Air-Handling Systems

Table of Contents

Chapter 1: Air Movement and Distribution

Topics: Air handling system; Comfort, process air conditioning; Heat and moisture transport; How air moves; Types of airflow; Pressure relationships; Controlled ventilation and pressurization; Dual-duct systems; System velocity

Learning Objectives:

• List the variables controlled by an air-handling system.
• Define comfort and explain how to predict whether or not people in a space will be comfortable.
• Define the following terms: laminar flow, turbulent flow, streamlining, and eddy currents.
• Differentiate between static pressure, velocity pressure, and total pressure in an air-distribution system.
• Compare a dual-duct system to a single-duct system in both structure and operation.

Chapter 2: Fans and Fan Motors

Topics: Fan construction; Centrifugal and axial-flow fans; Fan performance curves; System characteristics; Preventive maintenance for fans; Impeller maintenance; Belt, drive-train, and bearing maintenance

Learning Objectives:

• Describe the two basic types of fans used in air-conditioning systems.
• Define the terms system characteristic and point of operation.
• Explain why a knowledge of fan laws and performance curves is necessary when altering an air-handling system.
• Describe preventive-maintenance procedures for typical fans.
• Explain how to replace the bearings in a centrifugal fan.

Chapter 3: Ductwork Types, Fabrication, and Repair

Topics: Types of ducts; Duct designations, fittings, and connections; Insulation; Terminal devices; Fabricating sheet metal ducts; Duct reinforcement; Duct maintenance

Learning Objectives:

• Define the term aspect ratio.
• Compare and contrast a radial duct system and an extended plenum system.
• Describe the structure and purpose of dampers and turning vanes.
• Identify a variety of fittings and connections used in a sheet metal ductwork system.
• Explain how and why ducts are insulated and reinforced.
• Identify common types of sheet metal seams and describe how each is fashioned.
• Explain the basic servicing and inspection procedures for ductwork systems.

Chapter 4: Air Filtration

Topics: Mechanical air filters; Service schedules; Servicing impingement filters; Replacing dry media filters; Installing HEPA filters; Electronic air cleaners

Learning Objectives:

• Explain the function of an air filter.
• Describe the two main types of mechanical air filters.
• Explain how to establish a service schedule for air filters.
• Explain how to clean and/or replace the filters in your HVAC system.
• Explain the operation of electronic air cleaners and tell how they are serviced.

Chapter 5: Air System Balancing and Troubleshooting

Topics: Measuring instruments; Pretest data collection; Preparing the system; Measuring and adjusting the main airflow, branch ducts, registers, and diffusers; Troubleshooting

Learning Objectives:

• Explain why air-handling systems need to be balanced.
• Describe the instruments used to test and balance an air-handling system.
• Demonstrate how to measure velocity pressure and show how airflow rates are calculated from these pressure readings.
• Describe a pitot-tube traverse.
• Explain in step-by-step fashion how to test and balance an air-handling system.
• Name common complaints related to air-handling systems and give common causes.

Chapter 6: Indoor Air Quality and Sick Building Syndrome

Topics: Sick building syndrome (SBS) characteristics, contributors; HVAC systems as contaminant sources; Pollutant pathways; Odors and contamination, Building-related illness

Learning Objectives:

• Discuss the characteristics of sick building syndrome (SBS).
• Describe the process for investigating an SBS complaint and explain how to conduct a facility site review.
• Discuss ways a facility can minimize the probability of perceived SBS problems.
• Discuss internal and external SBS contributors, including HVAC systems, and discuss ways to eliminate or reduce the problems.
• Describe specific ways to control particulates, odors, and other contaminants.
• Define the abbreviations SBS, IAQ, BRI, VOC, and MCS.

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