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23 05 93: Testing, Adjusting, and Balancing for HVAC

Modern construction is taking advanatage of the newest HVAC technologies and systems that are being designed with many more individually controlled temperature zones to improve occupant comfort. Variable speed fans and pumps are becoming more commonplace to provide the exact amount of heating and cooling system capacity in a manner that minimizes overall energy usage. New occupant air ventilation codes are much more restrictive and at the same time building envelopes are becoming much tighter. The combination of constantly changing HVAC airflow rates and increased demand for fresh- and filtered-ventilation air for all occupants is placing more emphasis on fine tuning HVAC system operation.

The purpose of testing, adjusting, and balancing (TAB) is to assure that an HVAC system is providing maximum occupant comfort at the lowest energy cost possible.

The following tips are included for initial planning.

Pre-planning for TAB work includes making certain that all the necessary parties and individuals to conduct the work are onboard. The type of building and systems to be tested and a realistic evaluation of what skills the TAB technician possesses are key planning elements.

Often, a controls specialist will be needed to operate the system for the TAB technician.
The representatives from the original equipment suppliers may be needed as a resource, at a minimum, but 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.

If the building has a facilities manager that individual is typically the most important participant with which the on-site TAB technicians will work. Facility managers have a substantial vested interest in ongoing customer satisfaction—the people who work or live in the building are actual end-use customers—and their satisfaction will ultimately be the key measure of success.

Occasionally, a system cannot be balanced or made to perform in accordance with the contract's design specifications regardless of the number of balancing dampers or valves that can be installed. Competent TAB technicians should be prepared for this possibility and work with the appropriate individuals to formulate recommendations as part of the final TAB report.

It should be made clear that the TAB work is not "commissioning." Most commissioning services are completed by firms having technicians experienced with each of the individual building systems—HVAC, lighting, plumbing, electrical, and security systems. ~ Whole Building Desing Guide, www.wbdg.org

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