Bosch Water Heating introduces the ProTankless™ models GWH 635 ES and GWH 635 ESO water heaters, along with the Tankless Link™ cascading kit accessory, which is designed to double the units' output. These units will provide an endless supply of hot water at a flow rate of more than 12 gallons per minute when installed together and connected by the Tankless Link. The cascading kit consists of a cable and a shunt and is easy to install. A cascading application, as it is known in the tankless water heating industry, allows for multiple appliances to be connected in parallel. Bosch Water Heating. Circle 17.