Arrived on site to perform maintenance on 4 year old Lennox furnace. Cycled system for heat. Verified proper heating sequence of operations. Temperature rise across heat exchanger is within range. Ran system through 20 point inspection. Homeowner did mention that the temperature difference between the home is pretty significant and they also get quite a bit of dust. After inspecting the ductwork, found ductwork is in very poor condition. Has some rips and tears and also it is only sealed with duct tape which is already coming off. Went over findings and recommendations with homeowner. Went over replacing ducting. They want to replace the ducts but need to see when is the best time for them. As for now they want to add a phenomenal air to the system for better air quality. Will be coming back out on Tuesday from 10-11 to install. Collected in full, nothing will be due upon completion. System is fully operational upon departure.