HVAC Testing, Adjusting and Balancing (TAB) are the three major steps used to achieve proper operation of HVAC (heating, ventilation, and air conditioning) systems. TAB usually refers to commercial building construction and specialized contractors that perform this service.

In general, the TAB specialist performs air and hydronic measurements on the HVAC systems and adjusts the flows as required to achieve optimum performance of the building environmental equipment. The balancing is usually based upon the design flow values required by the Mechanical Engineer for the project, and the TAB contractor submits a written report which summarizes the testing and balancing and notes any deficiencies found during the TAB work. Many times facility managers will use a TAB contractor to assist in identifying preexisting or common issues with a facility. While not necessary to be a TAB contractor, many contractors tend to hold professional air balancing certifications

Testing establishes the quantitative aspects of the HVAC system, such as the volume of airflow that’s being produced or the heat transfer rate.

Balancing ensures that proportional airflow, heat transfer and other characteristics are equalized among all terminals, branches and subsystems.