Got an issue. I’m using the 3 inch PL vent starter stub 1-00-674039 and using an adapter from duravent 3pvp-ADHB that is Specific for a Harman. I was told that this is the part and well it doesn’t fit So does anyone know what the correct adapter that is to fit this. The OD of the stub is 3.55” which is about 1/8 bigger that the adapter. I’m confused and lost with this thing and need some guidance. My 3rd pellet install and this thing is the most difficult