If I remember correctly, there are only seven major manufacturers of HVAC equipment, however this equipment is sold under about 50 different brands. United Technology has about 10 brands, Goodman about 4 brands, American Standard (Trane also), Lennox about 4 brands, Rhemm/Paloma two brands, York about 3 or 4 brands, and Nortek about 7 or 8 brands. Anyway the actual companies are far fewer than brands they make. And the largest selling single brand? Goodman (now you know why some contractors hate Goodman, especially if they lost sales to them)!