Pressure Independent Valve Technology Provides Long Term Solution
Shell Point Retirement Community in Fort Myers, FL, is an extraordinary property. With over 400 acres and nearly 2000 residents, it is Florida's largest life care retirement community, combining all the services of a comprehensive staged elder care facility and the amenities of an all-inclusive resort. Also extraordinary is the fact that this sprawling property, which includes a 75-acre island and a wide assortment of medical, recreational, and living facilities, is served almost entirely by one central energy plant. The efficient and seamless delivery of heating and cooling to the outlying buildings is, in no small part, thanks to the nearly 1500 Pressure Independent Control Valves (PICCV).
Belimo has played an important role in Shell Point’s HVAC system since the property embarked on a 20-year multistage expansion several years ago. In addition to numerous new construction projects, this expansion included transference of several independently cooled buildings onto the central plant system. Ultimately the centralized cooling system would include 5 miles of underground piping. This massive system and a desire to resolve existing low ΔT problems led Shell Point Energy Plant Manager, Dan Parker, and Project Development Engineer, John Trowbridge, P. E. to explore Belimo pressure independent technology.
According to Trowbridge, pressure independent control eliminated the need for balancing newly constructed systems, as well as rebalancing systems already connected to the central load. Balancing would have been especially burdensome since all the air handling units already connected to the central plant would require rebalancing at the same time; a daunting challenge for even the most skilled contractor. This, along with the high differential pressures found in some areas of Shell Point, made Belimo PICCVs an appealing solution.
How the PICCV works:
The PICCV combines a differential pressure regulator with a two-way control valve and actuator for electronic flow control. The pressure regulator controls the amount of flow passing through the valve according to the change in pressure. All pressure changes are absorbed by the pressure regulator allowing the differential to be held constant over the control valve section, thereby providing consistent flow. This is different from conventional 2-way control valves, whose operation can be severely distorted by system pressure changes.
“The PICCVs circumvented the issues we had and provided us with a totally self-balancing system,” says Trowbridge. “With the PICCVs, we are assured that the ΔT across the coils is at design conditions, working optimally, and pumping energy is minimized.” Because the PICCV has a very high close-off pressure rating, it can easily close off against the higher pressures found at some of the air handlers on the property, making it every bit as reliable as globe valves in many applications, often at a fraction of the installed cost. Even so, Dan Parker, a seasoned veteran in chilled water systems, was prepared for certain flow issues to crop up when the first PICCV controlled system went on-line. He was pleasantly surprised. “There was no impact on the system whatsoever. No increases in flow, chilled water demand, or pump power,” said Parker, adding “that since startup, no manual balancing has been required thanks to the dynamic system balancing the PICCV provides.”Download complete case study.