The end product from duct cleaning

When I moved into our new house, I did our best to take good care of the boiler upgrade. I made sure consistently to do it to prolong the lifespan of the whole condo oil furnace, however for the past more than three years, I had not missed any oil furnace/heater tune-up, and when I started noticing that our condo was a little stuffy, I was alarmed. I consistently cleaned the washable filter every two weeks, so something else had to be the issue. I called a neighbor who works in a heating corp as an HVAC repairman and told him about our concerns which did not have to do with the actual gas oil furnace. After our talk, it was obvious that our focus should have gone to the air duct. I instantly called condo services and asked to have a duct cleaning. The day the heating provider came, I commanded to see the dirt out of the air duct. I was shocked to see the amount of muck that was there. The weird section was that there was a lot of hair, and I could tell from the dirt that it was from way before I moved into that house. I could have expected hair from a drainage plan however not in the vents. I did not bother asking for energy-saving help tips because the ones I had were laboring, and I would continue with things as they were. That day I fell asleep in the residing room and did not even bother going to bed, the gas fireplace soothing me into a dreamless slumber, my niece was surprised to find me fast asleep in the residing room.
hvac duct