Just Bought a Furnace Need Help with Chimney
"B" vent is for gas furnaces, it is not approved for oil!!!
For oil furnaces you need "L" vent, or "C" vent
Also remember the burner most be at least 18" or more above the floor.
Talk to a heating contractor or dealer.
Check local codes.
Do it right the first time, it may cost more a little more to do it right, but it could save you from having a costly fire, or GOD forbid personal injury to you or someone you love.