The drive towards embedded intelligence has long included microprocessor based chiller and boiler controllers. Each machine came with a tested and validated, special purpose controller designed to manage the piece of equipment it is applied to. Capacity control is as much of a given as is management of operating and overload safeties. Typically, there are inherent energy efficiency strategies built into the multiple lines of programming code embedded in the unit’s controller—flow measurement, thermal capacity monitoring and management, refrigerant vessel protection, flue gas management, purge cycles, and so forth. Essentially, ‘smart’ controllers creating a completely self-contained and functioning piece of equipment.
Where it gets complicated is when a building’s heating or cooling needs require combining multiple pieces of equipment (chillers, boilers, cooling towers) into a functional and fully automatic heating or cooling plant. Ideally, the plant resembles a single ‘module’ designed to specifically provide the capacity of heating or cooling medium for the least energy cost and with no need for operator intervention—set it and forget it.
Unfortunately, every building is a custom prototype defying standardization. Consequently, the goal of a productized multi-chiller or boiler ‘Plant Controller’ still remains elusive. Custom plants still require custom controls and integration approaches.
Success requires early planning of desired outcomes and careful selection of equipment. Insuring that the prime movers (chillers and boilers) include open protocol interfaces is the first step. Secondarily, pump and cooling tower fans should only be installed with variable speed drives and those must also include the ability to communicate using open protocols.
Relying on the manufacturer of a singular piece of equipment to provide a turn-key, customized plant control and operations strategy incorporating other equipment that they don’t manufacture is still marginal at best. The successful implementation of custom plant control remains the domain of competent designers, builders and systems integrators.