HVAC Chilled Water Distribution Schemes

In HVAC Chilled Water Distribution Schemes, you'll learn ...

• How constant volume chilled water systems differ from primary/secondary arrangement
• What are the causes and mitigation measures to prevent low delta-T syndrome
• How primary/secondary chilled water systems create hydraulically independent loops
• How the variable primary flow system compare with primary/secondary system in terms of cost and energy

Overview

Preview a portion of this course before purchasing it.

Credit: 5 PDH

Length: 48 pages

In large commercial and industrial systems, chilled water system serves as means to transfer heat from building spaces to the refrigeration system. Initially, when energy costs were low, constant volume and primary-secondary systems provided a stable and simple operation of the chillers and distribution systems. However, as energy costs increased, particularly in the late 1970s, the efficiency of the chillers and the costs associated with operating the distribution system became more important. As a result, the need for new schemes to improve chiller performance and reduce energy costs drove the HVAC industry to advance chilled water technology, particularly in the manner that chilled water is delivered.

To understand the hydraulic considerations associated with delivering chilled water and how they influence system performance, it is important to understand how technology and design challenges over the years have influenced today's approach to chilled water pumping.

This five-hour course discusses the history of chilled water distribution systems and the development of "variable primary flow system." Problems such as low delta-T syndrome associated with the chilled water pumping schemes are defined and discussed and finally, this course compares the advantages and disadvantages of primary-secondary and direct-primary pumping schemes.

Learning Objectives

Upon completion of this course, participants will be able to:

• Compare constant-volume chilled-water systems with primary-secondary arrangements.
• Identify the causes of low delta-T syndrome and describe measures used to mitigate it.
• Explain how primary-secondary chilled-water systems create hydraulically independent loops.
• Compare variable-primary-flow systems with primary-secondary systems in terms of cost and energy use.
• Explain the importance of design tube velocity and chilled-water flow variation in variable-primary-flow systems.
• Apply basic hydronic principles relating chilled-water flow rate to cooling load and energy savings from adjustable-speed pumps.
• Describe low delta-T syndrome and its effect on chiller loading.
• Explain why distributed pumping may be preferable to a headered arrangement for constant-flow systems.
• Calculate the required size of a decoupler bridge.
• Compare control-valve characteristics and explain why a two-way valve is preferable to a three-way valve in variable-flow systems.

Certificate of Completion

You will be able to immediately print a certificate of completion after passing a multiple-choice quiz consisting of 25 questions. PDH credits are not awarded until the course is completed and quiz is passed.