Testing, Adjusting, and Balancing Bureau (TABB) and International Certification Board (ICB) have worked together to develop a national set of standards for HVAC technicians. They offer certifications for technicians to evaluate whether they meet this set of standards, and while these certifications fulfill no legal obligations, they are widely recognized and demonstrate to employers and customers a high level of competence on behalf of the certification holder.
In order to obtain TABB certification, you must either complete a training program offered by the International Training Institute (ITI) or have worked at least 2 years in the HVAC industry. If you meet this requirement, you must then pass a written exam as well as a 2-day hands-on practical exam. You must also complete at least 600 hours of HVAC work every year to maintain your certification, and must meet the criteria for re-certification every 2 years.
You can learn more about TABB certification by visiting the ICB website here.