The Texas A&M University (TAMU) main campus in College Station consists of 110 buildings with12.5 million square feet of gross building space. Seventy-one of these buildings are connected to the maincampus domestic hot water (DHW) distribution system. The DHW loop is more than 50 years old and has hadcontinuing distribution problems. The main problems reported from several buildings were low hot watertemperature and long delays in obtaining hot water at fixtures. The objective of this study was to investigate thecauses of these problems and help determine how to best operate the system.It was found that reported problems of low flows, low temperatures and long hot water lag time resultedfrom reverse flows and no hot water circulation caused by: 1) Unadjusted return pumps with heads too high. 2) Pumps not installed or not running where needed. 3) Pumps with heads too low. 4) Check valves not installed where needed. 5) Insufficient piping capacity in two locations. This paper presents possible control strategies to alleviate these problems identified during the fieldinvestigation.
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