For the job, I worked on a heating tune-up on this furnace system. I went through all the mechanical and electrical parts of the system and checked for maximum efficiency. I notified the customer about building her drain lines and about the dust levels in her home, however customer mentioned that she has bleach there and that she pours it down herself and that she will vacuum her return plenum to help with us levels. Thank you for choosing Comfort Experts, have a great day!