NPLV rating is valid “weather” your plant has single or multiple chillers -- The NPLV rating has become the industry’s standard measurement for water-chiller efficiency. Originally, the rating was derived from analysis of single-chiller plants, even though most plants contain multiple chillers. However, research by Johnson Controls shows that the NPLV rating is applicable to both single-chiller and multiple-chiller plants. This HVAC&R Engineering Update will explain those findings.

Hermetic motor burnout: how to avoid the catastrophic cost. -- If your centrifugal chiller utilizes a hermetic motor and the motor suffers a burn-out, the downtime is counted in months. But if your chiller utilizes an open motor, the downtime is counted in days. And the repair cost is significantly less, too. This Update explains why.

Designing for LEED certification? There is help under your feet. -- If a building is being designed with LEED certification as a goal, it is important to know that the HVAC system can be a major contributor toward that goal. This HVAC&R Engineering Update will explain how a variable-air-volume, underfloor-air-distribution (VAVUFAD) system can garner a significant portion of the LEED points required for building certification.

New ARI chiller rating eliminates need for design kW/Ton specs -- A new rating method for chiller performance has been developed by the Air-conditioning and Refrigeration Institute (ARI). It closely tracks real-world, chiller-energy performance by more accurately accounting for chiller operation at off-design conditions. As a result, engineers no longer need to specify design kW/Ton.

Reduced condenser-water flow rate: energy-saving miracle or mirage? -- Recently, there have been challenges to the long-time guideline that chiller systems should be designed with 3 GPM/TR of condenser waterflow. The claim is that low-flow systems will save both first cost and energy cost. This Update shows there are pitfalls to low-flow systems that are not immediately apparent, and that a 3 GPM/TR design is still the best for most situations.

The impact of HCFC-22 phase-out On DX chillers -- HCFC-22 is the world’s most widely used refrigerant. It serves in both residential and commercial applications, from small window units to large water chillers, and everything in between. Its particular combination of efficiency, capacity and pressure has made it a popular choice for equipment designers. Recently, extensive use of HCFC-22 has made it possible to reduce the use of CFC refrigerants...

Chiller-plant design in a deregulated electric environment -- Understanding the real-time-pricing concepts employed by electric utilities is crucial to chiller selection for a multiple-chiller facility. An examination of hybrid plants shows that a mix of electric and absorption or gas-engine drive chillers substantially cuts operating costs during high-demand periods. This combination also lowers on-peak demand and flattens the overall electric load profile.

Chiller-plant energy performance -- Traditional efficiency comparisons for chiller plants have been based on energy ratings at design conditions (full load and warmest tower water). But chillers typically spend 99% of their operating hours at off-design conditions. For greatest efficiency, the selection and operation of chiller-plant components must take this fact into account.