Commercial HVAC is licensed mechanical work, and most states split the air-conditioning license into a full-scope Class A (unlimited equipment size) and a limited Class B capped at 25 tons of cooling per system. That 25-ton line is the cleanest regulator-grade marker of where residential-scale work ends and commercial-scale work begins — a single large rooftop unit or a chiller plant sits well above it.
In Texas, the TDLR Air Conditioning & Refrigeration license makes Class A good for any size unit, while Class B is limited to cooling systems of 25 tons and under and heating of 1.5 million BTU/hr and under. In Florida, Fla. Stat. §489.105 defines a Class A air-conditioning contractor as unlimited, and a Class B contractor as limited to 25 tons of cooling and 500,000 BTU of heating in any one system. Both states share the 25-ton cooling threshold; note the heating caps differ (1.5M BTU/hr in Texas, 500,000 BTU in Florida), so the classes are not identical across state lines.
For an owner, the takeaway is to match the license class to the equipment. A contractor holding only a Class B (or a residential-scope license) is not the right party to replace a 30-ton rooftop unit or service a chiller, regardless of how the company markets itself. State-license scope is a stronger commercial signal than any voluntary certification, because it's the one credential the law actually ties to equipment size — verify the class on the state board's public license lookup, not just the truck.