You can check if your contractor has the Comfort Specialists Certification. According to information from the Trane official website, it meets the highest standards when it comes to unit installation and, customer service and contractor training. Trane Comfort Specialists are required to sell a decent amount of Trane products annually, and it will be withdrawn if the contractor can get an average 90 (out of 100) rating for customer satisfaction. North American Technician Excellence is another persuasive certification that we have mentioned many times.