Performed QA on Trane Gas Furnace install. Reviewed installation with homeowner. He had some questions about the system but he said it has been working well. He said it was very loud when it kicked into high stage heat. I tested system and was able to lower the high stage heat CFM. Retested temperature splits after adjusting. He also had the Humidifier set to 50%. I talked to him and I lowered it to 40%. He said that he adjusts the humidity if it is dry. I let him know that it can cause condensation issues if it’s turned up too high. Completed checklist form in system. Follow up: Need to go back and install a surge protector for the Furnace (AG3000). It was on the proposal and I did not mark it on the job notes so it is my fault. I did not have one on the truck to install now. Also when we go back we should cut the vertical flue pipe section coming out of the furnace to make it shorter and to pitch the entire pipe correctly. I did not have my metal tools to cut the pipe. System is ru