Abstract
An analysis is presented concerning the relative proportion betwen the sums of rated capacities of on-off controlled and modulating controlled terminal units in differential-pressure-bypass type chilled water distribution systems. In these systems, there is the chance that differential temperature across the supply and return mains at system part-load conditions could be lower than the system design value. The ratio of the sum of rated capacities of on-off controlled terminal units to the sum of the rated capacities of all terminal units should be smaller than the smallest value of the ratios of the pressure difference across the mains at the distribution end (when all the connected terminal units are receiving their rated water flows) to the constant supply differential pressure for all distribution circuits. This excludes units designed for precooling intake outdoor air to or above the design room air temperature.
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