Got a question about chiller staging on FirstEnergy's Schedule CI-2 here in Akron. Client has three 150-ton chillers and they're getting hit hard on demand charges during startup sequences. Current setup brings chillers online based purely on cooling load but doesn't consider electrical demand timing. Anyone have experience with demand-based staging for multiple chillers? The summer demand charge is $11.85/kW so even small improvements could add up quickly.
FirstEnergy Schedule CI-2 - chiller staging to minimize demand charges
TVA here in Knoxville and chiller staging is all about the startup sequence Lloyd. We typically stage large chillers 5-10 minutes apart minimum to avoid simultaneous compressor starts. Also consider the building's thermal mass - you might be able to delay the second chiller start by 15-20 minutes without losing comfort. The key is monitoring both electrical demand and cooling load in real time to optimize the sequence.
Duke Energy territory and we use demand controllers that monitor 15-minute rolling averages. If bringing the next chiller online would push demand over a preset limit, the controller delays the start until demand drops or the cooling load becomes critical. Works well for most office buildings where you have some flexibility in timing. Terry's right about thermal mass too - concrete buildings can coast for quite a while on stored cooling capacity.