According to the Testing, Adjusting, and Balancing Bureau (TABB) of the National Energy Management Institute Committee (NEMIC), "The purpose of TAB is to ensure that an HVAC system is providing maximum occupant comfort at the lowest energy cost possible."
"HVAC contractors who don't perform TAB work misunderstand the necessity for TAB testing," said Roy Ringwood, board trustee of the Labor Management Coalition Trust (LMCT) between Orange County (Calif.) Local Sheet Metal Union 105 and Orange Empire Sheet Metal and Air Conditioning Contractors' National Association (SMACNA).
Ringwood has served on the National Test & Air Balance Technical Task Force.
"You can have an environmentally safe building without TAB, but IAQ and energy consumption can be affected by problems that TAB testing would have caught."
TAB has been around for quite some time. How has it changed? "In particular, enactment of the certification program is one of the major changes that TAB has undergone," Ringwood said.
Today's TAB certification means that the contractor, supervisor, and technician are all trained and certified. "There is a direct, comprehensive certification program for TAB. Before, a TAB-certified contractor didn't have to have a certified technician." Having certified techs, among other things, helps ensure that testing is performed accurately.
Another change in the program is that contractors have to sign a quality and integrity agreement, he pointed out. All three parties (contractor, supervisor, technician) must be recertified periodically.
The TAB Tech"The journeyman sheet metal worker who has achieved national certification in testing, adjusting, and balancing environmental systems is at the highest level of HVAC technical skill and knowledge," according to Sheet Metal Workers' International Association (SMWIA).
TAB procedures on a complicated HVAC system require that the TAB tech be well-trained, highly skilled, and knowledgeable.
"This person must know the fundamentals of airflow, hydronic flow, refrigeration, and electricity and be familiar with all types of HVAC temperature controls and refrigeration systems," according to the bureau.
"They must also know how to take pressure, temperature, and flow measurements and be able to perform effective troubleshooting."
James S. Barrie, owner of Rocky Mountain Balance Co., Denver, described the ideal TAB 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 almost designing them."
A TAB-certified technician will have completed a National Training Fund (NTF)-approved training program or worked at least two years as a TAB tech under supervision; be a member in good standing of SMWIA; and pass a five-hour written test and 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," according to the bureau.
Some TAB jobs can be done by one person. However, many HVAC systems need a TAB team to complete the work efficiently and in a reasonable time period.
It is equally important that the other members of the TAB team be trained and knowledgeable in the basic fundamentals and procedures of TAB work. Getting one person on staff certified may be a good place to start, but it could limit the TAB jobs a contractor pursues.
TAB JobsThe goal of TAB work, for any new construction or renovation project, is to verify that all HVAC water and air flows and pressures meet both the design intent and equipment manufacturer's operating requirements, the bureau explained.
"It is rare to find an HVAC system of any size that will perform completely satisfactorily without the benefit of final adjustments. This is why it is considered a â€˜best practice' for the designer to specify that TAB work be part of the overall HVAC system installation."
Preplanning comes first. "Preplanning for TAB work includes making certain that all the necessary parties and individuals to conduct the work are on board," the bureau stated.
Key considerations include the type of building and systems to be tested, and "a realistic evaluation of what skills the TAB technician possesses."
Sometimes a controls specialist is needed to operate the system for the tech. In addition, OEM supply representatives may be needed as a resource, at a minimum. "For complex equipment and systems, or in a new building startup, a manufacturer's representative may be required at the site to operate the mechanical equipment," the bureau said.
The facilities manager is typically the most important team member with whom TAB technicians will work. "Facility managers have a substantial vested interest in ongoing customer satisfaction," the bureau said. "The people who work or live in the building are actual end-use customers; their satisfaction will ultimately be the key measure of success."
If a system cannot be balanced or made to perform according to the contract's design specifications regardless of the number of balancing dampers or valves that can be installed, TAB techs need to be prepared to work with the appropriate people, and together formulate recommendations for the final TAB report.
Two methods of balancing are taught: proportional and sequential. The proportional method involves starting at the low point in a system and working back toward the fan, the bureau explained. "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 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.
Critical NeedsTesting, adjusting, and balancing all of the HVAC systems in a new building is very important to completing the installation and making sure the system performs as the designer intended. "Contamination in new structures can include formaldehyde, off gassing from new furnishings and glue, even mold and moisture," said Ringwood.
In any building, energy management and IAQ are good reasons to repeat the test every year. "Building owners may not know how building systems affect those two areas," Ringwood said.
"I've seen strange things uncovered by technicians," he continued. "One new building, for example, was mostly occupied but some floors were unoccupied. A fire damper was left shut by the contractor." Off gassing building materials could not vent adequately, making several occupants ill.
"Testing, adjusting, and balancing of the HVAC system fine-tunes occupant comfort levels while keeping energy use to the lowest level possible," the bureau said. "This is extremely important in this era of rising energy costs."
"The International Certification Board certifies contractors and supervisors," Ringwood explained. "The International Training Institute trains technicians."
There currently are formal TAB training programs and certification test centers at these local union Joint Apprenticeship Training Committees (JATCs): Local 9, Denver; Local 19, Philadelphia; Local 73, Chicago; and Local 105, Los Angeles. Future sites will include Local 104, San Francisco; Local 80, Detroit; and Local 66, Seattle.
For more information, visit www.tabbcertified.org.
Sidebar: TAB Tools And InstrumentsCertified TAB techs use an array of test instruments to gather accurate, repeatable, and reliable data. Using these tools, they examine and test each air distribution system and hydronic distribution system in a building, and set and adjust the system to design specifications. Here is a list of some of the tools and test instruments they may use, according to the Testing, Adjusting, and Balancing Bureau (TABB).
Airflow measuring instruments:
Temperature measuring instruments:
- B. Checket-Hanks
Publication date: 04/25/2005