Doyle et al. (1993) explain the disadvantages of run-around systems for a laboratory project in the Midwest of the U.S.
A run-around heat recovery system was also considered and rejected for several reasons [in this example]. First, acids are commonly used in several of the laboratories, and there were concerns that a conventional copper/aluminum water coil would soon be corroded. Special coatings or stainless steel were found to be expensive and to reduce heat recovery efficiency. Therefore, the exhaust air stream would require filters installed upstream of any heat recovery coils, adding additional first cost to the project as well as a long-term maintenance expense and hazard. In addition, the physical layout of the existing exhaust plenums and fans was restrictive and would have required extensive modification to incorporate heat recovery coils. Finally, there was insufficient space to install new heat recovery coils in the existing supply systems, and the potential for mixing of glycol for heat recovery and central plant chilled water precluded the use of the existing cooling coils.
