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 Sheet Metal Workers actively working in the heating, ventilating, and air conditioning section of the industry will tell you that HVAC systems have become increasingly more complex.
Digital control systems have boomed during the past five years. Experience and familiarity with computers is a must to install and maintain these new systems.
 Credit rightfully is given the National Training Fund for preparing our young apprentices to be journeymen and for keeping journeymen upgraded in the latest technology.
At the very highest level of HVAC technical skill and knowledge is the journeyman sheet metal worker who has achieved national certification in testing, adjusting and balancing environmental systems. We call them "TAB Certified Technicians."
As of December, 1994, less than 200 craftsmen are "TAB Certified Technicians." However, the numbers are steadily growing and the future for work in this highly complex field looks very good indeed, driven in large part by the role of TAB work in achieving improved indoor air quality and in saving building energy costs.
 Sheet Metal Industry certification of TAB technicians is done by the National TAB Certification Board, which is sponsored by the Sheet Metal Workers' International Association, the Sheet Metal and Air Conditioning Contractors' National Association, the Test and Air Balance Institute for Certification and the National Training Fund.
Currently, formal training programs in TAB work and certification test centers exist at these local union JATCs: Local 9, Denver, Colorado; Local 19, Philadelphia, Pennsylvania; Local 73, Chicago, Illinois; and Local 105, Los Angeles, California. Future sites include: Local 104, San Francisco, California; Local 80, Detroit, Michigan; and Local 66, Seattle, Washington.
 A TAB Certified Technician will have completed an NTF-approved TAB training program or worked at least two years as a TAB technician under supervision, be a good standing member of the SMWIA, and pass a five-hour written test and a two-day hands on performance test. One must work at least 600 hours per year in TAB work to maintain certification, and the certification can be revoked for failure to meet established professional standards.
Becoming a "TAB Certified Technician" is a proud moment in the career of a sheet metal worker. Certification comes from the hard work and study that go into completing a sheet metal apprenticeship program and then additional advanced study and work in the TAB field and successful examination by the Board.
 James S. Barrie, owner of the Rocky Mountain Balance Company, an SMWIA contractor who specializes in TAB work out of Denver, Colorado, describes the ideal TAB certified technician as a person "who likes to solve problems, who enjoys working by himself or with one or two other persons, who feels comfortable with computers, and who gets a kick out of understanding HVAC systems and in almost designing them."
TAB technicians test, adjust, and balance all building environmental systems, air and hydronic distribution, to the building's engineering design specifications.
To accomplish this task, certified TAB technicians have achieved proficiency in the following areas: mathematics, fluid flow, heat flow, psychometrics (measurement of dryness of air), HVAC system understanding--including air distribution system, hydronic distribution, steam systems, refrigeration systems, automatic control systems, and electrical systems.
 Certified TAB technicians, using an impressive variety of test instruments, are able to gather accurate, repeatable, and reliable data. Using this data, they will examine and test each air distribution system and hydronic distribution system in a building and set and adjust to design specifications with the least expenditure of energy.
With the above work completed, they finally will balance each system using the most appropriate procedures that will result in the least possible resistance imposed. Balancing basically involves adjusting the dampers in the system until all terminals deliver the proper proportion of air, resulting in airflow within design tolerances.
 Two methods of balancing are taught: proportional balancing and sequential balancing. The "proportional method" involves starting at the low point in a system and working back toward the fan. The TAB technician balances one outlet to another, each damper is set correctly the first time.
The "sequential method" involves setting the outlets in sequence away from the fan. This method is also called the "traverse method" because each time a branch damper is set, the duct CFM is determined by a pitot tube traverse, and then dampers reset to produce the CFM in each branch duct.
Certified TAB technicians balance hydronic systems using either of two methods taught: differential pressure and temperature difference.
 Engineers, architects, and building owners increasingly are relying on "Certified TAB Technicians" and their SMWIA union contractors as the qualified professionals who are the mark of excellence in the HVAC industry.
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