The short answer is they all should. A group of industry experts from all sector of HVAC industry experts from all sectors of the HVAC industry developed a standard that defines how an HVAC system must be designed and installed if it is going to work properly. Their work, over a three year perioud, resulted in an industry standard: the ACCA/ANSI HVAC Quality Installation Specification. The standard requires balancing on all newly-installed HVAC systems. Unfortunately, the QI Specification is not a requirement in all local jurisdictions. Therefore, many contractors still skip the TAB work. This is especially true in new construction where teh low bid has traditionally rules. You should always find a professioal contractor who is capable of following QI Specification’s procedures for any HVAC TAB work.