My parents and I have used Flanagan’s and found that they did a great job. My house has 18 vents, and it took them just over an hour to clean everything. They tested the furnace before they left and gave some advice on a reusable furnace filter that we had. They also found crayons and junk from the previous owners. I had had another furnace cleaner out year ago, and I was surprised that there was junk from kids still in there. The technicians are very nice, and it was easy to book an appointment.