Question: The owner of a small office building has decided to design and install a piping network that includes five tank less water heaters to heat and transport water. The owner currently requires 18 gpm of hot water service. Cold water (feed water) from the city will be supplied to each heater, and the piping connections were previously installed by the building contractor. The hot water, at 160?F, from the heaters will be transported through a main header for distribution in the rest of the building. Each heater has been specified to provide a maximum of 4.6 gpm of water.

The heater unit has a dedicated pump that serves only to circulate the cold water through its internal finned coil system. Unfortunately, the city supplies the feed water at a low pressure of 40 psia, and the owner needs hot water at 80 psia for complete distribution though the building. Based on the sketch provided below, complete the design of the hot water supply lines in this system. Bear in mind that the owner would like to maintain flexibility to expand the system in the future to its maximum capabilities. Further Information: In practice, the lengths of the hot water supply piping that connect directly to the heaters are small in comparison to that of the main supply header.