SF-86-10-5 -- Variations in Relative Humidity in a Conditioned Space Due to Coil Bypass Control Systems ✓ Most Recent

The coil bypass system is a common means for controlling temperature in many air-conditioning systems. The problem that arises is that the relative humidity deviates from the design condition. For some situations, there can be extreme changes in the relative humidity, which can cause discomfort for occupants in the conditioned space. Computerized iterative calculations are made using the ASHRAE psychrometric algorithms to determine the room relative humidity for both a room air and a mixed air bypass control system. The design sensible heat ratio, quantity of ventilation air, and outdoor design conditions are used as parameters in the analysis. The room sensible cooling load is varied in a typical manner resulting in changes in the room relative humidity for fixed air conditions coming off the cooling coil.

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