The technician arrived well within the time window. He was courteous. The furnace made a noise when he first started it. I explained it has made this noise after a period of inactivity. He was able to quickly track down the general area but by then the noise stopped. He said he suspected where the problem might be but he would not recommend doing anything until he knew for sure. He completed the rest of the service call and no noise, he shared the results of his testing of my system and said he had copied down the model and serial number and would be calling Lennox to see if there were any known instances of this particular model making this particular noise and what they had determined the issue to be. He said he would get back with any news. I call that going above and beyond.