Laboratory Assessment of Demand Response Rooftop Unit (RTU) Controller
This laboratory project was initiated to evaluate the DR capabilities of an add-on retrofit controller on a five-ton rooftop unit. To communicate with the controller using OpenADR 2.0 protocol, the controller vendor chose a third-party central gateway, which received the OpenADR 2.0 signal and transferred that information to the controller, to perform pre-programmed demand-limiting control strategies. The manufacturer’s certified contractor installed and set up the controller. The controller was set to vary the frequency from 40 Hertz (Hz) to 60 Hz in cooling mode. When the compressor cycles off, the indoor fan’s frequency drops to 20 Hz.