In many cases, the annual pumping energy for chilled water systems exceeds the chiller energy consumption, sometimes by a factor of two or three. In the great majority of cases, the pump head installed in piped systems significantly exceeds the head required. The result is that either the system circulates too much water, increasing both pump and chiller energy use, or the excess head is taken out in balancing, again increasing pump energy use. One reason for these excessive pump heads may be inaccuracies in the available pressure loss data for large fittings. Available sources give substantially different estimates of pressure loss sometimes varying by a factor of 2. A second major reason for excessive pump heads is the tendency of design engineers to add large margins of error to their loss estimates due to uncertainty about fitting losses. This needs to be corrected. The objective of this research project is to provide engineers with data that will enable them to optimize hydronic system design by: a) Extending the K values and range of variation of K values given in Tables 2 and 3 of Chapter 33 of the 1997 Fundamentals Handbook through laboratory tests to include fittings for which almost no test data are currently available, specifically, fittings from 12 inches to 24 inches, and b) Providing a well-documented reference that can be cited in the Handbook.

Principal Investigator: William Rahmeyer, Utah State University

Conducted: April 1998 - July 1999

Sponsored by: TC 6.1, Hydronic and Steam Equipment and Systems