From the editor...
Chilled-water systems that vary flow through chiller evaporators have caught the attention of engineers, contractors, building owners, and operators. Chiller manufacturers are increasingly receptive to this interest, thanks to ongoing advancements in control technology. If asked about variable evaporator flow ten years ago, many of these manufacturers would have simply declared, "No, you can't do that!" Five years ago, they would have counseled, "You probably shouldn't do that." Today they will point to existing installations that successfully use variable evaporator flow.

This issue of the Engineers Newsletter considers several aspects of the variable-primary-flow (VPF) system, including: its benefits and complexities; criteria that can help you recognize when a VPF design is a viable option; and tips for its successful implementation.

Table of Contents

• What Is A VPF System?
• Weighing The Pros And Cons
  • Dispelling A Common Misconception
  • A Comparison Of Pump Operating Costs
• What About The Real World?
• Implementing A VPF System
• A Parting Thought...