity for operation.
Delivers up to 5.2 gallons per minute at a 35 deg F temperature rise. Minimum flow of 0.6 gpm to activate. 117,000 BTU. 80% efficiency. Non-Condensing.
The 520-HN is approximately 36-3/4" H x 18-1/2" W x 10-1/2" D. Weighs 35 pounds (shipping weight is slightly higher). You will need sufficient wall space to mount the unit, and be able to install an exhaust vent to the outdoors. The optional AQ4 power vent allows you to install a horizontal vent, which may be easier in your home than the standard vertical venting configuration.

Bosch ProTankless water heaters are state of the art tankless heaters with a 15 year limited manufacturers warranty on the heat exchanger, 2 years on the other parts, 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.

Not Energy Star Rated.

GWH425HN, GWH425-HN, Aquastar, 520HN