FAQ / Why is Testing, Adjusting and Balancing (TAB) work necessary?
Most of today’s newest HVAC systems 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 building construction industry is experiencing a major growth in demand for experienced and certified testing, adjusting, and balancing (TAB) contractors who can balance today’s complex HVAC systems.
TAB in New Buildings
Testing, adjusting, and balancing of all HVAC systems in a new building is needed to complete the installation and to make the system perform as the designer intended. Assuming that the system design and installation meets the comfort needs of the building occupants, testing, adjusting, and balancing of the HVAC system fine tunes occupant comfort levels while keeping energy use to the lowest level possible. This is extremely important in this era of rising energy costs.
It is important to make sure that all factory equipment startup service has been completed before beginning any TAB work. Most specifications on new building construction usually require a factory representative to be present during the initial startup and adjustment of the mechanical equipment—central boilers, chillers, large variable-speed motor drives, and cooling towers. This initial equipment checkout is also usually required to activate the factory warranties and is not part of the TAB contractor’s responsibility. After this initial startup service has been completed, the TAB contractor should be informed that the systems are operating properly, that all safety interlocks and protective devices are functioning, and the systems are ready to be balanced.
The TAB phase of any building construction or renovation is intended to verify that all HVAC water- and air-flows and pressures meet the design intent and equipment manufacturer’s operating requirements. 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 “best practice” for the designer to specify that TAB work be part of the overall HVAC system installation.
TAB in Existing Buildings
There are few buildings in existence that have not experienced changes in internal loads and space layout changes since they were designed and built. These buildings should periodically have their HVAC systems rebalanced to achieve maximum operating performance, efficiency, and comfort.