Oil boiler soot questions

Having the boiler cleaned tomorrow - a Weil McLain GO-4 with a QB180 burner (yes, the burner is still working after ~18 years; knock on wood).

I've a few general questions on soot.

1. Seem like I always having some soot on top of the boiler where it blow out from the damper. Is some soot ok? How much is not ok?

2. CO2 is supposed to be between 11 and 12.5%. Mine has been rising for the last few years, 13.2 (as I recall 2 years ago), 14 last year. The QB180 calls for the air attenuating setting to be 5.5. The tech last years was able to get 0 smoke by setting it from 4.5 (previous year) to 5.

The burner manual notes to decrease the CO2 level, open the attenuating air band setting.

2a. Is opening the setting move up on the setting from 5 to 5.5?

2b. The tech did not want to adjust it further from the setting last year; he said it would result in a sootier burn. Will it if it is increased to 5.5?

Each year I try to learn a little more about how the system works.

Thanks

 

In my opinion, NO, ANY

Ummm... something is wrong. I'm not sure what your tune up guys are doing or thinking, but if your CO2 is that high (over 12%) they should not be leaving the boiler running in that way.

The setting of the air band is sorta relative... the 5.5 is a suggested starting point.

I think you need a new tech. One that understands combustion, and if there is something wrong with your boiler/burner, to let you know.