Twig, have you contacted your oil comp. or the building dept.? It could be there is a variance from International Code permitted in Minn. You need to check local regs in this regard. In at least one state, Maine, your current setup is permissible. In most others, solid fuel appliances need to have a dedicated flue. Also call US Stove and ask what the register and duct clearances are for a furnace to floor vent with a direct take off from the Hotblast.