The objective of the computer program presented in this paper is for simuation, not for equipment selection. A simulation predicts pressures, water flow rates, energy flow rates, and water temperatures at all critical locations in the system. In selecting equipment, on the other hand, the pressures, temperatures, and flow rates are assigned at all critical locations. The individual components can then be selected to abide by the designated combinations of variables, e.g., a pump selected to provide the stipulated elevation in pressure at the designated flow rate. A simulation program requires as input data the performance characteristics of all components (pressure-flow relationships of pumps, pressure-drop characteristics of pipes and fittings, heat transfer characteristics of coilS, etc.), and the simulation program computes how the system performs in order to satisfy all of these individual characteristics. Although a simulation program is different from an equipment selection program, the simulation program can be used as a design tool by repeated application of the program for various thermal load combinations on the system being explored.

This paper represents a progress report of ASHRAE Research Project 141 monitored by Technical Committee 6.1, Steam and Hot Water.