Performed heat check. Checked the electrical, mechanical, safety, and performance of the system. I cleared the condensation drain lines and flow tested the system with two gallons of water. I also treated the drain line. The air filters are clean and had been recently replaced by the homeowner. I did find that part of the flu pipe for the furnace was sagging. I secured the flue pipe so it has a straight run without any sagging. No major issues were found. The system was running at the completion of service.