ML-11-017 -- Prevention of Compressor Short Cycling in Direct-Expansion (DX) Rooftop Units—Part 2: Field Investigation PDF

An advanced control algorithm was demonstrated in a companion paper (Pang and Liu 2011). It aims to address the compressor short-cycling challenge associated with traditional direct-expansion rooftop unit (DX RTU) operation. This paper presents the results of implementing this advanced control algorithm in a real building. The comparison between system performance of the improved control algorithm and the conventional control algorithm is also demonstrated. A newly installed DX RTU was selected, and field investigation showed that the conventional control algorithms caused serious compressor short cycling. By implementing the advanced control algorithm, the compressor short cycling was completely eliminated, resulting in a 15% total electricity savings.