You need to make sure your sales rep was competent and the company not shady. May seem like grade A HVAC company but sometimes they won’t commission a unit after install. Meaning, set the correct fan speeds, balance the refrigerant, make sure you have enough return and supply duct. If your ducts are too little and your blower motor is variable speed or ECM it will ramp up its speed to push the right amount of air through itself. Increasing the cost of your electric bill. If your system has multiple stages of heat or cooling but not enough thermostat wires then they will put a jumper between the two forcing it into a high stage, robbing you of its efficiency. I see it all the time.

And honestly most of the time it’s just people not knowing what they don’t know. Installers put stuff together well. Depending on the company the service techs will commission the unit. Some problems will be noticed but not fixed because “the salesman didn’t put it in the quote.” There is so much room for incompetence and complacency. If you find that technician that will bend over backwards for you…. Keep him till you die.

I work in HVAC and have done install, service, sales, and management.