Smoky smell from new furnace - Slant/Fin Direct Vent

[mw123]

I have a 3 year old slant/fin direct vent furnace with a riello burner. oil fired. It has a smoke smell that seems to come from the boiler when running. The smell is not a gas like smell, but more of a burnt smell. I have tried two carbon monoxide detectors and neither register on the LCD, so I believe it is not exhaust.

My furnace technician has cleaned the furnace yearly, has resealed with high temp silicone the hood each year, and this year put on a post purge blower, but it still smells. It is a 3 year old furnace.

The technician recommends we convert from direct vent to a chimney with flu. Will this really fix the problem. Are there other options?

[rmw]

I am not sure why he put on a post purge this year as all direct vents i installed come standard with post purge. Is the burner designed for direct vent or conventional vent? is the air intake to close to the vent( could be drawing exaust back in). Model number for the burner and furnace would help indetermining if the equipment is compatiable with direct vent.

[mw123]

Slant fin Model

The furnace is a slant fin intrepid direct vent TR-DV with riello bf5, the riello did not come stock with post purge control so it was added. It is set at 2mins post purge time.

The vent is an all in one round vent with intake and outtake in the same vent. (kind of an inner ring and outer ring). Once inside the house it splits into two channels for the clean air and exhaust.

The manual shows this as a valid combination of riello with slant fin trdv