I have been dealing with a flame roll of issue on a Lennox TGA roof top unit. One of my check was the heat exchanger. Took the burner box assembly apart and took off the panel that the inducer in mounted on to see the ends of the tubes. Did a clean up and completed a good inspection.

Now my question is not so much about the rollout issue but about the tubes themselves. How the HE double hockey sticks do you clean the top portion (I would call them turbulator area) of those tubes. The bottom runs, no problem. But I was dumb founded. I talked to my journeyman and he said you can't. I was getting cigerettes and saw the manager of the local propane company (a friend) and asked him, he said he uses an air compresser with a blower tip and a 3/8 copper tube. Then when home for lunch I called my instuctor from school and he said he was unfamilular with the TGA series roof tops and has been out of the field for a while but in the day he used a fishtape and steel wool.

Now I know the rules and an not looking for a step by stap process. Just is is possible and is there special tube brushes or is it something you have come up with on your own....or is my journeyman correct in that it is not possible.